Revert of Moving SkBlurImageFilter into core

src/effects/SkBlurImageFilter.cpp

+/*
+ * Copyright 2011 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBlurImageFilter.h"
+
+#include "SkAutoPixmapStorage.h"
+#include "SkColorPriv.h"
+#include "SkGpuBlurUtils.h"
+#include "SkOpts.h"
+#include "SkReadBuffer.h"
+#include "SkSpecialImage.h"
+#include "SkWriteBuffer.h"
+
+#if SK_SUPPORT_GPU
+#include "GrContext.h"
+#include "SkGr.h"
+#endif
+
+sk_sp<SkImageFilter> SkBlurImageFilter::Make(SkScalar sigmaX, SkScalar sigmaY, 
+                                             sk_sp<SkImageFilter> input,
+                                             const CropRect* cropRect) {
+    if (0 == sigmaX && 0 == sigmaY && !cropRect) {
+        return input;
+    }
+    return sk_sp<SkImageFilter>(new SkBlurImageFilter(sigmaX, sigmaY, input, cropRect));
+}
+
+// This rather arbitrary-looking value results in a maximum box blur kernel size
+// of 1000 pixels on the raster path, which matches the WebKit and Firefox
+// implementations. Since the GPU path does not compute a box blur, putting
+// the limit on sigma ensures consistent behaviour between the GPU and
+// raster paths.
+#define MAX_SIGMA SkIntToScalar(532)
+
+static SkVector map_sigma(const SkSize& localSigma, const SkMatrix& ctm) {
+    SkVector sigma = SkVector::Make(localSigma.width(), localSigma.height());
+    ctm.mapVectors(&sigma, 1);
+    sigma.fX = SkMinScalar(SkScalarAbs(sigma.fX), MAX_SIGMA);
+    sigma.fY = SkMinScalar(SkScalarAbs(sigma.fY), MAX_SIGMA);
+    return sigma;
+}
+
+SkBlurImageFilter::SkBlurImageFilter(SkScalar sigmaX,
+                                     SkScalar sigmaY,
+                                     sk_sp<SkImageFilter> input,
+                                     const CropRect* cropRect)
+    : INHERITED(&input, 1, cropRect)
+    , fSigma(SkSize::Make(sigmaX, sigmaY)) {
+}
+
+sk_sp<SkFlattenable> SkBlurImageFilter::CreateProc(SkReadBuffer& buffer) {
+    SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
+    SkScalar sigmaX = buffer.readScalar();
+    SkScalar sigmaY = buffer.readScalar();
+    return Make(sigmaX, sigmaY, common.getInput(0), &common.cropRect());
+}
+
+void SkBlurImageFilter::flatten(SkWriteBuffer& buffer) const {
+    this->INHERITED::flatten(buffer);
+    buffer.writeScalar(fSigma.fWidth);
+    buffer.writeScalar(fSigma.fHeight);
+}
+
+static void get_box3_params(SkScalar s, int *kernelSize, int* kernelSize3, int *lowOffset,
+                            int *highOffset) {
+    float pi = SkScalarToFloat(SK_ScalarPI);
+    int d = static_cast<int>(floorf(SkScalarToFloat(s) * 3.0f * sqrtf(2.0f * pi) / 4.0f + 0.5f));
+    *kernelSize = d;
+    if (d % 2 == 1) {
+        *lowOffset = *highOffset = (d - 1) / 2;
+        *kernelSize3 = d;
+    } else {
+        *highOffset = d / 2;
+        *lowOffset = *highOffset - 1;
+        *kernelSize3 = d + 1;
+    }
+}
+
+sk_sp<SkSpecialImage> SkBlurImageFilter::onFilterImage(SkSpecialImage* source,
+                                                       const Context& ctx,
+                                                       SkIPoint* offset) const {
+    SkIPoint inputOffset = SkIPoint::Make(0, 0);
+
+    sk_sp<SkSpecialImage> input(this->filterInput(0, source, ctx, &inputOffset));
+    if (!input) {
+        return nullptr;
+    }
+
+    SkIRect inputBounds = SkIRect::MakeXYWH(inputOffset.fX, inputOffset.fY,
+                                            input->width(), input->height());
+
+    SkIRect dstBounds;
+    if (!this->applyCropRect(this->mapContext(ctx), inputBounds, &dstBounds)) {
+        return nullptr;
+    }
+    if (!inputBounds.intersect(dstBounds)) {
+        return nullptr;
+    }
+
+    const SkVector sigma = map_sigma(fSigma, ctx.ctm());
+
+#if SK_SUPPORT_GPU
+    if (source->isTextureBacked()) {
+        GrContext* context = source->getContext();
