text: /*
   * Copyright 2012 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 "include/core/SkImageFilter.h"
  
  #include "include/core/SkCanvas.h"
  #include "include/core/SkRect.h"
  #include "include/private/SkSafe32.h"
  #include "src/core/SkFuzzLogging.h"
  #include "src/core/SkImageFilterCache.h"
  #include "src/core/SkImageFilter_Base.h"
  #include "src/core/SkLocalMatrixImageFilter.h"
  #include "src/core/SkMatrixImageFilter.h"
  #include "src/core/SkReadBuffer.h"
  #include "src/core/SkSpecialImage.h"
  #include "src/core/SkSpecialSurface.h"
  #include "src/core/SkValidationUtils.h"
  #include "src/core/SkWriteBuffer.h"
  #if SK_SUPPORT_GPU
  #include "include/gpu/GrRecordingContext.h"
  #include "src/gpu/GrColorSpaceXform.h"
  #include "src/gpu/GrDirectContextPriv.h"
  #include "src/gpu/GrRecordingContextPriv.h"
  #include "src/gpu/GrSurfaceFillContext.h"
  #include "src/gpu/GrTextureProxy.h"
  #include "src/gpu/SkGr.h"
  #endif
  #include <atomic>
  
  ///////////////////////////////////////////////////////////////////////////////////////////////////
  // SkImageFilter - A number of the public APIs on SkImageFilter downcast to SkImageFilter_Base
  // in order to perform their actual work.
  ///////////////////////////////////////////////////////////////////////////////////////////////////
  
  /**
   *  Returns the number of inputs this filter will accept (some inputs can
   *  be NULL).
   */
  int SkImageFilter::countInputs() const { return as_IFB(this)->fInputs.count(); }
  
  /**
   *  Returns the input filter at a given index, or NULL if no input is
   *  connected.  The indices used are filter-specific.
   */
  const SkImageFilter* SkImageFilter::getInput(int i) const {
      SkASSERT(i < this->countInputs());
      return as_IFB(this)->fInputs[i].get();
  }
  
  bool SkImageFilter::isColorFilterNode(SkColorFilter** filterPtr) const {
      return as_IFB(this)->onIsColorFilterNode(filterPtr);
  }
  
  SkIRect SkImageFilter::filterBounds(const SkIRect& src, const SkMatrix& ctm,
                                      MapDirection direction, const SkIRect* inputRect) const {
      // The old filterBounds() function uses SkIRects that are defined in layer space so, while
      // we still are supporting it, bypass SkIF_B's new public filter bounds functions and go right
      // to the internal layer-space calculations.
      skif::Mapping mapping(SkMatrix::I(), ctm);
      if (kReverse_MapDirection == direction) {
          skif::LayerSpace<SkIRect> targetOutput(src);
          if (as_IFB(this)->cropRectIsSet()) {
             skif::LayerSpace<SkIRect> outputCrop = mapping.paramToLayer(
                      skif::ParameterSpace<SkRect>(as_IFB(this)->getCropRect().rect())).roundOut();
              // Just intersect directly; unlike the forward-mapping case, since we start with the
              // external target output, there's no need to embiggen due to affecting trans. black
              if (!targetOutput.intersect(outputCrop)) {
                  // Nothing would be output by the filter, so return empty rect
                  return SkIRect::MakeEmpty();
              }
          }
          skif::LayerSpace<SkIRect> content(inputRect ? *inputRect : src);
          return SkIRect(as_IFB(this)->onGetInputLayerBounds(mapping, targetOutput, content));
      } else {
          SkASSERT(!inputRect);
          skif::LayerSpace<SkIRect> content(src);
          skif::LayerSpace<SkIRect> output = as_IFB(this)->onGetOutputLayerBounds(mapping, content);
          // Manually apply the crop rect for now, until cropping is performed by a dedicated SkIF.
          SkIRect dst;
          as_IFB(this)->getCropRect().applyTo(
                  SkIRect(output), ctm, as_IFB(this)->affectsTransparentBlack(), &dst);
          return dst;
      }
  }
  
