gecko-dev/layout/generic/nsVideoFrame.cpp
Robert O'Callahan 6d646878f1 Bug 630835. Make BuildLayer responsible for setting a visible region on the layer, and let FrameLayerBuilder only reduce it. r=tnikkel,a=blocking
This avoids problems with FrameLayerBuilder making the visible region bigger than we expected, invalidating CONTENT_OPAQUE flags set on the layer.
In particular, we had been using TransformBounds to compute the new visible region, and for non-axis-aligned transforms this gives us a visible
region which contains areas not actually painted by the layer contents.
2011-02-23 18:38:09 +13:00

647 lines
24 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla code.
*
* The Initial Developer of the Original Code is the Mozilla Corporation.
* Portions created by the Initial Developer are Copyright (C) 2007
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Chris Double <chris.double@double.co.nz>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
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* decision by deleting the provisions above and replace them with the notice
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* the provisions above, a recipient may use your version of this file under
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*
* ***** END LICENSE BLOCK ***** */
/* rendering object for the HTML <video> element */
#include "nsHTMLParts.h"
#include "nsCOMPtr.h"
#include "nsIServiceManager.h"
#include "nsGkAtoms.h"
#include "nsVideoFrame.h"
#include "nsHTMLVideoElement.h"
#include "nsIDOMHTMLVideoElement.h"
#include "nsDisplayList.h"
#include "nsIRenderingContext.h"
#include "gfxContext.h"
#include "gfxImageSurface.h"
#include "nsPresContext.h"
#include "nsTransform2D.h"
#include "nsContentCreatorFunctions.h"
#include "nsBoxLayoutState.h"
#include "nsBoxFrame.h"
#include "nsImageFrame.h"
#include "nsIImageLoadingContent.h"
#include "nsDisplayList.h"
#include "nsCSSRendering.h"
#ifdef ACCESSIBILITY
#include "nsIServiceManager.h"
#include "nsAccessibilityService.h"
#endif
using namespace mozilla;
using namespace mozilla::layers;
nsIFrame*
NS_NewHTMLVideoFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
return new (aPresShell) nsVideoFrame(aContext);
}
NS_IMPL_FRAMEARENA_HELPERS(nsVideoFrame)
nsVideoFrame::nsVideoFrame(nsStyleContext* aContext) :
nsContainerFrame(aContext)
{
}
nsVideoFrame::~nsVideoFrame()
{
}
NS_QUERYFRAME_HEAD(nsVideoFrame)
NS_QUERYFRAME_ENTRY(nsIAnonymousContentCreator)
NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame)
nsresult
nsVideoFrame::CreateAnonymousContent(nsTArray<nsIContent*>& aElements)
{
nsNodeInfoManager *nodeInfoManager = GetContent()->GetCurrentDoc()->NodeInfoManager();
nsCOMPtr<nsINodeInfo> nodeInfo;
if (HasVideoElement()) {
// Create an anonymous image element as a child to hold the poster
// image. We may not have a poster image now, but one could be added
// before we load, or on a subsequent load.
nodeInfo = nodeInfoManager->GetNodeInfo(nsGkAtoms::img,
nsnull,
kNameSpaceID_XHTML);
NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
mPosterImage = NS_NewHTMLImageElement(nodeInfo.forget());
NS_ENSURE_TRUE(mPosterImage, NS_ERROR_OUT_OF_MEMORY);
// Push a null JSContext on the stack so that code that runs
// within the below code doesn't think it's being called by
// JS. See bug 604262.
nsCxPusher pusher;
pusher.PushNull();
// Set the nsImageLoadingContent::ImageState() to 0. This means that the
// image will always report its state as 0, so it will never be reframed
// to show frames for loading or the broken image icon. This is important,
// as the image is native anonymous, and so can't be reframed (currently).
