gecko-dev/layout/svg/nsSVGClipPathFrame.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 "nsSVGClipPathFrame.h"

// Keep others in (case-insensitive) order:
#include "gfxContext.h"
#include "mozilla/dom/SVGClipPathElement.h"
#include "nsGkAtoms.h"
#include "nsSVGEffects.h"
#include "nsSVGPathGeometryElement.h"
#include "nsSVGPathGeometryFrame.h"
#include "nsSVGUtils.h"

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

//----------------------------------------------------------------------
// Implementation

nsIFrame*
NS_NewSVGClipPathFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
  return new (aPresShell) nsSVGClipPathFrame(aContext);
}

NS_IMPL_FRAMEARENA_HELPERS(nsSVGClipPathFrame)

nsresult
nsSVGClipPathFrame::ApplyClipOrPaintClipMask(gfxContext& aContext,
                                             nsIFrame* aClippedFrame,
                                             const gfxMatrix& aMatrix)
{
  DrawTarget& aDrawTarget = *aContext.GetDrawTarget();

  // If the flag is set when we get here, it means this clipPath frame
  // has already been used painting the current clip, and the document
  // has a clip reference loop.
  if (mInUse) {
    NS_WARNING("Clip loop detected!");
    return NS_OK;
  }
  AutoClipPathReferencer clipRef(this);

  mMatrixForChildren = GetClipPathTransform(aClippedFrame) * aMatrix;

  nsISVGChildFrame* singleClipPathChild = nullptr;

  if (IsTrivial(&singleClipPathChild)) {
    gfxContextMatrixAutoSaveRestore autoRestore(&aContext);
    RefPtr<Path> clipPath;
    if (singleClipPathChild) {
      nsSVGPathGeometryFrame* pathFrame = do_QueryFrame(singleClipPathChild);
      if (pathFrame) {
        nsSVGPathGeometryElement* pathElement =
          static_cast<nsSVGPathGeometryElement*>(pathFrame->GetContent());
        gfxMatrix toChildsUserSpace = pathElement->
          PrependLocalTransformsTo(mMatrixForChildren, eUserSpaceToParent);
        gfxMatrix newMatrix =
          aContext.CurrentMatrix().PreMultiply(toChildsUserSpace).NudgeToIntegers();
        if (!newMatrix.IsSingular()) {
          aContext.SetMatrix(newMatrix);
          clipPath = pathElement->GetOrBuildPath(aDrawTarget,
                                                 nsSVGUtils::ToFillRule(pathFrame->StyleSVG()->mClipRule));
        }
      }
    }
    if (clipPath) {
      aContext.Clip(clipPath);
    } else {
      // The spec says clip away everything if we have no children or the
      // clipping path otherwise can't be resolved:
      aContext.Clip(Rect());
    }
    return NS_OK;
  }

  // This is a non-trivial clipPath, so we need to paint its contents into a
  // temporary surface and use that to mask the clipped content.  Note that
  // nsSVGPathGeometryFrame::Render checks for the NS_STATE_SVG_CLIPPATH_CHILD
  // state bit and paints into our mask surface using opaque black in that case.

  // Check if this clipPath is itself clipped by another clipPath:
  nsSVGClipPathFrame *clipPathFrame =
    nsSVGEffects::GetEffectProperties(this).GetClipPathFrame(nullptr);
  bool referencedClipIsTrivial;
  if (clipPathFrame) {
    referencedClipIsTrivial = clipPathFrame->IsTrivial();
    aContext.Save();
    if (referencedClipIsTrivial) {
      clipPathFrame->ApplyClipOrPaintClipMask(aContext, aClippedFrame, aMatrix);
    } else {
      Matrix maskTransform;
      RefPtr<SourceSurface> mask = clipPathFrame->GetClipMask(aContext, aClippedFrame, aMatrix, &maskTransform);

      aContext.PushGroupForBlendBack(gfxContentType::ALPHA, 1.0, mask, maskTransform);
    }
  }

