# Rebased from: https://github.com/i3/i3/compare/4.13...mickael9:window-icons.diff
# For i3-4.14

# Add support for window icons in the i3 title bar.
# This makes it easier to distinguish windows without reading their names,
#   and makes it possible to use browsers like qutebrowser in tabbed mode.

diff --git a/include/atoms_rest.xmacro b/include/atoms_rest.xmacro
index d461dc08..f32a7e1e 100644
--- a/include/atoms_rest.xmacro
+++ b/include/atoms_rest.xmacro
@@ -1,6 +1,7 @@
 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)
diff --git a/include/data.h b/include/data.h
index 69a79ade..4bd84a02 100644
--- a/include/data.h
+++ b/include/data.h
@@ -460,6 +460,11 @@ struct Window {
 
     /* aspect ratio from WM_NORMAL_HINTS (MPlayer uses this for example) */
     double aspect_ratio;
+
+    /** Window icon, as array of ARGB pixels */
+    uint32_t* icon;
+    int icon_width;
+    int icon_height;
 };
 
 /**
diff --git a/include/libi3.h b/include/libi3.h
index dbb29e1f..bd898b06 100644
--- a/include/libi3.h
+++ b/include/libi3.h
@@ -601,6 +601,11 @@ 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(unsigned char *src, int src_width, int src_height, 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
diff --git a/include/window.h b/include/window.h
index 77e3f48f..894ee9fd 100644
--- a/include/window.h
+++ b/include/window.h
@@ -89,3 +89,9 @@ void window_update_hints(i3Window *win, xcb_get_property_reply_t *prop, bool *ur
  *
  */
 void window_update_motif_hints(i3Window *win, xcb_get_property_reply_t *prop, border_style_t *motif_border_style);
+
+/**
+ * Updates the _NET_WM_ICON
+ *
+ */
+void window_update_icon(i3Window *win, xcb_get_property_reply_t *prop);
diff --git a/libi3/draw_util.c b/libi3/draw_util.c
index 6a2e93dc..2147effc 100644
--- a/libi3/draw_util.c
+++ b/libi3/draw_util.c
@@ -140,6 +140,42 @@ void draw_util_text(i3String *text, surface_t *surface, color_t fg_color, color_
     cairo_surface_mark_dirty(surface->surface);
 }
 
+
+/**
+ * Draw the given image using libi3.
+ * This function is a convenience wrapper and takes care of flushing the
+ * surface as well as restoring the cairo state.
+ *
+ */
+void draw_util_image(unsigned char *src, int src_width, int src_height, surface_t *surface, int x, int y, int width, int height) {
+    RETURN_UNLESS_SURFACE_INITIALIZED(surface);
+
+    double scale;
+
+    cairo_save(surface->cr);
+
+    cairo_surface_t *image;
+
+    image = cairo_image_surface_create_for_data(
+            src,
+            CAIRO_FORMAT_ARGB32,
+            src_width,
+            src_height,
+            src_width * 4);
+
+    cairo_translate(surface->cr, x, y);
+
+    scale = MIN((double)width / src_width, (double)height / src_height);
+    cairo_scale(surface->cr, scale, scale);
+
+    cairo_set_source_surface(surface->cr, image, 0, 0);
+    cairo_paint(surface->cr);
+
+    cairo_surface_destroy(image);
+
+    cairo_restore(surface->cr);
+}
+
 /**
  * Draws a filled rectangle.
  * This function is a convenience wrapper and takes care of flushing the
diff --git a/src/handlers.c b/src/handlers.c
index c273e116..0bea73bb 100644
--- a/src/handlers.c
+++ b/src/handlers.c
@@ -1400,6 +1400,19 @@ static bool handle_strut_partial_change(void *data, xcb_connection_t *conn, uint
     return true;
 }
 
+static bool handle_windowicon_change(void *data, xcb_connection_t *conn, uint8_t state,
+                                     xcb_window_t window, xcb_atom_t atom, xcb_get_property_reply_t *prop) {
+    Con *con;
+    if ((con = con_by_window_id(window)) == NULL || con->window == NULL)
+        return false;
+
+    window_update_icon(con->window, prop);
+
+    x_push_changes(croot);
+
+    return true;
+}
+
 /* Returns false if the event could not be processed (e.g. the window could not
  * be found), true otherwise */
 typedef bool (*cb_property_handler_t)(void *data, xcb_connection_t *c, uint8_t state, xcb_window_t window, xcb_atom_t atom, xcb_get_property_reply_t *property);
@@ -1421,7 +1434,8 @@ static struct property_handler_t property_handlers[] = {
     {0, 128, handle_class_change},
     {0, UINT_MAX, handle_strut_partial_change},
     {0, UINT_MAX, handle_window_type},
-    {0, 5 * sizeof(uint64_t), handle_motif_hints_change}};
+    {0, 5 * sizeof(uint64_t), handle_motif_hints_change},
+    {0, UINT_MAX, handle_windowicon_change}};
 #define NUM_HANDLERS (sizeof(property_handlers) / sizeof(struct property_handler_t))
 
