SkBlurImageFilter.cpp revision e426babe7552b1cb4e27cdf4e90826feabb9e3b0 
1/*
2 * Copyright 2011 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "SkAutoPixmapStorage.h"
9#include "SkColorPriv.h"
10#include "SkGpuBlurUtils.h"
11#include "SkOpts.h"
12#include "SkReadBuffer.h"
13#include "SkSpecialImage.h"
14#include "SkWriteBuffer.h"
15
16#if SK_SUPPORT_GPU
17#include "GrContext.h"
18#include "SkGr.h"
19#endif
20
21class SkBlurImageFilterImpl : public SkImageFilter {
22public:
23    SkBlurImageFilterImpl(SkScalar sigmaX,
24                      SkScalar sigmaY,
25                      sk_sp<SkImageFilter> input,
26                      const CropRect* cropRect);
27
28    SkRect computeFastBounds(const SkRect&) const override;
29
30    SK_TO_STRING_OVERRIDE()
31    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBlurImageFilterImpl)
32
33#ifdef SK_SUPPORT_LEGACY_IMAGEFILTER_PTR
34    static SkImageFilter* Create(SkScalar sigmaX, SkScalar sigmaY, SkImageFilter* input = nullptr,
35                                 const CropRect* cropRect = nullptr) {
36        return SkImageInfo::Make(sigmaX, sigmaY, sk_ref_sp<SkImageFilter>(input), cropRect).release();
37    }
38#endif
39
40protected:
41    void flatten(SkWriteBuffer&) const override;
42    sk_sp<SkSpecialImage> onFilterImage(SkSpecialImage* source, const Context&,
43                                        SkIPoint* offset) const override;
44    SkIRect onFilterNodeBounds(const SkIRect& src, const SkMatrix&, MapDirection) const override;
45
46private:
47    SkSize   fSigma;
48    typedef SkImageFilter INHERITED;
49
50    friend class SkImageFilter;
51};
52
53SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkImageFilter)
54    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkBlurImageFilterImpl)
55SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
56
57///////////////////////////////////////////////////////////////////////////////
58
59sk_sp<SkImageFilter> SkImageFilter::MakeBlur(SkScalar sigmaX, SkScalar sigmaY,
60                                             sk_sp<SkImageFilter> input,
61                                             const CropRect* cropRect) {
62    if (0 == sigmaX && 0 == sigmaY && !cropRect) {
63        return input;
64    }
65    return sk_sp<SkImageFilter>(new SkBlurImageFilterImpl(sigmaX, sigmaY, input, cropRect));
66}
67
68// This rather arbitrary-looking value results in a maximum box blur kernel size
69// of 1000 pixels on the raster path, which matches the WebKit and Firefox
70// implementations. Since the GPU path does not compute a box blur, putting
71// the limit on sigma ensures consistent behaviour between the GPU and
72// raster paths.
73#define MAX_SIGMA SkIntToScalar(532)
74
75static SkVector map_sigma(const SkSize& localSigma, const SkMatrix& ctm) {
76    SkVector sigma = SkVector::Make(localSigma.width(), localSigma.height());
77    ctm.mapVectors(&sigma, 1);
78    sigma.fX = SkMinScalar(SkScalarAbs(sigma.fX), MAX_SIGMA);
79    sigma.fY = SkMinScalar(SkScalarAbs(sigma.fY), MAX_SIGMA);
80    return sigma;
81}
82
83SkBlurImageFilterImpl::SkBlurImageFilterImpl(SkScalar sigmaX,
84                                     SkScalar sigmaY,
85                                     sk_sp<SkImageFilter> input,
86                                     const CropRect* cropRect)
87    : INHERITED(&input, 1, cropRect)
88    , fSigma(SkSize::Make(sigmaX, sigmaY)) {
89}
90
91sk_sp<SkFlattenable> SkBlurImageFilterImpl::CreateProc(SkReadBuffer& buffer) {
92    SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
93    SkScalar sigmaX = buffer.readScalar();
94    SkScalar sigmaY = buffer.readScalar();
95    return SkImageFilter::MakeBlur(sigmaX, sigmaY, common.getInput(0), &common.cropRect());
96}
97
98void SkBlurImageFilterImpl::flatten(SkWriteBuffer& buffer) const {
99    this->INHERITED::flatten(buffer);
100    buffer.writeScalar(fSigma.fWidth);
101    buffer.writeScalar(fSigma.fHeight);
102}
103
104static void get_box3_params(SkScalar s, int *kernelSize, int* kernelSize3, int *lowOffset,
105                            int *highOffset) {
106    float pi = SkScalarToFloat(SK_ScalarPI);
107    int d = static_cast<int>(floorf(SkScalarToFloat(s) * 3.0f * sqrtf(2.0f * pi) / 4.0f + 0.5f));
108    *kernelSize = d;
109    if (d % 2 == 1) {
110        *lowOffset = *highOffset = (d - 1) / 2;
111        *kernelSize3 = d;
112    } else {
113        *highOffset = d / 2;
114        *lowOffset = *highOffset - 1;
115        *kernelSize3 = d + 1;
116    }
117}
118
119sk_sp<SkSpecialImage> SkBlurImageFilterImpl::onFilterImage(SkSpecialImage* source,
120                                                       const Context& ctx,
121                                                       SkIPoint* offset) const {
122    SkIPoint inputOffset = SkIPoint::Make(0, 0);
123
124    sk_sp<SkSpecialImage> input(this->filterInput(0, source, ctx, &inputOffset));
125    if (!input) {
126        return nullptr;
127    }
128
129    SkIRect inputBounds = SkIRect::MakeXYWH(inputOffset.fX, inputOffset.fY,
130                                            input->width(), input->height());
131
132    SkIRect dstBounds;
133    if (!this->applyCropRect(this->mapContext(ctx), inputBounds, &dstBounds)) {
134        return nullptr;
135    }
136    if (!inputBounds.intersect(dstBounds)) {
137        return nullptr;
138    }
139
140    const SkVector sigma = map_sigma(fSigma, ctx.ctm());
141
142#if SK_SUPPORT_GPU
143    if (source->isTextureBacked()) {
144        GrContext* context = source->getContext();
145        sk_sp<GrTexture> inputTexture(input->asTextureRef(context));
146        SkASSERT(inputTexture);
147
148        if (0 == sigma.x() && 0 == sigma.y()) {
149            offset->fX = inputBounds.x();
150            offset->fY = inputBounds.y();
151            return input->makeSubset(inputBounds.makeOffset(-inputOffset.x(),
152                                                            -inputOffset.y()));
153        }
154
155        offset->fX = dstBounds.fLeft;
156        offset->fY = dstBounds.fTop;
157        inputBounds.offset(-inputOffset);
158        dstBounds.offset(-inputOffset);
159        sk_sp<GrDrawContext> drawContext(SkGpuBlurUtils::GaussianBlur(
160                                                                context,
161                                                                inputTexture.get(),
162                                                                sk_ref_sp(source->getColorSpace()),
163                                                                dstBounds,
164                                                                &inputBounds,
165                                                                sigma.x(),
166                                                                sigma.y()));
167        if (!drawContext) {
168            return nullptr;
169        }
170
171        // TODO: Get the colorSpace from the drawContext (once it has one)
172        return SkSpecialImage::MakeFromGpu(SkIRect::MakeWH(dstBounds.width(), dstBounds.height()),
173                                           kNeedNewImageUniqueID_SpecialImage,
174                                           drawContext->asTexture(),
175                                           sk_ref_sp(input->getColorSpace()), &source->props());
176    }
177#endif
178
179    int kernelSizeX, kernelSizeX3, lowOffsetX, highOffsetX;
180    int kernelSizeY, kernelSizeY3, lowOffsetY, highOffsetY;
181    get_box3_params(sigma.x(), &kernelSizeX, &kernelSizeX3, &lowOffsetX, &highOffsetX);
182    get_box3_params(sigma.y(), &kernelSizeY, &kernelSizeY3, &lowOffsetY, &highOffsetY);
183
184    if (kernelSizeX < 0 || kernelSizeY < 0) {
185        return nullptr;
186    }
187
188    if (kernelSizeX == 0 && kernelSizeY == 0) {
189        offset->fX = inputBounds.x();
190        offset->fY = inputBounds.y();
191        return input->makeSubset(inputBounds.makeOffset(-inputOffset.x(),
192                                                        -inputOffset.y()));
193    }
194
195    SkBitmap inputBM;
196
197    if (!input->getROPixels(&inputBM)) {
198        return nullptr;
199    }
200
201    if (inputBM.colorType() != kN32_SkColorType) {
202        return nullptr;
203    }
204
205    SkImageInfo info = SkImageInfo::Make(dstBounds.width(), dstBounds.height(),
206                                         inputBM.colorType(), inputBM.alphaType());
207
208    SkBitmap tmp, dst;
209    if (!tmp.tryAllocPixels(info) || !dst.tryAllocPixels(info)) {
210        return nullptr;
211    }
212
213    SkAutoLockPixels inputLock(inputBM), tmpLock(tmp), dstLock(dst);
214
215    offset->fX = dstBounds.fLeft;
216    offset->fY = dstBounds.fTop;
217    SkPMColor* t = tmp.getAddr32(0, 0);
218    SkPMColor* d = dst.getAddr32(0, 0);
219    int w = dstBounds.width(), h = dstBounds.height();
220    const SkPMColor* s = inputBM.getAddr32(inputBounds.x() - inputOffset.x(),
221                                           inputBounds.y() - inputOffset.y());
222    inputBounds.offset(-dstBounds.x(), -dstBounds.y());
223    dstBounds.offset(-dstBounds.x(), -dstBounds.y());
224    SkIRect inputBoundsT = SkIRect::MakeLTRB(inputBounds.top(), inputBounds.left(),
225                                             inputBounds.bottom(), inputBounds.right());
226    SkIRect dstBoundsT = SkIRect::MakeWH(dstBounds.height(), dstBounds.width());
227    int sw = int(inputBM.rowBytes() >> 2);
228
229    /**
230     *
231     * In order to make memory accesses cache-friendly, we reorder the passes to
232     * use contiguous memory reads wherever possible.
233     *
234     * For example, the 6 passes of the X-and-Y blur case are rewritten as
235     * follows. Instead of 3 passes in X and 3 passes in Y, we perform
236     * 2 passes in X, 1 pass in X transposed to Y on write, 2 passes in X,
237     * then 1 pass in X transposed to Y on write.
238     *
239     * +----+       +----+       +----+        +---+       +---+       +---+        +----+
240     * + AB + ----> | AB | ----> | AB | -----> | A | ----> | A | ----> | A | -----> | AB |
241     * +----+ blurX +----+ blurX +----+ blurXY | B | blurX | B | blurX | B | blurXY +----+
242     *                                         +---+       +---+       +---+
243     *
244     * In this way, two of the y-blurs become x-blurs applied to transposed
245     * images, and all memory reads are contiguous.
246     */
247    if (kernelSizeX > 0 && kernelSizeY > 0) {
248        SkOpts::box_blur_xx(s, sw,  inputBounds,  t, kernelSizeX,  lowOffsetX,  highOffsetX, w, h);
249        SkOpts::box_blur_xx(t,  w,  dstBounds,    d, kernelSizeX,  highOffsetX, lowOffsetX,  w, h);
250        SkOpts::box_blur_xy(d,  w,  dstBounds,    t, kernelSizeX3, highOffsetX, highOffsetX, w, h);
251        SkOpts::box_blur_xx(t,  h,  dstBoundsT,   d, kernelSizeY,  lowOffsetY,  highOffsetY, h, w);
252        SkOpts::box_blur_xx(d,  h,  dstBoundsT,   t, kernelSizeY,  highOffsetY, lowOffsetY,  h, w);
253        SkOpts::box_blur_xy(t,  h,  dstBoundsT,   d, kernelSizeY3, highOffsetY, highOffsetY, h, w);
254    } else if (kernelSizeX > 0) {
255        SkOpts::box_blur_xx(s, sw,  inputBounds,  d, kernelSizeX,  lowOffsetX,  highOffsetX, w, h);
256        SkOpts::box_blur_xx(d,  w,  dstBounds,    t, kernelSizeX,  highOffsetX, lowOffsetX,  w, h);
257        SkOpts::box_blur_xx(t,  w,  dstBounds,    d, kernelSizeX3, highOffsetX, highOffsetX, w, h);
258    } else if (kernelSizeY > 0) {
259        SkOpts::box_blur_yx(s, sw,  inputBoundsT, d, kernelSizeY,  lowOffsetY,  highOffsetY, h, w);
260        SkOpts::box_blur_xx(d,  h,  dstBoundsT,   t, kernelSizeY,  highOffsetY, lowOffsetY,  h, w);
261        SkOpts::box_blur_xy(t,  h,  dstBoundsT,   d, kernelSizeY3, highOffsetY, highOffsetY, h, w);
262    }
263
264    return SkSpecialImage::MakeFromRaster(SkIRect::MakeWH(dstBounds.width(),
265                                                          dstBounds.height()),
266                                          dst, &source->props());
267}
268
269
270SkRect SkBlurImageFilterImpl::computeFastBounds(const SkRect& src) const {
271    SkRect bounds = this->getInput(0) ? this->getInput(0)->computeFastBounds(src) : src;
272    bounds.outset(SkScalarMul(fSigma.width(), SkIntToScalar(3)),
273                  SkScalarMul(fSigma.height(), SkIntToScalar(3)));
274    return bounds;
275}
276
277SkIRect SkBlurImageFilterImpl::onFilterNodeBounds(const SkIRect& src, const SkMatrix& ctm,
278                                              MapDirection) const {
279    SkVector sigma = map_sigma(fSigma, ctm);
280    return src.makeOutset(SkScalarCeilToInt(SkScalarMul(sigma.x(), SkIntToScalar(3))),
281                          SkScalarCeilToInt(SkScalarMul(sigma.y(), SkIntToScalar(3))));
282}
283
284#ifndef SK_IGNORE_TO_STRING
285void SkBlurImageFilterImpl::toString(SkString* str) const {
286    str->appendf("SkBlurImageFilterImpl: (");
287    str->appendf("sigma: (%f, %f) input (", fSigma.fWidth, fSigma.fHeight);
288
289    if (this->getInput(0)) {
290        this->getInput(0)->toString(str);
291    }
292
293    str->append("))");
294}
295#endif
296