  SkRect SkImageFilter::computeFastBounds(const SkRect& src) const {
      if (0 == this->countInputs()) {
          return src;
      }
      SkRect combinedBounds = this->getInput(0) ? this->getInput(0)->computeFastBounds(src) : src;
      for (int i = 1; i < this->countInputs(); i++) {
          const SkImageFilter* input = this->getInput(i);
          if (input) {
              combinedBounds.join(input->computeFastBounds(src));
          } else {
              combinedBounds.join(src);
          }
      }
      return combinedBounds;
  }
  
  bool SkImageFilter::canComputeFastBounds() const {
      if (as_IFB(this)->affectsTransparentBlack()) {
          return false;
      }
      for (int i = 0; i < this->countInputs(); i++) {
          const SkImageFilter* input = this->getInput(i);
          if (input && !input->canComputeFastBounds()) {
              return false;
          }
      }
      return true;
  }
  
  bool SkImageFilter::asAColorFilter(SkColorFilter** filterPtr) const {
      SkASSERT(nullptr != filterPtr);
      if (!this->isColorFilterNode(filterPtr)) {
          return false;
      }
      if (nullptr != this->getInput(0) || as_CFB(*filterPtr)->affectsTransparentBlack()) {
          (*filterPtr)->unref();
          return false;
      }
      return true;
  }
  
  sk_sp<SkImageFilter> SkImageFilter::makeWithLocalMatrix(const SkMatrix& matrix) const {
      return SkLocalMatrixImageFilter::Make(matrix, this->refMe());
  }
  
  ///////////////////////////////////////////////////////////////////////////////////////////////////
  // SkImageFilter_Base
  ///////////////////////////////////////////////////////////////////////////////////////////////////
  
  SK_USE_FLUENT_IMAGE_FILTER_TYPES
  
  static int32_t next_image_filter_unique_id() {
      static std::atomic<int32_t> nextID{1};
  
      int32_t id;
      do {
          id = nextID.fetch_add(1, std::memory_order_relaxed);
      } while (id == 0);
      return id;
  }
  
  SkImageFilter_Base::SkImageFilter_Base(sk_sp<SkImageFilter> const* inputs,
                                         int inputCount, const SkRect* cropRect)
          : fUsesSrcInput(false)
          , fCropRect(cropRect)
          , fUniqueID(next_image_filter_unique_id()) {
      fInputs.reset(inputCount);
  
      for (int i = 0; i < inputCount; ++i) {
          if (!inputs[i] || as_IFB(inputs[i])->fUsesSrcInput) {
              fUsesSrcInput = true;
          }
          fInputs[i] = inputs[i];
      }
  }
  
  SkImageFilter_Base::~SkImageFilter_Base() {
      SkImageFilterCache::Get()->purgeByImageFilter(this);
  }
  
  bool SkImageFilter_Base::Common::unflatten(SkReadBuffer& buffer, int expectedCount) {
      const int count = buffer.readInt();
      if (!buffer.validate(count >= 0)) {
          return false;
      }
      if (!buffer.validate(expectedCount < 0 || count == expectedCount)) {
          return false;
      }
  
  #if defined(SK_BUILD_FOR_FUZZER)
      if (count > 4) {
          return false;
      }
  #endif
  
      SkASSERT(fInputs.empty());
      for (int i = 0; i < count; i++) {
          fInputs.push_back(buffer.readBool() ? buffer.readImageFilter() : nullptr);
          if (!buffer.isValid()) {
              return false;
          }
      }
      SkRect rect;
      buffer.readRect(&rect);
      if (!buffer.isValid() || !buffer.validate(SkIsValidRect(rect))) {
          return false;
      }
  
      uint32_t flags = buffer.readUInt();
      if (!buffer.isValid() ||
          !buffer.validate(flags == 0x0 || flags == CropRect::kHasAll_CropEdge)) {
          return false;
      }
      fCropRect = CropRect(flags ? &rect : nullptr);
      return buffer.isValid();
  }
  
  void SkImageFilter_Base::flatten(SkWriteBuffer& buffer) const {
      buffer.writeInt(fInputs.count());
      for (int i = 0; i < fInputs.count(); i++) {
          const SkImageFilter* input = this->getInput(i);
          buffer.writeBool(input != nullptr);
          if (input != nullptr) {
              buffer.writeFlattenable(input);
          }
      }
      buffer.writeRect(fCropRect.rect());
      buffer.writeUInt(fCropRect.flags());
  }
  
