samplecode/SampleAARectModes.cpp

/*
 * Copyright 2011 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 "SkView.h"
#include "SkCanvas.h"
#include "SkDevice.h"
#include "SkColorPriv.h"
#include "SkShader.h"

static SkCanvas* create_canvas(int w, int h) {
    SkBitmap bm;
    bm.setConfig(SkBitmap::kARGB_8888_Config, w, h);
    bm.allocPixels();
    bm.eraseColor(0);
    return new SkCanvas(bm);
}

static const SkBitmap& extract_bitmap(SkCanvas* canvas) {
    return canvas->getDevice()->accessBitmap(false);
}

static 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"       },
};

const int gWidth = 64;
const int gHeight = 64;
const SkScalar W = SkIntToScalar(gWidth);
const SkScalar H = SkIntToScalar(gHeight);

static SkScalar drawCell(SkCanvas* canvas, SkXfermode* mode,
                         SkAlpha a0, SkAlpha a1) {

    SkPaint paint;
    paint.setAntiAlias(true);

    SkRect r = SkRect::MakeWH(W, H);
    r.inset(W/10, H/10);

    paint.setColor(SK_ColorBLUE);
    paint.setAlpha(a0);
    canvas->drawOval(r, paint);

    paint.setColor(SK_ColorRED);
    paint.setAlpha(a1);
    paint.setXfermode(mode);

    SkScalar offset = SK_Scalar1 / 3;
    SkRect rect = SkRect::MakeXYWH(W / 4 + offset,
                                   H / 4 + offset,
                                   W / 2, H / 2);
    canvas->drawRect(rect, paint);
    
    return H;
}

static SkShader* make_bg_shader() {
    SkBitmap bm;
    bm.setConfig(SkBitmap::kARGB_8888_Config, 2, 2);
    bm.allocPixels();
    *bm.getAddr32(0, 0) = *bm.getAddr32(1, 1) = 0xFFFFFFFF;
    *bm.getAddr32(1, 0) = *bm.getAddr32(0, 1) = SkPackARGB32(0xFF, 0xCC,
                                                             0xCC, 0xCC);

    SkShader* s = SkShader::CreateBitmapShader(bm,
                                               SkShader::kRepeat_TileMode,
                                               SkShader::kRepeat_TileMode);
    
    SkMatrix m;
    m.setScale(SkIntToScalar(6), SkIntToScalar(6));
    s->setLocalMatrix(m);
    return s;
}

class AARectsModesView : public SampleView {
    SkPaint fBGPaint;
public:
    AARectsModesView () {
        fBGPaint.setShader(make_bg_shader())->unref();
    }

protected:
    // overrides from SkEventSink
    virtual bool onQuery(SkEvent* evt) {
        if (SampleCode::TitleQ(*evt)) {
            SampleCode::TitleR(evt, "AARectsModes");
            return true;
        }
        return this->INHERITED::onQuery(evt);
    }

    virtual void onDrawContent(SkCanvas* canvas) {
        const SkRect bounds = SkRect::MakeWH(W, H);
        static const SkAlpha gAlphaValue[] = { 0xFF, 0x88, 0x88 };

        canvas->translate(SkIntToScalar(4), SkIntToScalar(4));

        for (int alpha = 0; alpha < 4; ++alpha) {
            canvas->save();
            canvas->save();
            for (size_t i = 0; i < SK_ARRAY_COUNT(gModes); ++i) {
                if (6 == i) {
                    canvas->restore();
                    canvas->translate(W * 5, 0);
                    canvas->save();
                }
                SkXfermode* mode = SkXfermode::Create(gModes[i].fMode);
                
                canvas->drawRect(bounds, fBGPaint);
                canvas->saveLayer(&bounds, NULL);
                SkScalar dy = drawCell(canvas, mode,
                                       gAlphaValue[alpha & 1],
                                       gAlphaValue[alpha & 2]);
                canvas->restore();

                canvas->translate(0, dy * 5 / 4);
                SkSafeUnref(mode);
            }
            canvas->restore();
            canvas->restore();
            canvas->translate(W * 5 / 4, 0);
        }
    }
    
private:
    typedef SampleView INHERITED;
};

///////////////////////////////////////////////////////////////////////////////

static SkView* MyFactory() { return new AARectsModesView; }
static SkViewRegister reg(MyFactory);