skia2/gm/imagescalealigned.cpp

/*
 * Copyright 2015 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/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkImage.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkSize.h"
#include "include/core/SkString.h"
#include "include/core/SkSurface.h"
#include "include/core/SkTypes.h"
#include "include/private/SkTArray.h"

class ImageScaleAlignedGM : public skiagm::GM {
protected:
    void onOnceBeforeDraw() override {
        const SkVector vectors[] = { { 1, 0 }, { 0, 1 } };

        for (size_t i = 0; i < std::size(vectors); ++i) {
           auto& set = fSets.push_back();

           set.fVector = vectors[i];
           set.fImages.push_back() = MakeImage(vectors[i], SK_ColorGREEN);
           set.fScales.push_back() = 1;
           set.fImages.push_back() = MakeImage(vectors[i], SK_ColorRED);
           set.fScales.push_back() = kStretchFactor;
           set.fImages.push_back() = MakeImage(vectors[i], SK_ColorGREEN);
           set.fScales.push_back() = 1;
        }
    }

    SkString onShortName() override {
        return SkString("image_scale_aligned");
    }

    SkISize onISize() override {
        return SkISize::Make(580, 780);
    }

    void onDraw(SkCanvas* canvas) override {
        struct {
            SkPoint offset;
            SkVector scale;
        } cfgs[] = {
            {{  10,    10    }, { 1, 1 }},
            {{ 300.5f, 10    }, { 1, 1 }},
            {{  10,    200.5f }, { 1, 1 }},
            {{ 300.5f, 200.5f }, { 1, 1 }},

            {{  10.5f, 400.5f }, {  1,  1 }},
            {{ 550.5f, 400.5f }, { -1,  1 }},
            {{  10.5f, 750.5f }, {  1, -1 }},
            {{ 550.5f, 750.5f }, { -1, -1 }},
        };

        for (size_t i = 0; i < std::size(cfgs); ++i) {
            SkAutoCanvasRestore acr(canvas, true);
            canvas->translate(cfgs[i].offset.x(), cfgs[i].offset.y());
            canvas->scale(cfgs[i].scale.x(), cfgs[i].scale.y());
            drawSets(canvas);
        }
    }

private:
    struct ImageSet {
        SkSTArray<3, sk_sp<SkImage>, true>  fImages;
        SkSTArray<3, SkScalar>              fScales;
        SkVector                            fVector;
    };

    static sk_sp<SkImage> MakeImage(const SkVector& vec, SkColor color) {
        const SkPoint start = SkPoint::Make(vec.y() * kSegLen / 2, vec.x() * kSegLen / 2);
        const SkPoint end   = SkPoint::Make(start.x() + vec.x() * (kSegLen - 1),
                                            start.y() + vec.y() * (kSegLen - 1));

        auto surface(SkSurface::MakeRasterN32Premul(kSegLen, kSegLen));
        surface->getCanvas()->clear(SK_ColorTRANSPARENT);

        SkPaint paint;
        paint.setAntiAlias(true);
        const SkRect border = SkRect::MakeIWH(kSegLen, kSegLen).makeInset(.5f, .5f);
        paint.setColor(SK_ColorBLUE);
        paint.setStyle(SkPaint::kStroke_Style);
        surface->getCanvas()->drawRect(border, paint);

        paint.setColor(SK_ColorBLACK);
        surface->getCanvas()->drawLine(start, end, paint);

        paint.reset();
        paint.setColor(color);
        const SkPoint pts[] = { start, end };
        surface->getCanvas()->drawPoints(SkCanvas::kPoints_PointMode, 2, pts, paint);

        return surface->makeImageSnapshot();
    }

    void drawSets(SkCanvas* canvas) const {
        SkAutoCanvasRestore acr(canvas, true);

        const SkSamplingOptions samplings[] = {
            SkSamplingOptions(SkFilterMode::kNearest),
            SkSamplingOptions(SkFilterMode::kLinear),
            SkSamplingOptions(SkFilterMode::kLinear, SkMipmapMode::kLinear),
            SkSamplingOptions(SkCubicResampler::Mitchell()),
        };
        const bool AAs[] = { false, true };

        SkPaint paint;
        for (int i = 0; i < fSets.count(); ++i) {
            auto& set = fSets[i];
            SkPoint lastPt;
            for (size_t j = 0; j < std::size(AAs); ++j) {
                paint.setAntiAlias(AAs[j]);
                for (size_t k = 0; k < std::size(samplings); ++k) {
                    lastPt = drawSet(canvas, set, samplings[k], paint);
                    canvas->translate((kSegLen + 4) * set.fVector.y(),
                                      (kSegLen + 4) * set.fVector.x());
                }
            }
            canvas->translate(lastPt.x() + kSegLen,
                - SkIntToScalar(kSegLen + 4) * std::size(samplings) * std::size(AAs));
        }
    }

    SkPoint drawSet(SkCanvas* canvas, const ImageSet& set, const SkSamplingOptions& sampling,
                    const SkPaint& paint) const {
        SkASSERT(set.fImages.count() == set.fScales.count());

        SkPoint pt = SkPoint::Make(0, 0);
        for (int i = 0; i < set.fImages.count(); ++i) {
            auto& img = set.fImages[i];
            const SkRect dst =
                SkRect::MakeXYWH(pt.x(), pt.y(),
                    img->width() * (1 + (set.fScales[i] - 1) * set.fVector.x()),
                    img->height() * (1 + (set.fScales[i] - 1) * set.fVector.y()));

            canvas->drawImageRect(img.get(), dst, sampling, &paint);
            pt.offset(dst.width() * set.fVector.x(), dst.height() * set.fVector.y());
        }

        return pt;
    }

    inline static constexpr unsigned  kSegLen = 15;
    inline static constexpr unsigned  kStretchFactor = 4;
    SkSTArray<2, ImageSet> fSets;

    using INHERITED = GM;
};

DEF_GM(return new ImageScaleAlignedGM();)