samplecode/SampleCircle.cpp

#include "SampleCode.h"
#include "SkView.h"
#include "SkCanvas.h"
#include "SkDevice.h"
#include "SkPaint.h"

// ensure that we don't accidentally screw up the bounds when the oval is
// fractional, and the impl computes the center and radii, and uses them to
// reconstruct the edges of the circle.
// see bug# 1504910
static void test_circlebounds(SkCanvas* canvas) {
#ifdef SK_SCALAR_IS_FLOAT
    SkRect r = { 1.39999998, 1, 21.3999996, 21 };
    SkPath p;
    p.addOval(r);
    SkRect r2;
    p.computeBounds(&r2, SkPath::kFast_BoundsType);
    SkASSERT(r == r2);
#endif
}

class CircleView : public SkView {
public:
    static const SkScalar ANIM_DX = SK_Scalar1 / 67;
    static const SkScalar ANIM_DY = SK_Scalar1 / 29;
    static const SkScalar ANIM_RAD = SK_Scalar1 / 19;
    SkScalar fDX, fDY, fRAD;

    CircleView() {
        fDX = fDY = fRAD = 0;
    }
    
protected:
    // overrides from SkEventSink
    virtual bool onQuery(SkEvent* evt) {
        if (SampleCode::TitleQ(*evt)) {
            SampleCode::TitleR(evt, "Circles");
            return true;
        }
        return this->INHERITED::onQuery(evt);
    }
    
    void drawBG(SkCanvas* canvas) {
        canvas->drawColor(SK_ColorWHITE);
    }
    
    void circle(SkCanvas* canvas, int width, bool aa) {
        SkPaint paint;
        
        paint.setAntiAlias(aa);
        if (width < 0) {
            paint.setStyle(SkPaint::kFill_Style);
        } else {
            paint.setStyle(SkPaint::kStroke_Style);
            paint.setStrokeWidth(SkIntToScalar(width));
        }
        canvas->drawCircle(0, 0, SkIntToScalar(9) + fRAD, paint);
    }
    
    void drawSix(SkCanvas* canvas, SkScalar dx, SkScalar dy) {
        for (int width = -1; width <= 1; width++) {
            canvas->save();
            circle(canvas, width, false);
            canvas->translate(0, dy);
            circle(canvas, width, true);
            canvas->restore();
            canvas->translate(dx, 0);
        }
    }
    
    static void blowup(SkCanvas* canvas, const SkIRect& src, const SkRect& dst) {
        SkDevice* device = canvas->getDevice();
        const SkBitmap& bm = device->accessBitmap(false);
        canvas->drawBitmapRect(bm, &src, dst, NULL);
    }

    virtual void onDraw(SkCanvas* canvas) {
        this->drawBG(canvas);
        
        test_circlebounds(canvas);
        
        if (false) {
          //  canvas->translate(SK_ScalarHalf, SK_ScalarHalf);

            SkPaint paint;
            paint.setAntiAlias(true);
            paint.setStyle(SkPaint::kStroke_Style);
            canvas->drawCircle(SkIntToScalar(10), SkIntToScalar(10), SkIntToScalar(2), paint);
            
            SkIRect r;
            r.set(7, 7, 13, 13);
            SkRect dst;
            dst.set(SkIntToScalar(100), SkIntToScalar(10), SkIntToScalar(200), SkIntToScalar(110));
            blowup(canvas, r, dst);
            return;
        }
        
        // test that degenerate rects do nothing
        if (true) {
            SkScalar x = SkIntToScalar(30);
            SkRect  r;
            r.set(x, x, x, x);
            SkPaint p;
            canvas->drawRect(r, p);
            p.setAntiAlias(true);
            canvas->drawRect(r, p);
        }

        SkScalar dx = SkIntToScalar(32);
        SkScalar dy = SkIntToScalar(32);
        
        canvas->translate(dx + fDX, dy + fDY);
        drawSix(canvas, dx, dy);

        canvas->translate(dx, 0);
        canvas->translate(SK_ScalarHalf, SK_ScalarHalf);
        drawSix(canvas, dx, dy);
        
        fDX += ANIM_DX;
        fDY += ANIM_DY;
        fRAD += ANIM_RAD;
        this->inval(NULL);
    }
    
private:
    typedef SkView INHERITED;
};

const SkScalar CircleView::ANIM_DX;
const SkScalar CircleView::ANIM_DY;
const SkScalar CircleView::ANIM_RAD;

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

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