gecko-dev/layout/svg/nsCSSFilterInstance.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// Main header first:
#include "nsCSSFilterInstance.h"

// Keep others in (case-insensitive) order:
#include "gfx2DGlue.h"
#include "gfxUtils.h"
#include "nsIFrame.h"
#include "nsStyleStruct.h"
#include "nsTArray.h"

using namespace mozilla;
using namespace mozilla::gfx;

static float ClampFactor(float aFactor)
{
  if (aFactor > 1) {
    return 1;
  } else if (aFactor < 0) {
    NS_NOTREACHED("A negative value should not have been parsed.");
    return 0;
  }

  return aFactor;
}

nsCSSFilterInstance::nsCSSFilterInstance(const nsStyleFilter& aFilter,
                                         nscolor aShadowFallbackColor,
                                         const nsIntRect& aTargetBoundsInFilterSpace,
                                         const gfxMatrix& aFrameSpaceInCSSPxToFilterSpaceTransform)
  : mFilter(aFilter)
  , mShadowFallbackColor(aShadowFallbackColor)
  , mTargetBoundsInFilterSpace(aTargetBoundsInFilterSpace)
  , mFrameSpaceInCSSPxToFilterSpaceTransform(aFrameSpaceInCSSPxToFilterSpaceTransform)
{
}

nsresult
nsCSSFilterInstance::BuildPrimitives(nsTArray<FilterPrimitiveDescription>& aPrimitiveDescrs,
                                     bool aInputIsTainted)
{
  FilterPrimitiveDescription descr;
  nsresult result;

  switch(mFilter.GetType()) {
    case NS_STYLE_FILTER_BLUR:
      descr = CreatePrimitiveDescription(PrimitiveType::GaussianBlur,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForBlur(descr);
      break;
    case NS_STYLE_FILTER_BRIGHTNESS:
      descr = CreatePrimitiveDescription(PrimitiveType::ComponentTransfer,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForBrightness(descr);
      break;
    case NS_STYLE_FILTER_CONTRAST:
      descr = CreatePrimitiveDescription(PrimitiveType::ComponentTransfer,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForContrast(descr);
      break;
    case NS_STYLE_FILTER_DROP_SHADOW:
      descr = CreatePrimitiveDescription(PrimitiveType::DropShadow,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForDropShadow(descr);
      break;
    case NS_STYLE_FILTER_GRAYSCALE:
      descr = CreatePrimitiveDescription(PrimitiveType::ColorMatrix,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForGrayscale(descr);
      break;
    case NS_STYLE_FILTER_HUE_ROTATE:
      descr = CreatePrimitiveDescription(PrimitiveType::ColorMatrix,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForHueRotate(descr);
      break;
    case NS_STYLE_FILTER_INVERT:
      descr = CreatePrimitiveDescription(PrimitiveType::ComponentTransfer,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForInvert(descr);
      break;
    case NS_STYLE_FILTER_OPACITY:
      descr = CreatePrimitiveDescription(PrimitiveType::ComponentTransfer,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForOpacity(descr);
      break;
    case NS_STYLE_FILTER_SATURATE:
      descr = CreatePrimitiveDescription(PrimitiveType::ColorMatrix,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForSaturate(descr);
      break;
    case NS_STYLE_FILTER_SEPIA:
      descr = CreatePrimitiveDescription(PrimitiveType::ColorMatrix,
                                         aPrimitiveDescrs,
                                         aInputIsTainted);
      result = SetAttributesForSepia(descr);
      break;
    default:
      NS_NOTREACHED("not a valid CSS filter type");
      return NS_ERROR_FAILURE;
  }

  if (NS_FAILED(result)) {
    return result;
  }

  // Compute the primitive's bounds now that we've determined its attributes.
  // Some attributes like blur radius can influence the bounds.
  SetBounds(descr, aPrimitiveDescrs);

  // Add this primitive to the filter chain.
  aPrimitiveDescrs.AppendElement(descr);
  return NS_OK;
}

