samplecode/ClockFaceView.cpp

#include "SampleCode.h"
#include "SkView.h"
#include "SkCanvas.h"
#include "SkGradientShader.h"
#include "SkPath.h"
#include "SkRegion.h"
#include "SkShader.h"
#include "SkUtils.h"
#include "SkColorPriv.h"
#include "SkColorFilter.h"
#include "SkTypeface.h"
#include "SkAvoidXfermode.h"

static inline SkPMColor rgb2gray(SkPMColor c)
{
    unsigned r = SkGetPackedR32(c);
    unsigned g = SkGetPackedG32(c);
    unsigned b = SkGetPackedB32(c);
    
    unsigned x = r * 5 + g * 7 + b * 4 >> 4;
    
    return SkPackARGB32(0, x, x, x) | (c & (SK_A32_MASK << SK_A32_SHIFT));
}

class SkGrayScaleColorFilter : public SkColorFilter {
public:
    virtual void filterSpan(const SkPMColor src[], int count, SkPMColor result[])
    {
        for (int i = 0; i < count; i++)
            result[i] = rgb2gray(src[i]);
    }
};

class SkChannelMaskColorFilter : public SkColorFilter {
public:
    SkChannelMaskColorFilter(U8CPU redMask, U8CPU greenMask, U8CPU blueMask)
    {
        fMask = SkPackARGB32(0xFF, redMask, greenMask, blueMask);
    }

    virtual void filterSpan(const SkPMColor src[], int count, SkPMColor result[])
    {
        SkPMColor mask = fMask;
        for (int i = 0; i < count; i++)
            result[i] = src[i] & mask;
    }
    
private:
    SkPMColor   fMask;
};

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

#include "SkGradientShader.h"
#include "SkLayerRasterizer.h"
#include "SkBlurMaskFilter.h"

#include "Sk2DPathEffect.h"

class Dot2DPathEffect : public Sk2DPathEffect {
public:
    Dot2DPathEffect(SkScalar radius, const SkMatrix& matrix,
                    SkTDArray<SkPoint>* pts)
    : Sk2DPathEffect(matrix), fRadius(radius), fPts(pts) {}

    virtual void flatten(SkFlattenableWriteBuffer& buffer)
    {
        this->INHERITED::flatten(buffer);
        
        buffer.writeScalar(fRadius);
    }
    virtual Factory getFactory() { return CreateProc; }

protected:
    virtual void begin(const SkIRect& uvBounds, SkPath* dst) {
        if (fPts) {
            fPts->reset();
        }
        this->INHERITED::begin(uvBounds, dst);
    }
//    virtual void end(SkPath* dst) {}
	virtual void next(const SkPoint& loc, int u, int v, SkPath* dst)
    {
        if (fPts) {
            *fPts->append() = loc;
        }
        dst->addCircle(loc.fX, loc.fY, fRadius);
    }
    
    Dot2DPathEffect(SkFlattenableReadBuffer& buffer) : Sk2DPathEffect(buffer)
    {
        fRadius = buffer.readScalar();
        fPts = NULL;
    }
private:
    SkScalar fRadius;
    SkTDArray<SkPoint>* fPts;

    static SkFlattenable* CreateProc(SkFlattenableReadBuffer& buffer)
    {
        return new Dot2DPathEffect(buffer);
    }

    typedef Sk2DPathEffect INHERITED;
};

class InverseFillPE : public SkPathEffect {
public:
    InverseFillPE() {}
    virtual bool filterPath(SkPath* dst, const SkPath& src, SkScalar* width) {
        *dst = src;
        dst->setFillType(SkPath::kInverseWinding_FillType);
        return true;
    }
    virtual Factory getFactory() { return Factory; }
protected:
//    InverseFillPE(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
private:
    static SkFlattenable* Factory(SkFlattenableReadBuffer& buffer) {
        return new InverseFillPE;
    }
    typedef SkPathEffect INHERITED;
};

