Since what we are doing is turning an icon with alpha into a
no-alpha icon + mask for legacy window managers, it makes more sense
to use the system visual than the window's visual, which might
be ARGB.
https://bugzilla.gnome.org/show_bug.cgi?id=634821
In this case, gnome-terminal sets an RGBA visual on its window,
and we need to be careful when creating the icon pixmap, to create
the pixmap with the same depth as the visual, or we risk a BadMatch
from XRenderCreatePicture deep inside cairo.
In particular, the following functions are gone:
- gdk_screen_get_default_colormap()
- gdk_screen_set_default_colormap()
- gdk_screen_get_system_colormap()
- gdk_screen_get_rgba_colormap()
This way, we can specify a colormap when constructing windows. And ew
must do that to avoid BadMatch from XCreateWindow when we use a
different visual.
Also add a priv pointer to GdkVisual and use it for the GdkVisualPrivate
structure. Then Make GdkVisualPrivate actually private to
gdkvisual-x11.c and make other callers use proper function calls to
access it.
Direct and TrueColor visuals don't alloc colors, so they don't need to
fiddle with colormaps. Just copy the code that computes the pixel value
from gdkcolor-x11.c and use it. For other visual types, don't set the
background color and fallback to background = None.
No more GdkPixmap to store the icon and its mask, but instead use cairo
surfaces. Also render the icon into the surfaces using Cairo instead of
gdk_pixbuf_render_threshold_alpha().
Now the window background is a cairo_pattern_t. The backends will try to
set this as good as they can on the windowing system, but no guarantees
are made on wether the windowing system supports the pattern.
Also gets rid of GDK_NO_BG as undefined behavior is not a good idea to
support, and GDK_NO_BG effectively made the window's contents undefined.
It wasn't effectively used in GTK anyway.
Basically copies the code for setting the WM icon hint from GtkWindow to
GdkWindow. This achieves the following:
- Putting this X11 specific code into the X11 backend
- Enables removal of gdk_window_set_icon()
- Gets rid of Pixmap/Bitmap usage outside of GDK.
The window move code needs special attention for multiple reasons:
- invalid areas for expose events need to be modified
- self-copy is not supported by Cairo
- in X11, copying from an overlapped Window might cause unexposed areas
to be copied in, spo expose events for those need to be generated.
This was all special cased in various parts of the code. By making it an
explicit vfunc, we can work around it.
Includes fixing all callers to use the cairo region API instead. This is
usually just replacing the function names, the only difference is
gdk_region_get_rectangles() being replaced by
cairo_region_num_rectangles() and cairo_region_get_rectangle() which
required a bit more work.
https://bugzilla.gnome.org/show_bug.cgi?id=613284