FilterPrimitiveDescription
nsCSSFilterInstance::CreatePrimitiveDescription(PrimitiveType aType,
                                                const nsTArray<FilterPrimitiveDescription>& aPrimitiveDescrs,
                                                bool aInputIsTainted) {
  FilterPrimitiveDescription descr(aType);
  int32_t inputIndex = GetLastResultIndex(aPrimitiveDescrs);
  descr.SetInputPrimitive(0, inputIndex);
  descr.SetIsTainted(inputIndex < 0 ? aInputIsTainted : aPrimitiveDescrs[inputIndex].IsTainted());
  descr.SetInputColorSpace(0, ColorSpace::SRGB);
  descr.SetOutputColorSpace(ColorSpace::SRGB);
  return descr;
}

nsresult
nsCSSFilterInstance::SetAttributesForBlur(FilterPrimitiveDescription& aDescr)
{
  const nsStyleCoord& radiusInFrameSpace = mFilter.GetFilterParameter();
  if (radiusInFrameSpace.GetUnit() != eStyleUnit_Coord) {
    NS_NOTREACHED("unexpected unit");
    return NS_ERROR_FAILURE;
  }

  Size radiusInFilterSpace = BlurRadiusToFilterSpace(radiusInFrameSpace.GetCoordValue());
  aDescr.Attributes().Set(eGaussianBlurStdDeviation, radiusInFilterSpace);
  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForBrightness(FilterPrimitiveDescription& aDescr)
{
  const nsStyleCoord& styleValue = mFilter.GetFilterParameter();
  float value = styleValue.GetFactorOrPercentValue();

  // Set transfer functions for RGB.
  AttributeMap brightnessAttrs;
  brightnessAttrs.Set(eComponentTransferFunctionType,
                      (uint32_t)SVG_FECOMPONENTTRANSFER_TYPE_LINEAR);
  brightnessAttrs.Set(eComponentTransferFunctionSlope, value);
  brightnessAttrs.Set(eComponentTransferFunctionIntercept, 0.0f);
  aDescr.Attributes().Set(eComponentTransferFunctionR, brightnessAttrs);
  aDescr.Attributes().Set(eComponentTransferFunctionG, brightnessAttrs);
  aDescr.Attributes().Set(eComponentTransferFunctionB, brightnessAttrs);

  // Set identity transfer function for A.
  AttributeMap identityAttrs;
  identityAttrs.Set(eComponentTransferFunctionType,
                    (uint32_t)SVG_FECOMPONENTTRANSFER_TYPE_IDENTITY);
  aDescr.Attributes().Set(eComponentTransferFunctionA, identityAttrs);

  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForContrast(FilterPrimitiveDescription& aDescr)
{
  const nsStyleCoord& styleValue = mFilter.GetFilterParameter();
  float value = styleValue.GetFactorOrPercentValue();
  float intercept = -(0.5 * value) + 0.5;

  // Set transfer functions for RGB.
  AttributeMap contrastAttrs;
  contrastAttrs.Set(eComponentTransferFunctionType,
                    (uint32_t)SVG_FECOMPONENTTRANSFER_TYPE_LINEAR);
  contrastAttrs.Set(eComponentTransferFunctionSlope, value);
  contrastAttrs.Set(eComponentTransferFunctionIntercept, intercept);
  aDescr.Attributes().Set(eComponentTransferFunctionR, contrastAttrs);
  aDescr.Attributes().Set(eComponentTransferFunctionG, contrastAttrs);
  aDescr.Attributes().Set(eComponentTransferFunctionB, contrastAttrs);

  // Set identity transfer function for A.
  AttributeMap identityAttrs;
  identityAttrs.Set(eComponentTransferFunctionType,
                    (uint32_t)SVG_FECOMPONENTTRANSFER_TYPE_IDENTITY);
  aDescr.Attributes().Set(eComponentTransferFunctionA, identityAttrs);

  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForDropShadow(FilterPrimitiveDescription& aDescr)
{
  nsCSSShadowArray* shadows = mFilter.GetDropShadow();
  if (!shadows || shadows->Length() != 1) {
    NS_NOTREACHED("Exactly one drop shadow should have been parsed.");
    return NS_ERROR_FAILURE;
  }

  nsCSSShadowItem* shadow = shadows->ShadowAt(0);

  // Set drop shadow blur radius.
  Size radiusInFilterSpace = BlurRadiusToFilterSpace(shadow->mRadius);
  aDescr.Attributes().Set(eDropShadowStdDeviation, radiusInFilterSpace);

  // Set offset.
  IntPoint offsetInFilterSpace = OffsetToFilterSpace(shadow->mXOffset, shadow->mYOffset);
  aDescr.Attributes().Set(eDropShadowOffset, offsetInFilterSpace);

