add interactive xfer sample

samplecode/SampleXfer.cpp

Index: samplecode/SampleXfer.cpp
diff --git a/samplecode/SampleXfer.cpp b/samplecode/SampleXfer.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..221ba5815ea36b4815213c837ce029566abad802
--- /dev/null
+++ b/samplecode/SampleXfer.cpp
@@ -0,0 +1,252 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SampleCode.h"
+#include "SkAnimTimer.h"
+#include "SkDrawable.h"
+#include "SkView.h"
+#include "SkCanvas.h"
+#include "SkDrawable.h"
+#include "SkPath.h"
+#include "SkRandom.h"
+#include "SkRSXform.h"
+#include "SkSurface.h"
+#include "SkGradientShader.h"
+
+const struct {
+    SkXfermode::Mode fMode;
+    const char*      fName;
+} gModes[] = {
+    { SkXfermode::kSrcOver_Mode, "src-over" },
+    { SkXfermode::kSrc_Mode,     "src" },
+    { SkXfermode::kSrcIn_Mode,   "src-in" },
+    { SkXfermode::kSrcOut_Mode,  "src-out" },
+    { SkXfermode::kSrcATop_Mode, "src-atop" },
+    { SkXfermode::kDstOver_Mode, "dst-over" },
+    { SkXfermode::kDstIn_Mode,   "dst-in" },
+    { SkXfermode::kDstOut_Mode,  "dst-out" },
+    { SkXfermode::kDstATop_Mode, "dst-atop" },
+};
+const int N_Modes = SK_ARRAY_COUNT(gModes);
+
+class HasEventWig : public SkView {
+public:
+    void postWidgetEvent() {
+        SkEvent evt;
+        this->onPrepareWidEvent(&evt);
+        this->postToListeners(evt, 0);
+    }
+
+protected:
+    virtual void onPrepareWidEvent(SkEvent*) {}
+};
+
+static SkRandom gRand;
+
+class PushButtonWig : public HasEventWig {
+    SkString fLabel;
+    SkColor  fColor;
+    uint32_t fFast32;
+
+public:
+    PushButtonWig(const char label[], uint32_t fast) : fLabel(label) {
+        fColor = (gRand.nextU() & 0x7F7F7F7F) | SkColorSetARGB(0xFF, 0, 0, 0x80);
+        fFast32 = fast;
+    }
+    
+protected:
+    void onPrepareWidEvent(SkEvent* evt) override {
+        evt->setType("push-button");
+        evt->setFast32(fFast32);
+        evt->setString("label", fLabel.c_str());
+    }
+
+//    bool onEvent(const SkEvent&) override;
+    void onDraw(SkCanvas* canvas) override {
+        SkRect r;
+        this->getLocalBounds(&r);
+        SkPaint paint;
+        paint.setAntiAlias(true);
+        paint.setColor(fColor);
+        canvas->drawRoundRect(r, 8, 8, paint);
+
+        paint.setColor(0xFFFFFFFF);
+        paint.setTextSize(16);
+        paint.setTextAlign(SkPaint::kCenter_Align);
+        paint.setLCDRenderText(true);
+        canvas->drawText(fLabel.c_str(), fLabel.size(), r.centerX(), r.fTop + 0.68f * r.height(), paint);
+    }
+
+    Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
+        return new Click(this);
+    }
+
+    bool onClick(Click* click) override {
+        SkRect target = SkRect::MakeXYWH(click->fCurr.x() - 1, click->fCurr.y() - 1, 3, 3);
+        SkRect r;
+        this->getLocalBounds(&r);
+        if (r.intersects(target)) {
+            fColor = SkColorSetA(fColor, 0x99);
+        } else {
+            fColor = SkColorSetA(fColor, 0xFF);
+        }
+        this->inval(nullptr);
+
+        if (click->fState == SkView::Click::kUp_State) {
+            this->postWidgetEvent();
+        }
+        return true;
+    }
+    
+private:
+    typedef HasEventWig INHERITED;
+};
+
+
+class ModeDrawable : public SkDrawable {
+public:
+    ModeDrawable() : fMode(SkXfermode::kSrcOver_Mode), fLoc(SkPoint::Make(0, 0)) {}
+
+    SkXfermode::Mode fMode;
+    SkPoint          fLoc;
+
+    bool hitTest(SkScalar x, SkScalar y) {
+        SkRect target = SkRect::MakeXYWH(x - fLoc.x() - 1, y - fLoc.y() - 1, 3, 3);
+        return this->getBounds().intersects(target);
+    }
+};
+
+class CircDrawable : public ModeDrawable {
+    SkPaint fPaint;
+    SkRect  fBounds;
+
+public:
+    CircDrawable(SkScalar size, SkColor c) {