  for (nsIFrame* kid = mFrames.FirstChild(); kid;
       kid = kid->GetNextSibling()) {
    nsISVGChildFrame* SVGFrame = do_QueryFrame(kid);
    if (SVGFrame) {
      // The CTM of each frame referencing us can be different.
      SVGFrame->NotifySVGChanged(nsISVGChildFrame::TRANSFORM_CHANGED);

      bool isOK = true;
      nsSVGClipPathFrame *clipPathFrame =
        nsSVGEffects::GetEffectProperties(kid).GetClipPathFrame(&isOK);
      if (!isOK) {
        continue;
      }

      bool isTrivial;

      if (clipPathFrame) {
        isTrivial = clipPathFrame->IsTrivial();
        aContext.Save();
        if (isTrivial) {
          clipPathFrame->ApplyClipOrPaintClipMask(aContext, aClippedFrame, aMatrix);
        } else {
          Matrix maskTransform;
          RefPtr<SourceSurface> mask = clipPathFrame->GetClipMask(aContext, aClippedFrame, aMatrix, &maskTransform);

          aContext.PushGroupForBlendBack(gfxContentType::ALPHA, 1.0, mask, maskTransform);
        }
      }

      gfxMatrix toChildsUserSpace = mMatrixForChildren;
      nsIFrame* child = do_QueryFrame(SVGFrame);
      nsIContent* childContent = child->GetContent();
      if (childContent->IsSVGElement()) {
        toChildsUserSpace =
          static_cast<const nsSVGElement*>(childContent)->
            PrependLocalTransformsTo(mMatrixForChildren, eUserSpaceToParent);
      }
      SVGFrame->PaintSVG(aContext, toChildsUserSpace);

      if (clipPathFrame) {
        if (!isTrivial) {
          aContext.PopGroupAndBlend();
        }
        aContext.Restore();
      }
    }
  }

  if (clipPathFrame) {
    if (!referencedClipIsTrivial) {
      aContext.PopGroupAndBlend();
    }
    aContext.Restore();
  }

  return NS_OK;
}

already_AddRefed<SourceSurface>
nsSVGClipPathFrame::GetClipMask(gfxContext& aReferenceContext, nsIFrame* aClippedFrame,
                                const gfxMatrix& aMatrix, Matrix* aMaskTransform,
                                SourceSurface* aInputMask, const Matrix& aInputMaskTransform)
{
  if (IsTrivial()) {
    return nullptr;
  }

  IntRect intRect;
  {
    gfxContextMatrixAutoSaveRestore autoRestoreMatrix(&aReferenceContext);

    aReferenceContext.SetMatrix(gfxMatrix());
    gfxRect rect = aReferenceContext.GetClipExtents();
    intRect = RoundedOut(ToRect(rect));
  }

  if (intRect.IsEmpty()) {
    // We don't need to create a mask surface, all drawing is clipped anyway.
    return nullptr;
  }

  RefPtr<DrawTarget> maskDT = aReferenceContext.GetDrawTarget()->CreateSimilarDrawTarget(intRect.Size(), SurfaceFormat::A8);

  gfxMatrix mat =
    aReferenceContext.CurrentMatrix() * gfxMatrix::Translation(-intRect.TopLeft());
  {
    RefPtr<gfxContext> ctx = new gfxContext(maskDT);
    ctx->SetMatrix(mat);
    ApplyClipOrPaintClipMask(*ctx, aClippedFrame, aMatrix);
  }

  mat.Invert();

  if (aInputMask) {
    MOZ_ASSERT(!aInputMaskTransform.HasNonTranslation());

    RefPtr<SourceSurface> currentMask = maskDT->Snapshot();
    maskDT->SetTransform(Matrix());
    maskDT->ClearRect(Rect(0, 0, intRect.width, intRect.height));
    maskDT->MaskSurface(SurfacePattern(currentMask, ExtendMode::CLAMP), aInputMask,
                        Point(aInputMaskTransform._31 - intRect.x, aInputMaskTransform._32 - intRect.y));
  }

