gm/overdrawcolorfilter.cpp

/*
 * Copyright 2016 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/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkColorFilter.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkPaint.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkSize.h"
#include "include/core/SkString.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkOverdrawColorFilter.h"
#include "include/effects/SkRuntimeEffect.h"

static const char* code = R"(
uniform half4 color0;
uniform half4 color1;
uniform half4 color2;
uniform half4 color3;
uniform half4 color4;
uniform half4 color5;

void main(inout half4 color) {
    half alpha = 255.0 * color.a;
    color = alpha < 0.5 ? color0
          : alpha < 1.5 ? color1
          : alpha < 2.5 ? color2
          : alpha < 3.5 ? color3
          : alpha < 4.5 ? color4
          :               color5;
}
)";

static inline void set_bitmap(SkBitmap* bitmap, uint8_t alpha) {
    for (int y = 0; y < bitmap->height(); y++) {
        for (int x = 0; x < bitmap->width(); x++) {
            uint8_t* addr = bitmap->getAddr8(x, y);
            *addr = alpha;
        }
    }

    bitmap->notifyPixelsChanged();
}

struct OverdrawColorFilter : public skiagm::GM {
    bool fRuntime;

    OverdrawColorFilter(bool runtime) : fRuntime(runtime) {}

    SkString onShortName() override {
        return SkString{fRuntime ? "overdrawcolorfilter_runtime"
                                 : "overdrawcolorfilter"};
    }

    SkISize onISize() override { return {200, 400}; }

    void onDraw(SkCanvas* canvas) override {
        static const SkColor colors[SkOverdrawColorFilter::kNumColors] = {
                0x80FF0000, 0x8000FF00, 0x800000FF, 0x80FFFF00, 0x8000FFFF, 0x80FF00FF,
        };

        SkPaint paint;
        if (fRuntime) {
            auto [effect, err] = SkRuntimeEffect::Make(SkString{code});
            if (effect) {

                SkRGBA4f<kPremul_SkAlphaType> uniforms[SK_ARRAY_COUNT(colors)];
                for (int i = 0; i < (int)SK_ARRAY_COUNT(colors); i++) {
                    uniforms[i] = SkColor4f::FromColor(colors[i]).premul();
                }

                paint.setColorFilter(
                    effect->makeColorFilter(SkData::MakeWithCopy(uniforms, sizeof(uniforms))));
            } else {
                SkDebugf("SkRuntimeEffect error: %s\n", err.c_str());
            }
        } else {
            paint.setColorFilter(SkOverdrawColorFilter::MakeWithSkColors(colors));
        }

        SkASSERT(paint.getColorFilter());

        SkImageInfo info = SkImageInfo::MakeA8(100, 100);
        SkBitmap bitmap;
        bitmap.allocPixels(info);
        set_bitmap(&bitmap, 0);
        canvas->drawBitmap(bitmap, 0, 0, &paint);
        set_bitmap(&bitmap, 1);
        canvas->drawBitmap(bitmap, 0, 100, &paint);
        set_bitmap(&bitmap, 2);
        canvas->drawBitmap(bitmap, 0, 200, &paint);
        set_bitmap(&bitmap, 3);
        canvas->drawBitmap(bitmap, 0, 300, &paint);
        set_bitmap(&bitmap, 4);
        canvas->drawBitmap(bitmap, 100, 0, &paint);
        set_bitmap(&bitmap, 5);
        canvas->drawBitmap(bitmap, 100, 100, &paint);
        set_bitmap(&bitmap, 6);
        canvas->drawBitmap(bitmap, 100, 200, &paint);
    }
};

DEF_GM(return new OverdrawColorFilter(false);)
DEF_GM(return new OverdrawColorFilter( true);)