gm/convexpaths.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 "gm.h"
#include "SkRandom.h"
#include "SkTArray.h"

class SkOnce : SkNoncopyable {
public:
    SkOnce() { fDidOnce = false; }
    
    bool needToDo() const { return !fDidOnce; }
    bool alreadyDone() const { return fDidOnce; }
    void accomplished() {
        SkASSERT(!fDidOnce);
        fDidOnce = true;
    }

private:
    bool fDidOnce;
};

namespace skiagm {

class ConvexPathsGM : public GM {
    SkOnce fOnce;
public:
    ConvexPathsGM() {
        this->setBGColor(0xFF000000);
    }

protected:
    virtual SkString onShortName() {
        return SkString("convexpaths");
    }


    virtual SkISize onISize() {
        return make_isize(1200, 900);
    }

    void makePaths() {
        if (fOnce.alreadyDone()) {
            return;
        }
        fOnce.accomplished();

        // CW
        fPaths.push_back().moveTo(0, 0);
        fPaths.back().quadTo(50 * SK_Scalar1, 100 * SK_Scalar1,
                             0, 100 * SK_Scalar1);
        fPaths.back().lineTo(0, 0);

        // CCW
        fPaths.push_back().moveTo(0, 0);
        fPaths.back().lineTo(0, 100 * SK_Scalar1);
        fPaths.back().quadTo(50 * SK_Scalar1, 100 * SK_Scalar1,
                             0, 0);

        // CW
        fPaths.push_back().moveTo(0, 50 * SK_Scalar1);
        fPaths.back().quadTo(50 * SK_Scalar1, 0,
                             100 * SK_Scalar1, 50 * SK_Scalar1);
        fPaths.back().quadTo(50 * SK_Scalar1, 100 * SK_Scalar1,
                             0, 50 * SK_Scalar1);

        // CCW
        fPaths.push_back().moveTo(0, 50 * SK_Scalar1);
        fPaths.back().quadTo(50 * SK_Scalar1, 100 * SK_Scalar1,
                             100 * SK_Scalar1, 50 * SK_Scalar1);
        fPaths.back().quadTo(50 * SK_Scalar1, 0,
                             0, 50 * SK_Scalar1);

        fPaths.push_back().addRect(0, 0,
                                   100 * SK_Scalar1, 100 * SK_Scalar1,
                                   SkPath::kCW_Direction);

        fPaths.push_back().addRect(0, 0,
                                   100 * SK_Scalar1, 100 * SK_Scalar1,
                                   SkPath::kCCW_Direction);

        fPaths.push_back().addCircle(50  * SK_Scalar1, 50  * SK_Scalar1,
                                     50  * SK_Scalar1, SkPath::kCW_Direction);

        fPaths.push_back().addCircle(50  * SK_Scalar1, 50  * SK_Scalar1,
                                     40  * SK_Scalar1, SkPath::kCCW_Direction);

        fPaths.push_back().addOval(SkRect::MakeXYWH(0, 0,
                                                    50 * SK_Scalar1,
                                                    100 * SK_Scalar1),
                                   SkPath::kCW_Direction);

        fPaths.push_back().addOval(SkRect::MakeXYWH(0, 0,
                                                    100 * SK_Scalar1,
                                                    50 * SK_Scalar1),
                                   SkPath::kCCW_Direction);

        fPaths.push_back().addOval(SkRect::MakeXYWH(0, 0,
                                                    100 * SK_Scalar1,
                                                    5 * SK_Scalar1),
                                   SkPath::kCCW_Direction);

        fPaths.push_back().addOval(SkRect::MakeXYWH(0, 0,
                                                    SK_Scalar1,
                                                    100 * SK_Scalar1),
                                   SkPath::kCCW_Direction);

        fPaths.push_back().addRoundRect(SkRect::MakeXYWH(0, 0,
                                                         SK_Scalar1 * 100,
                                                         SK_Scalar1 * 100),
                                        40 * SK_Scalar1, 20 * SK_Scalar1,
                                        SkPath::kCW_Direction);

        fPaths.push_back().addRoundRect(SkRect::MakeXYWH(0, 0,
                                                         SK_Scalar1 * 100,
                                                         SK_Scalar1 * 100),
                                        20 * SK_Scalar1, 40 * SK_Scalar1,
                                        SkPath::kCCW_Direction);

        // shallow diagonals
        fPaths.push_back().lineTo(100 * SK_Scalar1, SK_Scalar1);
        fPaths.back().lineTo(98 * SK_Scalar1, 100 * SK_Scalar1);
        fPaths.back().lineTo(3 * SK_Scalar1, 96 * SK_Scalar1);

        /*
        It turns out arcTos are not automatically marked as convex and they
        may in fact be ever so slightly concave.
        fPaths.push_back().arcTo(SkRect::MakeXYWH(0, 0,
                                                  50 * SK_Scalar1,
                                                  100 * SK_Scalar1),
                                 25 * SK_Scalar1,  130 * SK_Scalar1, false);
        */
        // cubics
        fPaths.push_back().cubicTo( 1 * SK_Scalar1,  1 * SK_Scalar1,
                                   10 * SK_Scalar1,  90 * SK_Scalar1,
                                    0 * SK_Scalar1, 100 * SK_Scalar1);
        fPaths.push_back().cubicTo(100 * SK_Scalar1,  50 * SK_Scalar1,
                                    20 * SK_Scalar1, 100 * SK_Scalar1,
                                     0 * SK_Scalar1,   0 * SK_Scalar1);

