Re: [Interest] Performance of QGraphics[View Scene] changes with zoom

[Lisandro Damián Nicanor Pérez Meyer]

On 18 May 2016 at 15:57, Lisandro Damián Nicanor Pérez
 wrote:
> Before I try to code a stripped-down version of my issue I would like to
> describe it in case I'm missing something obvious.
>
> I have an app with a QGraphicsScene that holds a vehicle which is constantly
> moving at a fixed rate (~10 times per second). Every time it moves it draws
> some polygons behind (the path it went trough). Up to that point, everything
> is ok.
>
> Now if I add a lot of straight lines (QGraphicsLineItem instances) performance
> (number of movements seen on screen per second) varies according the zoom. If
> I zoom in I get to a point in which everything is too slow. If I zoom out
> things go back to normal. Note that once the lines are generated they are not
> changed in any way.
>
> I understand that performance might decrease if those lines are near 45º due
> to bounding boxes, but I fail to understand why it varies with zoom.

I minimized my code to simple lines and drawing the bounding box of
the vehicle, and found
out that the problems starts if I use anything different than
Qt::SolidLine for drawing the lines.

As soon as I zoom out enough (the transformation matrix becoming
0.1*Identity) the problem
"goes away", so I suspect a rasterization issue.


-- 
Lisandro Damián Nicanor Pérez Meyer
http://perezmeyer.com.ar/
http://perezmeyer.blogspot.com/
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Re: [Interest] qt5 embedded using uitools

[Thiago Macieira]

On quinta-feira, 12 de maio de 2016 15:22:17 PDT Kyle Yost wrote:
> I am trying to use Qt5 using uitools library on uclinux.  I can compile
> the library but doesn't see to include the right path.  I do a qmake and
> get the Error
> Project ERROR: Unknown module(s) in QT: uitools. Is it recommended to
> use the uitools for uclinux?

How did you install Qt? If you installed a pre-compiled version, verify that 
you installed whichever package provides the file 
mkspecs/modules/qt_lib_uitools.pri

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center

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Re: [Interest] Why int for size() of containers instead of quint32?

[Thiago Macieira]

On quarta-feira, 18 de maio de 2016 22:04:41 PDT André Pönitz wrote:
> Both signed-vs-unsigned, and 32bit-vs-sizeof(size_t) have been discussed
> before on this and sibling lists multiple times. Please check the
> archives.
> 
> Arguments that keep coming up:
> 
[cut]
> 6. Proof-by-guru:
>B.S: "Using an unsigned instead of an int to gain one more bit
>
>  to represent positive integers is almost never a good idea.
>  Attempts to ensure that some values are positive by declaring
>  variables unsigned will typically be defeated by the implicit
>  conversion rules" (TC++PL)
>
>S.M: www.aristeia.com/Papers/C++ReportColumns/sep95.pdf

Even the C++ standard people have now subscribed to this argument and the 
direction for the new API is to use unsigned if you need modulo-2 overflow 
behaviour, signed otherwise (exception: unsigned char).

What the C++ standard people haven't decided is what type should be used for 
sizes, since ssize_t is not a C++ type, it's from POSIX, and size_t is not 
required to be very wide.

So the discussion on signedness is not welcome in Qt, until circumstances 
change drastically. The discussion on width may come up again in Qt 6.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center

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Re: [Interest] Why int for size() of containers instead of quint32?

[Jason H]

> Sent: Wednesday, May 18, 2016 at 4:04 PM
> From: "André Pönitz" 
> To: "Николай Шатохин" 
> Cc: "interest@qt-project.org" 
> Subject: Re: [Interest] Why int for size() of containers instead of quint32?
>
> On Tue, Mar 29, 2016 at 10:29:38PM +0300, Николай Шатохин wrote:
> > Hello.
> > 
> > I see that Qt uses int type many times in containers implementations? Why?
> > Why do you not use your own quint32? Why do you using signed and platform
> > dependent type for this purpose?
> 
> Both signed-vs-unsigned, and 32bit-vs-sizeof(size_t) have been discussed
> before on this and sibling lists multiple times. Please check the
> archives.
> 
> Arguments that keep coming up:
> 
> 1. 'int' is *not* platform-dependent on platform Qt runs on. It's always
> 32 bit signed two's complement. Serialization/deserialization of 'int'
> is naturally cross-platform *on all supported platforms*.
> 
> 2. the compiler does not need to handle signed int overflow, leaving
> room for tighter code.
> 
> 3. Negative offsets can be given usable interpretations (count from
> end, or -1 as invalid)
> 
> 4. unsigned breaks backward index loop idioms
> 
> 5. History.
> 
> 6. Proof-by-guru:
>B.S: "Using an unsigned instead of an int to gain one more bit
>  to represent positive integers is almost never a good idea.
>  Attempts to ensure that some values are positive by declaring
>  variables unsigned will typically be defeated by the implicit
>  conversion rules" (TC++PL)
>S.M: www.aristeia.com/Papers/C++ReportColumns/sep95.pdf
> 
> 7. Counter-proof-by-guru:
>A.K: http://www.drdobbs.com/cpp/the-case-against-int-part-*

1. "2^31-1 aught to be enough for anybody"
2. I use "q"-prefixed datatypes when writing portable code. quint32, qint32, 
etc. 

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Re: [Interest] Why int for size() of containers instead of quint32?

[André Pönitz]

On Tue, Mar 29, 2016 at 10:29:38PM +0300, Николай Шатохин wrote:
> Hello.
> 
> I see that Qt uses int type many times in containers implementations? Why?
> Why do you not use your own quint32? Why do you using signed and platform
> dependent type for this purpose?

Both signed-vs-unsigned, and 32bit-vs-sizeof(size_t) have been discussed
before on this and sibling lists multiple times. Please check the
archives.

Arguments that keep coming up:

1. 'int' is *not* platform-dependent on platform Qt runs on. It's always
32 bit signed two's complement. Serialization/deserialization of 'int'
is naturally cross-platform *on all supported platforms*.

2. the compiler does not need to handle signed int overflow, leaving
room for tighter code.

3. Negative offsets can be given usable interpretations (count from
end, or -1 as invalid)

4. unsigned breaks backward index loop idioms

5. History.

6. Proof-by-guru:
   B.S: "Using an unsigned instead of an int to gain one more bit
 to represent positive integers is almost never a good idea.
 Attempts to ensure that some values are positive by declaring
 variables unsigned will typically be defeated by the implicit
 conversion rules" (TC++PL)
   S.M: www.aristeia.com/Papers/C++ReportColumns/sep95.pdf

7. Counter-proof-by-guru:
   A.K: http://www.drdobbs.com/cpp/the-case-against-int-part-*

Etc, etc.

