From 1a2e5f4932a17c9804ca6d201b7d8cf84d7f19d9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Sat, 19 Apr 2025 07:46:06 +0200
Subject: [PATCH] render: fix colors.alpha-mode=matching

Before this patch, it only matched RGB color sources. It did not match
the default bg color, or indexed colors. That is, e.g. CSI 43m didn't
apply alpha, even if the color3 matched the default background color.
---
 CHANGELOG.md | 4 ++++
 render.c     | 9 ++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d8787775..6958c869 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -66,6 +66,10 @@
 ### Deprecated
 ### Removed
 ### Fixed
+
+* `colors.alpha-mode=matching` not working as intended.
+
+
 ### Security
 ### Contributors
 
diff --git a/render.c b/render.c
index fdf7015c..0e403949 100644
--- a/render.c
+++ b/render.c
@@ -754,8 +754,15 @@ render_cell(struct terminal *term, pixman_image_t *pix,
             }
 
             case ALPHA_MODE_MATCHING: {
-                if (cell->attrs.bg == term->colors.bg)
+                if (cell->attrs.bg_src == COLOR_DEFAULT ||
+                    ((cell->attrs.bg_src == COLOR_BASE16 ||
+                      cell->attrs.bg_src == COLOR_BASE256) &&
+                     term->colors.table[cell->attrs.bg] == term->colors.bg) ||
+                    (cell->attrs.bg_src == COLOR_RGB &&
+                     cell->attrs.bg == term->colors.bg))
+                {
                     alpha = term->colors.alpha;
+                }
                 break;
             }