  *aMaskTransform = ToMatrix(mat);
  return maskDT->Snapshot();
}

bool
nsSVGClipPathFrame::PointIsInsideClipPath(nsIFrame* aClippedFrame,
                                          const gfxPoint &aPoint)
{
  // If the flag is set when we get here, it means this clipPath frame
  // has already been used in hit testing against the current clip,
  // and the document has a clip reference loop.
  if (mInUse) {
    NS_WARNING("Clip loop detected!");
    return false;
  }
  AutoClipPathReferencer clipRef(this);

  gfxMatrix matrix = GetClipPathTransform(aClippedFrame);
  if (!matrix.Invert()) {
    return false;
  }
  gfxPoint point = matrix.Transform(aPoint);

  // clipPath elements can themselves be clipped by a different clip path. In
  // that case the other clip path further clips away the element that is being
  // clipped by the original clipPath. If this clipPath is being clipped by a
  // different clip path we need to check if it prevents the original element
  // from recieving events at aPoint:
  nsSVGClipPathFrame *clipPathFrame =
    nsSVGEffects::GetEffectProperties(this).GetClipPathFrame(nullptr);
  if (clipPathFrame &&
      !clipPathFrame->PointIsInsideClipPath(aClippedFrame, aPoint)) {
    return false;
  }

  for (nsIFrame* kid = mFrames.FirstChild(); kid;
       kid = kid->GetNextSibling()) {
    nsISVGChildFrame* SVGFrame = do_QueryFrame(kid);
    if (SVGFrame) {
      gfxPoint pointForChild = point;
      gfxMatrix m = static_cast<nsSVGElement*>(kid->GetContent())->
        PrependLocalTransformsTo(gfxMatrix(), eUserSpaceToParent);
      if (!m.IsIdentity()) {
        if (!m.Invert()) {
          return false;
        }
        pointForChild = m.Transform(point);
      }
      if (SVGFrame->GetFrameForPoint(pointForChild)) {
        return true;
      }
    }
  }
  return false;
}

bool
nsSVGClipPathFrame::IsTrivial(nsISVGChildFrame **aSingleChild)
{
  // If the clip path is clipped then it's non-trivial
  if (nsSVGEffects::GetEffectProperties(this).GetClipPathFrame(nullptr))
    return false;

  if (aSingleChild) {
    *aSingleChild = nullptr;
  }

  nsISVGChildFrame *foundChild = nullptr;

  for (nsIFrame* kid = mFrames.FirstChild(); kid;
       kid = kid->GetNextSibling()) {
    nsISVGChildFrame *svgChild = do_QueryFrame(kid);
    if (svgChild) {
      // We consider a non-trivial clipPath to be one containing
      // either more than one svg child and/or a svg container
      if (foundChild || svgChild->IsDisplayContainer())
        return false;

      // or where the child is itself clipped
      if (nsSVGEffects::GetEffectProperties(kid).GetClipPathFrame(nullptr))
        return false;

      foundChild = svgChild;
    }
  }
  if (aSingleChild) {
    *aSingleChild = foundChild;
  }
  return true;
}

bool
nsSVGClipPathFrame::IsValid()
{
  if (mInUse) {
    NS_WARNING("Clip loop detected!");
    return false;
  }
  AutoClipPathReferencer clipRef(this);

  bool isOK = true;
  nsSVGEffects::GetEffectProperties(this).GetClipPathFrame(&isOK);
  if (!isOK) {
    return false;
  }

  for (nsIFrame* kid = mFrames.FirstChild(); kid;
       kid = kid->GetNextSibling()) {

    nsIAtom *type = kid->GetType();

    if (type == nsGkAtoms::svgUseFrame) {
      for (nsIFrame* grandKid = kid->GetFirstPrincipalChild(); grandKid;
           grandKid = grandKid->GetNextSibling()) {

        nsIAtom *type = grandKid->GetType();