  skif::FilterResult<For::kOutput> SkImageFilter_Base::filterImage(const skif::Context& context) const {
      // TODO (michaelludwig) - Old filters have an implicit assumption that the source image
      // (originally passed separately) has an origin of (0, 0). SkComposeImageFilter makes an effort
      // to ensure that remains the case. Once everyone uses the new type systems for bounds, non
      // (0, 0) source origins will be easy to support.
      SkASSERT(context.source().layerOrigin().x() == 0 && context.source().layerOrigin().y() == 0);
  
      skif::FilterResult<For::kOutput> result;
      if (!context.isValid()) {
          return result;
      }
  
      uint32_t srcGenID = fUsesSrcInput ? context.sourceImage()->uniqueID() : 0;
      const SkIRect srcSubset = fUsesSrcInput ? context.sourceImage()->subset()
                                              : SkIRect::MakeWH(0, 0);
  
      SkImageFilterCacheKey key(fUniqueID, context.mapping().layerMatrix(), context.clipBounds(),
                                srcGenID, srcSubset);
      if (context.cache() && context.cache()->get(key, &result)) {
          return result;
      }
  
      result = this->onFilterImage(context);
  
      if (context.gpuBacked()) {
          SkASSERT(!result.image() || result.image()->isTextureBacked());
      }
  
      if (context.cache()) {
          context.cache()->set(key, this, result);
      }
  
      return result;
  }
  
  skif::LayerSpace<SkIRect> SkImageFilter_Base::getInputBounds(
          const skif::Mapping& mapping, const skif::DeviceSpace<SkIRect>& desiredOutput,
          const skif::ParameterSpace<SkRect>* knownContentBounds) const {
      // Map both the device-space desired coverage area and the known content bounds to layer space
      skif::LayerSpace<SkIRect> desiredBounds = mapping.deviceToLayer(desiredOutput);
  
      // TODO (michaelludwig) - To be removed once cropping is its own filter, since then an output
      // crop would automatically adjust the required input of its child filter in this same way.
      if (this->cropRectIsSet()) {
          skif::LayerSpace<SkIRect> outputCrop =
                  mapping.paramToLayer(skif::ParameterSpace<SkRect>(fCropRect.rect())).roundOut();
          if (!desiredBounds.intersect(outputCrop)) {
              // Nothing would be output by the filter, so return empty rect
              return skif::LayerSpace<SkIRect>(SkIRect::MakeEmpty());
          }
      }
  
      // If we have no known content bounds use the desired coverage area, because that is the most
      // conservative possibility.
      skif::LayerSpace<SkIRect> contentBounds =
              knownContentBounds ? mapping.paramToLayer(*knownContentBounds).roundOut()
                                 : desiredBounds;
  
      // Process the layer-space desired output with the filter DAG to determine required input
      skif::LayerSpace<SkIRect> requiredInput = this->onGetInputLayerBounds(
              mapping, desiredBounds, contentBounds);
      // If we know what's actually going to be drawn into the layer, and we don't change transparent
      // black, then we can further restrict the layer to what the known content is
      if (knownContentBounds && this->canComputeFastBounds()) {
          if (!requiredInput.intersect(contentBounds)) {
              // Nothing would be output by the filter, so return empty rect
              return skif::LayerSpace<SkIRect>(SkIRect::MakeEmpty());
          }
      }
      return requiredInput;
  }
  
  skif::DeviceSpace<SkIRect> SkImageFilter_Base::getOutputBounds(
          const skif::Mapping& mapping, const skif::ParameterSpace<SkRect>& contentBounds) const {
      // Map the input content into the layer space where filtering will occur
      skif::LayerSpace<SkRect> layerContent = mapping.paramToLayer(contentBounds);
      // Determine the filter DAGs output bounds in layer space
      skif::LayerSpace<SkIRect> filterOutput = this->onGetOutputLayerBounds(
              mapping, layerContent.roundOut());
      // FIXME (michaelludwig) - To be removed once cropping is isolated, but remain consistent with
      // old filterBounds(kForward) behavior.
      SkIRect dst;
      as_IFB(this)->getCropRect().applyTo(
              SkIRect(filterOutput), mapping.layerMatrix(),
              as_IFB(this)->affectsTransparentBlack(), &dst);
  
      // Map all the way to device space
      return mapping.layerToDevice(skif::LayerSpace<SkIRect>(dst));
  }
  