+        sk_sp<GrTexture> inputTexture(input->asTextureRef(context));
+        SkASSERT(inputTexture);
+
+        if (0 == sigma.x() && 0 == sigma.y()) {
+            offset->fX = inputBounds.x();
+            offset->fY = inputBounds.y();
+            return input->makeSubset(inputBounds.makeOffset(-inputOffset.x(),
+                                                            -inputOffset.y()));
+        }
+
+        offset->fX = dstBounds.fLeft;
+        offset->fY = dstBounds.fTop;
+        inputBounds.offset(-inputOffset);
+        dstBounds.offset(-inputOffset);
+        sk_sp<GrDrawContext> drawContext(SkGpuBlurUtils::GaussianBlur(
+                                                                context,
+                                                                inputTexture.get(),
+                                                                sk_ref_sp(source->getColorSpace()),
+                                                                dstBounds,
+                                                                &inputBounds,
+                                                                sigma.x(),
+                                                                sigma.y()));
+        if (!drawContext) {
+            return nullptr;
+        }
+
+        // TODO: Get the colorSpace from the drawContext (once it has one)
+        return SkSpecialImage::MakeFromGpu(SkIRect::MakeWH(dstBounds.width(), dstBounds.height()),
+                                           kNeedNewImageUniqueID_SpecialImage,
+                                           drawContext->asTexture(),
+                                           sk_ref_sp(input->getColorSpace()), &source->props());
+    }
+#endif
+
+    int kernelSizeX, kernelSizeX3, lowOffsetX, highOffsetX;
+    int kernelSizeY, kernelSizeY3, lowOffsetY, highOffsetY;
+    get_box3_params(sigma.x(), &kernelSizeX, &kernelSizeX3, &lowOffsetX, &highOffsetX);
+    get_box3_params(sigma.y(), &kernelSizeY, &kernelSizeY3, &lowOffsetY, &highOffsetY);
+
+    if (kernelSizeX < 0 || kernelSizeY < 0) {
+        return nullptr;
+    }
+
+    if (kernelSizeX == 0 && kernelSizeY == 0) {
+        offset->fX = inputBounds.x();
+        offset->fY = inputBounds.y();
+        return input->makeSubset(inputBounds.makeOffset(-inputOffset.x(),
+                                                        -inputOffset.y()));
+    }
+
+    SkBitmap inputBM;
+
+    if (!input->getROPixels(&inputBM)) {
+        return nullptr;
+    }
+
+    if (inputBM.colorType() != kN32_SkColorType) {
+        return nullptr;
+    }
+
+    SkImageInfo info = SkImageInfo::Make(dstBounds.width(), dstBounds.height(),
+                                         inputBM.colorType(), inputBM.alphaType());
+
+    SkBitmap tmp, dst;
+    if (!tmp.tryAllocPixels(info) || !dst.tryAllocPixels(info)) {
+        return nullptr;
+    }
+
+    SkAutoLockPixels inputLock(inputBM), tmpLock(tmp), dstLock(dst);
+
+    offset->fX = dstBounds.fLeft;
+    offset->fY = dstBounds.fTop;
+    SkPMColor* t = tmp.getAddr32(0, 0);
+    SkPMColor* d = dst.getAddr32(0, 0);
+    int w = dstBounds.width(), h = dstBounds.height();
+    const SkPMColor* s = inputBM.getAddr32(inputBounds.x() - inputOffset.x(),
+                                           inputBounds.y() - inputOffset.y());
+    inputBounds.offset(-dstBounds.x(), -dstBounds.y());
+    dstBounds.offset(-dstBounds.x(), -dstBounds.y());
+    SkIRect inputBoundsT = SkIRect::MakeLTRB(inputBounds.top(), inputBounds.left(),
+                                             inputBounds.bottom(), inputBounds.right());
+    SkIRect dstBoundsT = SkIRect::MakeWH(dstBounds.height(), dstBounds.width());
+    int sw = int(inputBM.rowBytes() >> 2);
+
+    /**
+     *
+     * In order to make memory accesses cache-friendly, we reorder the passes to
+     * use contiguous memory reads wherever possible.
