add backdrop option to SaveLayerRec

samplecode/SampleLayers.cpp

Index: samplecode/SampleLayers.cpp
diff --git a/samplecode/SampleLayers.cpp b/samplecode/SampleLayers.cpp
index 52bf5b357b2b7e308f8819c0c24d5cc31d01177a..f8ebd7c94f5077e88feb92edb13d1b249a228ff9 100644
--- a/samplecode/SampleLayers.cpp
+++ b/samplecode/SampleLayers.cpp
@@ -232,8 +232,80 @@ protected:
 private:
     typedef SkView INHERITED;
 };
+DEF_SAMPLE( return new LayersView; )
 
 //////////////////////////////////////////////////////////////////////////////
 
-static SkView* MyFactory() { return new LayersView; }
-static SkViewRegister reg(MyFactory);
+#include "SkBlurImageFilter.h"
+#include "SkMatrixConvolutionImageFilter.h"
+#include "SkMorphologyImageFilter.h"
+
+#include "Resources.h"
+#include "SkAnimTimer.h"
+
+class BackdropView : public SampleView {
+    SkPoint fCenter;
+    SkScalar fAngle;
+    SkAutoTUnref<SkImage> fImage;
+    SkAutoTUnref<SkImageFilter> fFilter;
+public:
+    BackdropView() {
+        fCenter.set(200, 150);
+        fAngle = 0;
+        fImage.reset(GetResourceAsImage("mandrill_512.png"));
+        fFilter.reset(SkDilateImageFilter::Create(8, 8));
+    }
+
+protected:
+    // overrides from SkEventSink
+    bool onQuery(SkEvent* evt) override {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "Backdrop");
+            return true;
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+
+    void onDrawContent(SkCanvas* canvas) override {
+        canvas->drawImage(fImage, 0, 0, nullptr);
+
+        const SkScalar w = 250;
+        const SkScalar h = 150;
+        SkPath path;
+        path.addOval(SkRect::MakeXYWH(-w/2, -h/2, w, h));
+        SkMatrix m;
+        m.setRotate(fAngle);
+        m.postTranslate(fCenter.x(), fCenter.y());
+        path.transform(m);
+
+        canvas->clipPath(path, SkRegion::kIntersect_Op, true);
+        const SkRect bounds = path.getBounds();
+
+        SkPaint paint;
+        paint.setAlpha(0xCC);
+        canvas->saveLayer({ &bounds, &paint, fFilter, 0 });
+
+        canvas->restore();
+    }
+
+    bool onAnimate(const SkAnimTimer& timer) override {
+        fAngle = SkDoubleToScalar(fmod(timer.secs() * 360 / 5, 360));
+        return true;
+    }
+
+    SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
+        this->inval(nullptr);
+        return new Click(this);
+    }
+
+    bool onClick(Click* click) override {
+        this->inval(nullptr);
+        fCenter = click->fCurr;
+        return this->INHERITED::onClick(click);
+    }
+
+private:
+    typedef SampleView INHERITED;
+};
+DEF_SAMPLE( return new BackdropView; )
+