linear gradients - GL implementation, vertical only

src/dlangui/graphics/drawbuf.d

@@ -288,6 +288,8 @@ class DrawBuf : RefCountedObject {
     abstract void fill(uint color);
     /// fill rectangle with solid color (clipping is applied)
     abstract void fillRect(Rect rc, uint color);
+    /// fill rectangle with a gradient (clipping is applied)
+    abstract void fillGradientRect(Rect rc, uint color1, uint color2);
     /// fill rectangle with solid color and pattern (clipping is applied) 0=solid fill, 1 = dotted
     void fillRectPattern(Rect rc, uint color, int pattern) {
         // default implementation: does not support patterns
@@ -1161,6 +1163,11 @@ class ColorDrawBufBase : DrawBuf {
         }
     }
 
+    override void fillGradientRect(Rect rc, uint color1, uint color2) {
+        // TODO
+        fillRect(rc, color1);
+    }
+
     /// fill rectangle with solid color and pattern (clipping is applied) 0=solid fill, 1 = dotted
     override void fillRectPattern(Rect rc, uint color, int pattern) {
         uint alpha = color >> 24;
@@ -1406,6 +1413,11 @@ class GrayDrawBuf : DrawBuf {
         }
     }
 
+    override void fillGradientRect(Rect rc, uint color1, uint color2) {
+        // TODO
+        fillRect(rc, color1);
+    }
+
     /// draw pixel at (x, y) with specified color
     override void drawPixel(int x, int y, uint color) {
         if (!_clipRect.isPointInside(x, y))

src/dlangui/graphics/gldrawbuf.d

@@ -114,6 +114,15 @@ class GLDrawBuf : DrawBuf, GLConfigCallback {
             _scene.add(new SolidRectSceneItem(rc, color));
     }
 
+    /// fill rectangle with a gradient (clipping is applied)
+    override void fillGradientRect(Rect rc, uint color1, uint color2) {
+        assert(_scene !is null);
+        color1 = applyAlpha(color1);
+        color2 = applyAlpha(color2);
+        if (!(isFullyTransparentColor(color1) && isFullyTransparentColor(color2)) && applyClipping(rc))
+            _scene.add(new GradientRectSceneItem(rc, color1, color2));
+    }
+
     /// fill rectangle with solid color and pattern (clipping is applied) 0=solid fill, 1 = dotted
     override void fillRectPattern(Rect rc, uint color, int pattern) {
         if (pattern == PatternType.solid)
@@ -749,6 +758,23 @@ public:
     }
 }
 
+private class GradientRectSceneItem : SceneItem {
+private:
+    Rect _rc;
+    uint _color1;
+    uint _color2;
+
+public:
+    this(Rect rc, uint color1, uint color2) {
+        _rc = rc;
+        _color1 = color1;
+        _color2 = color2;
+    }
+    override void draw() {
+        glSupport.queue.addGradientRect(_rc, _color1, _color2, _color1, _color2);
+    }
+}
+
 private class PatternRectSceneItem : SceneItem {
 private:
     Rect _rc;

src/dlangui/graphics/resources.d

@@ -337,7 +337,7 @@ class GradientDrawable : Drawable {
         _color2 = color2;
     }
     override void drawTo(DrawBuf buf, Rect rc, uint state = 0, int tilex0 = 0, int tiley0 = 0) {
-        buf.fillRect(rc, _color1); // stub
+        buf.fillGradientRect(rc, _color1, _color2);
     }
     @property override int width() { return 1; }
     @property override int height() { return 1; }

src/dlangui/platforms/console/consoleapp.d

@@ -406,6 +406,11 @@ class ConsoleDrawBuf : DrawBuf {
         }
     }
 
+    override void fillGradientRect(Rect rc, uint color1, uint color2) {
+        // TODO
+        fillRect(rc, color1);
+    }
+
     /// fill rectangle with solid color and pattern (clipping is applied) 0=solid fill, 1 = dotted
     override void fillRectPattern(Rect rc, uint color, int pattern) {
         // default implementation: does not support patterns