  // Set color. If unspecified, use the CSS color property.
  nscolor shadowColor = shadow->mHasColor ? shadow->mColor : mShadowFallbackColor;
  aDescr.Attributes().Set(eDropShadowColor, ToAttributeColor(shadowColor));

  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForGrayscale(FilterPrimitiveDescription& aDescr)
{
  // Set color matrix type.
  aDescr.Attributes().Set(eColorMatrixType, (uint32_t)SVG_FECOLORMATRIX_TYPE_SATURATE);

  // Set color matrix values.
  const nsStyleCoord& styleValue = mFilter.GetFilterParameter();
  float value = 1 - ClampFactor(styleValue.GetFactorOrPercentValue());
  aDescr.Attributes().Set(eColorMatrixValues, &value, 1);

  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForHueRotate(FilterPrimitiveDescription& aDescr)
{
  // Set color matrix type.
  aDescr.Attributes().Set(eColorMatrixType, (uint32_t)SVG_FECOLORMATRIX_TYPE_HUE_ROTATE);

  // Set color matrix values.
  const nsStyleCoord& styleValue = mFilter.GetFilterParameter();
  float value = styleValue.GetAngleValueInDegrees();
  aDescr.Attributes().Set(eColorMatrixValues, &value, 1);

  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForInvert(FilterPrimitiveDescription& aDescr)
{
  const nsStyleCoord& styleValue = mFilter.GetFilterParameter();
  float value = ClampFactor(styleValue.GetFactorOrPercentValue());

  // Set transfer functions for RGB.
  AttributeMap invertAttrs;
  float invertTableValues[2];
  invertTableValues[0] = value;
  invertTableValues[1] = 1 - value;
  invertAttrs.Set(eComponentTransferFunctionType,
                  (uint32_t)SVG_FECOMPONENTTRANSFER_TYPE_TABLE);
  invertAttrs.Set(eComponentTransferFunctionTableValues, invertTableValues, 2);
  aDescr.Attributes().Set(eComponentTransferFunctionR, invertAttrs);
  aDescr.Attributes().Set(eComponentTransferFunctionG, invertAttrs);
  aDescr.Attributes().Set(eComponentTransferFunctionB, invertAttrs);

  // Set identity transfer function for A.
  AttributeMap identityAttrs;
  identityAttrs.Set(eComponentTransferFunctionType,
                    (uint32_t)SVG_FECOMPONENTTRANSFER_TYPE_IDENTITY);
  aDescr.Attributes().Set(eComponentTransferFunctionA, identityAttrs);

  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForOpacity(FilterPrimitiveDescription& aDescr)
{
  const nsStyleCoord& styleValue = mFilter.GetFilterParameter();
  float value = ClampFactor(styleValue.GetFactorOrPercentValue());

  // Set identity transfer functions for RGB.
  AttributeMap identityAttrs;
  identityAttrs.Set(eComponentTransferFunctionType,
                    (uint32_t)SVG_FECOMPONENTTRANSFER_TYPE_IDENTITY);
  aDescr.Attributes().Set(eComponentTransferFunctionR, identityAttrs);
  aDescr.Attributes().Set(eComponentTransferFunctionG, identityAttrs);
  aDescr.Attributes().Set(eComponentTransferFunctionB, identityAttrs);

  // Set transfer function for A.
  AttributeMap opacityAttrs;
  float opacityTableValues[2];
  opacityTableValues[0] = 0;
  opacityTableValues[1] = value;
  opacityAttrs.Set(eComponentTransferFunctionType,
                  (uint32_t)SVG_FECOMPONENTTRANSFER_TYPE_TABLE);
  opacityAttrs.Set(eComponentTransferFunctionTableValues, opacityTableValues, 2);
  aDescr.Attributes().Set(eComponentTransferFunctionA, opacityAttrs);

  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForSaturate(FilterPrimitiveDescription& aDescr)
{
  // Set color matrix type.
  aDescr.Attributes().Set(eColorMatrixType, (uint32_t)SVG_FECOLORMATRIX_TYPE_SATURATE);

  // Set color matrix values.
  const nsStyleCoord& styleValue = mFilter.GetFilterParameter();
  float value = styleValue.GetFactorOrPercentValue();
  aDescr.Attributes().Set(eColorMatrixValues, &value, 1);

  return NS_OK;
}

nsresult
nsCSSFilterInstance::SetAttributesForSepia(FilterPrimitiveDescription& aDescr)
{
  // Set color matrix type.
  aDescr.Attributes().Set(eColorMatrixType, (uint32_t)SVG_FECOLORMATRIX_TYPE_SEPIA);