static SkPathEffect* makepe(float interp, SkTDArray<SkPoint>* pts) {
    SkMatrix    lattice;
    SkScalar    rad = 3 + SkIntToScalar(4) * (1 - interp);
    lattice.setScale(rad*2, rad*2, 0, 0);
    lattice.postSkew(SK_Scalar1/3, 0, 0, 0);
    return new Dot2DPathEffect(rad, lattice, pts);
}

static void r7(SkLayerRasterizer* rast, SkPaint& p, SkScalar interp) {
    p.setPathEffect(makepe(interp, NULL))->unref();
    rast->addLayer(p);
#if 0
    p.setPathEffect(new InverseFillPE())->unref();
    p.setXfermodeMode(SkXfermode::kSrcIn_Mode);
    p.setXfermodeMode(SkXfermode::kClear_Mode);
    p.setAlpha((1 - interp) * 255);
    rast->addLayer(p);
#endif
}

typedef void (*raster_proc)(SkLayerRasterizer*, SkPaint&);

#include "SkXfermode.h"

static void apply_shader(SkPaint* paint, float scale)
{    
    SkPaint p;
    SkLayerRasterizer*  rast = new SkLayerRasterizer;

    p.setAntiAlias(true);
    r7(rast, p, scale);
    paint->setRasterizer(rast)->unref();

    paint->setColor(SK_ColorBLUE);
}

class ClockFaceView : public SkView {
    SkTypeface* fFace;
    SkScalar fInterp;
    SkScalar fDx;
public:
	ClockFaceView()
    {
        fFace = SkTypeface::CreateFromFile("/Users/reed/Downloads/p052024l.pfb");
        fInterp = 0;
        fDx = SK_Scalar1/64;
    }
    
    virtual ~ClockFaceView()
    {
        fFace->safeUnref();
    }

protected:
    // overrides from SkEventSink
    virtual bool onQuery(SkEvent* evt)
    {
        if (SampleCode::TitleQ(*evt))
        {
            SampleCode::TitleR(evt, "Text Effects");
            return true;
        }
        return this->INHERITED::onQuery(evt);
    }
    
    void drawBG(SkCanvas* canvas)
    {
//        canvas->drawColor(0xFFDDDDDD);
        canvas->drawColor(SK_ColorWHITE);
    }
    
    static void drawdots(SkCanvas* canvas, const SkPaint& orig) {
        SkTDArray<SkPoint> pts;
        SkPathEffect* pe = makepe(0, &pts);
        
        SkScalar width = -1;
        SkPath path, dstPath;
        orig.getTextPath("9", 1, 0, 0, &path);
        pe->filterPath(&dstPath, path, &width);
        
        SkPaint p;
        p.setAntiAlias(true);
        p.setStrokeWidth(10);
        p.setColor(SK_ColorRED);
        canvas->drawPoints(SkCanvas::kPoints_PointMode, pts.count(), pts.begin(),
                           p);
    }
    
    virtual void onDraw(SkCanvas* canvas) {
        this->drawBG(canvas);
        
        SkScalar    x = SkIntToScalar(20);
        SkScalar    y = SkIntToScalar(300);
        SkPaint     paint;
        
        paint.setAntiAlias(true);
        paint.setTextSize(SkIntToScalar(240));
        paint.setTypeface(SkTypeface::CreateFromName("sans-serif",
                                                     SkTypeface::kBold));

        SkString str("9");

        paint.setTypeface(fFace);
        
        apply_shader(&paint, fInterp);
        canvas->drawText(str.c_str(), str.size(), x, y, paint);

    //    drawdots(canvas, paint);

        if (false) {
            fInterp += fDx;
            if (fInterp > 1) {
                fInterp = 1;
                fDx = -fDx;
            } else if (fInterp < 0) {
                fInterp = 0;
                fDx = -fDx;
            }
            this->inval(NULL);
        }
    }

private:
    typedef SkView INHERITED;
};

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

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