  // TODO (michaelludwig) - Default to using the old onFilterImage, as filters are updated one by one.
  // Once the old function is gone, this onFilterImage() will be made a pure virtual.
  skif::FilterResult<For::kOutput> SkImageFilter_Base::onFilterImage(const skif::Context& context) const {
      SkIPoint origin;
      auto image = this->onFilterImage(context, &origin);
      return skif::FilterResult<For::kOutput>(std::move(image), skif::LayerSpace<SkIPoint>(origin));
  }
  
  SkImageFilter_Base::MatrixCapability SkImageFilter_Base::getCTMCapability() const {
      MatrixCapability result = this->onGetCTMCapability();
      // CropRects need to apply in the source coordinate system, but are not aware of complex CTMs
      // when performing clipping. For a simple fix, any filter with a crop rect set cannot support
      // more than scale+translate CTMs until that's updated.
      if (this->cropRectIsSet()) {
          result = std::min(result, MatrixCapability::kScaleTranslate);
      }
      const int count = this->countInputs();
      for (int i = 0; i < count; ++i) {
          if (const SkImageFilter_Base* input = as_IFB(this->getInput(i))) {
              result = std::min(result, input->getCTMCapability());
          }
      }
      return result;
  }
  
  void SkImageFilter_Base::CropRect::applyTo(const SkIRect& imageBounds, const SkMatrix& ctm,
                                             bool embiggen, SkIRect* cropped) const {
      *cropped = imageBounds;
      if (fFlags) {
          SkRect devCropR;
          ctm.mapRect(&devCropR, fRect);
          SkIRect devICropR = devCropR.roundOut();
  
          // Compute the left/top first, in case we need to modify the right/bottom for a missing edge
          if (fFlags & kHasLeft_CropEdge) {
              if (embiggen || devICropR.fLeft > cropped->fLeft) {
                  cropped->fLeft = devICropR.fLeft;
              }
          } else {
              devICropR.fRight = Sk32_sat_add(cropped->fLeft, devICropR.width());
          }
          if (fFlags & kHasTop_CropEdge) {
              if (embiggen || devICropR.fTop > cropped->fTop) {
                  cropped->fTop = devICropR.fTop;
              }
          } else {
              devICropR.fBottom = Sk32_sat_add(cropped->fTop, devICropR.height());
          }
          if (fFlags & kHasWidth_CropEdge) {
              if (embiggen || devICropR.fRight < cropped->fRight) {
                  cropped->fRight = devICropR.fRight;
              }
          }
          if (fFlags & kHasHeight_CropEdge) {
              if (embiggen || devICropR.fBottom < cropped->fBottom) {
                  cropped->fBottom = devICropR.fBottom;
              }
          }
      }
  }
  
  bool SkImageFilter_Base::applyCropRect(const Context& ctx, const SkIRect& srcBounds,
                                         SkIRect* dstBounds) const {
      SkIRect tmpDst = this->onFilterNodeBounds(srcBounds, ctx.ctm(), kForward_MapDirection, nullptr);
      fCropRect.applyTo(tmpDst, ctx.ctm(), this->affectsTransparentBlack(), dstBounds);
      // Intersect against the clip bounds, in case the crop rect has
      // grown the bounds beyond the original clip. This can happen for
      // example in tiling, where the clip is much smaller than the filtered
      // primitive. If we didn't do this, we would be processing the filter
      // at the full crop rect size in every tile.
      return dstBounds->intersect(ctx.clipBounds());
  }
  
  // Return a larger (newWidth x newHeight) copy of 'src' with black padding
  // around it.
  static sk_sp<SkSpecialImage> pad_image(SkSpecialImage* src, const SkImageFilter_Base::Context& ctx,
                                         int newWidth, int newHeight, int offX, int offY) {
      // We would like to operate in the source's color space (so that we return an "identical"
      // image, other than the padding. To achieve that, we'd create a new context using
      // src->getColorSpace() to replace ctx.colorSpace().
  