Andre'
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Re: [Interest] [Development] Qt World Summit call for papers open

[Olivier Goffart]

Hi,
In addition to the Qt World Summit, I would like to remind you about QtCon. 
There will be the Qt Contribution summit hapening there, but it is also some 
kind of substitute for the fact that there will not be devdays or QtWS in 
europe this year.
Any talk that is relevant for the technical track of the Qt Wold Summit would 
also be relevant for QtCon. So have a look at the call for paper:  
https://qtcon.org/cfp
the deadline for submission is on May 15. (This Sunday, so hurry up, altough 
there will probably be an extension)

QtCon will be in Berlin, 2-4 September 2016: https://qtcon.org/

-- 
Olivier


On Donnerstag, 12. Mai 2016 12:55:52 CEST Tero Kojo wrote:
> Hello,
> 
> The call for papers for Qt World Summit 2016 has been opened!
> 
> This year the premier Qt event is held October 18-20, 2016 in San Francisco,
> CA.
> 
> The main themes of the summit are:
> 
> -  Creating Connected Devices and Internet of Things
> 
> -  Things getting smaller
> 
> -  Next generation graphics approaches
> 
> -  The future of user interfaces and 3D
> 
> -  Software as a differentiator - Industries being revolutionized by
> software: Automotive, Medical/Health, Consumer Electronics,  Industrial
> Automation, Aerospace/Defense and more
> 
> -  Software solution for multi-platform development - desktop,
> mobile and embedded
> 
> For these themes, we are looking for inspiring strategy and industry talks
> (Technology Strategy) as well as more hands-on technical talks (Qt for
> Application Development and Device Creation).
> 
> The deadline for submissions is May 20.
> Show us your best work!
> 
> The direct link to submit your talks is this:
> https://www.surveymonkey.com/r/QtWS16
> 
> For more details including the full call see:
> http://blog.qt.io/blog/2016/04/28/call-for-papers-qt-world-summit-2016/
> 
> Best,
> Tero


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[Interest] QtCon Call for Papers extended

[Olivier Goffart]

Hi, 
The deadline for the QtCon call for paper was extended to the 22nd of May.

https://qtcon.org/cfp

---
This is a Call for Papers to a unique event. KDE Akademy, Qt Contributors' 
Summit, FSFE Summit, KDAB and VideoLAN Dev Days have come together to create 
QtCon 2016, Sept 1 - 4, 2016, to be held in Berlin, Germany.

On Sept 1 there will be a day of Training from KDAB. The conference runs from 
Sept 2 - 4. There will be talks, workshops, Birds of a Feather sessions (BoFs) 
and meetings, contributed to by everyone, as well as the traditional social 
events. KDE Akademy will then continue with BoFs from Monday 5th to Thursday 
8th elsewhere in Berlin.

The conference will be at the bcc, in Berlin, which has the flexibility to run 
a diverse program of events so participants can attend presentations and 
meetings with a great variety of focus and interest. If you are a Qt user, 
you'll get the top quality talks you'd expect from a Qt conference, as well as 
presentations and meetings across each of the participating communities. If 
you normally attend the VideoLAN annual event, you will have access to 
everything you usually expect from that, as well as the opportunity to learn 
what’s new from Qt contributors, KDE and FSFE, and so on.

Attendees who are not members of any of these communities are also welcome to 
join this unique, one-off event and take their pick from the unusually wide 
range of material.

What we are looking for
This brings a difference to the Call for Papers you might be familiar with. 
The reason is that we want presentations, workshop and BoFs that cater for one 
or more of the whole communities of KDE, Qt, VideoLAN, FSFE and the wider Free 
software community. The program aims to present a unified event.

We are asking for talk proposals on topics relevant to this including:

- Collaboration between KDE, the Qt Project and other projects that use KDE or 
Qt
- Design and Usability
- Free software in action: use cases of technology in real life; be it mobile, 
desktop deployments and so on.
- Going multi-platform all the way: from design to distribution
- Improving our soft skills and processes
- Increasing our reach through efforts such as accessibility, promotion, 
translation and localization
- Insights about C++ and QML
- Learning what is new and exciting in Qt
- Open Standards
- Overview of what is going on in the various areas of each of the communities
- Presentation of new applications; new features and functions in existing 
applications
- Quality and testing of applications
- Using KDE Frameworks 5 for Qt developers
- Writing custom Qt Quick components using OpenGL

Don't let this list restrict your ideas though. You can submit a proposal even 
if it doesn't fit the list of topics as long as it is relevant

Proposal guidelines
Provide the following information on the proposal form:

- Title—the title of your session/presentation
- Abstract—a brief summary of your presentation
Description—information about your topic and its potential benefits for the 
audience
- A short bio—including anything that qualifies you to speak on your subject
- Tags—add appropriate tags to your proposal to help the committee sort 
through the categories of proposals

We encourage you to rehearse your presentation well. If you don't have someone 
to test your talk on or would like help practising your presentation, you can 
ask the Program Committee

Proposals must be submitted by May 22nd, 23:59:59 CEST.

QtCon will attract people from all over the world. For this reason, all talks 
are in English. Please don't let this requirement stop you. Your ideas and 
commitment are what your audience will want to know about.

- Lightning talks are 10 minutes long
- Other talks are 30 or 60 minutes
- Workshops, BoFs and meetings can be between 1 and 2 hours (Proposals for KDE 
after the weekend will be collected separately)
Workshops and talks include time for Q Lightning talks do not have Q

QtCon has a tight schedule, so beginning and ending times are enforced.

If your presentation must be longer than the standard time, please provide 
reasons why this is so. For lightning talks, we will be collecting all of the 
presentations the day before the lightning track. All of the presentations 
will be set-up and ready to go at the start of the lightning track.

QtCon is upbeat, but it is not frivolous. Help us see that you care about your 
topic, your presentation and your audience. Typos, sloppy or all-lowercase 
formatting and similar appearance oversights leave a bad impression and may 
count against your proposal. There's no need to overdo it. If it takes more 
than two paragraphs to get to the point of your topic, it's too much and 
should be slimmed down. The quicker you can make a good impression, the 
better.

We are looking for originality. Having the same people talking about the same 
things doesn't accomplish that goal. Thus, we favor original and novel 
content. If you have presented on 

Re: [Interest] Qt5 C++ Widgets and Animated ListView

[Sebastian Diel]

Hi,

Am 17.05.2016 um 21:21 schrieb Simone:


You mean that with QListView i have natively the scrolling by finger with 
deceleration and bouncing effect? I need exactly the same result as the QML 
ListView component.
I remember to have used a flickcharm on widgets a few years ago. I don't 
know if it meets all your needs (bouncing), though.


Here is a random example from the web:

https://doc.qt.io/archives/4.6/demos-embedded-anomaly-src-flickcharm-cpp.html

Others may have better ideas :-)

Best regards,

Sebastian

--
http://www.classintouch.de  - Tablet-Software für Lehrer

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[Interest] qt5 embedded using uitools

[Kyle Yost]

I am trying to use Qt5 using uitools library on uclinux.  I can compile 
the library but doesn't see to include the right path.  I do a qmake and 
get the Error
Project ERROR: Unknown module(s) in QT: uitools. Is it recommended to 
use the uitools for uclinux?


Thanks,
Kyle
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[Interest] LocalStorage - WebView - QML

[malek . khlif]

Hi everybody,

This is my first participation.

How to enable LocalStorage in QML WebView for Android?

Regards,
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[Interest] Using Qt3D with the Oculus SDK

[Nicolas Brown]

Hello,

I am working on a project that requires that I use Qt3D with the OculusVR
sdk. The issue i am having is the inability to know when it is the end of a
frame in the rendersystem so i can submit the scene's rendertexture to the
ovr sdk. The obvious solution would be to use the QRenderAspect in
synchronous rendering mode then submit the scene's rendertexture to the ovr
sdk after calling renderAspect->renderSynchronous(). I am trying to achieve
something similarly to what is done here
http://code.qt.io/cgit/qt/qt3d.git/tree/src/quick3d/imports/scene3d/scene3drenderer.cpp?h=5.7#n211
as recommended by Seam Harmer, however I am working purely in c++ and not
qml. I am also trying to avoid building a custom version of qt3d as much as
possible.

Is synchronous rendering using plain old qt and c++ currently possible in
the qt3d version that comes in the 5.6 release? Can anyone provide a small
sample or just a snippet of how to initialize and render using synchronous
rendering?

Any help would be appreciated.

Regards,
Nicolas
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[Interest] [Qt3d]Using texture with transparency as material on PlaneMesh

[Mateusz Kwiecień]

Hi,

I want to create something like painting on glass effect using texture with
transparency. What is the best way to do that in Qt3D? I wondering if only
way is to create custom material with shaders etc.

Regards,
Mateusz
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[Interest] Qt installer framework

[Isaac Garcia]

Hi,

Is there any form to change the language to the default pages in the
installer? I've seen that in SDK code exists a translation in the file
es.ts but It doesn't translate or I'm doing something wrong.

Thanks in advance.

-- 
Isaac Garcia
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Re: [Interest] Qt 5.5 LinuxFb Plugin with Base Layer Transparency

[Peter Seiderer]

Hello Jack,

> Our application requires that we blend 3 layers with 3 framebuffers on a TI
> device. The base layer is opaque video, the middle layer is video blended
> on top of the base layer with a global alpha channel that we need to be
> able to modify on the fly, and a top GUI layer with transparency. This
> approach worked great with Qt 4.8 and we are trying to get it to work with
> Qt 5.5.
>
> The problem is that when we run the top level GUI application, we cannot
> set the background of the to be fully transparent. It simply appears black.
> This covers the 2 lower z-order applications and they are no longer visible.
>
> We attempted to investigate this issue by looking at the Qt5.5 linuxfb
> plugin source code. Beginning at line 251 of qfbscreen.cpp in the Qt5.5
> source ( located in qt5base-5.5.1/src/platformsupport/fbconvenience ), we
> see where the linuxfb plugin sets the base layer to black. If we change
> that one line to "qt::transparent", and re-launch our app, then we see the
> lower 2 layers "through" the GUI in the regions of the GUI where it is
> fully transparent. Initially, the fully transparent GUI displays correctly.
> It displays a menu, which initially appears correct. A problem occurs when
> we then try to hide the menu. It remains displayed on the screen.
> Apparently, the redraw of the base layer, which is transparent, does not
> replace the pixels from the menu, but is instead blended with the menu
> pixels.
>
> We have tried several composition modes in the base layer's paint event,
> including Source and Clear, but neither fixes the problem. On previous
> products ( using the DM3730 ), we used this same approach ( DSS blended
> framebuffers ) with Qt 4.8 and it worked as expected. How can we make this
> work with Qt 5.5?
>

Did have the same problem (but on a NXP/Freescale i.MX6 board), solved it
by the following patch/hack for Qt5.4.1 and a simple OSD GUI:

--- begin ---
>From dab806c4dce22efc5eb6615287cf803a1d72ee6a Mon Sep 17 00:00:00 2001
From: Peter Seiderer 
Date: Tue, 30 Sep 2014 16:53:00 +0200
Subject: [PATCH] platforms/linuxfb: enabel alpha channel on framebuffer output

---
 src/platformsupport/fbconvenience/qfbscreen.cpp  | 9 +++--
 src/plugins/platforms/linuxfb/qlinuxfbscreen.cpp | 4 +++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/platformsupport/fbconvenience/qfbscreen.cpp 
b/src/platformsupport/fbconvenience/qfbscreen.cpp
index aa35825..6670f8e 100644
--- a/src/platformsupport/fbconvenience/qfbscreen.cpp
+++ b/src/platformsupport/fbconvenience/qfbscreen.cpp
@@ -217,8 +217,13 @@ QRegion QFbScreen::doRedraw()
 if (!mIsUpToDate)
 generateRects();

-if (!mCompositePainter)
+if (!mCompositePainter) {
 mCompositePainter = new QPainter(mScreenImage);
+// simple solution for OSD rendering (real solution should 
invalidate/init
+// background always before rendering widget content with alpha 
blending)
+
mCompositePainter->setCompositionMode(QPainter::CompositionMode_Source);
+}
+
 for (int rectIndex = 0; rectIndex < mRepaintRegion.rectCount(); 
rectIndex++) {
 QRegion rectRegion = rects[rectIndex];

@@ -236,7 +241,7 @@ QRegion QFbScreen::doRedraw()
 foreach (const QRect , intersect.rects()) {
 bool firstLayer = true;
 if (layer == -1) {
-mCompositePainter->fillRect(rect, Qt::black);
+mCompositePainter->fillRect(rect, Qt::transparent);
 firstLayer = false;
 layer = mWindowStack.size() - 1;
 }
diff --git a/src/plugins/platforms/linuxfb/qlinuxfbscreen.cpp 
b/src/plugins/platforms/linuxfb/qlinuxfbscreen.cpp
index a66c9fa..522088c 100644
--- a/src/plugins/platforms/linuxfb/qlinuxfbscreen.cpp
+++ b/src/plugins/platforms/linuxfb/qlinuxfbscreen.cpp
@@ -431,8 +431,10 @@ QRegion QLinuxFbScreen::doRedraw()
 if (touched.isEmpty())
 return touched;

-if (!mBlitter)
+if (!mBlitter) {
 mBlitter = new QPainter();
+mBlitter->setCompositionMode(QPainter::CompositionMode_Source);
+}

 QVector rects = touched.rects();
 for (int i = 0; i < rects.size(); i++)
--
2.1.4
--- end ---

Regards,
Peter

> qfbscreen.cpp:
>
> // we only expect one rectangle, but defensive coding...
> foreach (const QRect , intersect.rects()) {
> bool firstLayer = true;
> if (layer == -1) {
> mCompositePainter->fillRect(rect, Qt::black);
> firstLayer = false;
> layer = mWindowStack.size() - 1;
> }
>
> for (int layerIndex = layer; layerIndex != -1; layerIndex--) {
> if (!mWindowStack[layerIndex]->window()->isVisible())
> continue;
> // if (mWindowStack[layerIndex]->isMinimized())
> // continue;
>
> QRect windowRect =
> 

[Interest] Signal Slot Ordering (or Not)

[Peter M. Groen]

In a simple setup ( One sender object with a signal, One receiver with
a slot, argument is sequence number, both objects running in a
single thread ) some unexpected behaviour (at least for me) is noticed.

The connect between the mentioned signal / slot is done with
Qt::DirectConnection. According to the documentation, each slot is
called directly. ( The slot is invoked immediately when the signal is
emitted. The slot is executed in the signalling thread. )

In a for-loop, I'm sending 10 signals directly in one burst, like so :

for( int nCount = 0; nCount < number_of_signals; nCount++ )
{
std::cout << "[SignalSender::timerTimeOut] - "
  << QString( "Signal Sending. Timer : %1, Run : %2,
Sequence : %3" ) .arg( timer_interval_msecs )
 .arg( run_number )
 .arg( nCount ).toStdString() << std::endl;
emit signalSendSequence( timer_interval_msecs, run_number,
nCount ); QCoreApplication::processEvents();
}

I'm expecting the output would be in ascending order, but every once in
a while, the output is all thrown together. That is quite unexpected,
based on the documentation.

Is this a bug, or by design?

Regards,

-- 
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Peter M. Groen
Het Buitenwater 54
2235 TB  Valkenburg (ZH)
Mob : +31 6 811 0 3537
Email : pe...@osdev.nl
Skype : peter_m_groen
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[Interest] Detecting QString encoding errors

[BAILLY Yves]

Greetings all,

Is it possible to detect errors while encoding a QString from char*?

Here's the case: I get a string as a char* form an external library (on which I 
don't have any control).
This string can use either UTF8 encoding, or "local8bit" encoding - thus may 
vary from a user to the other.

