This requires the image size query to be window independent and go
through the backend instead.
This implies minor changes for the Qt backend and bigger ones for the GL
backend:
* There exists now a thread-local IMAGE_CACHE, which is used by the
backend's image_size() function as well as by the renderer for
loading CPU side images.
* The image remain as decoded images in there (including SVG tree)
and the window now has a texture_cache, which holds CachedImage
with ImageData::Texture.
* Rendering an image item therefore fetches the CPU side image,
calls upload_to_gpu() on it, which creates a new Rc<CachedImage>
and that's stored in the texture_cache.
* The texture cache continues to be pruned when hiding the window.
Split the vertical and horizontal pass into different property cache
This will allow to implement "height for with"
This patch does not port the Rust or C++ binding yet
When a Text element has wrapping enabled, it should not have zero
minimum size. Otherwise the layout will give it a height of zero in the
layout in the test case and that'll make the text disappear. There are
different options but this patch goes for minimum height as if no
wrapping was enabled (so at least one line plus forced line breaks).
Fixes#246
We use a weight of 900 in the demo, which results in a QFont::Weight of 100.
Unfortunately QFont::setWeight() doesn't cap itself, but brutally asserts
if the value is > 99. So let's cap ourselves.
Pass everything needed for delayed evaluation for
`PlatformWindow::font_metrics()` to permit caching the font matching
result in the Text/TextInput's rendering cache.
We query text metrics frequently for text items, for example when in
layouts. This requires font resolution, which is about to become more
much more expensive due to analysis of the underlying text. To speed
this up, the objective is to use the item rendering cache. Making that
work in turn requires querying all related properties inside a property
tracker. That means we need to delay querying anything related to that,
including the font request needed for the `font_metrics()` function on
the PlatformWindow trait.
The component layout needs to be re-calculated. For some reason it is with
the Qt backend but not with GL.
Either way we can force it to re-calculate when the component changes.
It possibly doesn't get dirty when the dependencies are deleted.
Remove the intermediate properties for width and height and - just like
qt backend - apply the width and height in apply_window_properties
and when receiving a window resize event.
This also elimiates the get_geometry() getter as that would otherwise just
have been a FIXME'ed default().
* Provide an internal behavior parameter to run_event_loop() that we can use
from the preview to not quit when the last window was closed.
* Fix Drop for the winit event loop GraphicsWindow to drop the backend window correctly
when unmapping, not when the graphics window dies. Otherwise QuitOnLastWindowClosed doesn't work.
