Add dual source blending support for proper blending with coverage.

Review URL: http://codereview.appspot.com/4535088/



git-svn-id: http://skia.googlecode.com/svn/trunk@1390 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 182 insertions, 0 deletions

diff --git a/samplecode/SampleXfermodesBlur.cpp b/samplecode/SampleXfermodesBlur.cpp
new file mode 100644
index 0000000000..166e4e5c7c
--- /dev/null
+++ b/samplecode/SampleXfermodesBlur.cpp
@@ -0,0 +1,182 @@
+#include "SampleCode.h"
+#include "SkView.h"
+#include "SkCanvas.h"
+#include "Sk64.h"
+#include "SkCornerPathEffect.h"
+#include "SkGradientShader.h"
+#include "SkGraphics.h"
+#include "SkImageDecoder.h"
+#include "SkKernel33MaskFilter.h"
+#include "SkPath.h"
+#include "SkRandom.h"
+#include "SkRegion.h"
+#include "SkShader.h"
+#include "SkUtils.h"
+#include "SkColorPriv.h"
+#include "SkColorFilter.h"
+#include "SkTime.h"
+#include "SkTypeface.h"
+#include "SkXfermode.h"
+
+#include "SkStream.h"
+#include "SkXMLParser.h"
+#include "SkColorPriv.h"
+#include "SkImageDecoder.h"
+#include "SkBlurMaskFilter.h"
+
+static void setNamedTypeface(SkPaint* paint, const char name[]) {
+    SkTypeface* face = SkTypeface::CreateFromName(name, SkTypeface::kNormal);
+    paint->setTypeface(face);
+    SkSafeUnref(face);
+}
+
+static uint16_t gBG[] = { 0xFFFF, 0xCCCF, 0xCCCF, 0xFFFF };
+
+class XfermodesBlurView : public SampleView {
+    SkBitmap    fBG;
+    SkBitmap    fSrcB, fDstB;
+
+    void draw_mode(SkCanvas* canvas, SkXfermode* mode, int alpha,
+                   SkScalar x, SkScalar y) {
+        SkPaint p;
+        SkMaskFilter* mf = SkBlurMaskFilter::Create(5, SkBlurMaskFilter::kNormal_BlurStyle, 0);
+        p.setMaskFilter(mf)->unref();
+
+        SkScalar ww = SkIntToScalar(W);
+        SkScalar hh = SkIntToScalar(H);
+
+        // draw a circle covering the upper
+        // left three quarters of the canvas
+        p.setColor(0xFFCC44FF);
+        SkRect r;
+        r.set(0, 0, ww*3/4, hh*3/4);
+        r.offset(x, y);
+        canvas->drawOval(r, p);
+
+        p.setXfermode(mode);
+
+        // draw a square overlapping the circle
+        // in the lower right of the canvas
+        p.setColor(0x00AA6633 | alpha << 24);
+        r.set(ww/3, hh/3, ww*19/20, hh*19/20);
+        r.offset(x, y);
+        canvas->drawRect(r, p);
+    }
+
+public:
+    const static int W = 64;
+    const static int H = 64;
+	XfermodesBlurView() {
+        const int W = 64;
+        const int H = 64;
+
+        fBG.setConfig(SkBitmap::kARGB_4444_Config, 2, 2, 4);
+        fBG.setPixels(gBG);
+        fBG.setIsOpaque(true);
+    }
+
+protected:
+    // overrides from SkEventSink
+    virtual bool onQuery(SkEvent* evt) {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "XfermodesBlur");
+            return true;
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+
+    virtual void onDrawContent(SkCanvas* canvas) {
+        canvas->translate(SkIntToScalar(10), SkIntToScalar(20));
+
+        const struct {
+            SkXfermode::Mode  fMode;
+            const char*         fLabel;
+        } gModes[] = {
+            { SkXfermode::kClear_Mode,    "Clear"     },
+            { SkXfermode::kSrc_Mode,      "Src"       },
+            { SkXfermode::kDst_Mode,      "Dst"       },
+            { SkXfermode::kSrcOver_Mode,  "SrcOver"   },
+            { SkXfermode::kDstOver_Mode,  "DstOver"   },
