gm/aarectmodes.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/gm.h"
#include "include/core/SkBitmap.h"
#include "include/core/SkBlendMode.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPath.h"
#include "include/core/SkPathBuilder.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkShader.h"
#include "include/core/SkTileMode.h"
#include "include/core/SkTypes.h"
#include "src/core/SkColorPriv.h"

#include <array>

static void test4(SkCanvas* canvas) {
    SkPaint paint;
    paint.setAntiAlias(true);
    SkPoint pts[] = {
        {10, 160}, {610, 160},
        {610, 160}, {10, 160},

        {610, 160}, {610, 160},
        {610, 199}, {610, 199},

        {10, 198}, {610, 198},
        {610, 199}, {10, 199},

        {10, 160}, {10, 160},
        {10, 199}, {10, 199}
    };
    char verbs[] = {
        0, 1, 1, 1, 4,
        0, 1, 1, 1, 4,
        0, 1, 1, 1, 4,
        0, 1, 1, 1, 4
    };
    SkPathBuilder path;
    SkPoint* ptPtr = pts;
    for (size_t i = 0; i < sizeof(verbs); ++i) {
        switch ((SkPath::Verb) verbs[i]) {
            case SkPath::kMove_Verb:
                path.moveTo(ptPtr->fX, ptPtr->fY);
                ++ptPtr;
                break;
            case SkPath::kLine_Verb:
                path.lineTo(ptPtr->fX, ptPtr->fY);
                ++ptPtr;
                break;
            case SkPath::kClose_Verb:
                path.close();
                break;
            default:
                SkASSERT(false);
                break;
        }
    }
    SkRect clip = {0, 130, 772, 531};
    canvas->clipRect(clip);
    canvas->drawPath(path.detach(), paint);
}

constexpr auto gModes = std::to_array<SkBlendMode>({
        SkBlendMode::kClear,
        SkBlendMode::kSrc,
        SkBlendMode::kDst,
        SkBlendMode::kSrcOver,
        SkBlendMode::kDstOver,
        SkBlendMode::kSrcIn,
        SkBlendMode::kDstIn,
        SkBlendMode::kSrcOut,
        SkBlendMode::kDstOut,
        SkBlendMode::kSrcATop,
        SkBlendMode::kDstATop,
        SkBlendMode::kXor,
});

const int gWidth = 64;
const int gHeight = 64;
const SkScalar W = SkIntToScalar(gWidth);
const SkScalar H = SkIntToScalar(gHeight);

static SkScalar drawCell(SkCanvas* canvas, SkBlendMode mode, SkAlpha a0, SkAlpha a1) {

    SkPaint paint;
    paint.setAntiAlias(true);

    SkRect r = SkRect::MakeWH(W, H);
    r.inset(W/10, H/10);

    paint.setColor(SK_ColorBLUE);
    paint.setAlpha(a0);
    canvas->drawOval(r, paint);

    paint.setColor(SK_ColorRED);
    paint.setAlpha(a1);
    paint.setBlendMode(mode);

    SkScalar offset = SK_Scalar1 / 3;
    SkRect rect = SkRect::MakeXYWH(W / 4 + offset,
                                   H / 4 + offset,
                                   W / 2, H / 2);
    canvas->drawRect(rect, paint);

    return H;
}

static sk_sp<SkShader> make_bg_shader() {
    SkBitmap bm;
    bm.allocN32Pixels(2, 2);
    *bm.getAddr32(0, 0) = *bm.getAddr32(1, 1) = 0xFFFFFFFF;
    *bm.getAddr32(1, 0) = *bm.getAddr32(0, 1) = SkPackARGB32(0xFF, 0xCE,
                                                             0xCF, 0xCE);

    return bm.makeShader(SkTileMode::kRepeat, SkTileMode::kRepeat, SkSamplingOptions(),
                         SkMatrix::Scale(6, 6));
}

DEF_SIMPLE_GM(aarectmodes, canvas, 640, 480) {
            SkPaint bgPaint;
            bgPaint.setShader(make_bg_shader());
            if ((false)) { // avoid bit rot, suppress warning
                test4(canvas);
            }
            const SkRect bounds = SkRect::MakeWH(W, H);
            constexpr auto gAlphaValue = std::to_array<SkAlpha>({0xFF, 0x88, 0x88});

            canvas->translate(SkIntToScalar(4), SkIntToScalar(4));

            for (int alpha = 0; alpha < 4; ++alpha) {
                canvas->save();
                canvas->save();
                for (size_t i = 0; i < std::size(gModes); ++i) {
                    if (6 == i) {
                        canvas->restore();
                        canvas->translate(W * 5, 0);
                        canvas->save();
                    }
                    canvas->drawRect(bounds, bgPaint);
                    canvas->saveLayer(&bounds, nullptr);
                    SkScalar dy = drawCell(canvas, gModes[i],
                                           gAlphaValue[alpha & 1],
                                           gAlphaValue[alpha & 2]);
                    canvas->restore();

                    canvas->translate(0, dy * 5 / 4);
                }
                canvas->restore();
                canvas->restore();
                canvas->translate(W * 5 / 4, 0);
            }
}