        if (type != nsGkAtoms::svgPathGeometryFrame &&
            type != nsGkAtoms::svgTextFrame) {
          return false;
        }
      }
      continue;
    }
    if (type != nsGkAtoms::svgPathGeometryFrame &&
        type != nsGkAtoms::svgTextFrame) {
      return false;
    }
  }
  return true;
}

nsresult
nsSVGClipPathFrame::AttributeChanged(int32_t         aNameSpaceID,
                                     nsIAtom*        aAttribute,
                                     int32_t         aModType)
{
  if (aNameSpaceID == kNameSpaceID_None) {
    if (aAttribute == nsGkAtoms::transform) {
      nsSVGEffects::InvalidateDirectRenderingObservers(this);
      nsSVGUtils::NotifyChildrenOfSVGChange(this,
                                            nsISVGChildFrame::TRANSFORM_CHANGED);
    }
    if (aAttribute == nsGkAtoms::clipPathUnits) {
      nsSVGEffects::InvalidateDirectRenderingObservers(this);
    }
  }

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

void
nsSVGClipPathFrame::Init(nsIContent*       aContent,
                         nsContainerFrame* aParent,
                         nsIFrame*         aPrevInFlow)
{
  NS_ASSERTION(aContent->IsSVGElement(nsGkAtoms::clipPath),
               "Content is not an SVG clipPath!");

  AddStateBits(NS_STATE_SVG_CLIPPATH_CHILD);
  nsSVGClipPathFrameBase::Init(aContent, aParent, aPrevInFlow);
}

nsIAtom *
nsSVGClipPathFrame::GetType() const
{
  return nsGkAtoms::svgClipPathFrame;
}

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

gfxMatrix
nsSVGClipPathFrame::GetClipPathTransform(nsIFrame* aClippedFrame)
{
  SVGClipPathElement *content = static_cast<SVGClipPathElement*>(mContent);

  gfxMatrix tm = content->PrependLocalTransformsTo(gfxMatrix());

  nsSVGEnum* clipPathUnits =
    &content->mEnumAttributes[SVGClipPathElement::CLIPPATHUNITS];

  return nsSVGUtils::AdjustMatrixForUnits(tm, clipPathUnits, aClippedFrame);
}

SVGBBox
nsSVGClipPathFrame::GetBBoxForClipPathFrame(const SVGBBox &aBBox, 
                                            const gfxMatrix &aMatrix)
{
  nsIContent* node = GetContent()->GetFirstChild();
  SVGBBox unionBBox, tmpBBox;
  for (; node; node = node->GetNextSibling()) {
    nsIFrame *frame = 
      static_cast<nsSVGElement*>(node)->GetPrimaryFrame();
    if (frame) {
      nsISVGChildFrame *svg = do_QueryFrame(frame);
      if (svg) {
        tmpBBox = svg->GetBBoxContribution(mozilla::gfx::ToMatrix(aMatrix), 
                                         nsSVGUtils::eBBoxIncludeFill);
        nsSVGEffects::EffectProperties effectProperties =
                              nsSVGEffects::GetEffectProperties(frame);
        bool isOK = true;
        nsSVGClipPathFrame *clipPathFrame = 
                              effectProperties.GetClipPathFrame(&isOK);
        if (clipPathFrame && isOK) {
          tmpBBox = clipPathFrame->GetBBoxForClipPathFrame(tmpBBox, aMatrix);
        } 
        tmpBBox.Intersect(aBBox);
        unionBBox.UnionEdges(tmpBBox);
      }
    }
  }
  nsSVGEffects::EffectProperties props = 
    nsSVGEffects::GetEffectProperties(this);    
  if (props.mClipPath) {
    bool isOK = true;
    nsSVGClipPathFrame *clipPathFrame = props.GetClipPathFrame(&isOK);
    if (clipPathFrame && isOK) {
      tmpBBox = clipPathFrame->GetBBoxForClipPathFrame(aBBox, aMatrix);                                                       
      unionBBox.Intersect(tmpBBox);
    } else if (!isOK) {
      unionBBox = SVGBBox();
    }
  }
  return unionBBox;
}