Use different colors for active/inactive titles

Implement the twin_active_pixmap() function to find the currently active
pixel map and the previously active pixel map. Utilize the window's
active variable to draw different frame colors for the active window
and inactive windows.

Close #86

Signed-off-by: Wei-Hsin Yeh <weihsinyeh168@gmail.com>

Author: weihsinyeh

include/twin.h

@@ -425,6 +425,7 @@ struct _twin_window {
     twin_window_style_t style;
     twin_rect_t client;
     twin_rect_t damage;
+    bool active;
     bool client_grab;
     bool want_focus;
     bool draw_queued;

src/screen.c

@@ -151,6 +151,25 @@ static void twin_screen_span_pixmap(twin_screen_t maybe_unused *screen,
         op32(dst, src, p_right - p_left);
 }
 
+static twin_pixmap_t *twin_active_pixmap(twin_screen_t *screen,
+                                         twin_pixmap_t **active_pix)
+{
+    twin_pixmap_t *p = NULL, *prev_active_pix = NULL;
+    /*
+     * Identify the previously active pixel map and the currently active pixel
+     * map, which is on the topmost layer.
+     */
+    for (p = screen->bottom; p; p = p->up) {
+        if (p->window->active == true) {
+            prev_active_pix = p;
+            prev_active_pix->window->active = false;
+        }
+        (*active_pix) = p;
+    }
+    (*active_pix)->window->active = true;
+    return prev_active_pix;
+}
+
 void twin_screen_update(twin_screen_t *screen)
 {
     twin_coord_t left = screen->damage.left;
@@ -170,7 +189,7 @@ void twin_screen_update(twin_screen_t *screen)
 
     if (!screen->disable && left < right && top < bottom) {
         twin_argb32_t *span;
-        twin_pixmap_t *p;
+        twin_pixmap_t *p, *active_pix = NULL, *prev_active_pix = NULL;
         twin_coord_t y;
         twin_coord_t width = right - left;
 
@@ -183,6 +202,24 @@ void twin_screen_update(twin_screen_t *screen)
 
         if (screen->put_begin)
             (*screen->put_begin)(left, top, right, bottom, screen->closure);
+
+        prev_active_pix = twin_active_pixmap(screen, &active_pix);
+
+        /*
+         * Mark the previously active pixel map as damaged to update its
+         * changes.
+         */
+        if (prev_active_pix && active_pix != prev_active_pix) {
+            twin_pixmap_damage(prev_active_pix, 0, 0, prev_active_pix->width,
+                               prev_active_pix->height);
+            twin_window_draw(prev_active_pix->window);
+        }
+
+        /* Mark the active pixel map as damaged to update its changes. */
+        twin_pixmap_damage(active_pix, 0, 0, active_pix->width,
+                           active_pix->height);
+        twin_window_draw(active_pix->window);
+
         for (y = top; y < bottom; y++) {
             if (screen->background) {
                 twin_pointer_t dst;

src/window.c

@@ -9,9 +9,10 @@
 #include "twin_private.h"
 
 #define TWIN_ACTIVE_BG 0xd03b80ae
-#define TWIN_INACTIVE_BG 0xff808080
+#define TWIN_INACTIVE_BG 0xffb0b0b0
 #define TWIN_FRAME_TEXT 0xffffffff
 #define TWIN_ACTIVE_BORDER 0xff606060
+#define TWIN_INACTIVE_BORDER 0xff909090
 #define TWIN_BW 0
 #define TWIN_TITLE_HEIGHT 20
 #define TWIN_RESIZE_SIZE ((TWIN_TITLE_HEIGHT + 4) / 5)
@@ -32,6 +33,7 @@ twin_window_t *twin_window_create(twin_screen_t *screen,
         return NULL;
     window->screen = screen;
     window->style = style;
+    window->active = false;
     switch (window->style) {
     case TwinWindowApplication:
         left = TWIN_BW;
@@ -226,9 +228,13 @@ static void twin_window_frame(twin_window_t *window)
                     c_left, c_top);
     twin_path_close(path);
 
-    twin_paint_path(pixmap, TWIN_ACTIVE_BG, path);
-
-    twin_paint_stroke(pixmap, TWIN_ACTIVE_BORDER, path, bw_2 * 2);
+    if (window->active) {
+        twin_paint_path(pixmap, TWIN_ACTIVE_BG, path);
+        twin_paint_stroke(pixmap, TWIN_ACTIVE_BORDER, path, bw_2 * 2);
+    } else {
+        twin_paint_path(pixmap, TWIN_INACTIVE_BG, path);
+        twin_paint_stroke(pixmap, TWIN_INACTIVE_BORDER, path, bw_2 * 2);
+    }
 
     twin_path_empty(path);