      // That fails in at least two ways. For formats that are texturable but not renderable (like
      // F16 on some ES implementations), we can't create a surface to do the work. For sRGB, images
      // may be tagged with an sRGB color space (which leads to an sRGB config in makeSurface). But
      // the actual config of that sRGB image on a device with no sRGB support is non-sRGB.
      //
      // Rather than try to special case these situations, we execute the image padding in the
      // destination color space. This should not affect the output of the DAG in (almost) any case,
      // because the result of this call is going to be used as an input, where it would have been
      // switched to the destination space anyway. The one exception would be a filter that expected
      // to consume unclamped F16 data, but the padded version of the image is pre-clamped to 8888.
      // We can revisit this logic if that ever becomes an actual problem.
      sk_sp<SkSpecialSurface> surf(ctx.makeSurface(SkISize::Make(newWidth, newHeight)));
      if (!surf) {
          return nullptr;
      }
  
      SkCanvas* canvas = surf->getCanvas();
      SkASSERT(canvas);
  
      canvas->clear(0x0);
  
      src->draw(canvas, offX, offY);
  
      return surf->makeImageSnapshot();
  }
  
  sk_sp<SkSpecialImage> SkImageFilter_Base::applyCropRectAndPad(const Context& ctx,
                                                                SkSpecialImage* src,
                                                                SkIPoint* srcOffset,
                                                                SkIRect* bounds) const {
      const SkIRect srcBounds = SkIRect::MakeXYWH(srcOffset->x(), srcOffset->y(),
                                                  src->width(), src->height());
  
      if (!this->applyCropRect(ctx, srcBounds, bounds)) {
          return nullptr;
      }
  
      if (srcBounds.contains(*bounds)) {
          return sk_sp<SkSpecialImage>(SkRef(src));
      } else {
          sk_sp<SkSpecialImage> img(pad_image(src, ctx, bounds->width(), bounds->height(),
                                              Sk32_sat_sub(srcOffset->x(), bounds->x()),
                                              Sk32_sat_sub(srcOffset->y(), bounds->y())));
          *srcOffset = SkIPoint::Make(bounds->x(), bounds->y());
          return img;
      }
  }
  
  // NOTE: The new onGetOutputLayerBounds() and onGetInputLayerBounds() default to calling into the
  // deprecated onFilterBounds and onFilterNodeBounds. While these functions are not tagged, they do
  // match the documented default behavior for the new bounds functions.
  SkIRect SkImageFilter_Base::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
                                             MapDirection dir, const SkIRect* inputRect) const {
      if (this->countInputs() < 1) {
          return src;
      }
  
      SkIRect totalBounds;
      for (int i = 0; i < this->countInputs(); ++i) {
          const SkImageFilter* filter = this->getInput(i);
          SkIRect rect = filter ? filter->filterBounds(src, ctm, dir, inputRect) : src;
          if (0 == i) {
              totalBounds = rect;
          } else {
              totalBounds.join(rect);
          }
      }
  
      return totalBounds;
  }
  
  SkIRect SkImageFilter_Base::onFilterNodeBounds(const SkIRect& src, const SkMatrix&,
                                                 MapDirection, const SkIRect*) const {
      return src;
  }
  
  skif::LayerSpace<SkIRect> SkImageFilter_Base::visitInputLayerBounds(
          const skif::Mapping& mapping, const skif::LayerSpace<SkIRect>& desiredOutput,
          const skif::LayerSpace<SkIRect>& contentBounds) const {
      if (this->countInputs() < 1) {
          // TODO (michaelludwig) - if a filter doesn't have any inputs, it doesn't need any
          // implicit source image, so arguably we could return an empty rect here. 'desiredOutput' is
          // consistent with original behavior, so empty bounds may have unintended side effects
          // but should be explored later.
          return desiredOutput;
      }
  
      skif::LayerSpace<SkIRect> netInput;
      for (int i = 0; i < this->countInputs(); ++i) {
          const SkImageFilter* filter = this->getInput(i);
          // The required input for this input filter, or 'targetOutput' if the filter is null and
          // the source image is used (so must be sized to cover 'targetOutput').
          skif::LayerSpace<SkIRect> requiredInput =
                  filter ? as_IFB(filter)->onGetInputLayerBounds(mapping, desiredOutput,
                                                                 contentBounds)
                         : desiredOutput;
          // Accumulate with all other filters
          if (i == 0) {
              netInput = requiredInput;
          } else {
              netInput.join(requiredInput);
          }
      }
      return netInput;
  }
  
  skif::LayerSpace<SkIRect> SkImageFilter_Base::visitOutputLayerBounds(
          const skif::Mapping& mapping, const skif::LayerSpace<SkIRect>& contentBounds) const {
      if (this->countInputs() < 1) {
          // TODO (michaelludwig) - if a filter doesn't have any inputs, it presumably is determining
          // its output size from something other than the implicit source contentBounds, in which
          // case it shouldn't be calling this helper function, so explore adding an unreachable test
          return contentBounds;
      }
  
