tests/BlurTest.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 "SkBlurMask.h"
#include "SkBlurMaskFilter.h"
#include "SkCanvas.h"
#include "SkMath.h"
#include "SkPaint.h"
#include "Test.h"

#if SK_SUPPORT_GPU
#include "GrContextFactory.h"
#include "SkGpuDevice.h"
#endif

#define WRITE_CSV 0

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

#define ILLEGAL_MODE    ((SkXfermode::Mode)-1)

static const int outset = 100;
static const SkColor bgColor = SK_ColorWHITE;
static const int strokeWidth = 4;

static void create(SkBitmap* bm, const SkIRect& bound) {
    bm->allocN32Pixels(bound.width(), bound.height());
}

static void drawBG(SkCanvas* canvas) {
    canvas->drawColor(bgColor);
}


struct BlurTest {
    void (*addPath)(SkPath*);
    int viewLen;
    SkIRect views[9];
};

//Path Draw Procs
//Beware that paths themselves my draw differently depending on the clip.
static void draw50x50Rect(SkPath* path) {
    path->addRect(0, 0, SkIntToScalar(50), SkIntToScalar(50));
}

//Tests
static BlurTest tests[] = {
    { draw50x50Rect, 3, {
        //inner half of blur
        { 0, 0, 50, 50 },
        //blur, but no path.
        { 50 + strokeWidth/2, 50 + strokeWidth/2, 100, 100 },
        //just an edge
        { 40, strokeWidth, 60, 50 - strokeWidth },
    }},
};

/** Assumes that the ref draw was completely inside ref canvas --
    implies that everything outside is "bgColor".
    Checks that all overlap is the same and that all non-overlap on the
    ref is "bgColor".
 */
static bool compare(const SkBitmap& ref, const SkIRect& iref,
                    const SkBitmap& test, const SkIRect& itest)
{
    const int xOff = itest.fLeft - iref.fLeft;
    const int yOff = itest.fTop - iref.fTop;

    SkAutoLockPixels alpRef(ref);
    SkAutoLockPixels alpTest(test);

    for (int y = 0; y < test.height(); ++y) {
        for (int x = 0; x < test.width(); ++x) {
            SkColor testColor = test.getColor(x, y);
            int refX = x + xOff;
            int refY = y + yOff;
            SkColor refColor;
            if (refX >= 0 && refX < ref.width() &&
                refY >= 0 && refY < ref.height())
            {
                refColor = ref.getColor(refX, refY);
            } else {
                refColor = bgColor;
            }
            if (refColor != testColor) {
                return false;
            }
        }
    }
    return true;
}

static void test_blur_drawing(skiatest::Reporter* reporter) {

    SkPaint paint;
    paint.setColor(SK_ColorGRAY);
    paint.setStyle(SkPaint::kStroke_Style);
    paint.setStrokeWidth(SkIntToScalar(strokeWidth));

    SkScalar sigma = SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(5));
    for (int style = 0; style < SkBlurMaskFilter::kBlurStyleCount; ++style) {
        SkBlurMaskFilter::BlurStyle blurStyle =
            static_cast<SkBlurMaskFilter::BlurStyle>(style);

        const uint32_t flagPermutations = SkBlurMaskFilter::kAll_BlurFlag;
        for (uint32_t flags = 0; flags < flagPermutations; ++flags) {
            SkMaskFilter* filter;
            filter = SkBlurMaskFilter::Create(blurStyle, sigma, flags);

            paint.setMaskFilter(filter);
            filter->unref();

            for (size_t test = 0; test < SK_ARRAY_COUNT(tests); ++test) {
                SkPath path;
                tests[test].addPath(&path);
                SkPath strokedPath;
                paint.getFillPath(path, &strokedPath);
                SkRect refBound = strokedPath.getBounds();
                SkIRect iref;
                refBound.roundOut(&iref);
                iref.inset(-outset, -outset);
                SkBitmap refBitmap;
                create(&refBitmap, iref);

                SkCanvas refCanvas(refBitmap);
                refCanvas.translate(SkIntToScalar(-iref.fLeft),
                                    SkIntToScalar(-iref.fTop));
                drawBG(&refCanvas);
                refCanvas.drawPath(path, paint);

                for (int view = 0; view < tests[test].viewLen; ++view) {
                    SkIRect itest = tests[test].views[view];
                    SkBitmap testBitmap;
                    create(&testBitmap, itest);

                    SkCanvas testCanvas(testBitmap);
                    testCanvas.translate(SkIntToScalar(-itest.fLeft),
                                         SkIntToScalar(-itest.fTop));
                    drawBG(&testCanvas);
                    testCanvas.drawPath(path, paint);