nsCOMPtr<nsIImageLoadingContent> imgContent = do_QueryInterface(mPosterImage);
NS_ENSURE_TRUE(imgContent, NS_ERROR_FAILURE);
imgContent->ForceImageState(PR_TRUE, 0);
nsresult res = UpdatePosterSource(PR_FALSE);
NS_ENSURE_SUCCESS(res,res);
if (!aElements.AppendElement(mPosterImage))
return NS_ERROR_OUT_OF_MEMORY;
}
// Set up "videocontrols" XUL element which will be XBL-bound to the
// actual controls.
nodeInfo = nodeInfoManager->GetNodeInfo(nsGkAtoms::videocontrols,
nsnull,
kNameSpaceID_XUL);
NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
NS_TrustedNewXULElement(getter_AddRefs(mVideoControls), nodeInfo.forget());
if (!aElements.AppendElement(mVideoControls))
return NS_ERROR_OUT_OF_MEMORY;
return NS_OK;
}
void
nsVideoFrame::AppendAnonymousContentTo(nsBaseContentList& aElements,
PRUint32 aFliter)
{
aElements.MaybeAppendElement(mPosterImage);
aElements.MaybeAppendElement(mVideoControls);
}
void
nsVideoFrame::DestroyFrom(nsIFrame* aDestructRoot)
{
nsContentUtils::DestroyAnonymousContent(&mVideoControls);
nsContentUtils::DestroyAnonymousContent(&mPosterImage);
nsContainerFrame::DestroyFrom(aDestructRoot);
}
PRBool
nsVideoFrame::IsLeaf() const
{
return PR_TRUE;
}
// Return the largest rectangle that fits in aRect and has the
// same aspect ratio as aRatio, centered at the center of aRect
static gfxRect
CorrectForAspectRatio(const gfxRect& aRect, const nsIntSize& aRatio)
{
NS_ASSERTION(aRatio.width > 0 && aRatio.height > 0 && !aRect.IsEmpty(),
"Nothing to draw");
// Choose scale factor that scales aRatio to just fit into aRect
gfxFloat scale =
NS_MIN(aRect.Width()/aRatio.width, aRect.Height()/aRatio.height);
gfxSize scaledRatio(scale*aRatio.width, scale*aRatio.height);
gfxPoint topLeft((aRect.Width() - scaledRatio.width)/2,
(aRect.Height() - scaledRatio.height)/2);
return gfxRect(aRect.TopLeft() + topLeft, scaledRatio);
}
already_AddRefed<Layer>
nsVideoFrame::BuildLayer(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
nsDisplayItem* aItem)
{
nsRect area = GetContentRect() - GetPosition() + aItem->ToReferenceFrame();
nsHTMLVideoElement* element = static_cast<nsHTMLVideoElement*>(GetContent());
nsIntSize videoSize = element->GetVideoSize(nsIntSize(0, 0));
if (videoSize.width <= 0 || videoSize.height <= 0 || area.IsEmpty())
return nsnull;
nsRefPtr<ImageContainer> container = element->GetImageContainer();
// If we have a container with a different layer manager, try to hand
// off the container to the new one.
if (container && container->Manager() != aManager) {
// we don't care about the return type here -- if the set didn't take, it'll
// be handled when we next check the manager
container->SetLayerManager(aManager);
}
// If we have a container of the correct type already, we don't need
// to do anything here. Otherwise we need to set up a temporary
// ImageContainer, capture the video data and store it in the temp
// container. For now we also check if the manager is equal since not all
// image containers are manager independent yet.
if (!container ||
(container->Manager() && container->Manager() != aManager) ||
container->GetBackendType() != aManager->GetBackendType())
{
nsRefPtr<ImageContainer> tmpContainer = aManager->CreateImageContainer();
if (!tmpContainer)
return nsnull;
// We get a reference to the video data as a cairo surface.