+            { SkXfermode::kSrcIn_Mode,    "SrcIn"     },
+            { SkXfermode::kDstIn_Mode,    "DstIn"     },
+            { SkXfermode::kSrcOut_Mode,   "SrcOut"    },
+            { SkXfermode::kDstOut_Mode,   "DstOut"    },
+            { SkXfermode::kSrcATop_Mode,  "SrcATop"   },
+            { SkXfermode::kDstATop_Mode,  "DstATop"   },
+            { SkXfermode::kXor_Mode,      "Xor"       },
+
+            { SkXfermode::kPlus_Mode,         "Plus"          },
+            /*{ SkXfermode::kMultiply_Mode,     "Multiply"      },
+            { SkXfermode::kScreen_Mode,       "Screen"        },
+            { SkXfermode::kOverlay_Mode,      "Overlay"       },
+            { SkXfermode::kDarken_Mode,       "Darken"        },
+            { SkXfermode::kLighten_Mode,      "Lighten"       },
+            { SkXfermode::kColorDodge_Mode,   "ColorDodge"    },
+            { SkXfermode::kColorBurn_Mode,    "ColorBurn"     },
+            { SkXfermode::kHardLight_Mode,    "HardLight"     },
+            { SkXfermode::kSoftLight_Mode,    "SoftLight"     },
+            { SkXfermode::kDifference_Mode,   "Difference"    },
+            { SkXfermode::kExclusion_Mode,    "Exclusion"     },*/
+        };
+
+        const SkScalar w = SkIntToScalar(W);
+        const SkScalar h = SkIntToScalar(H);
+        SkShader* s = SkShader::CreateBitmapShader(fBG,
+                                                   SkShader::kRepeat_TileMode,
+                                                   SkShader::kRepeat_TileMode);
+        SkMatrix m;
+        m.setScale(SkIntToScalar(6), SkIntToScalar(6));
+        s->setLocalMatrix(m);
+
+        SkPaint labelP;
+        labelP.setAntiAlias(true);
+        labelP.setLCDRenderText(true);
+        labelP.setTextAlign(SkPaint::kCenter_Align);
+        setNamedTypeface(&labelP, "Menlo Regular");
+
+        const int W = 5;
+
+        SkScalar x0 = 0;
+        for (int twice = 0; twice < 2; twice++) {
+            SkScalar x = x0, y = 0;
+            for (size_t i = 0; i < SK_ARRAY_COUNT(gModes); i++) {
+                SkXfermode* mode = SkXfermode::Create(gModes[i].fMode);
+                SkAutoUnref aur(mode);
+                SkRect r;
+                r.set(x, y, x+w, y+h);
+
+                SkPaint p;
+                p.setStyle(SkPaint::kFill_Style);
+                p.setShader(s);
+                canvas->drawRect(r, p);
+
+                canvas->saveLayer(&r, NULL, SkCanvas::kARGB_ClipLayer_SaveFlag);
+                draw_mode(canvas, mode, twice ? 0x88 : 0xFF, r.fLeft, r.fTop);
+                canvas->restore();
+
+                r.inset(-SK_ScalarHalf, -SK_ScalarHalf);
+                p.setStyle(SkPaint::kStroke_Style);
+                p.setShader(NULL);
+                canvas->drawRect(r, p);
+
+                canvas->drawText(gModes[i].fLabel, strlen(gModes[i].fLabel),
+                                 x + w/2, y - labelP.getTextSize()/2, labelP);
+                x += w + SkIntToScalar(10);
+                if ((i % W) == W - 1) {
+                    x = x0;
+                    y += h + SkIntToScalar(30);
+                }
+            }
+            x0 += SkIntToScalar(400);
+        }
+        s->unref();
+    }
+
+private:
+    typedef SampleView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static SkView* MyFactory() { return new XfermodesBlurView; }
+static SkViewRegister reg(MyFactory);