                    REPORTER_ASSERT(reporter,
                        compare(refBitmap, iref, testBitmap, itest));
                }
            }
        }
    }
}

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

// Use SkBlurMask::BlurGroundTruth to blur a 'width' x 'height' solid
// white rect. Return the right half of the middle row in 'result'.
static void ground_truth_2d(int width, int height,
                            SkScalar sigma,
                            int* result, int resultCount) {
    SkMask src, dst;

    src.fBounds.set(0, 0, width, height);
    src.fFormat = SkMask::kA8_Format;
    src.fRowBytes = src.fBounds.width();
    src.fImage = SkMask::AllocImage(src.computeTotalImageSize());

    memset(src.fImage, 0xff, src.computeTotalImageSize());

    dst.fImage = NULL;
    SkBlurMask::BlurGroundTruth(sigma, &dst, src, SkBlurMask::kNormal_Style);

    int midX = dst.fBounds.centerX();
    int midY = dst.fBounds.centerY();
    uint8_t* bytes = dst.getAddr8(midX, midY);
    int i;
    for (i = 0; i < dst.fBounds.width()-(midX-dst.fBounds.fLeft); ++i) {
        if (i < resultCount) {
            result[i] = bytes[i];
        }
    }
    for ( ; i < resultCount; ++i) {
        result[i] = 0;
    }

    SkMask::FreeImage(src.fImage);
    SkMask::FreeImage(dst.fImage);
}

// Implement a step function that is 255 between min and max; 0 elsewhere.
static int step(int x, SkScalar min, SkScalar max) {
    if (min < x && x < max) {
        return 255;
    }
    return 0;
}

// Implement a Gaussian function with 0 mean and std.dev. of 'sigma'.
static float gaussian(int x, SkScalar sigma) {
    float k = SK_Scalar1/(sigma * sqrtf(2.0f*SK_ScalarPI));
    float exponent = -(x * x) / (2 * sigma * sigma);
    return k * expf(exponent);
}

// Perform a brute force convolution of a step function with a Gaussian.
// Return the right half in 'result'
static void brute_force_1d(SkScalar stepMin, SkScalar stepMax,
                           SkScalar gaussianSigma,
                           int* result, int resultCount) {

    int gaussianRange = SkScalarCeilToInt(10 * gaussianSigma);

    for (int i = 0; i < resultCount; ++i) {
        SkScalar sum = 0.0f;
        for (int j = -gaussianRange; j < gaussianRange; ++j) {
            sum += gaussian(j, gaussianSigma) * step(i-j, stepMin, stepMax);
        }

        result[i] = SkClampMax(SkClampPos(int(sum + 0.5f)), 255);
    }
}

static void blur_path(SkCanvas* canvas, const SkPath& path,
                      SkScalar gaussianSigma) {

    SkScalar midX = path.getBounds().centerX();
    SkScalar midY = path.getBounds().centerY();

    canvas->translate(-midX, -midY);

    SkPaint blurPaint;
    blurPaint.setColor(SK_ColorWHITE);
    SkMaskFilter* filter = SkBlurMaskFilter::Create(SkBlurMaskFilter::kNormal_BlurStyle,
                                                    gaussianSigma,
                                                    SkBlurMaskFilter::kHighQuality_BlurFlag);
    blurPaint.setMaskFilter(filter)->unref();

    canvas->drawColor(SK_ColorBLACK);
    canvas->drawPath(path, blurPaint);
}

// Readback the blurred draw results from the canvas
static void readback(SkCanvas* canvas, int* result, int resultCount) {
    SkBitmap readback;
    readback.allocN32Pixels(resultCount, 30);

    SkIRect readBackRect = { 0, 0, resultCount, 30 };

    canvas->readPixels(readBackRect, &readback);

    readback.lockPixels();
    SkPMColor* pixels = (SkPMColor*) readback.getAddr32(0, 15);

    for (int i = 0; i < resultCount; ++i) {
        result[i] = SkColorGetR(pixels[i]);
    }
}

// Draw a blurred version of the provided path.
// Return the right half of the middle row in 'result'.
static void cpu_blur_path(const SkPath& path, SkScalar gaussianSigma,
                          int* result, int resultCount) {

    SkBitmap bitmap;
    bitmap.allocN32Pixels(resultCount, 30);
    SkCanvas canvas(bitmap);

    blur_path(&canvas, path, gaussianSigma);
    readback(&canvas, result, resultCount);
}

