gecko-dev/layout/svg/nsSVGMaskFrame.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsSVGMaskFrame.h"

// Keep others in (case-insensitive) order:
#include "AutoReferenceChainGuard.h"
#include "gfx2DGlue.h"
#include "gfxContext.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/RefPtr.h"
#include "nsSVGEffects.h"
#include "mozilla/dom/SVGMaskElement.h"

using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::gfx;
using namespace mozilla::image;

static LuminanceType
GetLuminanceType(uint8_t aNSMaskType)
{
  switch (aNSMaskType) {
    case NS_STYLE_MASK_TYPE_LUMINANCE:
      return LuminanceType::LUMINANCE;
    case NS_STYLE_COLOR_INTERPOLATION_LINEARRGB:
      return LuminanceType::LINEARRGB;
    default:
    {
      NS_WARNING("Unknown SVG mask type, defaulting to luminance");
      return LuminanceType::LUMINANCE;
    }
  }
}

nsIFrame*
NS_NewSVGMaskFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
  return new (aPresShell) nsSVGMaskFrame(aContext);
}

NS_IMPL_FRAMEARENA_HELPERS(nsSVGMaskFrame)

already_AddRefed<SourceSurface>
nsSVGMaskFrame::GetMaskForMaskedFrame(MaskParams& aParams)
{
  // Make sure we break reference loops and over long reference chains:
  static int16_t sRefChainLengthCounter = AutoReferenceChainGuard::noChain;
  AutoReferenceChainGuard refChainGuard(this, &mInUse,
                                        &sRefChainLengthCounter);
  if (MOZ_UNLIKELY(!refChainGuard.Reference())) {
    // Break reference chain
    return nullptr;
  }

  gfxRect maskArea = GetMaskArea(aParams.maskedFrame);
  gfxContext* context = aParams.ctx;
  // Get the clip extents in device space:
  // Minimizing the mask surface extents (using both the current clip extents
  // and maskArea) is important for performance.
  context->Save();
  nsSVGUtils::SetClipRect(context, aParams.toUserSpace, maskArea);
  context->SetMatrix(gfxMatrix());
  gfxRect maskSurfaceRect = context->GetClipExtents();
  maskSurfaceRect.RoundOut();
  context->Restore();

  bool resultOverflows;
  IntSize maskSurfaceSize =
    nsSVGUtils::ConvertToSurfaceSize(maskSurfaceRect.Size(), &resultOverflows);

  if (resultOverflows || maskSurfaceSize.IsEmpty()) {
    // Return value other then DrawResult::SUCCESS, so the caller can skip
    // painting the masked frame(aParams.maskedFrame).
    return nullptr;
  }

  uint8_t maskType;
  if (aParams.maskMode == NS_STYLE_MASK_MODE_MATCH_SOURCE) {
    maskType = StyleSVGReset()->mMaskType;
  } else {
    maskType = aParams.maskMode == NS_STYLE_MASK_MODE_LUMINANCE
               ? NS_STYLE_MASK_TYPE_LUMINANCE : NS_STYLE_MASK_TYPE_ALPHA;
  }

  RefPtr<DrawTarget> maskDT;
  if (maskType == NS_STYLE_MASK_TYPE_LUMINANCE) {
    maskDT = gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(
               maskSurfaceSize, SurfaceFormat::B8G8R8A8);
  } else {
    maskDT = gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(
               maskSurfaceSize, SurfaceFormat::A8);
  }

  if (!maskDT || !maskDT->IsValid()) {
    return nullptr;
  }

  gfxMatrix maskSurfaceMatrix =
    context->CurrentMatrix() * gfxMatrix::Translation(-maskSurfaceRect.TopLeft());

  RefPtr<gfxContext> tmpCtx = gfxContext::CreateOrNull(maskDT);
  MOZ_ASSERT(tmpCtx); // already checked the draw target above
  tmpCtx->SetMatrix(maskSurfaceMatrix);

  mMatrixForChildren = GetMaskTransform(aParams.maskedFrame) *
                       aParams.toUserSpace;

  for (nsIFrame* kid = mFrames.FirstChild(); kid;
       kid = kid->GetNextSibling()) {
    // The CTM of each frame referencing us can be different
    nsSVGDisplayableFrame* SVGFrame = do_QueryFrame(kid);
    if (SVGFrame) {
      SVGFrame->NotifySVGChanged(nsSVGDisplayableFrame::TRANSFORM_CHANGED);
    }
    gfxMatrix m = mMatrixForChildren;
    if (kid->GetContent()->IsSVGElement()) {
      m = static_cast<nsSVGElement*>(kid->GetContent())->
            PrependLocalTransformsTo(m, eUserSpaceToParent);
    }
    nsSVGUtils::PaintFrameWithEffects(kid, *tmpCtx, m, aParams.imgParams);
  }