 /*
@@ -1443,6 +1457,7 @@ void property_handlers_init(void) {
     property_handlers[8].atom = A__NET_WM_STRUT_PARTIAL;
     property_handlers[9].atom = A__NET_WM_WINDOW_TYPE;
     property_handlers[10].atom = A__MOTIF_WM_HINTS;
+    property_handlers[11].atom = A__NET_WM_ICON;
 }
 
 static void property_notify(uint8_t state, xcb_window_t window, xcb_atom_t atom) {
diff --git a/src/manage.c b/src/manage.c
index 86a361c3..adbd3456 100644
--- a/src/manage.c
+++ b/src/manage.c
@@ -91,6 +91,8 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
         role_cookie, startup_id_cookie, wm_hints_cookie,
         wm_normal_hints_cookie, motif_wm_hints_cookie, wm_user_time_cookie, wm_desktop_cookie;
 
+    xcb_get_property_cookie_t wm_icon_cookie;
+
     geomc = xcb_get_geometry(conn, d);
 
     /* Check if the window is mapped (it could be not mapped when intializing and
@@ -162,6 +164,7 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
     motif_wm_hints_cookie = GET_PROPERTY(A__MOTIF_WM_HINTS, 5 * sizeof(uint64_t));
     wm_user_time_cookie = GET_PROPERTY(A__NET_WM_USER_TIME, UINT32_MAX);
     wm_desktop_cookie = GET_PROPERTY(A__NET_WM_DESKTOP, UINT32_MAX);
+    wm_icon_cookie = GET_PROPERTY(A__NET_WM_ICON, UINT32_MAX);
 
     DLOG("Managing window 0x%08x\n", window);
 
@@ -177,6 +180,7 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
     window_update_class(cwindow, xcb_get_property_reply(conn, class_cookie, NULL), true);
     window_update_name_legacy(cwindow, xcb_get_property_reply(conn, title_cookie, NULL), true);
     window_update_name(cwindow, xcb_get_property_reply(conn, utf8_title_cookie, NULL), true);
+    window_update_icon(cwindow, xcb_get_property_reply(conn, wm_icon_cookie, NULL));
     window_update_leader(cwindow, xcb_get_property_reply(conn, leader_cookie, NULL));
     window_update_transient_for(cwindow, xcb_get_property_reply(conn, transient_cookie, NULL));
     window_update_strut_partial(cwindow, xcb_get_property_reply(conn, strut_cookie, NULL));
@@ -185,6 +189,8 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
     window_update_hints(cwindow, xcb_get_property_reply(conn, wm_hints_cookie, NULL), &urgency_hint);
     border_style_t motif_border_style = BS_NORMAL;
     window_update_motif_hints(cwindow, xcb_get_property_reply(conn, motif_wm_hints_cookie, NULL), &motif_border_style);
+
+
     xcb_size_hints_t wm_size_hints;
     if (!xcb_icccm_get_wm_size_hints_reply(conn, wm_normal_hints_cookie, &wm_size_hints, NULL))
         memset(&wm_size_hints, '\0', sizeof(xcb_size_hints_t));
diff --git a/src/render.c b/src/render.c
index 85548f26..6380f51a 100644
--- a/src/render.c
+++ b/src/render.c
@@ -125,6 +125,10 @@ void render_con(Con *con, bool render_fullscreen) {
     /* find the height for the decorations */
     params.deco_height = render_deco_height();
 
+    /* minimum decoration height to allow icon to fit
+     * not actually required, icon would be cropped otherwise */
+    params.deco_height = (params.deco_height < 16) ? 16 : params.deco_height;
+
     /* precalculate the sizes to be able to correct rounding errors */
     params.sizes = precalculate_sizes(con, &params);
 
