An addition
Try to draw some line diagrams in qml please.
HTML5 Canvas no problem.
QML ? Please write your own c++ class that you register at qml.
Fail
Am 10.10.2011 08:15, schrieb Ganshorn Thomas:
- Some of the UI in my case are created dynamically either at
compile time or at runtime. The former depending on the target
platform and the latter depending on the device screen resolution. I
don't see this possibility with QML.
Why is that? The fact that the UI is declarative in nature does not
mean that it is static or that you have to declare everything
beforehand. That is a misconception. It is far easier to change the
UI dynamically than it ever was with QWidget and .ui files. Qt Quick
is actually designed precicely to target multiple resolutions. Did
you have a specific use case in mind?
Regards,
Jens Bache-Wiig
I don't know about his usecases but because this discussion is really
interesting for me i can send my usecases.
I have an application.
This application needs to control multiple objects (character rig in
vfx, or rig for fluid simulation of flowline)
I need now an ui that can, in certain circumstances reconfigure itself
based on the existing and configured objects.
That means as one example for each object we have some common states
(enabled, disabled, animated or not, active, inactive, stopped,
running, keyframe, .... )
and we want to have a dynamic ui that shows these objects in a grouped
grid (see windows explorer) where the grouping can be changed at
runtime and even created at runtime.
Currently this is a nobrainer in qt widgets.
i have eg an "SysButton" class that shows the name of the system, the
state, some functionality.
If i have 100 systems i just create 100 buttons, give them in their
"initialize" function the name of the system, the button uses that
name to find the system from a global class and connecting itself with it.
For the 100 buttons i created my own layout class that can show them
based on the screensize.
The buttons are simply organized in groups, if the screensize is to
small for the number of system buttons it will use automatic scale so
that the non important buttons get smaller, it can scroll and reorder
the buttons if necessary
to show the "Important" ones (they red or orange ones) at top.
This is just a "simple" example.
We have much more complex Userinterfaces that need to be automatically
created by the software based on the current scene or workflow step.
Now i thought cool with qml this might be easier and we can have a
cooler looking ui for all the artists. They can probably even modify
that stuff for their own needs.
Part of it is, i don't have to write my SysButton class in c++ and can
easily change the visual style great.
BUT ... how can i create 100 of them without extreme large development
overhead ?
I can't. In C++ it is only
SysButton* newButton = new SysButton ( myUIContainer, sysName );
FINISHED !
I did not find a good way to do it in qml, show me one please.
I tried to work with models but really ? Writing a modell for creating
a list of sysbuttons ?
Sorry this is just not real. It can't be because this would be just
stupid.
What is with layout ? i have no idea of how to create a real working
dynamic layout in qml.
It is just not working in real world situations. Yes it may be
possible by using hacks and thousand of lines of javascript code, but
this is just not practical.
We thought in the end even about creating hundred of qml views in the
end that are controlled by c++.
How can i connect the QML SysButtons ? Only if i make all my systems
accessible to qml (wich are in the end several thousand objects that i
have to make accessible.
And doing this IS a large overhead runtime and development wise)
(Also here show me a good way instead of having a c++ initialize
function that belongs to my widget, having a javascript function that
belongs to my qml object)
Yes i know exactly HERE qml COULD be better because of its runtime
capabilities. But the truth is ... it is just not usable
Because debugging IS a REAL nightmare.
Whatever you say i can say from my metrics that using qml took as more
than 12 times longer for the current tests than with qwidgets.
And yes there is stuff like learning time. But the debugging is just
real shit and i know why i say shit. It can be only worse if you have
to use remote debugging on a ui application that only writes some
traces every now and then and you do not have an debugger.
The ui quality gets much worse than before, not because of missing
features but because of the really bad separation of logic and ui.
Whatever you say including javascript in files that are to be handled
by designers was NOT a good idea and WILL NEVER be a good idea.
We dont have ANY designer who can code. Yes they CAN hack some
javascript yay. But that is exactly the SHIT that costs time.
Because they can't code, they can only hack some stuff into it, That
is untested, in many cases not working and just (if you need to
integrate more complex functionality) way to much for them.
So we realized we have to divide javascript functions and qml
separately creating an additional layer on our own that the designers
could use.
That leaded to much more effort for code maintenance, more complex
project structure and more error possibilities.
So we tried another approach ... we use javascript and html5 and what
to say ?
It has in reality less problems because it wants to do less.
it works better in our case because there is a separation between
layout, look and code.
And we have more functionality (we can now easily have a remote ui and
even use an ipad to control the system).
Needless to say we needed less time to develop this approach including
an integrated http server for the communication with our server
process than it took as to use qml.
So in reality
i LOVE the idea of an explicit ui layer.
But not like qml does it.
Although html5 has its own problems it IS much better than qml is.
Not performance wise, that is true. But in all other parts.
It is a better structure of
- a html file containing your basic data and elements that can easily
created by a c++ part (the 100 button problem).
- css for the style
- at least some layout mechanisms for different screensizes (even if
you have to use sometimes device dependent css files, but because
these css rules work togehter you do not have to do everyting again
and again for each resolution)
- a clear separation from code and ui, the code is in its own js file.
You only have to initialize your ui once in one initial function that
does something like
function initUi()
{
uiLib.createSlider ( divId );
uiLib.createTextLine ( divId );
uiLib.bindFunction ( divId, function );
}
Can qml come to this ? Yes if the nokia trolls really think about that
is the problem of html5, how to make it better, where are the
strengths of it.
Currently they don't do it.
Thats why qml is a fail and WILL fail
Because why should you use it ?
if the ui is small enough to be managable, you can easily do it in
html5 and javascript and be real platform independent.
iOs, android, win8 metro, macosX even the nokia smartphones can use it.
For now qml has only ONE pro.
It is theoretically faster (but not if you do not know how to overcome
the billion of speed problems you can easily create)
But it has many cons like
-> untested not finished
-> missing features
-> platform independency
-> way more overhead to accomplish things.
Greetings Thomas
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