What I basically need is to be table to write something like this:
char const* src = ...;
bool encoding_failed = false;
QString qs = QString::fromUtf8(src, _failed);
if ( encoding_failed )
{
  qs = QString::fromLocal8Bit(src);
}

I looked at the docs for QString and QTextCodec, but I couldn't find any error 
support.

Is there any (portable) way of achieving this?

Thanks in advance for any hint.

--
Yves Bailly
Software developer


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Re: [Interest] login.qt.io down => cannot install Qt

[Boris Dalstein]

Thank you for your answer.

It was not working from at least 05:00 GMT to 06:00 GMT. It was working 
again at 08:00 GMT. Login.qt.io wasn't working from either the 
Maintainance Tool or the browser. Blog.qt.io wasn't working from the 
browser. The main webpage www.qt.io was working though.


Good to know that you don't need to login to download and install if you 
have a commercial license, at least this makes some sort of sense. 
Still, I find it questionable to force non-commercial users to login, 
this is highly non-standard for open source products.


Have a good day :-)

On 16-04-05 03:51 AM, Robert Buchinger wrote:

On Tuesday, April 5, 2016 5:50:20 AM CEST Boris wrote:

I am installing a new machine and setting up my development environment.
However, I cannot install Qt because the Qt installer forces to login to your
account, and login.qt.io appears to be down, resulting in a "TIMEOUT" error
when trying to login. Anyone has this error as well? The blog seems down as
well, I get "No application configured" when going to blog.qt.io.

Seriously, this is very embarrassing for Digia. Users cannot get work done
because of their incredibly bad decision to force users to login to install
their software.

This is both a rant and a feature request: Digia, please make login optional
to install your software, because if you think you can guarantee that the
login system is never down, you are fooling yourself. Such a lack of
professionalism.


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For me both login.qt.io and blog.qt.io are working.

Does this happen within the Maintenance Tool or from the browser?

As long as you not have a commercial license you not need to log in to download 
and install Qt.




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[Interest] Qt and Unity

[Tyler Brown]

Hi everybody,

Does anybody have experience using Qt with Unity.  We've coded a fairly
large architecture with the plan to use QML, but we're doing UI/UX through
a 3rd party company and they use Unity.

With the research I've done it looks like there are three options
1) Use the Qt code as a plugin within Unity
2) Use Qt's webview to encapsulate Unity into a window
3) Use Unity Standalone, get a WinID handle and then embed it into the Qt
app (this is Windows only, so not sure if I can resort to other method on
other platforms)

#1 might prove difficult with polymorphism, marshalling, etc...?
#2 might not give great performance?
#3 only works if we have different solutions for other platforms, even then
we'd have to set up a lot of shared memory etc... So I feel that it isn't
great

Platforms to be supported:
OS X
iOS
Windows
Android

We do want almost real-time feedback (delay of less than .5 seconds), so
performance is fairly important.  Framerate and smoothness would be of
higher priority.

If anyone can shed light on this, it would be great!  Apologies if the
question is poorly worded or if I'm missing vital information, just let me
know and I'll do my best to fix it.

Thanks!
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[Interest] QJSEngine replacement for QScriptEngine misses newFunction

[Walter Stefan]

Hi,

I am looking into migrating my code to QJSEngine, because of the deprecation of 
the QScriptEngine (QtScript). As we have used the functionality of newFunction 
very extensive and all related scripts are depending on this, the newFunction 
in QJSEngine is for us mandatory or something that creates and equivalent 
result.

How do I currently map a native C++ class member function to the engine:
QScriptValue func_sqrt = m_engine->newFunction(sqrt, liEngine);
m_engine->globalObject().setProperty("sqrt", func_sqrt, QScriptValue::ReadOnly 
| QScriptValue::Undeletable);

This is an example of a native function:
QScriptValue ScriptModuleMath::sqrt(QScriptContext *context, QScriptEngine 
*engine, void *arg)
{
Q_UNUSED(engine)
Q_UNUSED(arg)
if (context->argumentCount()!=1)
{
return context->throwError( QScriptContext::SyntaxError, "sqrt(...): 
illegal number of arguments.");
} else if (!context->argument(0).isNumber())
{
return context->throwError( QScriptContext::SyntaxError, "sqrt(...): 
argument 1 is not a number.");
}

return qSqrt(context->argument(0).toNumber());
}

And in this way. I can use it then in the script:
value = sqrt(4);

I actually don't want to map a whole QObject, because that would require a call 
like this:
value = MyMath.sqrt(4);

Is there any way to achive in QJSEngine the same result as I do within the 
QScriptEngine?

Best Regards,
Stefan

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Re: [Interest] [Qtwebengine] Inject QWebChannel and/or JQuery into QWebEnginePage

[Aleksey Yermakov]

Hi,

You don't have to inject QWebChannel.js every time if you use
QWebEngineScriptCollection in your QWebEngineProfile. Here is a sample code
from my project:

const char s_qWebChannelAdditionalScript[] = "new
QWebChannel(qt.webChannelTransport, function(channel) {"
 "  window.exported_object =
channel.objects.exported_object;"
 "});";

QWebEngineProfile *WebEngineView::prepareProfile()
{
QWebEngineProfile *profile = new QWebEngineProfile("Profile", this);

...

// Preparing qwebchannel.js for injection
QFile qWebChannelJsFile(":/qtwebchannel/qwebchannel.js");

if(! qWebChannelJsFile.open(QIODevice::ReadOnly)) {
MY_ERROR("Failed to load qwebchannel.js with error: " +
qWebChannelJsFile.errorString());
} else {
QByteArray qWebChannelJs = qWebChannelJsFile.readAll();

qWebChannelJs.append(QString(s_qWebChannelAdditionalScript));

QWebEngineScript script;

script.setSourceCode(qWebChannelJs);
script.setName("qwebchannel.js");
script.setWorldId(QWebEngineScript::MainWorld);
script.setInjectionPoint(QWebEngineScript::DocumentCreation);
script.setRunsOnSubFrames(false);

profile->scripts()->insert(script);
}

return profile;
}

Don't forget to create your QWebEnginePage with this profile instead of
default one.

Cheers,
Aleksey

On Sun, Mar 20, 2016 at 9:30 PM, NoRulez  wrote:

> Hello,
>
> Did I have to inject QWebChannel and for example JQuery every time before
> or after I call setUrl()/load() to QWebEngineView or only once?
>
> Because the jquery event for loading a site is only called once and if
> loaded then it has the previous url:
>
> $(window).load(function () {
> alert('page is loaded');
> alert(window.location.href);
> });
>
> Thanks in advance
>
> Best Regards
>
> ___
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> qtwebeng...@qt-project.org
> http://lists.qt-project.org/mailman/listinfo/qtwebengine
>



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Re: [Interest] qtwebview with qtwebchannel

[Milian Wolff]

On Thursday, April 7, 2016 9:38:01 AM CEST Sylvain Pointeau wrote:
> Hello,
> 
> Do you have any idea how to use WebSocket or WebChannel on iOS?
> Should I conclude that we cannot do hybrid apps with Qt on iOS (works on
> desktop, don't know about Android)?

I'm not an iOS person but the problem you are describing has nothing to do 
with the webchannel - you seem to fail already when constructing a websocket 
server. Have you tried to run the examples/tests of QWebSocket on iOS? That's 
where I'd start.

Bye

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Re: [Interest] CLion to replace QtCreator?

[Guenter Schwann]

On Tuesday, April 05, 2016 05:18:08 PM Emre Besirik wrote:
> Some of the lacking features are smart autocomplete maybe

At least with QtCreator 4.0 beta most issues are resolved for me.
What exactly do you mean by "smart"?

