gm/xfermodes.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 "SkBitmap.h"
#include "SkShader.h"
#include "SkXfermode.h"

namespace skiagm {

static void make_bitmaps(int w, int h, SkBitmap* src, SkBitmap* dst,
                         SkBitmap* transparent) {
    src->allocN32Pixels(w, h);
    src->eraseColor(SK_ColorTRANSPARENT);

    SkPaint p;
    p.setAntiAlias(true);

    SkRect r;
    SkScalar ww = SkIntToScalar(w);
    SkScalar hh = SkIntToScalar(h);

    {
        SkCanvas c(*src);
        p.setColor(0xFFFFCC44);
        r.set(0, 0, ww*3/4, hh*3/4);
        c.drawOval(r, p);
    }

    dst->allocN32Pixels(w, h);
    dst->eraseColor(SK_ColorTRANSPARENT);

    {
        SkCanvas c(*dst);
        p.setColor(0xFF66AAFF);
        r.set(ww/3, hh/3, ww*19/20, hh*19/20);
        c.drawRect(r, p);
    }

    transparent->allocN32Pixels(w, h);
    transparent->eraseColor(SK_ColorTRANSPARENT);
}

static uint16_t gData[] = { 0xFFFF, 0xCCCF, 0xCCCF, 0xFFFF };

class XfermodesGM : public GM {
    enum SrcType {
     //! A WxH image with a rectangle in the lower right.
     kRectangleImage_SrcType               = 0x01,
     //! kRectangleImage_SrcType with an alpha of 34.5%.
     kRectangleImageWithAlpha_SrcType      = 0x02,
     //! kRectnagleImageWithAlpha_SrcType scaled down by half.
     kSmallRectangleImageWithAlpha_SrcType = 0x04,
     //! kRectangleImage_SrcType drawn directly instead in an image.
     kRectangle_SrcType                    = 0x08,
     //! Two rectangles, first on the right half, second on the bottom half.
     kQuarterClear_SrcType                 = 0x10,
     //! kQuarterClear_SrcType in a layer.
     kQuarterClearInLayer_SrcType          = 0x20,
     //! A W/2xH/2 transparent image.
     kSmallTransparentImage_SrcType        = 0x40,
     //! kRectangleImage_SrcType drawn directly with a mask.
     kRectangleWithMask_SrcType            = 0x80,

     kAll_SrcType                          = 0xFF, //!< All the source types.
     kBasic_SrcType                        = 0x03, //!< Just basic source types.
    };

    SkBitmap    fBG;
    SkBitmap    fSrcB, fDstB, fTransparent;

    /* The srcType argument indicates what to draw for the source part. Skia
     * uses the implied shape of the drawing command and these modes
     * demonstrate that.
     */
    void draw_mode(SkCanvas* canvas, SkXfermode* mode, SrcType srcType,
                   SkScalar x, SkScalar y) {
        SkPaint p;
        SkMatrix m;
        bool restoreNeeded = false;
        m.setTranslate(x, y);

        canvas->drawBitmapMatrix(fSrcB, m, &p);
        p.setXfermode(mode);
        switch (srcType) {
            case kSmallTransparentImage_SrcType:
                m.postScale(SK_ScalarHalf, SK_ScalarHalf, x, y);
                canvas->drawBitmapMatrix(fTransparent, m, &p);
                break;
            case kQuarterClearInLayer_SrcType: {
                SkRect bounds = SkRect::MakeXYWH(x, y, SkIntToScalar(W),
                                                 SkIntToScalar(H));
                canvas->saveLayer(&bounds, &p);
                restoreNeeded = true;
                p.setXfermodeMode(SkXfermode::kSrcOver_Mode);
                // Fall through.
            }
            case kQuarterClear_SrcType: {
                SkScalar halfW = SkIntToScalar(W) / 2;
                SkScalar halfH = SkIntToScalar(H) / 2;
                p.setColor(0xFF66AAFF);
                SkRect r = SkRect::MakeXYWH(x + halfW, y, halfW,
                                            SkIntToScalar(H));
                canvas->drawRect(r, p);
                p.setColor(0xFFAA66FF);
                r = SkRect::MakeXYWH(x, y + halfH, SkIntToScalar(W), halfH);
                canvas->drawRect(r, p);
                break;
            }
            case kRectangleWithMask_SrcType: {
                canvas->save();
                restoreNeeded = true;
                SkScalar w = SkIntToScalar(W);
                SkScalar h = SkIntToScalar(H);
                SkRect r = SkRect::MakeXYWH(x, y + h / 4, w, h * 23 / 60);
                canvas->clipRect(r);
                // Fall through.
            }
            case kRectangle_SrcType: {
                SkScalar w = SkIntToScalar(W);
                SkScalar h = SkIntToScalar(H);
                SkRect r = SkRect::MakeXYWH(x + w / 3, y + h / 3,
                                            w * 37 / 60, h * 37 / 60);
                p.setColor(0xFF66AAFF);
                canvas->drawRect(r, p);
                break;
            }
            case kSmallRectangleImageWithAlpha_SrcType:
                m.postScale(SK_ScalarHalf, SK_ScalarHalf, x, y);
                // Fall through.
            case kRectangleImageWithAlpha_SrcType:
                p.setAlpha(0x88);
                // Fall through.
            case kRectangleImage_SrcType:
                canvas->drawBitmapMatrix(fDstB, m, &p);
                break;
            default:
                break;
        }

        if (restoreNeeded) {
            canvas->restore();
        }
    }

    virtual void onOnceBeforeDraw() SK_OVERRIDE {
        fBG.installPixels(SkImageInfo::Make(2, 2, kARGB_4444_SkColorType,
                                            kOpaque_SkAlphaType),
                          gData, 4);

        make_bitmaps(W, H, &fSrcB, &fDstB, &fTransparent);
    }

public:
    const static int W = 64;
    const static int H = 64;
    XfermodesGM() {}

