Its not really reasonable to handle failures to make_current, it
basically only happens if you pass invalid arguments to it, and
thats not something we trap on similar things on the X drawing side.
If GL is not supported that should be handled by the context creation
failing, and anything going wrong after that is essentially a critical
(or an async X error).
We make user facing gl contexts not attached to a surface if possible,
or attached to dummy surfaces. This means nothing can accidentally
read/write to the toplevel back buffer.
This adds the new type GdkGLContext that wraps an OpenGL context for a
particular native window. It also adds support for the gdk paint
machinery to use OpenGL to draw everything. As soon as anyone creates
a GL context for a native window we create a "paint context" for that
GdkWindow and switch to using GL for painting it.
This commit contains only an implementation for X11 (using GLX).
The way painting works is that all client gl contexts draw into
offscreen buffers rather than directly to the back buffer, and the
way something gets onto the window is by using gdk_cairo_draw_from_gl()
to draw part of that buffer onto the draw cairo context.
As a fallback (if we're doing redirected drawing or some effect like a
cairo_push_group()) we read back the gl buffer into memory and composite
using cairo. This means that GL rendering works in all cases, including
rendering to a PDF. However, this is not particularly fast.
In the *typical* case, where we're drawing directly to the window in
the regular paint loop we hit the fast path. The fast path uses opengl
to draw the buffer to the window back buffer, either by blitting or
texturing. Then we track the region that was drawn, and when the draw
ends we paint the normal cairo surface to the window (using
texture-from-pixmap in the X11 case, or texture from cairo image
otherwise) in the regions where there is no gl painted.
There are some complexities wrt layering of gl and cairo areas though:
* We track via gdk_window_mark_paint_from_clip() whenever gtk is
painting over a region we previously rendered with opengl
(flushed_region). This area (needs_blend_region) is blended
rather than copied at the end of the frame.
* If we're drawing a gl texture with alpha we first copy the current
cairo_surface inside the target region to the back buffer before
we blend over it.
These two operations allow us full stacking of transparent gl and cairo
regions.
This is a new function that gets called every time we're drawing
some area in the Gtk paint machinery. It is a no-op right now, but
it will be required later to keep track of what areas which
we previously rendered with GL was overwritten with cairo contents.
First of all we track the current update area during an
update in window->active_update_area. This will be used later
in end_paint to know the damaged area.
Secondly we keep track of old update areas for the last 2
frames. This will later allow us to reuse old framebuffer
contents in double or tripple buffer setups, only painting
what has changed since then.
Parent is guaranteed to not be NULL. It can only ever be NULL for root
windows and root windows cannot be created with gdk_window_new() and
gdk_window_ensure_native() will exit early because they already are
native.
Also, both functions would crash a few lines below where parent gets
dereferenced.
If !owner_events, the pointer window has been usually set to NULL if
the pointer fell outside the grabbing widget, but it was not being
checked that the pointer_window is actually a child of the grab
window, in which case it should be obtained as if ungrabbed.
https://bugzilla.gnome.org/show_bug.cgi?id=735749
When recursing the update area down into native subwindows we forgot
to apply the native window position. This caused us to repaint the
wrong thing in certain cases. I noticed this when playing with the
wip/gdk-gl branch, because it was triggering unnecessary repaints
of the (native window) gl widgets.
Some windows, like GtkWindow and some other apps, set a transparent
background. The guarantee for begin_paint_region is that there should
be a full clear to the specified background color, not a composite
against what was there before.
This fixes repaint artifacts in Wayland and Weston in a better way than
76922c169f.
The resize grip code in GTK+ likes to call gdk_window_raise a lot. The
unfortunate side effect of gdk_window_raise is that it queues an
invalidation on the entire window, even if it's already the topmost
child.
Add a return value to gdk_window_raise_internal, and only queue the
invalidation if the raise had an effect.
