gecko-dev/layout/generic/nsHTMLCanvasFrame.cpp

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/* -*- 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/. */
/* rendering object for the HTML <canvas> element */
#include "nsHTMLCanvasFrame.h"
#include "nsGkAtoms.h"
#include "mozilla/Assertions.h"
#include "mozilla/dom/HTMLCanvasElement.h"
#include "nsDisplayList.h"
#include "nsLayoutUtils.h"
#include "nsStyleUtil.h"
#include "Layers.h"
#include "ActiveLayerTracker.h"
#include <algorithm>
using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::layers;
using namespace mozilla::gfx;
/* Helper for our nsIFrame::GetIntrinsicSize() impl. Takes the result of
* "GetCanvasSize()" as a parameter, which may help avoid redundant
* indirect calls to GetCanvasSize().
*
* @param aCanvasSizeInPx The canvas's size in CSS pixels, as returned
* by GetCanvasSize().
* @return The canvas's intrinsic size, as an IntrinsicSize object.
*/
static IntrinsicSize
IntrinsicSizeFromCanvasSize(const nsIntSize& aCanvasSizeInPx)
{
IntrinsicSize intrinsicSize;
intrinsicSize.width.SetCoordValue(
nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.width));
intrinsicSize.height.SetCoordValue(
nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.height));
return intrinsicSize;
}
/* Helper for our nsIFrame::GetIntrinsicRatio() impl. Takes the result of
* "GetCanvasSize()" as a parameter, which may help avoid redundant
* indirect calls to GetCanvasSize().
*
* @param aCanvasSizeInPx The canvas's size in CSS pixels, as returned
* by GetCanvasSize().
* @return The canvas's intrinsic ratio, as a nsSize.
*/
static nsSize
IntrinsicRatioFromCanvasSize(const nsIntSize& aCanvasSizeInPx)
{
return nsSize(nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.width),
nsPresContext::CSSPixelsToAppUnits(aCanvasSizeInPx.height));
}
class nsDisplayCanvas : public nsDisplayItem {
public:
nsDisplayCanvas(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
: nsDisplayItem(aBuilder, aFrame)
{
MOZ_COUNT_CTOR(nsDisplayCanvas);
}
#ifdef NS_BUILD_REFCNT_LOGGING
virtual ~nsDisplayCanvas() {
MOZ_COUNT_DTOR(nsDisplayCanvas);
}
#endif
NS_DISPLAY_DECL_NAME("nsDisplayCanvas", TYPE_CANVAS)
virtual nsRegion GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
bool* aSnap) override {
*aSnap = false;
nsHTMLCanvasFrame* f = static_cast<nsHTMLCanvasFrame*>(Frame());
HTMLCanvasElement* canvas =
HTMLCanvasElement::FromContent(f->GetContent());
nsRegion result;
if (canvas->GetIsOpaque()) {
// OK, the entire region painted by the canvas is opaque. But what is
// that region? It's the canvas's "dest rect" (controlled by the
// object-fit/object-position CSS properties), clipped to the container's
// content box (which is what GetBounds() returns). So, we grab those
// rects and intersect them.
