From 393ee574b68f09ec2a12bf7ec0286532be8fec55 Mon Sep 17 00:00:00 2001
From: Benjamin Otte <otte@redhat.com>
Date: Mon, 11 Dec 2023 04:25:32 +0100
Subject: [PATCH] gl: Print debug for CPU conversions of textures

When the GL renderer cannot upload a given format, print a FALLBACK
debug message with the failed format and the alternative that was
picked, for example:

Unsupported format b8g8r8a8, converting on CPU to b8g8r8a8-premultiplied

Makes it easier to figure out what's happening, especially when using
old GLES versions that don't support all formats.
---
 gsk/gl/gskglcommandqueue.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/gsk/gl/gskglcommandqueue.c b/gsk/gl/gskglcommandqueue.c
index d560919f31..8c50654673 100644
--- a/gsk/gl/gskglcommandqueue.c
+++ b/gsk/gl/gskglcommandqueue.c
@@ -1568,6 +1568,18 @@ gsk_gl_command_queue_do_upload_texture_chunk (GskGLCommandQueue *self,
                                          &gl_type,
                                          gl_swizzle);
 
+  if (GSK_DEBUG_CHECK (FALLBACK) &&
+      data_format != gdk_texture_get_format (texture))
+    {
+      GEnumClass *enum_class = g_type_class_ref (GDK_TYPE_MEMORY_FORMAT);
+
+      gdk_debug_message ("Unsupported format %s, converting on CPU to %s",
+                         g_enum_get_value (enum_class, gdk_texture_get_format (texture))->value_nick,
+                         g_enum_get_value (enum_class, data_format)->value_nick);
+
+      g_type_class_unref (enum_class);
+    }
+
   gdk_texture_downloader_init (&downloader, texture);
   gdk_texture_downloader_set_format (&downloader, data_format);
   bytes = gdk_texture_downloader_download_bytes (&downloader, &stride);