CairoImage::Data cairoData;
nsRefPtr<gfxASurface> imageSurface;
if (container) {
// Get video from the existing container. It was created for a
// different layer manager, so we do fallback through cairo.
imageSurface = container->GetCurrentAsSurface(&cairoData.mSize);
if (!imageSurface) {
// we couldn't do fallback, so we've got nothing to do here
return nsnull;
}
cairoData.mSurface = imageSurface;
} else {
// We're probably printing.
cairoData.mSurface = element->GetPrintSurface();
if (!cairoData.mSurface)
return nsnull;
cairoData.mSize = gfxIntSize(videoSize.width, videoSize.height);
}
// Now create a CairoImage to display the surface.
Image::Format cairoFormat = Image::CAIRO_SURFACE;
nsRefPtr<Image> image = tmpContainer->CreateImage(&cairoFormat, 1);
if (!image)
return nsnull;
NS_ASSERTION(image->GetFormat() == cairoFormat, "Wrong format");
static_cast<CairoImage*>(image.get())->SetData(cairoData);
tmpContainer->SetCurrentImage(image);
container = tmpContainer.forget();
}
// Retrieve the size of the decoded video frame, before being scaled
// by pixel aspect ratio.
gfxIntSize frameSize = container->GetCurrentSize();
if (frameSize.width == 0 || frameSize.height == 0) {
// No image, or zero-sized image. No point creating a layer.
return nsnull;
}
// Compute the rectangle in which to paint the video. We need to use
// the largest rectangle that fills our content-box and has the
// correct aspect ratio.
nsPresContext* presContext = PresContext();
gfxRect r = gfxRect(presContext->AppUnitsToGfxUnits(area.x),
presContext->AppUnitsToGfxUnits(area.y),
presContext->AppUnitsToGfxUnits(area.width),
presContext->AppUnitsToGfxUnits(area.height));
r = CorrectForAspectRatio(r, videoSize);
r.Round();
gfxIntSize scaleHint(static_cast<PRInt32>(r.Width()),
static_cast<PRInt32>(r.Height()));
container->SetScaleHint(scaleHint);
nsRefPtr<ImageLayer> layer = static_cast<ImageLayer*>
(aBuilder->LayerBuilder()->GetLeafLayerFor(aBuilder, aManager, aItem));
if (!layer) {
layer = aManager->CreateImageLayer();
if (!layer)
return nsnull;
}
layer->SetContainer(container);
layer->SetFilter(nsLayoutUtils::GetGraphicsFilterForFrame(this));
// Set a transform on the layer to draw the video in the right place
gfxMatrix transform;
transform.Translate(r.pos);
transform.Scale(r.Width()/frameSize.width, r.Height()/frameSize.height);
layer->SetTransform(gfx3DMatrix::From2D(transform));
layer->SetVisibleRegion(nsIntRect(0, 0, videoSize.width, videoSize.height));
nsRefPtr<Layer> result = layer.forget();
return result.forget();
}
NS_IMETHODIMP
nsVideoFrame::Reflow(nsPresContext* aPresContext,
nsHTMLReflowMetrics& aMetrics,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus)
{
DO_GLOBAL_REFLOW_COUNT("nsVideoFrame");
DISPLAY_REFLOW(aPresContext, this, aReflowState, aMetrics, aStatus);
NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
("enter nsVideoFrame::Reflow: availSize=%d,%d",
aReflowState.availableWidth, aReflowState.availableHeight));
NS_PRECONDITION(mState & NS_FRAME_IN_REFLOW, "frame is not in reflow");
aStatus = NS_FRAME_COMPLETE;
aMetrics.width = aReflowState.ComputedWidth();
aMetrics.height = aReflowState.ComputedHeight();
// stash this away so we can compute our inner area later
mBorderPadding = aReflowState.mComputedBorderPadding;
aMetrics.width += mBorderPadding.left + mBorderPadding.right;
aMetrics.height += mBorderPadding.top + mBorderPadding.bottom;
// Reflow the child frames. We may have up to two, an image frame
// which is the poster, and a box frame, which is the video controls.
for (nsIFrame *child = mFrames.FirstChild();
child;
child = child->GetNextSibling()) {
if (child->GetType() == nsGkAtoms::imageFrame) {
// Reflow the poster frame.
nsImageFrame* imageFrame = static_cast<nsImageFrame*>(child);
nsHTMLReflowMetrics kidDesiredSize;
nsSize availableSize = nsSize(aReflowState.availableWidth,
aReflowState.availableHeight);
nsHTMLReflowState kidReflowState(aPresContext,
aReflowState,
imageFrame,
availableSize,
aMetrics.width,
aMetrics.height);
if (ShouldDisplayPoster()) {
kidReflowState.SetComputedWidth(aReflowState.ComputedWidth());
kidReflowState.SetComputedHeight(aReflowState.ComputedHeight());
} else {
kidReflowState.SetComputedWidth(0);
kidReflowState.SetComputedHeight(0);
}
ReflowChild(imageFrame, aPresContext, kidDesiredSize, kidReflowState,
mBorderPadding.left, mBorderPadding.top, 0, aStatus);
FinishReflowChild(imageFrame, aPresContext,
&kidReflowState, kidDesiredSize,
mBorderPadding.left, mBorderPadding.top, 0);
} else if (child->GetType() == nsGkAtoms::boxFrame) {
// Reflow the video controls frame.
nsBoxLayoutState boxState(PresContext(), aReflowState.rendContext);
nsBoxFrame::LayoutChildAt(boxState,
child,
nsRect(mBorderPadding.left,
mBorderPadding.top,
aReflowState.ComputedWidth(),
aReflowState.ComputedHeight()));
}
}
aMetrics.SetOverflowAreasToDesiredBounds();
FinishAndStoreOverflow(&aMetrics);
if (mRect.width != aMetrics.width || mRect.height != aMetrics.height) {
Invalidate(nsRect(0, 0, mRect.width, mRect.height));
}
NS_FRAME_TRACE(NS_FRAME_TRACE_CALLS,
("exit nsVideoFrame::Reflow: size=%d,%d",
aMetrics.width, aMetrics.height));
NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aMetrics);
return NS_OK;
}
class nsDisplayVideo : public nsDisplayItem {
public:
nsDisplayVideo(nsDisplayListBuilder* aBuilder, nsVideoFrame* aFrame)
: nsDisplayItem(aBuilder, aFrame)
{
MOZ_COUNT_CTOR(nsDisplayVideo);
}
#ifdef NS_BUILD_REFCNT_LOGGING
virtual ~nsDisplayVideo() {
MOZ_COUNT_DTOR(nsDisplayVideo);
}
#endif
NS_DISPLAY_DECL_NAME("Video", TYPE_VIDEO)
// It would be great if we could override GetOpaqueRegion to return nonempty here,
// but it's probably not safe to do so in general. Video frames are
// updated asynchronously from decoder threads, and it's possible that
// we might have an opaque video frame when GetOpaqueRegion is called, but
// when we come to paint, the video frame is transparent or has gone
// away completely (e.g. because of a decoder error). The problem would
// be especially acute if we have off-main-thread rendering.
virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder)
{
nsIFrame* f = GetUnderlyingFrame();
return f->GetContentRect() - f->GetPosition() + ToReferenceFrame();
}
virtual already_AddRefed<Layer> BuildLayer(nsDisplayListBuilder* aBuilder,
LayerManager* aManager)
{
return static_cast<nsVideoFrame*>(mFrame)->BuildLayer(aBuilder, aManager, this);
}
virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
LayerManager* aManager)
{
if (aManager->GetBackendType() != LayerManager::LAYERS_BASIC) {
// For non-basic layer managers we can assume that compositing
// layers is very cheap, and since ImageLayers don't require
// additional memory of the video frames we have to have anyway,
// we can't save much by making layers inactive. Also, for many
// accelerated layer managers calling
// imageContainer->GetCurrentAsSurface can be very expensive. So
// just always be active for these managers.
