pjs/layout/base/FrameLayerBuilder.h

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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* ***** 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 Corporation code.
*
* The Initial Developer of the Original Code is Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Robert O'Callahan <robert@ocallahan.org>
*
* 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
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef FRAMELAYERBUILDER_H_
#define FRAMELAYERBUILDER_H_
#include "nsTHashtable.h"
#include "nsHashKeys.h"
#include "nsTArray.h"
#include "nsRegion.h"
#include "nsIFrame.h"
#include "Layers.h"
class nsDisplayListBuilder;
class nsDisplayList;
class nsDisplayItem;
class gfxContext;
class nsRootPresContext;
namespace mozilla {
enum LayerState {
LAYER_NONE,
LAYER_INACTIVE,
LAYER_ACTIVE,
// Force an active layer even if it causes incorrect rendering, e.g.
// when the layer has rounded rect clips.
LAYER_ACTIVE_FORCE,
// Special layer that is metadata only.
LAYER_ACTIVE_EMPTY
};
/**
* The FrameLayerBuilder belongs to an nsDisplayListBuilder and is
* responsible for converting display lists into layer trees.
*
* The most important API in this class is BuildContainerLayerFor. This
* method takes a display list as input and constructs a ContainerLayer
* with child layers that render the contents of the display list. It
* also updates userdata for the retained layer manager, and
* DisplayItemDataProperty data for frames, to record the relationship
* between frames and layers.
*
* That data enables us to retain layer trees. When constructing a
* ContainerLayer, we first check to see if there's an existing
* ContainerLayer for the same frame that can be recycled. If we recycle
* it, we also try to reuse its existing ThebesLayer children to render
* the display items without layers of their own. The idea is that by
* recycling layers deterministically, we can ensure that when nothing
* changes in a display list, we will reuse the existing layers without
* changes.
*
* We expose a GetLeafLayerFor method that can be called by display items
* that make their own layers (e.g. canvas and video); this method
* locates the last layer used to render the display item, if any, and
* return it as a candidate for recycling.
*
* FrameLayerBuilder sets up ThebesLayers so that 0,0 in the Thebes layer
* corresponds to the (pixel-snapped) top-left of the aActiveScrolledRoot.
* It sets up ContainerLayers so that 0,0 in the container layer
* corresponds to the snapped top-left of the display list reference frame.
*
* When we construct a container layer, we know the transform that will be
* applied to the layer. If the transform scales the content, we can get
* better results when intermediate buffers are used by pushing some scale
* from the container's transform down to the children. For ThebesLayer
* children, the scaling can be achieved by changing the size of the layer
* and drawing into it with increased or decreased resolution. By convention,
* integer types (nsIntPoint/nsIntSize/nsIntRect/nsIntRegion) are all in layer
* coordinates, post-scaling, whereas appunit types are all pre-scaling.
*/
class FrameLayerBuilder {
public:
typedef layers::ContainerLayer ContainerLayer;
typedef layers::Layer Layer;
typedef layers::ThebesLayer ThebesLayer;
typedef layers::LayerManager LayerManager;
FrameLayerBuilder() :
mRetainingManager(nsnull),
mDetectedDOMModification(PR_FALSE),
mInvalidateAllLayers(PR_FALSE)
{
mNewDisplayItemData.Init();
mThebesLayerItems.Init();
}
void Init(nsDisplayListBuilder* aBuilder);
/**
* Call this to notify that we have just started a transaction on the
* retained layer manager aManager.
*/
void DidBeginRetainedLayerTransaction(LayerManager* aManager);
/**
* Call this just before we end a transaction on aManager. If aManager
* is not the retained layer manager then it must be a temporary layer
* manager that will not be used again.
*/
void WillEndTransaction(LayerManager* aManager);
/**
* Call this after we end a transaction on aManager. If aManager
* is not the retained layer manager then it must be a temporary layer
* manager that will not be used again.
