render/gles2: don't constrain shm formats to ones that support reading

commit 44e8451cd93e ("render/gles2: hide shm formats without GL
support") added the is_gles2_pixel_format_supported() function to
render/gles2/pixel_format.c, whose stated purpose is to "check whether
the renderer has the needed GL extensions to read a given pixel format."
It then used that function to filter the pixel formats returned by
get_gles2_shm_formats().

The result of this change is that RGB formats are no longer reported for
GL drivers that don't implement EXT_read_format_bgra, even when those
formats are supported for rendering (which they have to be for
wlr_gles2_renderer_create() to succeed). This is a pretty clear
regression, since wlr_renderer_init_wl_shm() fails when either of
WL_SHM_FORMAT_ARGB8888 or WL_SHM_FORMAT_XRGB8888 are missing.

To fix the regression, change is_gles2_pixel_format_supported() to
accept all pixel formats that support rendering, regardless of whether
we can read them or not, and move the check for EXT_read_format_bgra
back into gles2_read_pixels(). (There's already a check for this
extension in gles2_preferred_read_format(), so we're not breaking any
abstraction that wasn't already broken.)

Tested on the NVIDIA 495.46 proprietary driver, which doesn't support
EXT_read_format_bgra.

Fixes: 44e8451cd93e ("render/gles2: hide shm formats without GL support")

1 files changed, 6 insertions, 0 deletions

diff --git a/render/gles2/renderer.c b/render/gles2/renderer.c
index 527d85bf..67b8ead4 100644
--- a/render/gles2/renderer.c
+++ b/render/gles2/renderer.c
@@ -441,6 +441,12 @@ static bool gles2_read_pixels(struct wlr_renderer *wlr_renderer,
 		return false;
 	}
 
+	if (fmt->gl_format == GL_BGRA_EXT && !renderer->exts.EXT_read_format_bgra) {
+		wlr_log(WLR_ERROR,
+			"Cannot read pixels: missing GL_EXT_read_format_bgra extension");
+		return false;
+	}
+
 	const struct wlr_pixel_format_info *drm_fmt =
 		drm_get_pixel_format_info(fmt->drm_format);
 	assert(drm_fmt);