return LAYER_ACTIVE;
}
nsHTMLMediaElement* elem =
static_cast<nsHTMLMediaElement*>(mFrame->GetContent());
return elem->IsPotentiallyPlaying() ? LAYER_ACTIVE : LAYER_INACTIVE;
}
};
NS_IMETHODIMP
nsVideoFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsRect& aDirtyRect,
const nsDisplayListSet& aLists)
{
if (!IsVisibleForPainting(aBuilder))
return NS_OK;
DO_GLOBAL_REFLOW_COUNT_DSP("nsVideoFrame");
nsresult rv = DisplayBorderBackgroundOutline(aBuilder, aLists);
NS_ENSURE_SUCCESS(rv, rv);
nsDisplayList replacedContent;
if (HasVideoElement() && !ShouldDisplayPoster()) {
rv = replacedContent.AppendNewToTop(
new (aBuilder) nsDisplayVideo(aBuilder, this));
NS_ENSURE_SUCCESS(rv, rv);
}
// Add child frames to display list. We expect up to two children, an image
// frame for the poster, and the box frame for the video controls.
for (nsIFrame *child = mFrames.FirstChild();
child;
child = child->GetNextSibling()) {
if (child->GetType() == nsGkAtoms::imageFrame && ShouldDisplayPoster()) {
rv = child->BuildDisplayListForStackingContext(aBuilder,
aDirtyRect - child->GetOffsetTo(this),
&replacedContent);
NS_ENSURE_SUCCESS(rv,rv);
} else if (child->GetType() == nsGkAtoms::boxFrame) {
rv = child->BuildDisplayListForStackingContext(aBuilder,
aDirtyRect - child->GetOffsetTo(this),
&replacedContent);
NS_ENSURE_SUCCESS(rv,rv);
}
}
WrapReplacedContentForBorderRadius(aBuilder, &replacedContent, aLists);
return NS_OK;
}
nsIAtom*
nsVideoFrame::GetType() const
{
return nsGkAtoms::HTMLVideoFrame;
}
#ifdef ACCESSIBILITY
already_AddRefed<nsAccessible>
nsVideoFrame::CreateAccessible()
{
nsAccessibilityService* accService = nsIPresShell::AccService();
return accService ?
accService->CreateHTMLMediaAccessible(mContent, PresContext()->PresShell()) :
nsnull;
}
#endif
#ifdef DEBUG
NS_IMETHODIMP
nsVideoFrame::GetFrameName(nsAString& aResult) const
{
return MakeFrameName(NS_LITERAL_STRING("HTMLVideo"), aResult);
}
#endif
nsSize nsVideoFrame::ComputeSize(nsIRenderingContext *aRenderingContext,
nsSize aCBSize,
nscoord aAvailableWidth,
nsSize aMargin,
nsSize aBorder,
nsSize aPadding,
PRBool aShrinkWrap)
{
nsSize size = GetVideoIntrinsicSize(aRenderingContext);
IntrinsicSize intrinsicSize;
intrinsicSize.width.SetCoordValue(size.width);
intrinsicSize.height.SetCoordValue(size.height);
nsSize& intrinsicRatio = size; // won't actually be used
return nsLayoutUtils::ComputeSizeWithIntrinsicDimensions(aRenderingContext,
this,
intrinsicSize,
intrinsicRatio,
aCBSize,
aMargin,
aBorder,
aPadding);
}
nscoord nsVideoFrame::GetMinWidth(nsIRenderingContext *aRenderingContext)
{
nscoord result = GetVideoIntrinsicSize(aRenderingContext).width;
DISPLAY_MIN_WIDTH(this, result);
return result;
}
nscoord nsVideoFrame::GetPrefWidth(nsIRenderingContext *aRenderingContext)
{
nscoord result = GetVideoIntrinsicSize(aRenderingContext).width;
DISPLAY_PREF_WIDTH(this, result);
return result;
}
nsSize nsVideoFrame::GetIntrinsicRatio()
{
return GetVideoIntrinsicSize(nsnull);
}
PRBool nsVideoFrame::ShouldDisplayPoster()
{
if (!HasVideoElement())
return PR_FALSE;
nsHTMLVideoElement* element = static_cast<nsHTMLVideoElement*>(GetContent());
if (element->GetPlayedOrSeeked() && HasVideoData())
return PR_FALSE;
nsCOMPtr<nsIImageLoadingContent> imgContent = do_QueryInterface(mPosterImage);
NS_ENSURE_TRUE(imgContent, PR_FALSE);
nsCOMPtr<imgIRequest> request;
nsresult res = imgContent->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
getter_AddRefs(request));
if (NS_FAILED(res) || !request) {
return PR_FALSE;
}
PRUint32 status = 0;
res = request->GetImageStatus(&status);
if (NS_FAILED(res) || (status & imgIRequest::STATUS_ERROR))
return PR_FALSE;
return PR_TRUE;
}
nsSize
nsVideoFrame::GetVideoIntrinsicSize(nsIRenderingContext *aRenderingContext)
{
// Defaulting size to 300x150 if no size given.