      skif::LayerSpace<SkIRect> netOutput;
      for (int i = 0; i < this->countInputs(); ++i) {
          const SkImageFilter* filter = this->getInput(i);
          // The output for just this input filter, or 'contentBounds' if the filter is null and
          // the source image is used (i.e. the identity filter applied to the source).
          skif::LayerSpace<SkIRect> output =
                  filter ? as_IFB(filter)->onGetOutputLayerBounds(mapping, contentBounds)
                         : contentBounds;
          // Accumulate with all other filters
          if (i == 0) {
              netOutput = output;
          } else {
              netOutput.join(output);
          }
      }
      return netOutput;
  }
  
  skif::LayerSpace<SkIRect> SkImageFilter_Base::onGetInputLayerBounds(
          const skif::Mapping& mapping, const skif::LayerSpace<SkIRect>& desiredOutput,
          const skif::LayerSpace<SkIRect>& contentBounds, VisitChildren recurse) const {
      // Call old functions for now since they may have been overridden by a subclass that's not been
      // updated yet; normally this would just default to visitInputLayerBounds()
      SkIRect content = SkIRect(contentBounds);
      SkIRect input = this->onFilterNodeBounds(SkIRect(desiredOutput), mapping.layerMatrix(),
                                               kReverse_MapDirection, &content);
      if (recurse == VisitChildren::kYes) {
          SkIRect aggregate = this->onFilterBounds(input, mapping.layerMatrix(),
                                                   kReverse_MapDirection, &input);
          return skif::LayerSpace<SkIRect>(aggregate);
      } else {
          return skif::LayerSpace<SkIRect>(input);
      }
  }
  
  skif::LayerSpace<SkIRect> SkImageFilter_Base::onGetOutputLayerBounds(
          const skif::Mapping& mapping, const skif::LayerSpace<SkIRect>& contentBounds) const {
      // Call old functions for now; normally this would default to visitOutputLayerBounds()
      SkIRect aggregate = this->onFilterBounds(SkIRect(contentBounds), mapping.layerMatrix(),
                                               kForward_MapDirection, nullptr);
      SkIRect output = this->onFilterNodeBounds(aggregate, mapping.layerMatrix(),
                                                kForward_MapDirection, nullptr);
      return skif::LayerSpace<SkIRect>(output);
  }
  
  template<skif::Usage kU>
  skif::FilterResult<kU> SkImageFilter_Base::filterInput(int index, const skif::Context& ctx) const {
      SkASSERT(kU != skif::Usage::kInput0 || index == 0);
      SkASSERT(kU != skif::Usage::kInput1 || index == 1);
  
      const SkImageFilter* input = this->getInput(index);
      if (!input) {
          // Convert from the generic kInput of the source image to kU
          return static_cast<skif::FilterResult<kU>>(ctx.source());
      }
  
      skif::FilterResult<For::kOutput> result = as_IFB(input)->filterImage(this->mapContext(ctx));
      SkASSERT(!result.image() || ctx.gpuBacked() == result.image()->isTextureBacked());
  
      // Map the output result of the input image filter to the input usage requested for this filter
      return static_cast<skif::FilterResult<kU>>(std::move(result));
  }
  // Instantiate filterInput() for kInput, kInput0, and kInput1. This does not provide a definition
  // for kOutput, which should never be used anyways, and this way the linker will fail for us then.
  template skif::FilterResult<For::kInput> SkImageFilter_Base::filterInput(int, const skif::Context&) const;
  template skif::FilterResult<For::kInput0> SkImageFilter_Base::filterInput(int, const skif::Context&) const;
  template skif::FilterResult<For::kInput1> SkImageFilter_Base::filterInput(int, const skif::Context&) const;
  
  SkImageFilter_Base::Context SkImageFilter_Base::mapContext(const Context& ctx) const {
      // We don't recurse through the child input filters because that happens automatically
      // as part of the filterImage() evaluation. In this case, we want the bounds for the
      // edge from this node to its children, without the effects of the child filters.
      skif::LayerSpace<SkIRect> childOutput = this->onGetInputLayerBounds(
              ctx.mapping(), ctx.desiredOutput(), ctx.desiredOutput(), VisitChildren::kNo);
      return ctx.withNewDesiredOutput(childOutput);
  }
  
