xserver: Branch 'master'

[GitLab Mirror]

 glamor/glamor_render.c |   28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

New commits:
commit d1bbf82d72566e16e90800c77cf70fe5fc4ef2e8
Author: Michel Dänzer <mdaenzer at redhat.com>
Date:   Fri Jan 5 18:31:11 2024 +0100

    glamor: Don't override source alpha to 1.0 if it's used for blending
    
    It caused an incorrect result of the blend operation.
    
    Use glColorMask to prevent non-1.0 alpha channel values in a depth 32
    pixmap backing an effective depth 24 window. For blending operations,
    the expectation is that the destination drawable contains valid pixel
    values, so the alpha channel should already be 1.0.
    
    Fixes: d1f142891ef3 ("glamor: Ignore destination alpha as necessary for composite operation")
    Issue: https://gitlab.gnome.org/GNOME/mutter/-/issues/3104

diff --git a/glamor/glamor_render.c b/glamor/glamor_render.c
index 179b62dd8..7545268f3 100644
--- a/glamor/glamor_render.c
+++ b/glamor/glamor_render.c
@@ -838,6 +838,20 @@ glamor_render_format_is_supported(PicturePtr picture)
     }
 }
 
+static Bool
+render_op_uses_src_alpha(CARD8 op)
+{
+    struct blendinfo *info = &composite_op_info[op];
+
+    switch (info->dest_blend) {
+    case GL_ONE_MINUS_SRC_ALPHA:
+    case GL_SRC_ALPHA:
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
 static Bool
 glamor_composite_choose_shader(CARD8 op,
                                PicturePtr source,
@@ -951,7 +965,8 @@ glamor_composite_choose_shader(CARD8 op,
         key.dest_swizzle = SHADER_DEST_SWIZZLE_ALPHA_TO_RED;
     } else {
         if (dest_pixmap->drawable.depth == 32 &&
-            glamor_drawable_effective_depth(dest->pDrawable) == 24)
+            glamor_drawable_effective_depth(dest->pDrawable) == 24 &&
+            !render_op_uses_src_alpha(op))
             key.dest_swizzle = SHADER_DEST_SWIZZLE_IGNORE_ALPHA;
         else
             key.dest_swizzle = SHADER_DEST_SWIZZLE_DEFAULT;
@@ -1185,6 +1200,7 @@ glamor_composite_with_shader(CARD8 op,
     Bool ret = FALSE;
     glamor_composite_shader *shader = NULL, *shader_ca = NULL;
     struct blendinfo op_info, op_info_ca;
+    Bool restore_colormask = FALSE;
 
     if (!glamor_composite_choose_shader(op, source, mask, dest,
                                         source_pixmap, mask_pixmap, dest_pixmap,
@@ -1209,6 +1225,14 @@ glamor_composite_with_shader(CARD8 op,
 
     glamor_make_current(glamor_priv);
 
+    if (ca_state != CA_TWO_PASS &&
+        key.dest_swizzle == SHADER_DEST_SWIZZLE_DEFAULT &&
+        dest_pixmap->drawable.depth == 32 &&
+        glamor_drawable_effective_depth(dest->pDrawable) == 24) {
+        glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_FALSE);
+        restore_colormask = TRUE;
+    }
+
     glamor_set_destination_pixmap_priv_nc(glamor_priv, dest_pixmap, dest_pixmap_priv);
     glamor_composite_set_shader_blend(glamor_priv, dest_pixmap_priv, &key, shader, &op_info);
     glamor_set_alu(screen, GXcopy);
@@ -1351,6 +1375,8 @@ glamor_composite_with_shader(CARD8 op,
 
     glDisable(GL_SCISSOR_TEST);
 disable_va:
+    if (restore_colormask)
+        glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
     glDisableVertexAttribArray(GLAMOR_VERTEX_POS);
     glDisableVertexAttribArray(GLAMOR_VERTEX_SOURCE);
     glDisableVertexAttribArray(GLAMOR_VERTEX_MASK);