> Ctrl+K like search but improved in a better UI
I watched https://www.youtube.com/watch?v=j7nT9QWjOBA

Nothing stunning there. Mostly the same as Ctrl-K (you see more options the 
poping up). Some are Ctrl-Tab, Ctrl-Shift-I, Ctrl-Shift-T.

Is there something like Alt-Left for CLion?

> but most lacking part comes in UI/UX

I like QtCreator because it doesn't come with a bloated UI (in constrast to 
Visual Studio).
The UI is very lightweight. Close to a simple editor. But as soon as you know 
some shortcuts, it gets extremely powerful.
Maybe you should have a look at https://www.kdab.com/qtcreator


And again - which technology or trends do you think QtCreator is _eons_ 
behind?

Regards
Guenter

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Re: [Interest] CLion to replace QtCreator?

[Guenter Schwann]

On Tuesday, April 05, 2016 04:19:42 PM NoMercy wrote:
> That QtCreator is eons behind current technology and trends, isn't it very
> obvious?

No! Absolutely not.
QtCreator is a really great IDE. Very lightweight, but still very powerful.
Simply using the "Esc" button is a single fantastic feature that I haven't 
seen elsewhere.

And for the technology: CLion as well as QtCreator are using clang for the 
code model (which is the heart of an IDE).
What other technology do you mean?

What trends do you see for IDEs?

> I would say just checkout features of ANY JetBrains product but
> you don't even intend to so you are in therefor denial. (Not personally you
> but many people who are objecting these)

I haven't used it yet - granted. But I have watched all the CLion releases so 
far.
They are looking promising. But I haven't seen any major feature that 
QtCreator would lack (C++ only).

I guess you haven't read the manual of QtCreator. So you missed tons of 
features.

And yes, QtCreator is not perfect. Especially the clang code model still needs 
polishing (speed is not up to the old model).
QtCreator 4.0 (beta) is looking really nice :)

Regards
Günter

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[Interest] Performance improvement using Qt Quick Compiler

[palearim]

  

Hello, I'm creating an application that must be able to manage
effectively a lot of panels/dialogs (500 and more) and in this moment
I'm focusing in performance problems using Qt.createComponent and
Qt.createObject APIs. In particular I'm investigating if the use of Qt
Quick Compiler can improve performance in panels/dialogs creation. 

To
investigate this topic I have developed, using Qt 5.5 Enterprise
Edition, a simple test program that in a for loop invokes the
Qt.createComponent() and the Qt.createObject() foreach panel/dialog to
create: 

for(var i=0 ; i< 500; i++)
{
var qmlFile =
"qrc:/qml/DTSControlPanel_"+ i + ".qml"
panels[i] =
Qt.createComponent(qmlFile)
} 

and subsequently 

for(var i=0 ; i<
panels.length; i++)
{
...
panels[i].createObject(appWindow, {"x":
startX, "y": startY});
} 

This code has been compiled with and without
Qt Quick Compiler and executed to get performance data.
The results are,
for my understanding, a little bit strange. In fact contrary to my
expectations the application built with Qt Quick Compiler is less
performant than the one compiled without Qt Quick Compiler. 

Can anyone
suggest to me a possible explanation of this behaviour? 

Many thanks. 



Connetti gratis il mondo con la nuova indoona:  hai la chat, le chiamate, le 
video chiamate e persino le chiamate di gruppo.
E chiami gratis anche i numeri fissi e mobili nel mondo!
Scarica subito l’app Vai su https://www.indoona.com/

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Re: [Interest] CLion to replace QtCreator?

[Alexey Rusakov]

I don't know what I'm doing wrong but the new compile-time-checked syntax is 
auto-completed by my Qt Creator (that came with Qt 5.5.1) as well :) and you're 
a bit blunt on not recommending the older syntax. Apparently you haven't spent 
enough time with QML.





On Mon, Apr 4, 2016 at 2:41 AM -0700, "Nikos Chantziaras"  
wrote:










It only works with the old, Qt4 string/macro-based syntax (using the 
SLOT and SIGNAL macros.) Which is totally unsafe and I don't use it 
anymore (I wouldn't even recommend it to anyone.) The new syntax, which 
is statically checked (compile time) and thus type-safe, even though 
it's the recommended one by Qt, is not supported in Creator using the 
clang model. This does not auto-complete:

   connect(this, ::mySignal, control, ::mySlot);

This is not the end of the world, but still it's unpleasant to work with.

The clang code model will get better in the future, I'm sure of it. But 
right now, it's pain all the way down.

The lacking auto-completion might not even be the worst of it. In the 
end, that's "just" a productivity and convenience issue. The lack of 
reliable "find all uses" in the clang model is actually a more serious 
problem, since if you trust it you're left with the false sense of 
security that you caught all the places in your code where a symbol was 
used and made whatever changes you needed to make to fix an issue. But 
it doesn't find all uses. Which is *dangerous*. So I have to do a 
text-based, project-wide search for a string instead to actually get to 
all uses of the symbol and update my code.


On 04/04/16 11:42, Alexey Rusakov wrote:
> Not sure what I'm doing wrong but auto-completion for connect() does
> work for me. Moreover, I don't expect CLion to be able to work with
> SIGNAL() and SLOT() notation without Qt-aware plugin.
>
> I might expect CLion to rule them all in some indefinite future but very
> hardly at the moment. Disclaimer: I am a switch-over from CLion to Qt
> Creator, exactly because Qt Creator worked for me much better than CLion
> for CMake-based Qt-using projects.
>
>
>
> On Mon, Apr 4, 2016 at 1:13 AM -0700, "Nikos Chantziaras"
> > wrote:
>
> On 03/04/16 22:00, Thiago Macieira wrote:
> > On domingo, 3 de abril de 2016 21:07:00 PDT Emre Besirik wrote:
> >> Do you also find it a littlebit unpleasent to code in QtCreator like 
> me?
> >> Does Qt plan to do something about this?
> >
> > It would be more constructive if you explained what your issues are and 
> what
> > you findto be unpleasant. Without that, nothing is ever going to happen.
>
> I assume the same things as the rest of us, perhaps:
>
> * Lack of auto-completion for connect().
> * Very slow auto-completion.
> * Generally auto-completion sometimes work, sometimes doesn't.
> * "Find uses" doesn't work, so you have to grep to find uses.
> * It gets very confused with smart pointers and templates in general.
> * Sometimes doesn't highlight local uses.
>
> This is the clang code model, and these things are a major PITA.
>
> The Creator code model was excellent for C++98. The last few months, I
> complete switched my projects to C++14, and that code model is now
> useless, so clang is the only choice. And it's not very pleasant to work
> with. In fact, I'd say it's very unpleasant.
>
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[Interest] Qt 5.5 LinuxFb Plugin with Base Layer Transparency

[Phillip Class]

Hello,

Our application requires that we blend 3 layers with 3 framebuffers on a TI
device. The base layer is opaque video, the middle layer is video blended
on top of the base layer with a global alpha channel that we need to be
able to modify on the fly, and a top GUI layer with transparency. This
approach worked great with Qt 4.8 and we are trying to get it to work with
Qt 5.5.

The problem is that when we run the top level GUI application, we cannot
set the background of the to be fully transparent. It simply appears black.
This covers the 2 lower z-order applications and they are no longer visible.

We attempted to investigate this issue by looking at the Qt5.5 linuxfb
plugin source code. Beginning at line 251 of qfbscreen.cpp in the Qt5.5
source ( located in qt5base-5.5.1/src/platformsupport/fbconvenience ), we
see where the linuxfb plugin sets the base layer to black. If we change
that one line to "qt::transparent", and re-launch our app, then we see the
lower 2 layers "through" the GUI in the regions of the GUI where it is
fully transparent. Initially, the fully transparent GUI displays correctly.
It displays a menu, which initially appears correct. A problem occurs when
we then try to hide the menu. It remains displayed on the screen.
Apparently, the redraw of the base layer, which is transparent, does not
replace the pixels from the menu, but is instead blended with the menu
pixels.

