From 212b9dcd383cfa16fa74c300cfe87e816deaea9c Mon Sep 17 00:00:00 2001
From: Mel Henning <mhenning@darkrefraction.com>
Date: Tue, 25 Nov 2025 18:00:18 -0500
Subject: [PATCH] util: Add util_format_is_red

---
 src/util/format/u_format.c | 17 +++++++++++++++++
 src/util/format/u_format.h |  3 +++
 2 files changed, 20 insertions(+)

diff --git a/src/util/format/u_format.c b/src/util/format/u_format.c
index 8f6defb3291..953e08f16fd 100644
--- a/src/util/format/u_format.c
+++ b/src/util/format/u_format.c
@@ -302,6 +302,23 @@ util_format_is_luminance_alpha(enum pipe_format format)
    return false;
 }
 
+bool
+util_format_is_red(enum pipe_format format)
+{
+   const struct util_format_description *desc =
+      util_format_description(format);
+
+   if ((desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB ||
+        desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB) &&
+       desc->swizzle[0] == PIPE_SWIZZLE_X &&
+       desc->swizzle[1] == PIPE_SWIZZLE_0 &&
+       desc->swizzle[2] == PIPE_SWIZZLE_0 &&
+       desc->swizzle[3] == PIPE_SWIZZLE_1) {
+      return true;
+   }
+   return false;
+}
+
 bool
 util_format_is_red_alpha(enum pipe_format format)
 {
diff --git a/src/util/format/u_format.h b/src/util/format/u_format.h
index 2614a16150d..74dd51e9951 100644
--- a/src/util/format/u_format.h
+++ b/src/util/format/u_format.h
@@ -805,6 +805,9 @@ util_format_is_alpha(enum pipe_format format) ATTRIBUTE_CONST;
 bool
 util_format_is_luminance_alpha(enum pipe_format format) ATTRIBUTE_CONST;
 
+bool
+util_format_is_red(enum pipe_format format) ATTRIBUTE_CONST;
+
 bool
 util_format_is_red_alpha(enum pipe_format format) ATTRIBUTE_CONST;