The API docs outline why quite well.
This should make it possible to do saving of textures to image files
without any private API with the same featureset that GTK uses.
Also remove the gsktextureprivate.h include where
gdk_texture_get_format() was the only reason for it.
Those property features don't seem to be in use anywhere.
They are redundant since the docs cover the same information
and more. They also created unnecessary translation work.
Closes#4904
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.
For MemoryTexture, this is a simple change.
For GLTexture, we need to query the format at texture creation. This
sounds like a bad idea and extra work until one realizes that we'd
need to do that anyway when using the texure the first time - either
when downloading, or when trying to use it in a rendernode, where we
will soon need that information to determine if the texture prefers high
depth.
This is a companion to gdk_texture_save_to_png, using
the tiff format, which will let us avoid lossy conversion
of HDR data, since we can store floating point data.
A private vfunc that downloads a texture as a GdkMemoryTexture in
whatever format the texture deems best.
There are multiple reasons for this:
* GLES cannot download the Cairo format. But it can download some
format and then just delegate to the GdkMemoryTexture implementation.
* All the other download vfuncs (including the ones still coming) can
be implemented via download_texture() and delegation, making the
interface easier.
* We want to implement image loading and saving support. By using
download_texture(), we can save in the actual format of the texture.
* A potential GdkCompressedTexture could be implemented by just
providing this one vfunc as a compress() step.
Remove a boatload of "or %NULL" from nullable parameters
and return values. gi-docgen generates suitable text from
the annotation that we don't need to duplicate.
This adds a few missing nullable annotations too.
The fact that we are using gdk-pixbuf for loading files currrently does not mean we will use it going forward.
Also, "anything gdk-pixbuf can load" does not mean anything, because what gdk-pixbuf can load is a compile-time option.
As new_from_resource() will assert() if it cannot load a resource, we must be very sure that people do not use anything but PNG and JPEG for resources and the docs were not clear on that.