diff --git a/src/window.c b/src/window.c
index db6215d0..5b694593 100644
--- a/src/window.c
+++ b/src/window.c
@@ -17,6 +17,7 @@ void window_free(i3Window *win) {
     FREE(win->class_class);
     FREE(win->class_instance);
     i3string_free(win->name);
+    FREE(win->icon);
     FREE(win->ran_assignments);
     FREE(win);
 }
@@ -365,3 +366,75 @@ void window_update_motif_hints(i3Window *win, xcb_get_property_reply_t *prop, bo
 #undef MWM_DECOR_BORDER
 #undef MWM_DECOR_TITLE
 }
+
+void window_update_icon(i3Window *win, xcb_get_property_reply_t *prop)
+{
+    uint32_t *data = NULL;
+    uint64_t len = 0;
+
+    if (!prop || prop->type != XCB_ATOM_CARDINAL || prop->format != 32) {
+        DLOG("_NET_WM_ICON is not set\n");
+        FREE(prop);
+        return;
+    }
+
+    uint32_t prop_value_len = xcb_get_property_value_length(prop);
+    uint32_t *prop_value = (uint32_t *) xcb_get_property_value(prop);
+
+    /* Find the number of icons in the reply. */
+    while (prop_value_len > (sizeof(uint32_t) * 2) && prop_value &&
+            prop_value[0] && prop_value[1])
+    {
+        /* Check that the property is as long as it should be (in bytes),
+           handling integer overflow. "+2" to handle the width and height
+           fields. */
+        const uint64_t crt_len = prop_value[0] * (uint64_t) prop_value[1];
+        const uint64_t expected_len = (crt_len + 2) * 4;
+
+        if (expected_len > prop_value_len) {
+            break;
+        }
+
+        if (len == 0 || (crt_len >= 16*16 && crt_len < len)) {
+            len = crt_len;
+            data = prop_value;
+        }
+        if (len == 16*16) {
+            break; /* found 16 pixels icon */
+        }
+
+        /* Find pointer to next icon in the reply. */
+        prop_value_len -= expected_len;
+        prop_value = (uint32_t *) (((uint8_t *) prop_value) + expected_len);
+    }
+
+    if (!data) {
+        DLOG("Could not get _NET_WM_ICON\n");
+        FREE(prop);
+        return;
+    }
+
+    LOG("Got _NET_WM_ICON of size: (%d,%d)\n", data[0], data[1]);
+    win->name_x_changed = true; /* trigger a redraw */
+
+    win->icon_width = data[0];
+    win->icon_height = data[1];
+    win->icon = srealloc(win->icon, len * 4);
+
+    for (uint64_t i = 0; i < len; i++) {
+        uint8_t r, g, b, a;
+        a = (data[2 + i] >> 24) & 0xff;
+        r = (data[2 + i] >> 16) & 0xff;
+        g = (data[2 + i] >>  8) & 0xff;
+        b = (data[2 + i] >>  0) & 0xff;
+
+        /* Cairo uses premultiplied alpha */
+        r = (r * a) / 0xff;
+        g = (g * a) / 0xff;
+        b = (b * a) / 0xff;
+
+        win->icon[i] = (a << 24) | (r << 16) | (g << 8) | b;
+    }
+
+    FREE(prop);
+}
diff --git a/src/x.c b/src/x.c
index ee5ed2ce..00d86829 100644
--- a/src/x.c
+++ b/src/x.c
@@ -546,6 +546,7 @@ void x_draw_decoration(Con *con) {
 
     /* 6: draw the title */
     int text_offset_y = (con->deco_rect.height - config.font.height) / 2;
+    int text_offset_x = 0;
 
     struct Window *win = con->window;
     if (win == NULL) {
@@ -572,6 +573,9 @@ void x_draw_decoration(Con *con) {
         goto after_title;
     }
 
+    if (win->icon)
+        text_offset_x = 18;
+
     int mark_width = 0;
     if (config.show_marks && !TAILQ_EMPTY(&(con->marks_head))) {
         char *formatted_mark = sstrdup("");
@@ -611,14 +615,32 @@ void x_draw_decoration(Con *con) {
 
     draw_util_text(title, &(parent->frame_buffer),
                    p->color->text, p->color->background,
-                   con->deco_rect.x + logical_px(2),
+                   con->deco_rect.x + text_offset_x + logical_px(2),
                    con->deco_rect.y + text_offset_y,
-                   con->deco_rect.width - mark_width - 2 * logical_px(2));
+                   con->deco_rect.width - text_offset_x - mark_width - 2 * logical_px(2));
 
     if (con->title_format != NULL) {
         I3STRING_FREE(title);
     }
 
+    /* Draw the icon */
+    if (win->icon) {
+        uint16_t width = 16;
+        uint16_t height = 16;
+
+        int icon_offset_y = (con->deco_rect.height - height) / 2;
+
+        draw_util_image(
+                (unsigned char *)win->icon,
+                win->icon_width,
+                win->icon_height,
+                &(parent->frame_buffer),
+                con->deco_rect.x + logical_px(2),
+                con->deco_rect.y + icon_offset_y,
+                width,
+                height);
+    }
+
 after_title:
     x_draw_decoration_after_title(con, p);
 copy_pixmaps: