When large viewports are passed to gsk_renderer_render_texture(), don't
fail (or even return NULL).
Instead, draw multiple tiles and assemble them into a memory texture.
Tests added to the testsuite for this.
There are situations where our "default framebuffer" is not actually
zero, yet we still want to apply a scissor rect.
Generally, 0 is the default framebuffer. But on platforms where we need
to bind a platform-specific feature to a GL_FRAMEBUFFER, we might have a
default that is not 0. For example, on macOS we bind an IOSurfaceRef to
a GL_TEXTURE_RECTANGLE which then is assigned as the backing store for a
framebuffer. This is different than using gsk_gl_renderer_render_texture()
in that we don't want to incur an extra copy to the destination surface
nor do we even have a way to pass a texture_id into render_texture().
If the rendering operation is over an opaque region, we can potentially
avoid clearing a large section of the framebuffer destination. Some cases
you do want to clear, such as when clearing the whole contents as some
drivers have fast paths for that to avoid bringing data back into the
framebuffer.
Instead of just passing major/minor, pass them twice, once for GL and
once for GLES. This way, we don't need to check for GL and GLES
separately.
If something is supported unconditionally, passing 0/0 works fine.
That said, I'd like to group the arguments somehow, because otherwise
it's just a confusing list of numbers - but I have no idea how to do
that.
For libANGLE to work with our shaders, we must use "300 es" for
the #version directive in our shaders, as well as using the non-legacy/
non-GLES codepath in the shaders. In order to check whether we are
using the GLSL 300 es shaders, we check whether we are using a GLES 3.0+
context. As a result, make ->glsl_version a const char* and make sure
the existing shader version macros are defined apprpriately, and add a
new macro for the "300 es" shader version string.
This will allow the gtk4 programs to run under Windows using EGL via
libANGLE. Some of the GL demos won't work for now, but at least this
makes things a lot better for using GL-accelerated graphics under Windows
for those that want to or need to use libANGLE (such as those with
graphics drivers that aren't capable of our Desktop (W)GL requirements in
GTK.
On Windows with nVidia drivers at least, when we create a legacy context
via wglCreateContext(), we may still get a (W)GL 4.x context. Allow
such contexts to also use GLSL version 130 instead of 110, so that
things do continue to work.
But don't call it too early, we only want to call it once we have
prepared the target.
This way, we guarantee that a GL context is always available and that it
is bound to the correct target.
Don't pass texture + rect, but instead have
gdk_memory_texture_new_subtexture()
and use it to generate subtextures and pass them.
This has the advantage of downloading the a too large texture only once
instead of N times.
It does not belong in GdkGLContext, it's a renderer thing.
It's also the only user of that API.
Introduce gdk_gl_context_check_version() private API to make version
checks simpler.
It turns out glReadPixels() cannot convert pixels and you are only
allowed to pass a single value into the function arguments. You need to
know which ones or things will explode.
GL is great.
Pass a format do GdkTextureClass::download(). That way we can download
data in any format.
Also replace gdk_texture_download_texture() with
gdk_memory_texture_from_texture() which again takes a format.
The old functionality is still there for code that wants it: Just pass
gdk_texture_get_format (texture) as the format argument.
Move the resources of each renderer to its subdirectory.
We've previously done that for the ngl renderer, but it
is better to be consistent and do it for all the renderers.
When we are rendering a texture node to an offscreen,
and we have a clip, we must force the offscreen rendering.
Otherwise, the code will notice: Hey, it already is a texture
node, so no need to render it to a texture again. But when
clipping is involved, that is exactly what we want to do.
Testcase included.
Fixes: #3651
