fix cairo global alpha

bin/.gitignore

@@ -1,13 +0,0 @@
-demoui
-genascii
-mem_test
-qt_to_xml
-runLua	
-themegen
-demo1		
-fontgen		
-imagegen	
-prefix_xml_ui	
-rc_to_xml	
-runTest		
-xml_to_ui

demos/demo_vg_app.c

@@ -336,6 +336,39 @@ static ret_t on_paint_vg(void* ctx, event_t* e) {
   return RET_OK;
 }
 
+static ret_t on_paint_global_alpha(void* ctx, event_t* e) {
+  bitmap_t img;
+  paint_event_t* evt = (paint_event_t*)e;
+  canvas_t* c = evt->c;
+  vgcanvas_t* vg = canvas_get_vgcanvas(c);
+  color_t fill = color_init(0x00, 0xff, 0x00,  0xff);
+  color_t stroke = color_init(0x00, 0x00, 0xff,  0xff);
+
+  vgcanvas_save(vg);
+
+  image_manager_get_bitmap(image_manager(), "bricks", &img);
+  vgcanvas_set_global_alpha(vg, 1);
+  vgcanvas_draw_image(vg, &img, 0, 0, img.w, img.h, 0, 0, img.w, img.h);
+  
+  vgcanvas_set_global_alpha(vg, 0.5);
+
+  vgcanvas_set_fill_color(vg, fill);
+  vgcanvas_rect(vg, 0, 0, 20, 20);
+  vgcanvas_fill(vg);
+  
+  vgcanvas_set_stroke_color(vg, stroke);
+  vgcanvas_set_line_width(vg, 5);
+  vgcanvas_rect(vg, 20, 20, 20, 20);
+  vgcanvas_stroke(vg);
+
+  vgcanvas_translate(vg, 15, 15);
+  vgcanvas_draw_image(vg, &img, 0, 0, img.w, img.h, 0, 0, img.w, img.h);
+
+  vgcanvas_restore(vg);
+
+  return RET_OK;
+}
+
 static ret_t on_paint_vg_simple(void* ctx, event_t* e) {
   bitmap_t img;
   paint_event_t* evt = (paint_event_t*)e;
@@ -417,6 +450,7 @@ ret_t application_init() {
 
   // widget_on(canvas, EVT_PAINT, on_paint_vg_simple, NULL);
   widget_on(canvas, EVT_PAINT, on_paint_vg, NULL);
+  //widget_on(canvas, EVT_PAINT, on_paint_global_alpha, NULL);
 
   timer_add(on_timer, win, 500);
 

docs/changes.md

@@ -2,6 +2,7 @@
 * 2019/06/25
   * 完善 slider。dragger 以实际 icon 为准。
   * 让 bitmap 引用 image\_manager 以区分 bitmap 是由哪个 image\_manager 加载的。
+  * 修改cairo global alpha的BUG，目前draw_image/fill/stroke支持global alpha, gradient暂时不支持。
 
 * 2019/06/24
   * 用 stb\_text\_edit 重新实现 edit 控件，支持取消、重做、全选、拷贝、剪切、粘贴和键盘选择等功能。

src/vgcanvas/vgcanvas_cairo.c

@@ -58,7 +58,7 @@ ret_t vgcanvas_cairo_begin_frame(vgcanvas_t* vgcanvas, rect_t* dirty_rect) {
   cairo_clip(vg);
   cairo_new_path(vg);
   cairo_save(vg);
-  vgcanvas->global_alpha = 0xff;
+  vgcanvas->global_alpha = 1;
 
   return RET_OK;
 }
@@ -301,8 +301,10 @@ static ret_t vgcanvas_cairo_fill(vgcanvas_t* vgcanvas) {
   vgcanvas_cairo_t* canvas = (vgcanvas_cairo_t*)vgcanvas;
 
   if (canvas->fill_source_type == CAIRO_SOURCE_GRADIENT) {
+    /*not support global alpha yet*/
     cairo_set_source(vg, canvas->fill_gradient);
   } else {
+    c.rgba.a = c.rgba.a * vgcanvas->global_alpha;
     cairo_set_source_color(vg, c);
   }
 
@@ -328,8 +330,10 @@ static ret_t vgcanvas_cairo_stroke(vgcanvas_t* vgcanvas) {
   vgcanvas_cairo_t* canvas = (vgcanvas_cairo_t*)vgcanvas;
 
   if (canvas->stroke_source_type == CAIRO_SOURCE_GRADIENT) {
+    /*not support global alpha yet*/
     cairo_set_source(vg, canvas->stroke_gradient);
   } else {
+    c.rgba.a = c.rgba.a * vgcanvas->global_alpha;
     cairo_set_source_color(vg, c);
   }
 
@@ -462,7 +466,7 @@ static ret_t vgcanvas_cairo_draw_image(vgcanvas_t* vgcanvas, bitmap_t* img, floa
                                        float_t dh) {
   float fx = (float)dw / sw;
   float fy = (float)dh / sh;
-  float_t global_alpha = 1;
+  float_t global_alpha = vgcanvas->global_alpha;
   cairo_t* vg = ((vgcanvas_cairo_t*)vgcanvas)->vg;
   cairo_surface_t* surface = vgcanvas_cairo_ensure_image((vgcanvas_cairo_t*)vgcanvas, img);
 
@@ -506,10 +510,6 @@ static ret_t vgcanvas_cairo_set_line_width(vgcanvas_t* vgcanvas, float_t value)
 }
 
 static ret_t vgcanvas_cairo_set_global_alpha(vgcanvas_t* vgcanvas, float_t value) {
-  cairo_t* vg = ((vgcanvas_cairo_t*)vgcanvas)->vg;
-
-  cairo_paint_with_alpha(vg, value);
-
   return RET_OK;
 }
 
@@ -841,7 +841,8 @@ vgcanvas_t* vgcanvas_create(uint32_t w, uint32_t h, uint32_t stride, bitmap_form
   cairo->vg = cairo_create(surface);
   return_value_if_fail(cairo->vg, NULL);
   darray_init(&(cairo->images), 10, (tk_destroy_t)bitmap_destroy, (tk_compare_t)cairo_bitmap_cmp);
-
+  vgcanvas_set_global_alpha((vgcanvas_t*)cairo, 1);
+  
   log_debug("vgcanvas_cairo created\n");
   return &(cairo->base);
 }