nsIntSize size(300, 150);
if (ShouldDisplayPoster()) {
// Use the poster image frame's size.
nsIFrame *child = mFrames.FirstChild();
if (child && child->GetType() == nsGkAtoms::imageFrame) {
nsImageFrame* imageFrame = static_cast<nsImageFrame*>(child);
nsSize imgsize;
if (NS_SUCCEEDED(imageFrame->GetIntrinsicImageSize(imgsize))) {
return imgsize;
}
}
}
if (!HasVideoElement()) {
if (!aRenderingContext || !mFrames.FirstChild()) {
// We just want our intrinsic ratio, but audio elements need no
// intrinsic ratio, so just return "no ratio". Also, if there's
// no controls frame, we prefer to be zero-sized.
return nsSize(0, 0);
}
// Ask the controls frame what its preferred height is
nsBoxLayoutState boxState(PresContext(), aRenderingContext, 0);
nscoord prefHeight = mFrames.LastChild()->GetPrefSize(boxState).height;
return nsSize(nsPresContext::CSSPixelsToAppUnits(size.width), prefHeight);
}
nsHTMLVideoElement* element = static_cast<nsHTMLVideoElement*>(GetContent());
size = element->GetVideoSize(size);
return nsSize(nsPresContext::CSSPixelsToAppUnits(size.width),
nsPresContext::CSSPixelsToAppUnits(size.height));
}
nsresult
nsVideoFrame::UpdatePosterSource(PRBool aNotify)
{
NS_ASSERTION(HasVideoElement(), "Only call this on <video> elements.");
nsHTMLVideoElement* element = static_cast<nsHTMLVideoElement*>(GetContent());
nsAutoString posterStr;
element->GetPoster(posterStr);
nsresult res = mPosterImage->SetAttr(kNameSpaceID_None,
nsGkAtoms::src,
posterStr,
aNotify);
NS_ENSURE_SUCCESS(res,res);
return NS_OK;
}
NS_IMETHODIMP
nsVideoFrame::AttributeChanged(PRInt32 aNameSpaceID,
nsIAtom* aAttribute,
PRInt32 aModType)
{
if (aAttribute == nsGkAtoms::poster && HasVideoElement()) {
nsresult res = UpdatePosterSource(PR_TRUE);
NS_ENSURE_SUCCESS(res,res);
}
return nsContainerFrame::AttributeChanged(aNameSpaceID,
aAttribute,
aModType);
}
PRBool nsVideoFrame::HasVideoElement() {
nsCOMPtr<nsIDOMHTMLVideoElement> videoDomElement = do_QueryInterface(mContent);
return videoDomElement != nsnull;
}
PRBool nsVideoFrame::HasVideoData()
{
if (!HasVideoElement())
return PR_FALSE;
nsHTMLVideoElement* element = static_cast<nsHTMLVideoElement*>(GetContent());
nsIntSize size = element->GetVideoSize(nsIntSize(0,0));
return size != nsIntSize(0,0);
}