+        const SkColor colors[] = { 0, c };
+        SkAutoTUnref<SkShader> shader(SkGradientShader::CreateRadial(SkPoint::Make(size/2, size/2), size/2,
+                                                                     colors, nullptr, 2,
+                                                                     SkShader::kClamp_TileMode));
+        fPaint.setShader(shader);
+        fBounds = SkRect::MakeWH(size, size);
+    }
+
+protected:
+    SkRect onGetBounds() override {
+        return fBounds;
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        fPaint.setXfermodeMode(fMode);
+        canvas->save();
+        canvas->translate(fLoc.x(), fLoc.y());
+        canvas->drawOval(fBounds, fPaint);
+        canvas->restore();
+    }
+};
+
+class XferDemo : public SampleView {
+    enum {
+        N = 4
+    };
+    
+    SkRect        fModeRect[N_Modes];
+    SkAutoTUnref<CircDrawable> fDrs[N];
+    CircDrawable* fSelected;
+
+    void addButtons() {
+        SkScalar x = 10;
+        SkScalar y = 10;
+        for (int i = 0; i < N_Modes; ++i) {
+            SkAutoTUnref<SkView> v(new PushButtonWig(gModes[i].fName, gModes[i].fMode));
+            v->setSize(70, 25);
+            v->setLoc(x, y);
+            v->setVisibleP(true);
+            v->setEnabledP(true);
+            v->addListenerID(this->getSinkID());
+            this->attachChildToFront(v);
+            fModeRect[i] = SkRect::MakeXYWH(x, y + 28, 70, 2);
+            x += 80;
+        }
+    }
+
+public:
+    XferDemo() {
+        const SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorBLACK };
+        for (int i = 0; i < N; ++i) {
+            fDrs[i].reset(new CircDrawable(200, colors[i]));
+            fDrs[i]->fLoc.set(100.f + i * 100, 100.f + i * 100);
+            fDrs[i]->fMode = SkXfermode::kSrcOver_Mode;
+        }
+        fSelected = nullptr;
+
+        this->addButtons();
+    }
+
+protected:
+    bool onEvent(const SkEvent& evt) override {
+        if (evt.isType("push-button")) {
+            if (fSelected) {
+                fSelected->fMode = (SkXfermode::Mode)evt.getFast32();
+                this->inval(nullptr);
+            }
+            return true;
+        }
+        return this->INHERITED::onEvent(evt);
+    }
+
+    bool onQuery(SkEvent* evt) override {
+        if (SampleCode::TitleQ(*evt)) {
+            SampleCode::TitleR(evt, "XferDemo");
+            return true;
+        }
+        return this->INHERITED::onQuery(evt);
+    }
+
+    void onDrawContent(SkCanvas* canvas) override {
+        SkPaint paint;
+        if (fSelected) {
+            for (int i = 0; i < N_Modes; ++i) {
+                if (fSelected->fMode == gModes[i].fMode) {
+                    canvas->drawRect(fModeRect[i], paint);
+                    break;
+                }
+            }
+        }
+
+        canvas->saveLayer(nullptr, nullptr);
+        for (int i = 0; i < N; ++i) {
+            fDrs[i]->draw(canvas);
+        }
+        canvas->restore();
+    }
+
+    SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned) override {
+        fSelected = nullptr;
+        for (int i = N - 1; i >= 0; --i) {
+            if (fDrs[i]->hitTest(x, y)) {
+                fSelected = fDrs[i];
+                break;
+            }
+        }
+        this->inval(nullptr);
+        return fSelected ? new Click(this) : nullptr;
+    }
+    
+    bool onClick(Click* click) override {
+        fSelected->fLoc.fX += click->fCurr.fX - click->fPrev.fX;
+        fSelected->fLoc.fY += click->fCurr.fY - click->fPrev.fY;
+        this->inval(nullptr);
+        return true;
+    }
+
+private:
+    typedef SampleView INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_SAMPLE( return new XferDemo; )