nsRect constraintRect = GetBounds(aBuilder, aSnap);
// Need intrinsic size & ratio, for ComputeObjectDestRect:
nsIntSize canvasSize = f->GetCanvasSize();
IntrinsicSize intrinsicSize = IntrinsicSizeFromCanvasSize(canvasSize);
nsSize intrinsicRatio = IntrinsicRatioFromCanvasSize(canvasSize);
const nsRect destRect =
nsLayoutUtils::ComputeObjectDestRect(constraintRect,
intrinsicSize, intrinsicRatio,
f->StylePosition());
return nsRegion(destRect.Intersect(constraintRect));
}
return result;
}
virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder,
bool* aSnap) override {
*aSnap = true;
nsHTMLCanvasFrame* f = static_cast<nsHTMLCanvasFrame*>(Frame());
return f->GetInnerArea() + ToReferenceFrame();
}
virtual already_AddRefed<Layer> BuildLayer(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
const ContainerLayerParameters& aContainerParameters) override
{
return static_cast<nsHTMLCanvasFrame*>(mFrame)->
BuildLayer(aBuilder, aManager, this, aContainerParameters);
}
virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
const ContainerLayerParameters& aParameters) override
{
if (HTMLCanvasElement::FromContent(mFrame->GetContent())->ShouldForceInactiveLayer(aManager))
return LAYER_INACTIVE;
// If compositing is cheap, just do that
if (aManager->IsCompositingCheap() ||
ActiveLayerTracker::IsContentActive(mFrame))
return mozilla::LAYER_ACTIVE;
return LAYER_INACTIVE;
}
};
nsIFrame*
NS_NewHTMLCanvasFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
return new (aPresShell) nsHTMLCanvasFrame(aContext);
}
NS_QUERYFRAME_HEAD(nsHTMLCanvasFrame)
NS_QUERYFRAME_ENTRY(nsHTMLCanvasFrame)
NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
NS_IMPL_FRAMEARENA_HELPERS(nsHTMLCanvasFrame)
void
nsHTMLCanvasFrame::Init(nsIContent* aContent,
nsContainerFrame* aParent,
nsIFrame* aPrevInFlow)
{
nsContainerFrame::Init(aContent, aParent, aPrevInFlow);
// We can fill in the canvas before the canvas frame is created, in
// which case we never get around to marking the content as active. Therefore,
// we mark it active here when we create the frame.
ActiveLayerTracker::NotifyContentChange(this);
}
nsHTMLCanvasFrame::~nsHTMLCanvasFrame()
{
}
nsIntSize
nsHTMLCanvasFrame::GetCanvasSize()
{
nsIntSize size(0,0);
HTMLCanvasElement *canvas =
HTMLCanvasElement::FromContentOrNull(GetContent());
if (canvas) {
size = canvas->GetSize();
MOZ_ASSERT(size.width >= 0 && size.height >= 0,
"we should've required <canvas> width/height attrs to be "
"unsigned (non-negative) values");
} else {
NS_NOTREACHED("couldn't get canvas size");
}
return size;
}
/* virtual */ nscoord
nsHTMLCanvasFrame::GetMinISize(nsRenderingContext *aRenderingContext)
{
// XXX The caller doesn't account for constraints of the height,
// min-height, and max-height properties.
bool vertical = GetWritingMode().IsVertical();
nscoord result = nsPresContext::CSSPixelsToAppUnits(
vertical ? GetCanvasSize().height : GetCanvasSize().width);
DISPLAY_MIN_WIDTH(this, result);
return result;
}
/* virtual */ nscoord
nsHTMLCanvasFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
{
// XXX The caller doesn't account for constraints of the height,
// min-height, and max-height properties.