  RefPtr<SourceSurface> surface;
  if (maskType == NS_STYLE_MASK_TYPE_LUMINANCE) {
    if (StyleSVG()->mColorInterpolation ==
        NS_STYLE_COLOR_INTERPOLATION_LINEARRGB) {
      maskType = NS_STYLE_COLOR_INTERPOLATION_LINEARRGB;
    }

    RefPtr<SourceSurface> maskSnapshot =
      maskDT->IntoLuminanceSource(GetLuminanceType(maskType),
                                  aParams.opacity);
    if (!maskSnapshot) {
      return nullptr;
    }
    surface = maskSnapshot.forget();
  } else {
    maskDT->SetTransform(Matrix());
    maskDT->FillRect(Rect(0, 0, maskSurfaceSize.width, maskSurfaceSize.height), ColorPattern(Color(1.0f, 1.0f, 1.0f, aParams.opacity)), DrawOptions(1, CompositionOp::OP_IN));
    RefPtr<SourceSurface> maskSnapshot = maskDT->Snapshot();
    if (!maskSnapshot) {
      return nullptr;
    }
    surface = maskSnapshot.forget();
  }

  // Moz2D transforms in the opposite direction to Thebes
  if (!maskSurfaceMatrix.Invert()) {
    return nullptr;
  }

  *aParams.maskTransform = ToMatrix(maskSurfaceMatrix);
  return surface.forget();
}

gfxRect
nsSVGMaskFrame::GetMaskArea(nsIFrame* aMaskedFrame)
{
  SVGMaskElement *maskElem = static_cast<SVGMaskElement*>(mContent);

  uint16_t units =
    maskElem->mEnumAttributes[SVGMaskElement::MASKUNITS].GetAnimValue();
  gfxRect bbox;
  if (units == SVG_UNIT_TYPE_OBJECTBOUNDINGBOX) {
    bbox =
      nsSVGUtils::GetBBox(aMaskedFrame,
                          nsSVGUtils::eUseFrameBoundsForOuterSVG |
                          nsSVGUtils::eBBoxIncludeFillGeometry);
  }

  // Bounds in the user space of aMaskedFrame
  gfxRect maskArea = nsSVGUtils::GetRelativeRect(units,
                       &maskElem->mLengthAttributes[SVGMaskElement::ATTR_X],
                       bbox, aMaskedFrame);

  return maskArea;
}

nsresult
nsSVGMaskFrame::AttributeChanged(int32_t  aNameSpaceID,
                                 nsIAtom* aAttribute,
                                 int32_t  aModType)
{
  if (aNameSpaceID == kNameSpaceID_None &&
      (aAttribute == nsGkAtoms::x ||
       aAttribute == nsGkAtoms::y ||
       aAttribute == nsGkAtoms::width ||
       aAttribute == nsGkAtoms::height||
       aAttribute == nsGkAtoms::maskUnits ||
       aAttribute == nsGkAtoms::maskContentUnits)) {
    nsSVGEffects::InvalidateDirectRenderingObservers(this);
  }

  return nsSVGContainerFrame::AttributeChanged(aNameSpaceID,
                                               aAttribute, aModType);
}

#ifdef DEBUG
void
nsSVGMaskFrame::Init(nsIContent*       aContent,
                     nsContainerFrame* aParent,
                     nsIFrame*         aPrevInFlow)
{
  NS_ASSERTION(aContent->IsSVGElement(nsGkAtoms::mask),
               "Content is not an SVG mask");

  nsSVGContainerFrame::Init(aContent, aParent, aPrevInFlow);
}
#endif /* DEBUG */

gfxMatrix
nsSVGMaskFrame::GetCanvasTM()
{
  return mMatrixForChildren;
}

gfxMatrix
nsSVGMaskFrame::GetMaskTransform(nsIFrame* aMaskedFrame)
{
  SVGMaskElement *content = static_cast<SVGMaskElement*>(mContent);

  nsSVGEnum* maskContentUnits =
    &content->mEnumAttributes[SVGMaskElement::MASKCONTENTUNITS];

  return nsSVGUtils::AdjustMatrixForUnits(gfxMatrix(), maskContentUnits,
                                          aMaskedFrame);
}