cairo: replace cairo with pixman in decos, particles and modules

All decoration, particle and module interfaces now takes a
pixman_image_t parameter, and all drawing is done using pixman APIs.

The wayland/xcb backends implement a new interface functions,
get_pixman_image(), that should return a pixman image instance that is
suitable for rendering.

In the wayland backend, the image uses the same backing data as the
cairo surface.

In the XCB backend, we create a new image each time, and then blit it
to the cairo surface at commit time.

bar/backend.h

@@ -11,7 +11,8 @@ struct backend {
                  void (*expose)(const struct bar *bar),
                  void (*on_mouse)(struct bar *bar, enum mouse_event event,
                                   int x, int y));
-    void (*commit_surface)(const struct bar *bar);
+    pixman_image_t *(*get_pixman_image)(const struct bar *bar);
+    void (*commit_pixman)(const struct bar *bar, pixman_image_t *pix);
     void (*refresh)(const struct bar *bar);
     void (*set_cursor)(struct bar *bar, const char *cursor);
 };

bar/bar.c

@@ -61,33 +61,21 @@ static void
 expose(const struct bar *_bar)
 {
     const struct private *bar = _bar->private;
+    pixman_image_t *pix = bar->backend.iface->get_pixman_image(_bar);
 
-    double r, g, b, a;
-    r = bar->background.red;
-    g = bar->background.green;
-    b = bar->background.blue;
-    a = bar->background.alpha;
-
-    cairo_set_source_rgba(bar->cairo, r, g, b, a);
-    cairo_set_operator(bar->cairo, CAIRO_OPERATOR_SOURCE);
-    cairo_paint(bar->cairo);
+    pixman_image_fill_rectangles(
+        PIXMAN_OP_SRC, pix, &bar->background, 1,
+        &(pixman_rectangle16_t){0, 0, bar->width, bar->height_with_border});
 
     if (bar->border.width > 0) {
-        r = bar->border.color.red;
-        g = bar->border.color.green;
-        b = bar->border.color.blue;
-        a = bar->border.color.alpha;
-
-        cairo_set_line_width(bar->cairo, bar->border.width);
-        cairo_set_source_rgba(bar->cairo, r, g, b, a);
-        cairo_set_operator(bar->cairo, CAIRO_OPERATOR_OVER);
-        cairo_rectangle(
-            bar->cairo,
-            bar->border.width / 2.0,
-            bar->border.width / 2.0,
-            bar->width - bar->border.width,
-            bar->height_with_border - bar->border.width);
-        cairo_stroke(bar->cairo);
+        pixman_image_fill_rectangles(
+            PIXMAN_OP_OVER, pix, &bar->border.color, 4,
+            (pixman_rectangle16_t[]){
+                {0, 0, bar->width, bar->border.width},
+                {0, 0, bar->border.width, bar->height},
+                {bar->width - bar->border.width, 0, bar->border.width, bar->height},
+                {0, bar->height - bar->border.width, bar->width, bar->border.width},
+            });
     }
 
     for (size_t i = 0; i < bar->left.count; i++) {
@@ -127,14 +115,14 @@ expose(const struct bar *_bar)
     int x = bar->border.width + bar->left_margin - bar->left_spacing;
     for (size_t i = 0; i < bar->left.count; i++) {
         const struct exposable *e = bar->left.exps[i];
-        e->expose(e, bar->cairo, x + bar->left_spacing, y, bar->height);
+        e->expose(e, pix, x + bar->left_spacing, y, bar->height);
         x += bar->left_spacing + e->width + bar->right_spacing;
     }
 
     x = bar->width / 2 - center_width / 2 - bar->left_spacing;
     for (size_t i = 0; i < bar->center.count; i++) {
         const struct exposable *e = bar->center.exps[i];
-        e->expose(e, bar->cairo, x + bar->left_spacing, y, bar->height);
+        e->expose(e, pix, x + bar->left_spacing, y, bar->height);
         x += bar->left_spacing + e->width + bar->right_spacing;
     }
 
@@ -146,12 +134,11 @@ expose(const struct bar *_bar)
 
     for (size_t i = 0; i < bar->right.count; i++) {
         const struct exposable *e = bar->right.exps[i];
-        e->expose(e, bar->cairo, x + bar->left_spacing, y, bar->height);
+        e->expose(e, pix, x + bar->left_spacing, y, bar->height);
         x += bar->left_spacing + e->width + bar->right_spacing;
     }
 
-    cairo_surface_flush(bar->cairo_surface);
-    bar->backend.iface->commit_surface(_bar);
+    bar->backend.iface->commit_pixman(_bar, pix);
 }
 
 

bar/bar.h

@@ -26,11 +26,11 @@ struct bar_config {
     int left_spacing, right_spacing;
     int left_margin, right_margin;
 
