skia/src/samplecode/SamplePolyToPoly.cpp

#include "SampleCode.h"
#include "SkView.h"
#include "SkCanvas.h"
#include "SkGraphics.h"
#include "SkPath.h"
#include "SkRandom.h"
#include "SkTime.h"

extern bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]);

class PolyToPolyView : public SkView {
public:    
	PolyToPolyView() {
        // tests
        {
            SkPoint src[] = { 0, 0, SK_Scalar1, 0, 0, SK_Scalar1 };
            SkPoint dst[] = { 0, 0, 2*SK_Scalar1, 0, 0, 2*SK_Scalar1 };
            SkMatrix m1, m2;
            bool success;
            
            success = m1.setPolyToPoly(src, dst, 3);
            SkDebugf("--- setPolyToPoly1 %d\n", success);

            m2.reset();            
            m2.set(SkMatrix::kMScaleX, dst[1].fX - dst[0].fX);
            m2.set(SkMatrix::kMSkewX,  dst[2].fX - dst[0].fX);
            m2.set(SkMatrix::kMTransX, dst[0].fX);
            m2.set(SkMatrix::kMSkewY,  dst[1].fY - dst[0].fY);
            m2.set(SkMatrix::kMScaleY, dst[2].fY - dst[0].fY);
            m2.set(SkMatrix::kMTransY, dst[0].fY);
            
            m1.reset();
            
            const SkScalar src1[] = {
                0, 0, 0, SkFloatToScalar(427), SkFloatToScalar(316), SkFloatToScalar(427), SkFloatToScalar(316), 0
            };
            const SkScalar dst1[] = {
                SkFloatToScalar(158), SkFloatToScalar(177.5f), SkFloatToScalar(158), SkFloatToScalar(249.5f),
                SkFloatToScalar(158), SkFloatToScalar(604.5f), SkFloatToScalar(158), SkFloatToScalar(-177.5f)
            };
            
            success = m2.setPolyToPoly((const SkPoint*)src1, (SkPoint*)dst1, 4);
            SkDebugf("--- setPolyToPoly2 %d\n", success);
            
            {
                const SkPoint src[] = {
                    SkIntToScalar(1), SkIntToScalar(0),
                    SkIntToScalar(4), SkIntToScalar(7),
                    SkIntToScalar(10), SkIntToScalar(2)
                };
                const SkPoint dst[] = {
                    SkIntToScalar(4), SkIntToScalar(2),
                    SkIntToScalar(45), SkIntToScalar(26),
                    SkIntToScalar(32), SkIntToScalar(17)
                };
                
                SkMatrix m0, m1;
                m0.setPolyToPoly(src, dst, 3);
                SkSetPoly3To3(&m1, src, dst);
                m0.dump();
                m1.dump();
            }
        }
    }
    
protected:
    // overrides from SkEventSink
    virtual bool onQuery(SkEvent* evt)  {
        if (SampleCode::TitleQ(*evt)) {
            SkString str("PolyToPolyView");
            SampleCode::TitleR(evt, str.c_str());
            return true;
        }
        return this->INHERITED::onQuery(evt);
    }
    
    void drawBG(SkCanvas* canvas) {
        canvas->drawColor(SK_ColorWHITE);
    }

    static void doDraw(SkCanvas* canvas, SkPaint* paint, const int isrc[],
                       const int idst[], int count) {
        SkMatrix matrix;
        SkPoint src[4], dst[4];
        
        for (int i = 0; i < count; i++) {
            src[i].set(SkIntToScalar(isrc[2*i+0]), SkIntToScalar(isrc[2*i+1]));
            dst[i].set(SkIntToScalar(idst[2*i+0]), SkIntToScalar(idst[2*i+1]));
        }
        
        canvas->save();
        matrix.setPolyToPoly(src, dst, count);
        canvas->concat(matrix);
        
        paint->setColor(SK_ColorGRAY);
        paint->setStyle(SkPaint::kStroke_Style);
        const SkScalar D = SkIntToScalar(64);
        canvas->drawRectCoords(0, 0, D, D, *paint);
        canvas->drawLine(0, 0, D, D, *paint);
        canvas->drawLine(0, D, D, 0, *paint);
        
        SkPaint::FontMetrics fm;
        paint->getFontMetrics(&fm);
        paint->setColor(SK_ColorRED);
        paint->setStyle(SkPaint::kFill_Style);
        SkScalar x = D/2;
        float y = D/2 - (fm.fAscent + fm.fDescent)/2;
        SkString str;
        str.appendS32(count);
        canvas->drawText(str.c_str(), str.size(), x, y, *paint);
        
        canvas->restore();
    }
    
    virtual void onDraw(SkCanvas* canvas) {
        this->drawBG(canvas);
        
        SkPaint paint;
        paint.setAntiAlias(true);
        paint.setStrokeWidth(SkIntToScalar(4));
        paint.setTextSize(SkIntToScalar(40));
        paint.setTextAlign(SkPaint::kCenter_Align);

        canvas->save();
        canvas->translate(SkIntToScalar(10), SkIntToScalar(10));
        // translate (1 point)
        const int src1[] = { 0, 0 };
        const int dst1[] = { 5, 5 };
        doDraw(canvas, &paint, src1, dst1, 1);
        canvas->restore();
        
        canvas->save();
        canvas->translate(SkIntToScalar(160), SkIntToScalar(10));
        // rotate/uniform-scale (2 points)
        const int src2[] = { 32, 32, 64, 32 };
        const int dst2[] = { 32, 32, 64, 48 };
        doDraw(canvas, &paint, src2, dst2, 2);
        canvas->restore();
        
        canvas->save();
        canvas->translate(SkIntToScalar(10), SkIntToScalar(110));
        // rotate/skew (3 points)
        const int src3[] = { 0, 0, 64, 0, 0, 64 };
        const int dst3[] = { 0, 0, 96, 0, 24, 64 };
        doDraw(canvas, &paint, src3, dst3, 3);
        canvas->restore();
        
        canvas->save();
        canvas->translate(SkIntToScalar(160), SkIntToScalar(110));
        // perspective (4 points)
        const int src4[] = { 0, 0, 64, 0, 64, 64, 0, 64 };
        const int dst4[] = { 0, 0, 96, 0, 64, 96, 0, 64 };
        doDraw(canvas, &paint, src4, dst4, 4);
        canvas->restore();
    }
    
private:
    typedef SkView INHERITED;
};

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

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