  #if SK_SUPPORT_GPU
  sk_sp<SkSpecialImage> SkImageFilter_Base::DrawWithFP(GrRecordingContext* rContext,
                                                       std::unique_ptr<GrFragmentProcessor> fp,
                                                       const SkIRect& bounds,
                                                       SkColorType colorType,
                                                       const SkColorSpace* colorSpace,
                                                       const SkSurfaceProps& surfaceProps,
                                                       GrProtected isProtected) {
      GrImageInfo info(SkColorTypeToGrColorType(colorType),
                       kPremul_SkAlphaType,
                       sk_ref_sp(colorSpace),
                       bounds.size());
  
      auto sfc = GrSurfaceFillContext::Make(rContext,
                                            info,
                                            SkBackingFit::kApprox,
                                            1,
                                            GrMipmapped::kNo,
                                            isProtected,
                                            kBottomLeft_GrSurfaceOrigin);
      if (!sfc) {
          return nullptr;
      }
  
      SkIRect dstIRect = SkIRect::MakeWH(bounds.width(), bounds.height());
      SkRect srcRect = SkRect::Make(bounds);
      sfc->fillRectToRectWithFP(srcRect, dstIRect, std::move(fp));
  
      return SkSpecialImage::MakeDeferredFromGpu(rContext,
                                                 dstIRect,
                                                 kNeedNewImageUniqueID_SpecialImage,
                                                 sfc->readSurfaceView(),
                                                 sfc->colorInfo().colorType(),
                                                 sfc->colorInfo().refColorSpace(),
                                                 surfaceProps);
  }
  
  sk_sp<SkSpecialImage> SkImageFilter_Base::ImageToColorSpace(SkSpecialImage* src,
                                                              SkColorType colorType,
                                                              SkColorSpace* colorSpace,
                                                              const SkSurfaceProps& surfaceProps) {
      // There are several conditions that determine if we actually need to convert the source to the
      // destination's color space. Rather than duplicate that logic here, just try to make an xform
      // object. If that produces something, then both are tagged, and the source is in a different
      // gamut than the dest. There is some overhead to making the xform, but those are cached, and
      // if we get one back, that means we're about to use it during the conversion anyway.
      auto colorSpaceXform = GrColorSpaceXform::Make(src->getColorSpace(),  src->alphaType(),
                                                     colorSpace, kPremul_SkAlphaType);
  
      if (!colorSpaceXform) {
          // No xform needed, just return the original image
          return sk_ref_sp(src);
      }
  
      sk_sp<SkSpecialSurface> surf(src->makeSurface(colorType, colorSpace,
                                                    SkISize::Make(src->width(), src->height()),
                                                    kPremul_SkAlphaType, surfaceProps));
      if (!surf) {
          return sk_ref_sp(src);
      }
  
      SkCanvas* canvas = surf->getCanvas();
      SkASSERT(canvas);
      SkPaint p;
      p.setBlendMode(SkBlendMode::kSrc);
      src->draw(canvas, 0, 0, SkSamplingOptions(), &p);
      return surf->makeImageSnapshot();
  }
  #endif
  
  // In repeat mode, when we are going to sample off one edge of the srcBounds we require the
  // opposite side be preserved.
  SkIRect SkImageFilter_Base::DetermineRepeatedSrcBound(const SkIRect& srcBounds,
                                                        const SkIVector& filterOffset,
                                                        const SkISize& filterSize,
                                                        const SkIRect& originalSrcBounds) {
      SkIRect tmp = srcBounds;
      tmp.adjust(-filterOffset.fX, -filterOffset.fY,
                 filterSize.fWidth - filterOffset.fX, filterSize.fHeight - filterOffset.fY);
  
      if (tmp.fLeft < originalSrcBounds.fLeft || tmp.fRight > originalSrcBounds.fRight) {
          tmp.fLeft = originalSrcBounds.fLeft;
          tmp.fRight = originalSrcBounds.fRight;
      }
      if (tmp.fTop < originalSrcBounds.fTop || tmp.fBottom > originalSrcBounds.fBottom) {
          tmp.fTop = originalSrcBounds.fTop;
          tmp.fBottom = originalSrcBounds.fBottom;
      }
  
      return tmp;
  }
  
  void SkImageFilter_Base::PurgeCache() {
      SkImageFilterCache::Get()->purge();
  }
  