#if SK_SUPPORT_GPU
static bool gpu_blur_path(GrContextFactory* factory, const SkPath& path,
                          SkScalar gaussianSigma,
                          int* result, int resultCount) {

    GrContext* grContext = factory->get(GrContextFactory::kNative_GLContextType);
    if (NULL == grContext) {
        return false;
    }

    GrTextureDesc desc;
    desc.fConfig = kSkia8888_GrPixelConfig;
    desc.fFlags = kRenderTarget_GrTextureFlagBit;
    desc.fWidth = resultCount;
    desc.fHeight = 30;
    desc.fSampleCnt = 0;

    SkAutoTUnref<GrTexture> texture(grContext->createUncachedTexture(desc, NULL, 0));
    SkAutoTUnref<SkGpuDevice> device(SkNEW_ARGS(SkGpuDevice, (grContext, texture.get())));
    SkCanvas canvas(device.get());

    blur_path(&canvas, path, gaussianSigma);
    readback(&canvas, result, resultCount);
    return true;
}
#endif

#if WRITE_CSV
static void write_as_csv(const char* label, SkScalar scale, int* data, int count) {
    SkDebugf("%s_%.2f,", label, scale);
    for (int i = 0; i < count-1; ++i) {
        SkDebugf("%d,", data[i]);
    }
    SkDebugf("%d\n", data[count-1]);
}
#endif

static bool match(int* first, int* second, int count, int tol) {
    int delta;
    for (int i = 0; i < count; ++i) {
        delta = first[i] - second[i];
        if (delta > tol || delta < -tol) {
            return false;
        }
    }

    return true;
}

// Test out the normal blur style with a wide range of sigmas
static void test_sigma_range(skiatest::Reporter* reporter, GrContextFactory* factory) {

    static const int kSize = 100;

    // The geometry is offset a smidge to trigger:
    // https://code.google.com/p/chromium/issues/detail?id=282418
    SkPath rectPath;
    rectPath.addRect(0.3f, 0.3f, 100.3f, 100.3f);

    SkPoint polyPts[] = {
        { 0.3f, 0.3f },
        { 100.3f, 0.3f },
        { 100.3f, 100.3f },
        { 0.3f, 100.3f },
        { 2.3f, 50.3f }     // a little divet to throw off the rect special case
    };
    SkPath polyPath;
    polyPath.addPoly(polyPts, SK_ARRAY_COUNT(polyPts), true);

    int rectSpecialCaseResult[kSize];
    int generalCaseResult[kSize];
#if SK_SUPPORT_GPU
    int gpuResult[kSize];
#endif
    int groundTruthResult[kSize];
    int bruteForce1DResult[kSize];

    SkScalar sigma = 10.0f;

    for (int i = 0; i < 4; ++i, sigma /= 10) {

        cpu_blur_path(rectPath, sigma, rectSpecialCaseResult, kSize);
        cpu_blur_path(polyPath, sigma, generalCaseResult, kSize);
#if SK_SUPPORT_GPU
        bool haveGPUResult = gpu_blur_path(factory, rectPath, sigma, gpuResult, kSize);
#endif
        ground_truth_2d(100, 100, sigma, groundTruthResult, kSize);
        brute_force_1d(-50.0f, 50.0f, sigma, bruteForce1DResult, kSize);

        REPORTER_ASSERT(reporter, match(rectSpecialCaseResult, bruteForce1DResult, kSize, 5));
        REPORTER_ASSERT(reporter, match(generalCaseResult, bruteForce1DResult, kSize, 15));
#if SK_SUPPORT_GPU
        if (haveGPUResult) {
            // 1 works everywhere but: Ubuntu13 & Nexus4
            REPORTER_ASSERT(reporter, match(gpuResult, bruteForce1DResult, kSize, 10));
        }
#endif
        REPORTER_ASSERT(reporter, match(groundTruthResult, bruteForce1DResult, kSize, 1));

#if WRITE_CSV
        write_as_csv("RectSpecialCase", sigma, rectSpecialCaseResult, kSize);
        write_as_csv("GeneralCase", sigma, generalCaseResult, kSize);
#if SK_SUPPORT_GPU
        write_as_csv("GPU", sigma, gpuResult, kSize);
#endif
        write_as_csv("GroundTruth2D", sigma, groundTruthResult, kSize);
        write_as_csv("BruteForce1D", sigma, bruteForce1DResult, kSize);
#endif
    }
}

DEF_GPUTEST(Blur, reporter, factory) {
    test_blur_drawing(reporter);
    test_sigma_range(reporter, factory);
}