-    struct rgba background;
+    pixman_color_t background;
 
     struct {
         int width;
-        struct rgba color;
+        pixman_color_t color;
         int left_margin, right_margin;
         int top_margin, bottom_margin;
     } border;

bar/private.h

@@ -14,11 +14,11 @@ struct private {
     int left_spacing, right_spacing;
     int left_margin, right_margin;
 
-    struct rgba background;
+    pixman_color_t background;
 
     struct {
         int width;
-        struct rgba color;
+        pixman_color_t color;
         int left_margin, right_margin;
         int top_margin, bottom_margin;
     } border;

bar/wayland.c

@@ -901,12 +901,31 @@ frame_callback(void *data, struct wl_callback *wl_callback, uint32_t callback_da
         ;//printf("nothing more to do\n");
 }
 
+static pixman_image_t *
+get_pixman_image(const struct bar *_bar)
+{
+    struct private *bar = _bar->private;
+
+    cairo_surface_t *surf = cairo_get_target(bar->cairo);
+    cairo_surface_flush(surf);
+
+    return pixman_image_create_bits_no_clear(
+        PIXMAN_a8r8g8b8,
+        cairo_image_surface_get_width(surf),
+        cairo_image_surface_get_height(surf),
+        (uint32_t *)cairo_image_surface_get_data(surf),
+        cairo_image_surface_get_stride(surf));
+}
+
 static void
-commit_surface(const struct bar *_bar)
+commit_pixman(const struct bar *_bar, pixman_image_t *pix)
 {
     struct private *bar = _bar->private;
     struct wayland_backend *backend = bar->backend.data;
 
+    pixman_image_unref(pix);
+    cairo_surface_mark_dirty(cairo_get_target(bar->cairo));
+
     //printf("commit: %dxl%d\n", backend->width, backend->height);
 
     assert(backend->next_buffer != NULL);
@@ -973,7 +992,8 @@ const struct backend wayland_backend_iface = {
     .setup = &setup,
     .cleanup = &cleanup,
     .loop = &loop,
-    .commit_surface = &commit_surface,
+    .get_pixman_image = &get_pixman_image,
+    .commit_pixman = &commit_pixman,
     .refresh = &refresh,
     .set_cursor = &set_cursor,
 };

bar/xcb.c

@@ -370,10 +370,56 @@ loop(struct bar *_bar,
 }
 
 static void
-commit_surface(const struct bar *_bar)
+free_pixman_bits(pixman_image_t *pix, void *data)
+{
+    free(data);
+}
+
+static pixman_image_t *
+get_pixman_image(const struct bar *_bar)
+{
+    const struct private *bar = _bar->private;
+    uint32_t *bits = malloc(
+        bar->width * bar->height_with_border * sizeof(uint32_t));
+
+    pixman_image_t *ret = pixman_image_create_bits_no_clear(
+        PIXMAN_a8r8g8b8,
+        bar->width,
+        bar->height_with_border,
+        bits,
+        bar->width * sizeof(uint32_t));
+
+    if (ret == NULL) {
+        free(bits);
+        return NULL;
+    }
+
+    pixman_image_set_destroy_function(ret, &free_pixman_bits, bits);
+    return ret;
+}
+
+static void
+commit_pixman(const struct bar *_bar, pixman_image_t *pix)
 {
     const struct private *bar = _bar->private;
     const struct xcb_backend *backend = bar->backend.data;
+
+    /* Blit pixman image to our XCB surface */
+    cairo_surface_t *surf = cairo_image_surface_create_for_data(
+        (unsigned char *)pixman_image_get_data(pix),
+        CAIRO_FORMAT_ARGB32,
+        bar->width,
+        bar->height_with_border,
+        cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, bar->width));
+
+    cairo_set_source_surface(bar->cairo, surf, 0, 0);
+    cairo_set_operator(bar->cairo, CAIRO_OPERATOR_SOURCE);
+    cairo_paint(bar->cairo);
+
+    cairo_surface_flush(bar->cairo_surface);
+    cairo_surface_destroy(surf);
+    pixman_image_unref(pix);
+
     xcb_copy_area(backend->conn, backend->pixmap, backend->win, backend->gc,
                   0, 0, 0, 0, bar->width, bar->height_with_border);
     xcb_flush(backend->conn);
@@ -430,7 +476,8 @@ const struct backend xcb_backend_iface = {
     .setup = &setup,
     .cleanup = &cleanup,
     .loop = &loop,
-    .commit_surface = &commit_surface,
+    .get_pixman_image = &get_pixman_image,
+    .commit_pixman = &commit_pixman,
     .refresh = &refresh,
     .set_cursor = &set_cursor,
 };