We have tried several composition modes in the base layer's paint event,
including Source and Clear, but neither fixes the problem. On previous
products ( using the DM3730 ), we used this same approach ( DSS blended
framebuffers ) with Qt 4.8 and it worked as expected. How can we make this
work with Qt 5.5?

qfbscreen.cpp:

// we only expect one rectangle, but defensive coding...
foreach (const QRect , intersect.rects()) {
bool firstLayer = true;
if (layer == -1) {
mCompositePainter->fillRect(rect, Qt::black);
firstLayer = false;
layer = mWindowStack.size() - 1;
}

for (int layerIndex = layer; layerIndex != -1; layerIndex--) {
if (!mWindowStack[layerIndex]->window()->isVisible())
continue;
// if (mWindowStack[layerIndex]->isMinimized())
// continue;

QRect windowRect =
mWindowStack[layerIndex]->geometry().translated(-screenOffset);
QRect windowIntersect = rect.translated(-windowRect.left(),
-windowRect.top());


QFbBackingStore *backingStore =
mWindowStack[layerIndex]->backingStore();

if (backingStore) {
backingStore->lock();
mCompositePainter->drawImage(rect,
backingStore->image(), windowIntersect);
backingStore->unlock();
}
if (firstLayer) {
firstLayer = false;
}
}
}

We greatly appreciate any help - thank you.
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Re: [Interest] CLion to replace QtCreator?

[Alexey Rusakov]

Not sure what I'm doing wrong but auto-completion for connect() does work for 
me. Moreover, I don't expect CLion to be able to work with SIGNAL() and SLOT() 
notation without Qt-aware plugin.
I might expect CLion to rule them all in some indefinite future but very hardly 
at the moment. Disclaimer: I am a switch-over from CLion to Qt Creator, exactly 
because Qt Creator worked for me much better than CLion for CMake-based 
Qt-using projects.




On Mon, Apr 4, 2016 at 1:13 AM -0700, "Nikos Chantziaras"  
wrote:










On 03/04/16 22:00, Thiago Macieira wrote:
> On domingo, 3 de abril de 2016 21:07:00 PDT Emre Besirik wrote:
>> Do you also find it a littlebit unpleasent to code in QtCreator like me?
>> Does Qt plan to do something about this?
>
> It would be more constructive if you explained what your issues are and what
> you findto be unpleasant. Without that, nothing is ever going to happen.

I assume the same things as the rest of us, perhaps:

* Lack of auto-completion for connect().
* Very slow auto-completion.
* Generally auto-completion sometimes work, sometimes doesn't.
* "Find uses" doesn't work, so you have to grep to find uses.
* It gets very confused with smart pointers and templates in general.
* Sometimes doesn't highlight local uses.

This is the clang code model, and these things are a major PITA.

The Creator code model was excellent for C++98. The last few months, I 
complete switched my projects to C++14, and that code model is now 
useless, so clang is the only choice. And it's not very pleasant to work 
with. In fact, I'd say it's very unpleasant.

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Re: [Interest] qtwebview with qtwebchannel

[Milian Wolff]

On Thursday, March 31, 2016 4:46:58 PM CEST Allan Sandfeld Jensen wrote:
> On Thursday 31 March 2016, Sylvain Pointeau wrote:
> > On Tue, Mar 29, 2016 at 10:24 AM, Sylvain Pointeau <
> > 
> > sylvain.point...@gmail.com> wrote:
> > > On Tue, Mar 29, 2016 at 8:31 AM, Kalinowski Maurice <
> > > 
> > > maurice.kalinow...@theqtcompany.com> wrote:
> > >> > QtWebView has a QtWebEngine backend, and that should be available on
> > >> 
> > >> Windows.
> > >> 
> > >> For UWP/WinRT there is a platform specific implementation loading Edge
> > >> into your application. For classic desktop applications you can use Qt
> > >> Webengine as Alan described.
> > > 
> > > Excellent! do you know if / how I can use the WebChannel (or WebSocket)
> > > with QtWebView?
> > > (I tried to use WebSocketServer but it does not work on iOS.)
> > 
> > any idea? I would like to know if I can use Qt on android/ios/windows for
> > hybrid applications...
> 
> I don't know if it is possible on iOS. I believe you have to be allowed to
> setup a websocket.

It should be possible, but I haven't tried it myself and have zero iOS 
knowledge. What you need:

Qt/C++ side:
1) initialize a Qt WebSocket server
2) wrap that server in a WebChannel transport

HTML side:
1) load your HTML in any web view
2) load qwebchannel there, you will have to copy it, or create a trivial HTML 
server in your C++ side to "deploy" it from the Qt resource system to the web 
view
3) initialize the webchannel with a websocket client using the server address 
from the Qt/C++ side

The Qt WebChannel examples contain a chat e.g. that uses your system browser 
to do the above, and it works fine with Explorer, Firefox and Chrome. So as 
long as WebSockets work on iOS WebView, and Qt WebSockets work on iOS, it 
should work.

Bye
-- 
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[Interest] Why int for size() of containers instead of quint32?

[Николай Шатохин]

Hello.

I see that Qt uses int type many times in containers implementations? Why?
Why do you not use your own quint32? Why do you using signed and platform
dependent type for this purpose?

Best regards,
Nick
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[Interest] qt 5.7 qt3d scene editor

[Александр Соломин]

Hello. I try to build qt-labs-qt3d-editor (
https://github.com/qtproject/qt-labs-qt3d-editor), but cannot.
When I start buildind I'm having errors. Could you please tell what's wrong?


..\qt-labs-qt3d-editor-master\src\editorviewportitem.cpp: In constructor
'FrameBufferObjectRenderer::FrameBufferObjectRenderer(EditorViewportItem*,
Qt3DCore::QAspectEngine*, Qt3DRender::QRenderAspect*,
Qt3DInput::QInputAspect*, Qt3DLogic::QLogicAspect*)':

..\qt-labs-qt3d-editor-master\src\editorviewportitem.cpp:90:93: error: no
matching function for call to
'Qt3DRender::QForwardRenderer::setSurface(QObject*)'

m_item->scene()->renderer()->setSurface(reinterpret_cast(saver.surface()));

^

..\qt-labs-qt3d-editor-master\src\editorviewportitem.cpp:90:93: note:
candidate is:

In file included from
..\..\Qt\Qt5.7.0\qt-everywhere-opensource-src-5.7.0\qt3d\include/Qt3DRender/qforwardrenderer.h:1:0,

from
..\..\Qt\Qt5.7.0\qt-everywhere-opensource-src-5.7.0\qt3d\include/Qt3DRender/QForwardRenderer:1,

from ..\qt-labs-qt3d-editor-master\src\editorviewportitem.cpp:43:

..\..\Qt\Qt5.7.0\qt-everywhere-opensource-src-5.7.0\qt3d\include/Qt3DRender/../../src/render/defaults/qforwardrenderer.h:75:10:
note: void Qt3DRender::QForwardRenderer::setSurface(QSurface*)

void setSurface(QSurface * surface);

^
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[Interest] QT Gtk3 style

[Gennady]

Do you have plans to support gtk3 styles?
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[Interest] Qt3D face culling

[Øyvind Bakken]

Hi,

we are developing a desktop application with 3D graphics using Qt3D. We
have run into some issues when using the Qt3DRender.CullFace settings in
the Qt3DRender.StateSet module.

