Implement showing window icons in titlebar (#4439)

This feature defaults to off, and can be turned on for individual windows,
or (with for_window) for all new windows. See the userguide change.

This commit is partially based on work by:

• Marius Muja
• mickael9
• Esteve Varela Colominas
• Bernardo Menicagli

include/commands.h

@@ -331,3 +331,9 @@ void cmd_shmlog(I3_CMD, const char *argument);
  *
  */
 void cmd_debuglog(I3_CMD, const char *argument);
+
+/**
+ * Implementation of 'title_window_icon <yes|no>' and 'title_window_icon padding <px>'
+ *
+ */
+void cmd_title_window_icon(I3_CMD, const char *enable, int padding);

include/data.h

@@ -15,6 +15,7 @@
 #include <xcb/randr.h>
 #include <pcre.h>
 #include <sys/time.h>
+#include <cairo/cairo.h>
 
 #include "queue.h"
 
@@ -471,6 +472,9 @@ struct Window {
     double min_aspect_ratio;
     double max_aspect_ratio;
 
+    /** Window icon, as Cairo surface */
+    cairo_surface_t *icon;
+
     /** The window has a nonrectangular shape. */
     bool shaped;
     /** The window has a nonrectangular input shape. */
@@ -656,6 +660,11 @@ struct Con {
     /** The format with which the window's name should be displayed. */
     char *title_format;
 
+    /** Whether the window icon should be displayed, and with what padding. -1
+      * means display no window icon (default behavior), 0 means display without
+      * any padding, 1 means display with 1 pixel of padding and so on. */
+    int window_icon_padding;
+
     /* a sticky-group is an identifier which bundles several containers to a
      * group. The contents are shared between all of them, that is they are
      * displayed on whichever of the containers is currently visible */

include/i3-atoms_rest.xmacro.h

@@ -3,6 +3,7 @@
 xmacro(_NET_WM_USER_TIME) \
 xmacro(_NET_STARTUP_ID) \
 xmacro(_NET_WORKAREA) \
+xmacro(_NET_WM_ICON) \
 xmacro(WM_PROTOCOLS) \
 xmacro(WM_DELETE_WINDOW) \
 xmacro(UTF8_STRING) \

include/libi3.h

@@ -611,6 +611,11 @@ color_t draw_util_hex_to_color(const char *color);
  */
 void draw_util_text(i3String *text, surface_t *surface, color_t fg_color, color_t bg_color, int x, int y, int max_width);
 
+/**
+ * Draw the given image using libi3.
+ */
+void draw_util_image(cairo_surface_t *image, surface_t *surface, int x, int y, int width, int height);
+
 /**
  * Draws a filled rectangle.
  * This function is a convenience wrapper and takes care of flushing the
@@ -668,3 +673,9 @@ void set_screenshot_as_wallpaper(xcb_connection_t *conn, xcb_screen_t *screen);
  * content of the window.
  */
 bool is_background_set(xcb_connection_t *conn, xcb_screen_t *screen);
+
+/**
+ * Reports whether str represents the enabled state (1, yes, true, …).
+ *
+ */
+bool boolstr(const char *str);

include/window.h

@@ -101,3 +101,9 @@ void window_update_motif_hints(i3Window *win, xcb_get_property_reply_t *prop, bo
  *
  */
 void window_update_machine(i3Window *win, xcb_get_property_reply_t *prop);
+
+/**
+ * Updates the _NET_WM_ICON
+ *
+ */
+void window_update_icon(i3Window *win, xcb_get_property_reply_t *prop);