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

    virtual SkISize onISize() {
        return SkISize::Make(1990, 640);
    }

    virtual void onDraw(SkCanvas* canvas) {
        canvas->translate(SkIntToScalar(10), SkIntToScalar(20));

        const struct {
            SkXfermode::Mode  fMode;
            const char*       fLabel;
            int               fSourceTypeMask;  // The source types to use this
                                                // mode with. See draw_mode for
                                                // an explanation of each type.
                                                // PDF has to play some tricks
                                                // to support the base modes,
                                                // test those more extensively.
        } gModes[] = {
            { SkXfermode::kClear_Mode,        "Clear",        kAll_SrcType   },
            { SkXfermode::kSrc_Mode,          "Src",          kAll_SrcType   },
            { SkXfermode::kDst_Mode,          "Dst",          kAll_SrcType   },
            { SkXfermode::kSrcOver_Mode,      "SrcOver",      kAll_SrcType   },
            { SkXfermode::kDstOver_Mode,      "DstOver",      kAll_SrcType   },
            { SkXfermode::kSrcIn_Mode,        "SrcIn",        kAll_SrcType   },
            { SkXfermode::kDstIn_Mode,        "DstIn",        kAll_SrcType   },
            { SkXfermode::kSrcOut_Mode,       "SrcOut",       kAll_SrcType   },
            { SkXfermode::kDstOut_Mode,       "DstOut",       kAll_SrcType   },
            { SkXfermode::kSrcATop_Mode,      "SrcATop",      kAll_SrcType   },
            { SkXfermode::kDstATop_Mode,      "DstATop",      kAll_SrcType   },

            { SkXfermode::kXor_Mode,          "Xor",          kBasic_SrcType },
            { SkXfermode::kPlus_Mode,         "Plus",         kBasic_SrcType },
            { SkXfermode::kModulate_Mode,     "Modulate",     kAll_SrcType   },
            { SkXfermode::kScreen_Mode,       "Screen",       kBasic_SrcType },
            { SkXfermode::kOverlay_Mode,      "Overlay",      kBasic_SrcType },
            { SkXfermode::kDarken_Mode,       "Darken",       kBasic_SrcType },
            { SkXfermode::kLighten_Mode,      "Lighten",      kBasic_SrcType },
            { SkXfermode::kColorDodge_Mode,   "ColorDodge",   kBasic_SrcType },
            { SkXfermode::kColorBurn_Mode,    "ColorBurn",    kBasic_SrcType },
            { SkXfermode::kHardLight_Mode,    "HardLight",    kBasic_SrcType },
            { SkXfermode::kSoftLight_Mode,    "SoftLight",    kBasic_SrcType },
            { SkXfermode::kDifference_Mode,   "Difference",   kBasic_SrcType },
            { SkXfermode::kExclusion_Mode,    "Exclusion",    kBasic_SrcType },
            { SkXfermode::kMultiply_Mode,     "Multiply",     kAll_SrcType   },
            { SkXfermode::kHue_Mode,          "Hue",          kBasic_SrcType },
            { SkXfermode::kSaturation_Mode,   "Saturation",   kBasic_SrcType },
            { SkXfermode::kColor_Mode,        "Color",        kBasic_SrcType },
            { SkXfermode::kLuminosity_Mode,   "Luminosity",   kBasic_SrcType },
        };

        const SkScalar w = SkIntToScalar(W);
        const SkScalar h = SkIntToScalar(H);
        SkMatrix m;
        m.setScale(SkIntToScalar(6), SkIntToScalar(6));
        SkShader* s = SkShader::CreateBitmapShader(fBG,
                                                   SkShader::kRepeat_TileMode,
                                                   SkShader::kRepeat_TileMode,
                                                   &m);

        SkPaint labelP;
        labelP.setAntiAlias(true);
        labelP.setTextAlign(SkPaint::kCenter_Align);

        const int W = 5;

        SkScalar x0 = 0;
        SkScalar y0 = 0;
        for (int sourceType = 1; sourceType & kAll_SrcType; sourceType <<= 1) {
            SkScalar x = x0, y = y0;
            for (size_t i = 0; i < SK_ARRAY_COUNT(gModes); i++) {
                if ((gModes[i].fSourceTypeMask & sourceType) == 0) {
                    continue;
                }
                SkXfermode* mode = SkXfermode::Create(gModes[i].fMode);
                SkAutoUnref aur(mode);
                SkRect r;
                r.set(x, y, x+w, y+h);

                SkPaint p;
                p.setStyle(SkPaint::kFill_Style);
                p.setShader(s);
                canvas->drawRect(r, p);

                canvas->saveLayer(&r, NULL);
                draw_mode(canvas, mode, static_cast<SrcType>(sourceType),
                          r.fLeft, r.fTop);
                canvas->restore();

                r.inset(-SK_ScalarHalf, -SK_ScalarHalf);
                p.setStyle(SkPaint::kStroke_Style);
                p.setShader(NULL);
                canvas->drawRect(r, p);

#if 1
                canvas->drawText(gModes[i].fLabel, strlen(gModes[i].fLabel),
                                 x + w/2, y - labelP.getTextSize()/2, labelP);
#endif
                x += w + SkIntToScalar(10);
                if ((i % W) == W - 1) {
                    x = x0;
                    y += h + SkIntToScalar(30);
                }
            }
            if (y < 320) {
                if (x > x0) {
                    y += h + SkIntToScalar(30);
                }
                y0 = y;
            } else {
                x0 += SkIntToScalar(400);
                y0 = 0;
            }
        }
        s->unref();
    }

private:
    typedef GM INHERITED;
};

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

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

}