Basically we have an open surface which was correctly rendering the front,
but not the back face. We then added the Qt3DRender.CullFace settings like
this (QML):


Scene3D { . . // Top-level entity entity: Qt3DCore.Entity { .
. // Simple framegraph that just renders the scene from the camera
components: [ Qt3DRender.FrameGraph { activeFrameGraph: Qt3DRender.Viewport
{ rect: Qt.rect(0, 0, 1, 1) // From Top Left clearColor: "transparent"
Qt3DRender.CameraSelector { camera: camera Qt3DRender.ClearBuffer { buffers
: Qt3DRender.ClearBuffer.ColorDepthBuffer Qt3DRender.StateSet {
Qt3DRender.CullFace { //mode: Qt3DRender.CullFace.FrontAndBack } } } } } }
] } //Top-level entity } //Scene3D

The obvious first strange thing here is that we don't even have to add the
mode setting of the CullFace to make it work - even though the line is
commented out, both the front and back face is rendered correctly.

The other issue is that when rotating the camera, the depth mode seems to
be broken - we have two objects in the scene, and now one of them is always
in the front of the other when rotating 360 degrees.

It seems to us that we are either not using the correct way of changing
culling settings, or that when adding the Qt3DRender.StateSet part this
overwrites other settings as well, related to depth etc.

Any ideas? Thanks in advance:)
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[Interest] Inclusion suggestion - Fwd: [Qt-Quick] GridStar layout for QML

[Casey Sanchez]

-- Forwarded message --
From: "Casey Sanchez" 
Date: Mar 2, 2016 11:40 AM
Subject: [Qt-Quick] GridStar layout for QML
To: 
Cc:

I've created a grid layout that I find to be more functional than the
default that is provided.

For full documentation please see:
https://forum.qt.io/topic/64699/gridstar-layout

The Git Repo can be found here:
https://github.com/Tannz0rz/GridStarLayout/tree/master/Quick
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[Interest] Performance of QGraphics[View Scene] changes with zoom

[Lisandro Damián Nicanor Pérez Meyer]

Before I try to code a stripped-down version of my issue I would like to 
describe it in case I'm missing something obvious.

I have an app with a QGraphicsScene that holds a vehicle which is constantly 
moving at a fixed rate (~10 times per second). Every time it moves it draws 
some polygons behind (the path it went trough). Up to that point, everything 
is ok.

Now if I add a lot of straight lines (QGraphicsLineItem instances) performance 
(number of movements seen on screen per second) varies according the zoom. If 
I zoom in I get to a point in which everything is too slow. If I zoom out 
things go back to normal. Note that once the lines are generated they are not 
changed in any way.

I understand that performance might decrease if those lines are near 45º due 
to bounding boxes, but I fail to understand why it varies with zoom.

I'm using Qt 5.5 on Linux.

Thanks in advance, Lisandro.

-- 
Lisandro Damián Nicanor Pérez Meyer
http://perezmeyer.com.ar/
http://perezmeyer.blogspot.com/


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[Interest] C++/QML Sequence Type to JavaScript Array

[Максим Бесчеревных]

In docs http://doc.qt.io/qt-5/qtqml-cppintegration-data.html mentioned:

"Certain C++ sequence types are supported transparently in QML as JavaScript 
Array types.
In particular, QML currently supports:
   QList
   QList
   QList
   QList and QStringList
   QList
Other sequence types are not supported transparently, and instead an instance of any 
other sequence type will be passed between QML and C++ as an opaque 
QVariantList."

Looks like that "opaque conversion" doesn't work:

   class MyData : public QObject {
Q_OBJECT
Q_PROPERTY(QList path READ path WRITE setPath NOTIFY 
pathChanged)
   public:
QList path() {
return _path;
}
   ...

MyData object filled with some data and exposed as context property to QML. At 
QML i imported QtPositioning, so QGeoCoordinate refers to coordinate QML basic 
type, but
   console.log(myData.path) prints QVariant(QList) 
   console.log(myData.path) prints undefined

- there is no sequence, no length.

Is it possible to expose QList sequence to QML, where Type known by meta 
object system and refers to QML basic type provided by an QtQuick module?
I know that i can expose C++ property of type QVariantList , but what is that 
opaque conversion mentioned in docs.

Maxim Beschecherevnykh
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Re: [Interest] Showcase Item in QML

[Jason H]

Should be pretty easy with graphical effects' OpacityMask
 

Sent: Wednesday, May 18, 2016 at 2:06 PM
From: "Majid Kamali" 
To: interest@qt-project.org
Subject: [Interest] Showcase Item in QML



Hi.
How can I create some showcase item in QML?
something like https://github.com/deano2390/MaterialShowcaseView

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Re: [Interest] [QT3D] Mesh sizes

[Oleg Evseev]

Sean Harmer answered this question already:
http://lists.qt-project.org/pipermail/interest/2016-April/022292.html

> At the moment, no. This is something we may well add for 5.8.
> For now you'll need to calculate it yourself or pass it in as metadata
somehow.
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[Interest] [QT3D] Mesh sizes

[Pierre Chicoine]

Is there a way to get the boundary or size of a mesh?

I have two uses, first to position my proportional fonts in 3d space as
they vary in size.

Secondly, and not as important, a boundary box to show selection of
objects. I can always deduce that from my scaling though but still would be
more convenient.

Pierre Chicoine
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[Interest] Showcase Item in QML

[Majid Kamali]

Hi.
How can I create some showcase item in QML?
something like https://github.com/deano2390/MaterialShowcaseView
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Re: [Interest] Questions about scaling

[Jason H]

> > 
> > I've attached an example what I mean.
> > The image with the blue background is the QML app.
> 
> I'm not sure what I am looking at. They look the same to me. That bar is 
> drawn by the OS, not you, so the only variation is it's color.

Oh, I see. I attached a composite image of the two screenshots.
It definitely looks different, but I have no idea why.

Perhaps Qt chooses a different bar style?

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Re: [Interest] Questions about scaling

[Jason H]

> Sent: Wednesday, May 18, 2016 at 11:44 AM
> From: NoRulez 
> To: "Qt Project MailingList" 
> Subject: Re: [Interest] Questions about scaling
>
> No one?
> 
> It look really ugly. 
> 
> I've attached an example what I mean.
> The image with the blue background is the QML app.

I'm not sure what I am looking at. They look the same to me. That bar is drawn 
by the OS, not you, so the only variation is it's color.

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Re: [Interest] Questions about scaling

[NoRulez]

No one?

It look really ugly. 

I've attached an example what I mean.
The image with the blue background is the QML app.





Thanks in advance

Regards

> Am 16.05.2016 um 22:54 schrieb NoRulez :
> 
> Hello,
> 
> When I start my app on the device, then it seems that the screen is scaled, 
> because the wireless icon, battery and time are bigger then before. After I 
> close my app, those icons has there normal size.
> 
> How can I manage to disable those scaling?
> 
> Regards
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[Interest] QML: How to dynamically create filter groups in DelegateModel based on another model?

[Viktória Nemkin]

Hello!

I want to create a QML application where I have a bunch of Buttons that you
can click on. These Buttons are categorized into groups.

At the top of the page there are CategoryButtons. When you click on one of
the CategoryButtons all the Buttons in that category appear on the page.
The Buttons not in that category remain hidden.

