imagefilters.cpp File Reference

#include "gm/gm.h"
#include "include/core/SkBlendMode.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkColorFilter.h"
#include "include/core/SkImage.h"
#include "include/core/SkImageFilter.h"
#include "include/core/SkImageInfo.h"
#include "include/core/SkMaskFilter.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkRRect.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkSurface.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkColorMatrix.h"
#include "include/effects/SkGradientShader.h"
#include "include/effects/SkHighContrastFilter.h"
#include "include/effects/SkImageFilters.h"
#include "include/effects/SkShaderMaskFilter.h"
#include "include/gpu/GrDirectContext.h"
#include "include/gpu/ganesh/SkImageGanesh.h"
#include "src/core/SkCanvasPriv.h"
#include "tools/DecodeUtils.h"
#include "tools/Resources.h"
#include "tools/ToolUtils.h"
#include <utility>

Go to the source code of this file.

Classes
class	SaveLayerWithBackdropGM

Functions
static void	do_draw (SkCanvas *canvas, SkBlendMode mode, sk_sp< SkImageFilter > imf)
	DEF_SIMPLE_GM (imagefilters_xfermodes, canvas, 480, 480)
static sk_sp< SkImage >	make_image (SkCanvas *canvas)
	DEF_SIMPLE_GM (fast_slow_blurimagefilter, canvas, 620, 260)
static void	draw_set (SkCanvas *canvas, sk_sp< SkImageFilter > filters[], int count)
	DEF_SIMPLE_GM (imagefilters_effect_order, canvas, 512, 512)
	DEF_SIMPLE_GM (multiple_filters, canvas, 415, 210)

Function Documentation

DEF_SIMPLE_GM() [1/4]

DEF_SIMPLE_GM	(	fast_slow_blurimagefilter	,
		canvas	,
		620	,
		260
	)

Definition at line 105 of file imagefilters.cpp.

                                                           {
    sk_sp<SkImage> image(make_image(canvas));
    const SkRect r = SkRect::MakeIWH(image->width(), image->height());
 
    canvas->translate(10, 10);
    for (SkScalar sigma = 8; sigma <= 128; sigma *= 2) {
        SkPaint paint;
        paint.setImageFilter(SkImageFilters::Blur(sigma, sigma, nullptr));
 
        canvas->save();
        // we outset the clip by 1, to fall out of the fast-case in drawImage
        // i.e. the clip is larger than the image
        for (SkScalar outset = 0; outset <= 1; ++outset) {
            canvas->save();
            canvas->clipRect(r.makeOutset(outset, outset));
            canvas->drawImage(image, 0, 0, SkSamplingOptions(), &paint);
            canvas->restore();
            canvas->translate(0, r.height() + 20);
        }
        canvas->restore();
        canvas->translate(r.width() + 20, 0);
    }
}

DEF_SIMPLE_GM() [2/4]

DEF_SIMPLE_GM	(	imagefilters_effect_order	,
		canvas	,
		512	,
		512
	)

Definition at line 204 of file imagefilters.cpp.

                                                           {
    sk_sp<SkImage> image(ToolUtils::GetResourceAsImage("images/mandrill_256.png"));
    auto direct = GrAsDirectContext(canvas->recordingContext());
    if (direct) {
        if (sk_sp<SkImage> gpuImage = SkImages::TextureFromImage(direct, image)) {
            image = std::move(gpuImage);
        }
    }
 
    SkISize kernelSize = SkISize::Make(3, 3);
    SkIPoint kernelOffset = SkIPoint::Make(1, 1);
    // A Laplacian edge detector, ie https://en.wikipedia.org/wiki/Kernel_(image_processing)
    SkScalar kernel[9] = {-1.f, -1.f, -1.f,
                          -1.f,  8.f, -1.f,
                          -1.f, -1.f, -1.f};
    auto edgeDetector = SkImageFilters::MatrixConvolution(
            kernelSize, kernel, 1.f, 0.f, kernelOffset, SkTileMode::kClamp, false, nullptr);
    // This uses the high contrast filter because it resembles a pre-processing step you may perform
    // prior to edge detection. The specifics of the high contrast algorithm don't matter for the GM
    auto edgeAmplify = SkHighContrastFilter::Make(
            {false, SkHighContrastConfig::InvertStyle::kNoInvert, 0.5f});
 
