From 31b4c27abc67911d9d70d7f7936bae60844a6979 Mon Sep 17 00:00:00 2001
From: bi4k8 <bi4k8@github>
Date: Tue, 3 Jan 2023 00:38:51 +0000
Subject: [PATCH] use ARGB, not RGBA, for Wayland color values

this impacts only colors from which we compute Cairo colors, not the
rendered pixel buffers themselves, which were already and remain
ARGB32.

this makes Wayland and (24-bit) X11 use the same representation of
colors, fixing bugs when both backends were enabled.

we should still eventually switch to a backend-independent color
representation, because there are no guarantees of which pixel format
X11 will use (it isn't alway ARGB32) and backends like ncurses have
their own color representation; in most code we just hope the
unsigned long will be interpreted by the same backend as wrote it.
---
 src/colours.cc         |  6 +++---
 src/display-wayland.cc | 28 ++++++++++++++--------------
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/colours.cc b/src/colours.cc
index f82cf999..24adbca7 100644
--- a/src/colours.cc
+++ b/src/colours.cc
@@ -104,14 +104,14 @@ long manually_get_x11_color(const char *name) {
   unsigned short r, g, b;
   size_t len = strlen(name);
   if (OsLookupColor(-1, name, len, &r, &g, &b)) {
-    return 0x000000ff | ((r & 0xff) << 24) | ((g & 0xff) << 16) |
-           ((b & 0xff) << 8);
+    return 0xff000000 | ((r & 0xff) << 16) | ((g & 0xff) << 8) | (b & 0xff);
   }
   if (name[0] == '#') {
     name++;
     len--;
   }
   if (len == 6 || len == 8) {
+    bool skip_alpha = (len == 6);
     unsigned char argb[4] = {0xff, 0, 0, 0};
     for (size_t i = 0; i + 1 < len; i += 2) {
       int nib1 = hex_nibble_value(name[i]);
@@ -119,7 +119,7 @@ long manually_get_x11_color(const char *name) {
       if (nib1 < 0 || nib2 < 0) { goto err; }
       int val = (nib1 << 4) + nib2;
 
-      argb[3 - i / 2] = val;
+      argb[skip_alpha + i / 2] = val;
     }
     long out;
     memcpy(static_cast<void *>(&out), argb, 4);
diff --git a/src/display-wayland.cc b/src/display-wayland.cc
index 7a3b0fa0..af68c7d5 100644
--- a/src/display-wayland.cc
+++ b/src/display-wayland.cc
@@ -666,15 +666,15 @@ void display_output_wayland::cleanup() {
 }
 
 void display_output_wayland::set_foreground_color(long c) {
-#ifdef BUILD_ARGB
-  current_color = (c & ~0xff) | own_window_argb_value.get(*state);
-#else
   current_color = c;
+#ifdef BUILD_ARGB
+  uint8_t a = own_window_argb_value.get(*state);
+#else
+  uint8_t a = current_color >> 24;
 #endif /* BUILD_ARGB */
-  uint8_t r = current_color >> 24;
-  uint8_t g = current_color >> 16;
-  uint8_t b = current_color >> 8;
-  uint8_t a = current_color;
+  uint8_t r = current_color >> 16;
+  uint8_t g = current_color >> 8;
+  uint8_t b = current_color;
   if (global_window->cr) {
     cairo_set_source_rgba(global_window->cr, r / 255.0, g / 255.0, b / 255.0,
                           a / 255.0);
@@ -707,9 +707,9 @@ void display_output_wayland::draw_string_at(int x, int y, const char *s,
   adjust_coords(x, y);
   pango_layout_set_text(window->layout, s, strlen(s));
   cairo_save(window->cr);
-  uint8_t r = current_color >> 24;
-  uint8_t g = current_color >> 16;
-  uint8_t b = current_color >> 8;
+  uint8_t r = current_color >> 16;
+  uint8_t g = current_color >> 8;
+  uint8_t b = current_color;
   unsigned int a = pango_fonts[selected_font].font_alpha;
   cairo_set_source_rgba(global_window->cr, r / 255.0, g / 255.0, b / 255.0,
                         a / 65535.);
@@ -815,10 +815,10 @@ void display_output_wayland::clear_text(int exposures) {
 #endif
   }
 #endif
-  uint8_t r = color >> 24;
-  uint8_t g = color >> 16;
-  uint8_t b = color >> 8;
-  uint8_t a = color;
+  uint8_t a = color >> 24;
+  uint8_t r = color >> 16;
+  uint8_t g = color >> 8;
+  uint8_t b = color;
   cairo_set_source_rgba(window->cr, r / 255.0, g / 255.0, b / 255.0, a / 255.);
   cairo_set_operator(window->cr, CAIRO_OPERATOR_SOURCE);
   cairo_paint(window->cr);