To accomplish this I have created two ListModels, one for the
CategoryButtons and one for the Buttons:

ListModel {

id: categoryButtonsModel

ListElement {

name: "Super Awesome Category"

filterKey: "super"

}

ListElement {

name: "Slightly More Awesome Category"

filterKey: "slight"

}

}


ListModel {

id: buttonsModel

ListElement {

name: "Cool Button"

filterKey: "super"

}

ListElement {

name: "Geek Button"

filterKey: "super"

}

ListElement {

name: "Hipster Button"

filterKey: "slight"

}

}


I have added a property to all of these called filterKey. I want all
Buttons to be in the category that has the same filterKey that they have.

Then created the views:

ListView {

id: categoryButtonsView

model: categoryButtonsModel

delegate: Button {

text: name

onClicked: buttonsDelegateModel.filterOnGroup = filterKey

}

orientation: Qt.Horizontal

height: 50

anchors.top: parent.top

anchors.left: parent.left

anchors.right: parent.right

}


ListView {

id: buttonsView

model: buttonsDelegateModel

anchors.top: categoryButtonsView.bottom

anchors.left: parent.left

anchors.right: parent.right

anchors.bottom: parent.bottom

}


Then I have added a DelegateModel to filter my buttons:

DelegateModel {

id: buttonsDelegateModel

model: buttonsModel

delegate:  Button {

text: name

}


filterOnGroup: "super"


groups: [

DelegateModelGroup {

includeByDefault: false

name: "super"

Component.onCompleted: {

for (var i = 0; i < buttonsModel.count; i++ ) {

var entry = buttonsModel.get(i);

if(entry.filterKey === name) insert(entry);

}

}

},

DelegateModelGroup {

includeByDefault: false

name: "slight"

Component.onCompleted: {

for (var i = 0; i < buttonsModel.count; i++ ) {

var entry = buttonsModel.get(i);

if(entry.filterKey === name) insert(entry);

}

}

}

]

}


This code works perfectly. I have one problem only:

The groups property of the above DelegateModel is basically some generic
code and the filterKeys in CategoryButtonsModel. I want to generate groups
based on CategoryButtonsModel so I don't have to specify the same things
two times.

I have tried using a Repeater but it does not seem to generate a list?

I have tried some javascript like this, but it is full of problems: :)

groups: {

var result = [];

var component = Qt.createComponent(DelegateModelGroup);

for(var i=0; i

Re: [Interest] Problem with XCB and OpenGL

[Sean Harmer]

On Wednesday 18 May 2016 13:13:42 Calogero Mauceri wrote:
> GLX  no

What OpenGL do you have? Any? You need the EGL (for OpenGL ES) or GLX for 
"desktop" OpenGL typically. Make sure configure can find those headers etc.

Cheers,

Sean

-- 
Dr Sean Harmer | sean.har...@kdab.com | Managing Director UK
KDAB (UK) Ltd, a KDAB Group company
Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
Mobile: +44 (0)7545 140604
KDAB - Qt Experts
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[Interest] Problem with XCB and OpenGL

[Calogero Mauceri]

Hi all,

My application is exiting with the following error whenever I try to use 
OpenGL


QXcbIntegration: Cannot create platform OpenGL context, neither GLX nor 
EGL are enabled


My desktop is Ubuntu 12.04 (32 bit).  I configured Qt 5.6.0 with the 
following options


./configure -qt-zlib -system-libpng -system-libjpeg -platform 
linux-g++-32 -fontconfig -qt-xcb -nomake examples -nomake tools


This is part of the configure output (full output attached)

OpenGL / OpenVG:
EGL .. yes
OpenGL ... desktop
OpenVG ... no

[...]

QPA backends:
DirectFB . no
EGLFS  yes
  EGLFS i.MX6  no
  EGLFS i.MX6 Wayland. no
  EGLFS EGLDevice  no
  EGLFS GBM .. no
  EGLFS Mali . no
  EGLFS Raspberry Pi . no
  EGLFS X11 .. yes
LinuxFB .. yes
Mir client no
XCB .. yes (bundled copy)
  EGL on X ... yes
  GLX  no
  MIT-SHM  yes
  Xcb-Xlib ... yes
  Xcursor  yes (loaded at runtime)
  Xfixes . yes (loaded at runtime)
  Xi . no
  Xi2  yes
  Xinerama ... yes (loaded at runtime)
  Xrandr . yes (loaded at runtime)
  Xrender  yes
  XKB  yes
  XShape . yes
  XSync .. yes
  XVideo . yes

I've googled a lot about this issue but I did not find any solution to it.
Do you have any clues on how to fix this issue?

Thanks in advance for your help,
Calogero

--
Calogero Mauceri
Software Engineer

Applied Coherent Technology Corporation (ACT)
www.actgate.com

Running configuration tests (phase 1)...
Done running configuration tests.
Creating qmake...
Done.
Running configuration tests (phase 2)...
Done running configuration tests.

   Configure summary

Build type:linux-g++-32 (i386, CPU features: none detected)

Build options:
  Configuration .. accessibility accessibility-atspi-bridge 
audio-backend avx c++11 clock-gettime clock-monotonic compile_examples 
concurrent dbus egl eglfs egl_x11 enable_new_dtags evdev eventfd fontconfig 
full-config getaddrinfo getifaddrs harfbuzz iconv inotify ipv6ifname 
large-config largefile linuxfb medium-config minimal-config mremap nis opengl 
openssl pcre png posix_fallocate precompile_header qpa qpa reduce_exports 
reduce_relocations release rpath shared small-config sse2 sse3 sse4_1 sse4_2 
ssse3 system-freetype system-jpeg system-png threadsafe-cloexec xcb xcb-plugin 
xcb-qt xcb-xlib xinput2 xkbcommon-qt xlib xrender zlib 
  Build parts  libs
  Mode ... release
  Using sanitizer(s).. none
  Using C++ standard . c++11
  Using gold linker... no
  Using new DTAGS  yes
  Using PCH .. yes
  Using LTCG . no
  Target compiler supports:
SSE2/SSE3/SSSE3 .. yes/yes/yes
SSE4.1/SSE4.2  yes/yes
AVX/AVX2 . yes/no

Qt modules and options:
  Qt D-Bus ... yes (loading dbus-1 at runtime)
  Qt Concurrent .. yes
  Qt GUI . yes
  Qt Widgets . yes
  Large File . yes
  QML debugging .. yes
  Use system proxies . no

Support enabled for:
  Accessibility .. yes
  ALSA ... no
  CUPS ... no
  Evdev .. yes
  FontConfig . yes
  FreeType ... yes (system library)
  Glib ... no
  GStreamer .. no
  GTK theme .. no
  HarfBuzz ... yes (bundled copy)
  Iconv .. yes
  ICU  no
  Image formats: 
GIF .. yes (plugin, using bundled copy)
JPEG . yes (plugin, using system library)
PNG .. yes (in QtGui, using system library)
  libinput no
  Logging backends: 
journald ... no
syslog   ... no
  mtdev .. no
  Networking: 
getaddrinfo .. yes
getifaddrs ... yes
IPv6 ifname .. yes
libproxy.. no
OpenSSL .. yes (loading libraries at run-time)
  NIS  yes
  OpenGL / OpenVG: 
EGL .. yes
OpenGL ... desktop
OpenVG ... no
  PCRE ... yes (bundled copy)
  pkg-config . yes 
  PulseAudio . no
  QPA backends: 
DirectFB . no
EGLFS  yes
  EGLFS i.MX6  no
  EGLFS i.MX6 Wayland. no
  EGLFS EGLDevice  no
  EGLFS GBM .. no
  EGLFS Mali . no
  EGLFS Raspberry Pi . no
  EGLFS X11 .. yes
LinuxFB .. yes
Mir client no
XCB .. yes (bundled