    SkPaint testCFPaint;
    testCFPaint.setColorFilter(edgeAmplify);
    testCFPaint.setImageFilter(edgeDetector);
 
    // The expected result is color filter then image filter, so represent this explicitly in the
    // image filter graph.
    SkPaint expectedCFPaint;
    expectedCFPaint.setImageFilter(SkImageFilters::Compose(edgeDetector,
            SkImageFilters::ColorFilter(edgeAmplify, nullptr)));
 
    // Draw the image twice (expected on the left, test on the right that should match)
    SkRect crop = SkRect::Make(image->bounds());
    canvas->save();
    canvas->clipRect(crop);
    canvas->drawImage(image, 0, 0, SkSamplingOptions(), &expectedCFPaint); // Filter applied by draw's SkPaint
    canvas->restore();
 
    canvas->save();
    canvas->translate(image->width(), 0);
    canvas->clipRect(crop);
    canvas->drawImage(image, 0, 0, SkSamplingOptions(), &testCFPaint);
    canvas->restore();
 
    // Now test mask filters. These should be run before the image filter, and thus have the same
    // effect as multiplying by an alpha mask.
 
    // This mask filter pokes a hole in the center of the image
    static constexpr SkColor kAlphas[] = { SK_ColorBLACK, SK_ColorTRANSPARENT };
    static constexpr SkScalar kPos[] = { 0.4f, 0.9f };
    sk_sp<SkShader> alphaMaskShader = SkGradientShader::MakeRadial(
            {128.f, 128.f}, 128.f, kAlphas, kPos, 2, SkTileMode::kClamp);
    sk_sp<SkMaskFilter> maskFilter = SkShaderMaskFilter::Make(alphaMaskShader);
 
    // If edge detector sees the mask filter, it'll have alpha and then blend with the original
    // image; otherwise the mask filter will apply late (incorrectly) and none of the original
    // image will be visible.
    sk_sp<SkImageFilter> edgeBlend = SkImageFilters::Blend(SkBlendMode::kSrcOver,
            SkImageFilters::Image(image, SkFilterMode::kNearest), edgeDetector);
 
    SkPaint testMaskPaint;
    testMaskPaint.setMaskFilter(maskFilter);
    testMaskPaint.setImageFilter(edgeBlend);
 
    SkPaint expectedMaskPaint;
    expectedMaskPaint.setImageFilter(SkImageFilters::Compose(edgeBlend,
            SkImageFilters::Blend(SkBlendMode::kSrcIn,
                                  SkImageFilters::Shader(alphaMaskShader))));
 
    canvas->save();
    canvas->translate(0, image->height());
    canvas->clipRect(crop);
    canvas->drawImage(image, 0, 0, SkSamplingOptions(), &expectedMaskPaint);
    canvas->restore();
 
    canvas->save();
    canvas->translate(image->width(), image->height());
    canvas->clipRect(crop);
    canvas->drawImage(image, 0, 0, SkSamplingOptions(), &testMaskPaint);
    canvas->restore();
}

DEF_SIMPLE_GM() [3/4]

DEF_SIMPLE_GM	(	imagefilters_xfermodes	,
		canvas	,
		480	,
		480
	)

Definition at line 71 of file imagefilters.cpp.

                                                        {
        canvas->translate(10, 10);
 
        // just need an imagefilter to trigger the code-path (which creates a tmp layer)
        sk_sp<SkImageFilter> imf(SkImageFilters::MatrixTransform(SkMatrix::I(),
                                                                 SkSamplingOptions(),
                                                                 nullptr));
 
        const SkBlendMode modes[] = {
            SkBlendMode::kSrcATop, SkBlendMode::kDstIn
        };
 
        for (size_t i = 0; i < std::size(modes); ++i) {
            canvas->save();
            do_draw(canvas, modes[i], nullptr);
            canvas->translate(240, 0);
            do_draw(canvas, modes[i], imf);
            canvas->restore();
 
            canvas->translate(0, 240);
        }
}

DEF_SIMPLE_GM() [4/4]

DEF_SIMPLE_GM	(	multiple_filters	,
		canvas	,
		415	,
		210
	)

Definition at line 287 of file imagefilters.cpp.