bool vertical = GetWritingMode().IsVertical();
nscoord result = nsPresContext::CSSPixelsToAppUnits(
vertical ? GetCanvasSize().height : GetCanvasSize().width);
DISPLAY_PREF_WIDTH(this, result);
return result;
}
/* virtual */ IntrinsicSize
nsHTMLCanvasFrame::GetIntrinsicSize()
{
return IntrinsicSizeFromCanvasSize(GetCanvasSize());
}
/* virtual */ nsSize
nsHTMLCanvasFrame::GetIntrinsicRatio()
{
return IntrinsicRatioFromCanvasSize(GetCanvasSize());
}
/* virtual */
LogicalSize
nsHTMLCanvasFrame::ComputeSize(nsRenderingContext *aRenderingContext,
WritingMode aWM,
const LogicalSize& aCBSize,
nscoord aAvailableISize,
const LogicalSize& aMargin,
const LogicalSize& aBorder,
const LogicalSize& aPadding,
ComputeSizeFlags aFlags)
{
nsIntSize size = GetCanvasSize();
IntrinsicSize intrinsicSize;
intrinsicSize.width.SetCoordValue(nsPresContext::CSSPixelsToAppUnits(size.width));
intrinsicSize.height.SetCoordValue(nsPresContext::CSSPixelsToAppUnits(size.height));
nsSize intrinsicRatio = GetIntrinsicRatio(); // won't actually be used
return nsLayoutUtils::ComputeSizeWithIntrinsicDimensions(
aWM,
aRenderingContext, this,
intrinsicSize, intrinsicRatio,
aCBSize,
aMargin,
aBorder,
aPadding);
}
void
nsHTMLCanvasFrame::Reflow(nsPresContext* aPresContext,
nsHTMLReflowMetrics& aMetrics,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus)
{
MarkInReflow();
DO_GLOBAL_REFLOW_COUNT("nsHTMLCanvasFrame");
DISPLAY_REFLOW(aPresContext, this, aReflowState, aMetrics, aStatus);
NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
("enter nsHTMLCanvasFrame::Reflow: availSize=%d,%d",
aReflowState.AvailableWidth(), aReflowState.AvailableHeight()));
NS_PRECONDITION(mState & NS_FRAME_IN_REFLOW, "frame is not in reflow");
aStatus = NS_FRAME_COMPLETE;
WritingMode wm = aReflowState.GetWritingMode();
LogicalSize finalSize(wm,
aReflowState.ComputedISize(),
aReflowState.ComputedBSize());
// stash this away so we can compute our inner area later
mBorderPadding = aReflowState.ComputedLogicalBorderPadding();
finalSize.ISize(wm) += mBorderPadding.IStartEnd(wm);
finalSize.BSize(wm) += mBorderPadding.BStartEnd(wm);
if (GetPrevInFlow()) {
nscoord y = GetContinuationOffset(&finalSize.ISize(wm));
finalSize.BSize(wm) -= y + mBorderPadding.BStart(wm);
finalSize.BSize(wm) = std::max(0, finalSize.BSize(wm));
}
aMetrics.SetSize(wm, finalSize);
aMetrics.SetOverflowAreasToDesiredBounds();
FinishAndStoreOverflow(&aMetrics);
// Reflow the single anon block child.
nsReflowStatus childStatus;
nsIFrame* childFrame = mFrames.FirstChild();
WritingMode childWM = childFrame->GetWritingMode();
LogicalSize availSize = aReflowState.ComputedSize(childWM);
availSize.BSize(childWM) = NS_UNCONSTRAINEDSIZE;
NS_ASSERTION(!childFrame->GetNextSibling(), "HTML canvas should have 1 kid");
nsHTMLReflowMetrics childDesiredSize(aReflowState.GetWritingMode(), aMetrics.mFlags);
nsHTMLReflowState childReflowState(aPresContext, aReflowState, childFrame,
availSize);
ReflowChild(childFrame, aPresContext, childDesiredSize, childReflowState,
0, 0, 0, childStatus, nullptr);
FinishReflowChild(childFrame, aPresContext, childDesiredSize,
&childReflowState, 0, 0, 0);
NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
("exit nsHTMLCanvasFrame::Reflow: size=%d,%d",
aMetrics.ISize(wm), aMetrics.BSize(wm)));
NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aMetrics);
}
// FIXME taken from nsImageFrame, but then had splittable frame stuff
// removed. That needs to be fixed.
// XXXdholbert As in nsImageFrame, this function's clients should probably
// just be calling GetContentRectRelativeToSelf().