  // Set color matrix values.
  const nsStyleCoord& styleValue = mFilter.GetFilterParameter();
  float value = ClampFactor(styleValue.GetFactorOrPercentValue());
  aDescr.Attributes().Set(eColorMatrixValues, &value, 1);

  return NS_OK;
}

Size
nsCSSFilterInstance::BlurRadiusToFilterSpace(nscoord aRadiusInFrameSpace)
{
  float radiusInFrameSpaceInCSSPx =
    nsPresContext::AppUnitsToFloatCSSPixels(aRadiusInFrameSpace);

  // Convert the radius to filter space.
  Size radiusInFilterSpace(radiusInFrameSpaceInCSSPx,
                           radiusInFrameSpaceInCSSPx);
  gfxSize frameSpaceInCSSPxToFilterSpaceScale =
    mFrameSpaceInCSSPxToFilterSpaceTransform.ScaleFactors(true);
  radiusInFilterSpace.Scale(frameSpaceInCSSPxToFilterSpaceScale.width,
                            frameSpaceInCSSPxToFilterSpaceScale.height);

  // Check the radius limits.
  if (radiusInFilterSpace.width < 0 || radiusInFilterSpace.height < 0) {
    NS_NOTREACHED("we shouldn't have parsed a negative radius in the style");
    return Size();
  }
  Float maxStdDeviation = (Float)kMaxStdDeviation;
  radiusInFilterSpace.width = std::min(radiusInFilterSpace.width, maxStdDeviation);
  radiusInFilterSpace.height = std::min(radiusInFilterSpace.height, maxStdDeviation);

  return radiusInFilterSpace;
}

IntPoint
nsCSSFilterInstance::OffsetToFilterSpace(nscoord aXOffsetInFrameSpace,
                                         nscoord aYOffsetInFrameSpace)
{
  gfxPoint offsetInFilterSpace(nsPresContext::AppUnitsToFloatCSSPixels(aXOffsetInFrameSpace),
                               nsPresContext::AppUnitsToFloatCSSPixels(aYOffsetInFrameSpace));

  // Convert the radius to filter space.
  gfxSize frameSpaceInCSSPxToFilterSpaceScale =
    mFrameSpaceInCSSPxToFilterSpaceTransform.ScaleFactors(true);
  offsetInFilterSpace.x *= frameSpaceInCSSPxToFilterSpaceScale.width;
  offsetInFilterSpace.y *= frameSpaceInCSSPxToFilterSpaceScale.height;

  return IntPoint(int32_t(offsetInFilterSpace.x), int32_t(offsetInFilterSpace.y));
}

Color
nsCSSFilterInstance::ToAttributeColor(nscolor aColor)
{
  return Color(
    NS_GET_R(aColor) / 255.0,
    NS_GET_G(aColor) / 255.0,
    NS_GET_B(aColor) / 255.0,
    NS_GET_A(aColor) / 255.0
  );
}

int32_t
nsCSSFilterInstance::GetLastResultIndex(const nsTArray<FilterPrimitiveDescription>& aPrimitiveDescrs)
{
  uint32_t numPrimitiveDescrs = aPrimitiveDescrs.Length();
  return !numPrimitiveDescrs ?
    FilterPrimitiveDescription::kPrimitiveIndexSourceGraphic :
    numPrimitiveDescrs - 1;
}

void
nsCSSFilterInstance::SetBounds(FilterPrimitiveDescription& aDescr,
                               const nsTArray<FilterPrimitiveDescription>& aPrimitiveDescrs)
{
  int32_t inputIndex = GetLastResultIndex(aPrimitiveDescrs);
  nsIntRect inputBounds = (inputIndex < 0) ?
    mTargetBoundsInFilterSpace : aPrimitiveDescrs[inputIndex].PrimitiveSubregion();

  nsTArray<nsIntRegion> inputExtents;
  inputExtents.AppendElement(inputBounds);

  nsIntRegion outputExtents =
    FilterSupport::PostFilterExtentsForPrimitive(aDescr, inputExtents);
  IntRect outputBounds = outputExtents.GetBounds();

  aDescr.SetPrimitiveSubregion(outputBounds);
  aDescr.SetFilterSpaceBounds(outputBounds);
}