fix copyTo to only copy the minimum pixels per row, and to lock the src before
trying to access its colorTable. Update unittest for copyTo. Add sample for
using a mask to clip a layer.



git-svn-id: http://skia.googlecode.com/svn/trunk@168 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleLayerMask.cpp b/samplecode/SampleLayerMask.cpp
new file mode 100644
index 0000000..8cbe76d
--- /dev/null
+++ b/samplecode/SampleLayerMask.cpp
@@ -0,0 +1,73 @@
+#include "SampleCode.h"
+#include "SkCanvas.h"
+#include "SkPaint.h"
+#include "SkPorterDuff.h"
+#include "SkView.h"
+
+///////////////////////////////////////////////////////////////////////////////
+
+class LayerMaskView : public SkView {
+public:
+	LayerMaskView() {}
+    
+protected:
+    // overrides from SkEventSink
+    virtual bool onQuery(SkEvent* evt) {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "LayerMask");
+            return true;
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+    
+    void drawMask(SkCanvas* canvas, const SkRect& r) {
+        SkPaint paint;
+        paint.setAntiAlias(true);
+
+        if (true) {
+            SkBitmap mask;
+            int w = SkScalarRound(r.width());
+            int h = SkScalarRound(r.height());
+            mask.setConfig(SkBitmap::kARGB_8888_Config, w, h);
+            mask.allocPixels();
+            mask.eraseColor(0);
+            SkCanvas c(mask);
+            SkRect bounds = r;
+            bounds.offset(-bounds.fLeft, -bounds.fTop);
+            c.drawOval(bounds, paint);
+            
+            paint.setPorterDuffXfermode(SkPorterDuff::kDstIn_Mode);
+            canvas->drawBitmap(mask, r.fLeft, r.fTop, &paint);
+        } else {
+            SkPath p;
+            p.addOval(r);
+            p.setFillType(SkPath::kInverseWinding_FillType);
+            paint.setPorterDuffXfermode(SkPorterDuff::kDstOut_Mode);
+            canvas->drawPath(p, paint);
+        }
+    }
+
+    void drawBG(SkCanvas* canvas) {
+        canvas->drawColor(0xFFDDDDDD);
+    }
+    
+    virtual void onDraw(SkCanvas* canvas) {
+        this->drawBG(canvas);
+        
+        SkRect  r;
+        r.set(SkIntToScalar(20), SkIntToScalar(20), SkIntToScalar(120), SkIntToScalar(120));
+        canvas->saveLayer(&r, NULL, SkCanvas::kARGB_ClipLayer_SaveFlag);
+        canvas->drawColor(SK_ColorRED);
+        drawMask(canvas, r);
+        canvas->restore();
+    }
+    
+private:
+    typedef SkView INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() { return new LayerMaskView; }
+static SkViewRegister reg(MyFactory);
+