+     *
+     * For example, the 6 passes of the X-and-Y blur case are rewritten as
+     * follows. Instead of 3 passes in X and 3 passes in Y, we perform
+     * 2 passes in X, 1 pass in X transposed to Y on write, 2 passes in X,
+     * then 1 pass in X transposed to Y on write.
+     *
+     * +----+       +----+       +----+        +---+       +---+       +---+        +----+
+     * + AB + ----> | AB | ----> | AB | -----> | A | ----> | A | ----> | A | -----> | AB |
+     * +----+ blurX +----+ blurX +----+ blurXY | B | blurX | B | blurX | B | blurXY +----+
+     *                                         +---+       +---+       +---+
+     *
+     * In this way, two of the y-blurs become x-blurs applied to transposed
+     * images, and all memory reads are contiguous.
+     */
+    if (kernelSizeX > 0 && kernelSizeY > 0) {
+        SkOpts::box_blur_xx(s, sw,  inputBounds,  t, kernelSizeX,  lowOffsetX,  highOffsetX, w, h);
+        SkOpts::box_blur_xx(t,  w,  dstBounds,    d, kernelSizeX,  highOffsetX, lowOffsetX,  w, h);
+        SkOpts::box_blur_xy(d,  w,  dstBounds,    t, kernelSizeX3, highOffsetX, highOffsetX, w, h);
+        SkOpts::box_blur_xx(t,  h,  dstBoundsT,   d, kernelSizeY,  lowOffsetY,  highOffsetY, h, w);
+        SkOpts::box_blur_xx(d,  h,  dstBoundsT,   t, kernelSizeY,  highOffsetY, lowOffsetY,  h, w);
+        SkOpts::box_blur_xy(t,  h,  dstBoundsT,   d, kernelSizeY3, highOffsetY, highOffsetY, h, w);
+    } else if (kernelSizeX > 0) {
+        SkOpts::box_blur_xx(s, sw,  inputBounds,  d, kernelSizeX,  lowOffsetX,  highOffsetX, w, h);
+        SkOpts::box_blur_xx(d,  w,  dstBounds,    t, kernelSizeX,  highOffsetX, lowOffsetX,  w, h);
+        SkOpts::box_blur_xx(t,  w,  dstBounds,    d, kernelSizeX3, highOffsetX, highOffsetX, w, h);
+    } else if (kernelSizeY > 0) {
+        SkOpts::box_blur_yx(s, sw,  inputBoundsT, d, kernelSizeY,  lowOffsetY,  highOffsetY, h, w);
+        SkOpts::box_blur_xx(d,  h,  dstBoundsT,   t, kernelSizeY,  highOffsetY, lowOffsetY,  h, w);
+        SkOpts::box_blur_xy(t,  h,  dstBoundsT,   d, kernelSizeY3, highOffsetY, highOffsetY, h, w);
+    }
+
+    return SkSpecialImage::MakeFromRaster(SkIRect::MakeWH(dstBounds.width(),
+                                                          dstBounds.height()),
+                                          dst, &source->props());
+}
+
+
+SkRect SkBlurImageFilter::computeFastBounds(const SkRect& src) const {
+    SkRect bounds = this->getInput(0) ? this->getInput(0)->computeFastBounds(src) : src;
+    bounds.outset(SkScalarMul(fSigma.width(), SkIntToScalar(3)),
+                  SkScalarMul(fSigma.height(), SkIntToScalar(3)));
+    return bounds;
+}
+
+SkIRect SkBlurImageFilter::onFilterNodeBounds(const SkIRect& src, const SkMatrix& ctm,
+                                              MapDirection) const {
+    SkVector sigma = map_sigma(fSigma, ctm);
+    return src.makeOutset(SkScalarCeilToInt(SkScalarMul(sigma.x(), SkIntToScalar(3))),
+                          SkScalarCeilToInt(SkScalarMul(sigma.y(), SkIntToScalar(3))));
+}
+
+#ifndef SK_IGNORE_TO_STRING
+void SkBlurImageFilter::toString(SkString* str) const {
+    str->appendf("SkBlurImageFilter: (");
+    str->appendf("sigma: (%f, %f) input (", fSigma.fWidth, fSigma.fHeight);
+
+    if (this->getInput(0)) {
+        this->getInput(0)->toString(str);
+    }
+
+    str->append("))");
+}
+#endif