                                                  {
    ToolUtils::draw_checkerboard(canvas);
    canvas->translate(5, 5);
 
    auto drawFilteredLayer = [=](SkCanvas::FilterSpan filters) {
        SkPaint restorePaint;
        restorePaint.setAlphaf(0.5f);
        SkCanvas::SaveLayerRec rec = SkCanvasPriv::ScaledBackdropLayer(
                /*bounds=*/nullptr,
                &restorePaint,
                /*backdrop=*/nullptr,
                /*backdropScale=*/1,
                /*saveLayerFlags=*/0,
                filters);
        canvas->save();
        canvas->clipRect({0, 0, 200, 200});
        canvas->saveLayer(rec);
 
        SkPaint paint;
        paint.setStyle(SkPaint::kStroke_Style);
        paint.setStrokeWidth(20);
        paint.setColor(SK_ColorGREEN);
        canvas->drawCircle(100, 100, 70, paint);
 
        canvas->restore();
        canvas->restore();
        canvas->translate(205, 0);
    };
 
    {
        // Test with two non-null filters that each change bounds in a different way:
        sk_sp<SkImageFilter> filters[2] = {SkImageFilters::Dilate(5, 5, nullptr),
                                           SkImageFilters::Erode(5, 5, nullptr)};
        drawFilteredLayer(filters);
    }
 
    {
        // Test with one null filter, to more closely mimic the canvas2D layers use-case:
        sk_sp<SkImageFilter> filters[2] = {
                SkImageFilters::DropShadowOnly(7, 7, 5, 5, SK_ColorBLUE, nullptr), nullptr};
        drawFilteredLayer(filters);
    }
}

do_draw()

static void do_draw ( SkCanvas *  canvas, SkBlendMode  mode, sk_sp< SkImageFilter >  imf  )

static

Test drawing a primitive w/ an imagefilter (in this case, just matrix w/ identity) to see that we apply the xfermode after the image has been created and filtered, and not during the creation step (i.e. before it is filtered).

see https://bug.skia.org/3741

Definition at line 46 of file imagefilters.cpp.

                                                                                  {
        SkAutoCanvasRestore acr(canvas, true);
        canvas->clipRect(SkRect::MakeWH(220, 220));
 
        // want to force a layer, so modes like DstIn can combine meaningfully, but the final
        // image can still be shown against our default (opaque) background. non-opaque GMs
        // are a lot more trouble to compare/triage.
        canvas->saveLayer(nullptr, nullptr);
        canvas->drawColor(SK_ColorGREEN);
 
        SkPaint paint;
        paint.setAntiAlias(true);
 
        SkRect r0 = SkRect::MakeXYWH(10, 60, 200, 100);
        SkRect r1 = SkRect::MakeXYWH(60, 10, 100, 200);
 
        paint.setColor(SK_ColorRED);
        canvas->drawOval(r0, paint);
 
        paint.setColor(0x660000FF);
        paint.setImageFilter(std::move(imf));
        paint.setBlendMode(mode);
        canvas->drawOval(r1, paint);
}

draw_set()

static void draw_set ( SkCanvas *  canvas, sk_sp< SkImageFilter >  filters[], int  count  )

static

Definition at line 131 of file imagefilters.cpp.

                                                                                  {
    const SkRect r = SkRect::MakeXYWH(30, 30, 200, 200);
    const SkScalar offset = 250;
    SkScalar dx = 0, dy = 0;
 
    for (int i = 0; i < count; ++i) {
        canvas->save();
        SkRRect rr = SkRRect::MakeRectXY(r.makeOffset(dx, dy), 20, 20);
        canvas->clipRRect(rr, true);
        canvas->saveLayer(SkCanvas::SaveLayerRec(&rr.getBounds(), nullptr, filters[i].get(), 0));
        canvas->drawColor(0x40FFFFFF);
        canvas->restore();
        canvas->restore();
 
        if (0 == dx) {
            dx = offset;
        } else {
            dx = 0;
            dy = offset;
        }
    }
}

make_image()

static sk_sp< SkImage > make_image ( SkCanvas *  canvas )

static

Definition at line 94 of file imagefilters.cpp.

                                                   {
    const SkImageInfo info = SkImageInfo::MakeS32(100, 100, kPremul_SkAlphaType);
    auto              surface(ToolUtils::makeSurface(canvas, info));
    surface->getCanvas()->drawRect(SkRect::MakeXYWH(25, 25, 50, 50), SkPaint());
    return surface->makeImageSnapshot();
}