        // path that has a cubic with a repeated first control point and
        // a repeated last control point.
        fPaths.push_back().moveTo(SK_Scalar1 * 10, SK_Scalar1 * 10);
        fPaths.back().cubicTo(10 * SK_Scalar1, 10 * SK_Scalar1,
                              10 * SK_Scalar1, 0,
                              20 * SK_Scalar1, 0);
        fPaths.back().lineTo(40 * SK_Scalar1, 0);
        fPaths.back().cubicTo(40 * SK_Scalar1, 0,
                              50 * SK_Scalar1, 0,
                              50 * SK_Scalar1, 10 * SK_Scalar1);

        // path that has two cubics with repeated middle control points.
        fPaths.push_back().moveTo(SK_Scalar1 * 10, SK_Scalar1 * 10);
        fPaths.back().cubicTo(10 * SK_Scalar1, 0,
                              10 * SK_Scalar1, 0,
                              20 * SK_Scalar1, 0);
        fPaths.back().lineTo(40 * SK_Scalar1, 0);
        fPaths.back().cubicTo(50 * SK_Scalar1, 0,
                              50 * SK_Scalar1, 0,
                              50 * SK_Scalar1, 10 * SK_Scalar1);

        // triangle where one edge is a degenerate quad
        fPaths.push_back().moveTo(SkFloatToScalar(8.59375f), 45 * SK_Scalar1);
        fPaths.back().quadTo(SkFloatToScalar(16.9921875f),   45 * SK_Scalar1,
                             SkFloatToScalar(31.25f),        45 * SK_Scalar1);
        fPaths.back().lineTo(100 * SK_Scalar1,              100 * SK_Scalar1);
        fPaths.back().lineTo(SkFloatToScalar(8.59375f),      45 * SK_Scalar1);

        // point degenerate
        fPaths.push_back().moveTo(50 * SK_Scalar1, 50 * SK_Scalar1);
        fPaths.back().lineTo(50 * SK_Scalar1, 50 * SK_Scalar1);
        
        fPaths.push_back().moveTo(50 * SK_Scalar1, 50 * SK_Scalar1);
        fPaths.back().quadTo(50 * SK_Scalar1, 50 * SK_Scalar1,
                             50 * SK_Scalar1, 50 * SK_Scalar1);
        fPaths.push_back().moveTo(50 * SK_Scalar1, 50 * SK_Scalar1);
        fPaths.back().cubicTo(50 * SK_Scalar1, 50 * SK_Scalar1,
                              50 * SK_Scalar1, 50 * SK_Scalar1,
                              50 * SK_Scalar1, 50 * SK_Scalar1);

        // moveTo only paths
        fPaths.push_back().moveTo(0, 0);
        fPaths.back().moveTo(0, 0);
        fPaths.back().moveTo(SK_Scalar1, SK_Scalar1);
        fPaths.back().moveTo(SK_Scalar1, SK_Scalar1);
        fPaths.back().moveTo(10 * SK_Scalar1, 10 * SK_Scalar1);

        fPaths.push_back().moveTo(0, 0);
        fPaths.back().moveTo(0, 0);

        // line degenerate
        fPaths.push_back().lineTo(100 * SK_Scalar1, 100 * SK_Scalar1);
        fPaths.push_back().quadTo(100 * SK_Scalar1, 100 * SK_Scalar1, 0, 0);
        fPaths.push_back().quadTo(100 * SK_Scalar1, 100 * SK_Scalar1,
                                  50 * SK_Scalar1, 50 * SK_Scalar1);
        fPaths.push_back().quadTo(50 * SK_Scalar1, 50 * SK_Scalar1,
                                  100 * SK_Scalar1, 100 * SK_Scalar1);
        fPaths.push_back().cubicTo(0, 0,
                                   0, 0,
                                   100 * SK_Scalar1, 100 * SK_Scalar1);

        // small circle. This is listed last so that it has device coords far
        // from the origin (small area relative to x,y values).
        fPaths.push_back().addCircle(0, 0, SkFloatToScalar(0.8f));
    }

    virtual void onDraw(SkCanvas* canvas) {
        this->makePaths();

    SkPaint paint;
    paint.setAntiAlias(true);
    SkRandom rand;
    canvas->translate(20 * SK_Scalar1, 20 * SK_Scalar1);
    for (int i = 0; i < fPaths.count(); ++i) {
        canvas->save();
        // position the path, and make it at off-integer coords.
        canvas->translate(SK_Scalar1 * 200 * (i % 5) + SK_Scalar1 / 4,
                          SK_Scalar1 * 200 * (i / 5) + 3 * SK_Scalar1 / 4);
        SkColor color = rand.nextU();
        color |= 0xff000000;
        paint.setColor(color);
        SkASSERT(fPaths[i].isConvex());
        canvas->drawPath(fPaths[i], paint);
        canvas->restore();
    }
    }
    
private:
    typedef GM INHERITED;
    SkTArray<SkPath> fPaths;
};

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

static GM* MyFactory(void*) { return new ConvexPathsGM; }
static GMRegistry reg(MyFactory);

}