nsRect
nsHTMLCanvasFrame::GetInnerArea() const
{
nsMargin bp = mBorderPadding.GetPhysicalMargin(GetWritingMode());
nsRect r;
r.x = bp.left;
r.y = bp.top;
r.width = mRect.width - bp.left - bp.right;
r.height = mRect.height - bp.top - bp.bottom;
return r;
}
already_AddRefed<Layer>
nsHTMLCanvasFrame::BuildLayer(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
nsDisplayItem* aItem,
const ContainerLayerParameters& aContainerParameters)
{
nsRect area = GetContentRectRelativeToSelf() + aItem->ToReferenceFrame();
HTMLCanvasElement* element = static_cast<HTMLCanvasElement*>(GetContent());
nsIntSize canvasSizeInPx = GetCanvasSize();
nsPresContext* presContext = PresContext();
element->HandlePrintCallback(presContext->Type());
if (canvasSizeInPx.width <= 0 || canvasSizeInPx.height <= 0 || area.IsEmpty())
return nullptr;
CanvasLayer* oldLayer = static_cast<CanvasLayer*>
(aManager->GetLayerBuilder()->GetLeafLayerFor(aBuilder, aItem));
nsRefPtr<CanvasLayer> layer = element->GetCanvasLayer(aBuilder, oldLayer, aManager);
if (!layer)
return nullptr;
IntrinsicSize intrinsicSize = IntrinsicSizeFromCanvasSize(canvasSizeInPx);
nsSize intrinsicRatio = IntrinsicRatioFromCanvasSize(canvasSizeInPx);
nsRect dest =
nsLayoutUtils::ComputeObjectDestRect(area, intrinsicSize, intrinsicRatio,
StylePosition());
gfxRect destGFXRect = presContext->AppUnitsToGfxUnits(dest);
// Transform the canvas into the right place
gfxPoint p = destGFXRect.TopLeft() + aContainerParameters.mOffset;
Matrix transform = Matrix::Translation(p.x, p.y);
transform.PreScale(destGFXRect.Width() / canvasSizeInPx.width,
destGFXRect.Height() / canvasSizeInPx.height);
layer->SetBaseTransform(gfx::Matrix4x4::From2D(transform));
layer->SetFilter(nsLayoutUtils::GetGraphicsFilterForFrame(this));
return layer.forget();
}
void
nsHTMLCanvasFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsRect& aDirtyRect,
const nsDisplayListSet& aLists)
{
if (!IsVisibleForPainting(aBuilder))
return;
DisplayBorderBackgroundOutline(aBuilder, aLists);
uint32_t clipFlags =
nsStyleUtil::ObjectPropsMightCauseOverflow(StylePosition()) ?
0 : DisplayListClipState::ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT;
DisplayListClipState::AutoClipContainingBlockDescendantsToContentBox
clip(aBuilder, this, clipFlags);
aLists.Content()->AppendNewToTop(
new (aBuilder) nsDisplayCanvas(aBuilder, this));
DisplaySelectionOverlay(aBuilder, aLists.Content(),
nsISelectionDisplay::DISPLAY_IMAGES);
}
nsIAtom*
nsHTMLCanvasFrame::GetType() const
{
return nsGkAtoms::HTMLCanvasFrame;
}
// get the offset into the content area of the image where aImg starts if it is a continuation.
// from nsImageFrame
nscoord
nsHTMLCanvasFrame::GetContinuationOffset(nscoord* aWidth) const
{
nscoord offset = 0;
if (aWidth) {
*aWidth = 0;
}
if (GetPrevInFlow()) {
for (nsIFrame* prevInFlow = GetPrevInFlow() ; prevInFlow; prevInFlow = prevInFlow->GetPrevInFlow()) {
nsRect rect = prevInFlow->GetRect();
if (aWidth) {
*aWidth = rect.width;
}
offset += rect.height;
}
offset -= mBorderPadding.GetPhysicalMargin(GetWritingMode()).top;
offset = std::max(0, offset);
}
return offset;
}
#ifdef ACCESSIBILITY
a11y::AccType
nsHTMLCanvasFrame::AccessibleType()
{
return a11y::eHTMLCanvasType;
}
#endif
#ifdef DEBUG_FRAME_DUMP
nsresult
nsHTMLCanvasFrame::GetFrameName(nsAString& aResult) const
{
return MakeFrameName(NS_LITERAL_STRING("HTMLCanvas"), aResult);
}
#endif