Otherwise, a user that calls gdk_window_resize (window, 0, 0); over and
over won't properly fizzle out, and will queue a redraw. Clipped, but
still. These redraws can be chatty on some platforms like Wayland, and
there's no good reason to not avoid them.
This was the case for resize grips.
This reverts commit b875572f2a.
Apps like Abiword, gnumeric and gnome-chess, and toolkits like
ClutterGTK were all using this for various purposes, and this made them
break. Bring back this feature for now.
It still won't work under Wayland.
Apps had quite a bit of difficulty getting used to the new rules.
While we weren't expecting anything too deadly, it seemed that
gnumeric and Abiword both used gdk_cairo_create like this.
If a window both has an impl and its impl_window is of type offscreen,
that must mean that it is the offscreen window, and the impl window is
itself. We can reduce the indirection here and make it more clear.
We removed the parameter from callers and from the implementation, but
not from the signature up top. I didn't notice because the branch I was
working on removed the signature entirely.
This code is only called with the current paint region as its argument.
Instead of having to copy it and do a no-op intersect against itself,
just use the current paint directly.
cairo_surface_create_for_rectangle takes a ref on the parent surface,
so we need to drop ours.
Rename get_window_surface to ref_window_surface to make the code more
clear and to stop this error from happening again.
Previously, each begin_paint_region added to a stack of current paints,
and when end_paint was called, the paint was popped off of the stack and
the surface was composited into the parent paint surface.
However, the code was broken in the case of a backend like Wayland which
didn't keep track of nested calls and simply wiped and returned the
native impl backing surface every time.
Since this feature is flat out unused by GTK+ and we don't want to
really support tricksy things like these for other clients, just remove
the feature. If somebody does call begin_paint_region more than once,
warn and return without doing anything.
Traditionally, the way painting was done in GTK+ was with the
"expose-event" handler, where you'd use GDK methods to do drawing on
your surface. In GTK+ 2.24, we added cairo support with gdk_cairo_create,
so you could paint your graphics with cairo.
Since then, we've added client-side windows, double buffering, the paint
clock, and various other enhancements, and the modern way to do drawing
is to connect to the "draw" signal on GtkWidget, which hands you a
cairo_t. To do double-buffering, the cairo_t we hand you is actually on
a secret surface, not the actual backing store of the window, and when
the draw handler completes we blit it into the main backing store
atomically.
The code to do this is with the APIs gdk_window_begin_paint_region,
which creates the temporary surface, and gdk_window_end_paint which
blits it back into the backing store. GTK+'s implementation of the
"draw" signal uses these APIs.
We've always sort-of supported people calling gdk_cairo_create
"outside" of a begin_paint / end_paint like old times, but then you're
not getting the benefit of double-buffering, and it's harder for GDK to
optimize.
Additionally, newer backends like Mir and Wayland can't actually support
this model, since they're based on double-buffering and swapping buffers
at various points in time. If we hand you a random cairo_t, we have no
idea when is a good time to swap.
Remove support for this.
This is technically a GDK API break: a warning is added in cases where
gdk_cairo_create is called outside of a paint cycle, and the returned
surface is a dummy that won't ever be composited back onto the main
surface. Testing with complex applications like Ardour didn't produce
any warnings.
gtk_widget_set_double_buffered is now deprecated, and we don't support
non-double-buffered widgets. This means that under normal circumstances,
paints are never outside of a begin_paint / end_paint sequence, which
natively-double-buffered backends like Wayland can't possibly support.
When the pointer cursor is updated on CSW, lookup for either a device
cursor, or a global one. It would previously lookup for windows with
a global cursor, and then check if it had a device cursor, which would
skip windows with only device cursors set, and unexpectedly set the
global cursor.
This avoids a bunch of policy problems with deciding how to lay
out the window menu under different WMs.
For now, we use the special event _GTK_SHOW_WINDOW_MENU, but we
hope to have this standardized in wm-spec quite soon, as KDE wants
it as well.
