On 12/15/2015 5:03 AM, Sorvig Morten wrote:
Hi,
I’d like to provide short update on the changes in this space, an also lay out
some plans and possibilities for the future. Thanks to everyone who has helped
out! New changes:
* @3x support landed, both for Qt Widgets and Qt Quick. Implemented as @Nx
support, with @9x as a maximum value.
* The internal documentation for scaling in Qt has been updated:
github.com/qtproject/qtbase/blob/dev/src/gui/kernel/qhighdpiscaling.cpp.
* Added C++ API for enabling/disabling high-dpi scaling:
Qt::AA_EnableHighDpiScaling
Qt::AA_DisableHighDpiScaling
Together with the environment variable (QT_AUTO_SCREEN_SCALE_FACTOR=1 or 0)
these provide comprehensive support for controlling whether scaling in Qt
should be enabled or not. Several use cases are supported:
* User wants to enable scaling (perhaps for “legacy” Qt apps):
QT_AUTO_SCREEN_SCALE_FACTOR=1
* User wants disable scaling (there may be a hardware config issue):
QT_AUTO_SCREEN_SCALE_FACTOR=0
* Developer wants to enable scaling:
Qt::AA_EnableHighDpiScaling
* Developer wants application to work in device pixels and disable scaling:
Qt::AA_DisableHighDpiScaling
In case of conflicts between the environment and C++ side the logic is
‘veto’.
The actual scale factor applied is controlled by the platform plugin, which
provides it by overriding QPlatformScreen::pixelDensity() The default
implementation returns 1. pixelDensity() is currently implemented by the
android, eglfs, windows, and xcb platform plugins.
What’s next?
5.6 series:
* Public overview documentation update.
* Misc fixing in Widgets and Quick. In particular I would like to land a series
of
GraphicsView fixes: https://codereview.qt-project.org/#/c/142920
dev:
* Improve support for fractional scale factors for QtWidgets (render at 2x and
then
downscale). Will require OpenGL for the scaling. Prototype at
https://codereview.qt-project.org/143819 (OS X only).
* Refactor qhighdpiscaling_h API and implementation:
https://codereview.qt-project.org/#/c/140176
* Improve pixmap versioning support, replacing/extending @Nx and QIcon:
QTBUG-49820
* Figure out auto-testing: We can run entire tests at a given scale factor, or
individual test functions can test at a range of scale factors. Or we can do
both.
We’ve so far relied on manual tests on actual high-dpi hardware. The
cross-platform
scaling layer in Qt Gui now gives us the ability to auto test on any hardware
(including CI virtual hardware).
If anyone is interested or has input on the above, drop me a note or comment on
the
mentioned task/changes.
Thanks,
Morten
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Morten:
My comment only deals with vector graphics SVG formats QT.
Instead of worrying about @2x and @3x and trying to generate artwork in
all of the sizes, would it not be advantageous
to only use SVG vector format and allow the svg plugin to generate and
scale at run-time a single svg file in the QRC file instead of having to
pre-generate files.
Image
{
id: gicon
source: qrc:/img/test.svg
anchors.fill: parent
}
Pro File:
QT += svg
Outside of the app, in the Android Manifext.xml and IOS, you need to
provide pre-generated launcher PNG icons, but inside the app as well?
Your thoughts on projects that use ONLY SVG image resources and not
PNG/JPEG?
md
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