From a5d4c7c9ab2759676dfe4623eb8848941f38ff7e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ingo=20B=C3=BCrk?= <ingo.buerk@tngtech.com>
Date: Wed, 7 Oct 2015 11:03:18 +0200
Subject: [PATCH] Allow text drawing to use the alpha channel.

We pass alpha channel information to the current text drawing code
and use it if it is available. The previous behavior of using full
opacity for RGB format colors is preserved.
---
 libi3/font.c           |  5 ++++-
 libi3/get_colorpixel.c | 22 ++++++++++++++++------
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/libi3/font.c b/libi3/font.c
index 8bdf3d60..e14bb080 100644
--- a/libi3/font.c
+++ b/libi3/font.c
@@ -29,6 +29,7 @@ static xcb_visualtype_t *root_visual_type;
 static double pango_font_red;
 static double pango_font_green;
 static double pango_font_blue;
+static double pango_font_alpha;
 
 /* Necessary to track whether the dpi changes and trigger a LOG() message,
  * which is more easily visible to users. */
@@ -123,7 +124,8 @@ static void draw_text_pango(const char *text, size_t text_len,
         pango_layout_set_text(layout, text, text_len);
 
     /* Do the drawing */
-    cairo_set_source_rgb(cr, pango_font_red, pango_font_green, pango_font_blue);
+    cairo_set_source_rgba(cr, pango_font_red, pango_font_green, pango_font_blue, pango_font_alpha);
+    cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
     pango_cairo_update_layout(cr, layout);
     pango_layout_get_pixel_size(layout, NULL, &height);
     /* Center the piece of text vertically if its height is smaller than the
@@ -332,6 +334,7 @@ void set_font_colors(xcb_gcontext_t gc, uint32_t foreground, uint32_t background
             pango_font_red = ((foreground >> 16) & 0xff) / 255.0;
             pango_font_green = ((foreground >> 8) & 0xff) / 255.0;
             pango_font_blue = (foreground & 0xff) / 255.0;
+            pango_font_alpha = ((foreground >> 24) & 0xff) / 255.0;
             break;
 #endif
         default:
diff --git a/libi3/get_colorpixel.c b/libi3/get_colorpixel.c
index 44ad295d..3a62a8e4 100644
--- a/libi3/get_colorpixel.c
+++ b/libi3/get_colorpixel.c
@@ -7,6 +7,7 @@
  */
 #include <stdlib.h>
 #include <stdint.h>
+#include <string.h>
 
 #include "libi3.h"
 
@@ -25,14 +26,23 @@
  *
  */
 uint32_t get_colorpixel(const char *hex) {
-    char strgroups[3][3] = {{hex[1], hex[2], '\0'},
-                            {hex[3], hex[4], '\0'},
-                            {hex[5], hex[6], '\0'}};
+    char alpha[2];
+    if (strlen(hex) == strlen("#rrggbbaa")) {
+        alpha[0] = hex[7];
+        alpha[1] = hex[8];
+    } else {
+        alpha[0] = alpha[1] = 'F';
+    }
+
+    char strgroups[4][3] = {
+        {hex[1], hex[2], '\0'},
+        {hex[3], hex[4], '\0'},
+        {hex[5], hex[6], '\0'},
+        {alpha[0], alpha[1], '\0'}};
     uint8_t r = strtol(strgroups[0], NULL, 16);
     uint8_t g = strtol(strgroups[1], NULL, 16);
     uint8_t b = strtol(strgroups[2], NULL, 16);
+    uint8_t a = strtol(strgroups[3], NULL, 16);
 
-    /* We set the first 8 bits high to have 100% opacity in case of a 32 bit
-     * color depth visual. */
-    return (0xFF << 24) | (r << 16 | g << 8 | b);
+    return (a << 24) | (r << 16 | g << 8 | b);
 }