*/
void DidEndTransaction(LayerManager* aManager);
struct ContainerParameters {
ContainerParameters() :
mXScale(1), mYScale(1),
mInTransformedSubtree(false), mInActiveTransformedSubtree(false) {}
ContainerParameters(float aXScale, float aYScale) :
mXScale(aXScale), mYScale(aYScale),
mInTransformedSubtree(false), mInActiveTransformedSubtree(false) {}
ContainerParameters(float aXScale, float aYScale,
const ContainerParameters& aParent) :
mXScale(aXScale), mYScale(aYScale),
mInTransformedSubtree(aParent.mInTransformedSubtree),
mInActiveTransformedSubtree(aParent.mInActiveTransformedSubtree) {}
float mXScale, mYScale;
bool mInTransformedSubtree;
bool mInActiveTransformedSubtree;
};
/**
* Build a container layer for a display item that contains a child
* list, either reusing an existing one or creating a new one. It
* sets the container layer children to layers which together render
* the contents of the display list. It reuses existing layers from
* the retained layer manager if possible.
* aContainer may be null, in which case we construct a root layer.
* This gets called by display list code. It calls BuildLayer on the
* items in the display list, making items with their own layers
* children of the new container, and assigning all other items to
* ThebesLayer children created and managed by the FrameLayerBuilder.
* Returns a layer with clip rect cleared; it is the
* caller's responsibility to add any clip rect. The visible region
* is set based on what's in the layer.
* The container layer is transformed by aTransform (if non-null), and
* the result is transformed by the scale factors in aContainerParameters.
*/
already_AddRefed<ContainerLayer>
BuildContainerLayerFor(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
nsIFrame* aContainerFrame,
nsDisplayItem* aContainerItem,
const nsDisplayList& aChildren,
const ContainerParameters& aContainerParameters,
const gfx3DMatrix* aTransform);
/**
* Get a retained layer for a display item that needs to create its own
* layer for rendering (i.e. under nsDisplayItem::BuildLayer). Returns
* null if no retained layer is available, which usually means that this
* display item didn't have a layer before so the caller will
* need to create one.
* Returns a layer with clip rect cleared; it is the
* caller's responsibility to add any clip rect and set the visible
* region.
*/
Layer* GetLeafLayerFor(nsDisplayListBuilder* aBuilder,
LayerManager* aManager,
nsDisplayItem* aItem);
/**
* Call this during invalidation if aFrame has
* the NS_FRAME_HAS_CONTAINER_LAYER state bit. Only the nearest
* ancestor frame of the damaged frame that has
* NS_FRAME_HAS_CONTAINER_LAYER needs to be invalidated this way.
*/
static void InvalidateThebesLayerContents(nsIFrame* aFrame,
const nsRect& aRect);
/**
* For any descendant frame of aFrame (including across documents) that
* has an associated container layer, invalidate all the contents of
* all ThebesLayer children of the container. Useful when aFrame is
* being moved and we need to invalidate everything in aFrame's subtree.
*/
static void InvalidateThebesLayersInSubtree(nsIFrame* aFrame);
/**
* Call this to force all retained layers to be discarded and recreated at
* the next paint.
*/
static void InvalidateAllLayers(LayerManager* aManager);
/**
* Call this to determine if a frame has a dedicated (non-Thebes) layer
* for the given display item key. If there isn't one, we return null,
* otherwise we return the layer.
*/
static Layer* GetDedicatedLayer(nsIFrame* aFrame, PRUint32 aDisplayItemKey);
/**
* This callback must be provided to EndTransaction. The callback data
* must be the nsDisplayListBuilder containing this FrameLayerBuilder.
*/
static void DrawThebesLayer(ThebesLayer* aLayer,
gfxContext* aContext,
const nsIntRegion& aRegionToDraw,
const nsIntRegion& aRegionToInvalidate,
void* aCallbackData);
#ifdef DEBUG
/**
* Dumps this FrameLayerBuilder's retained layer manager's retained
* layer tree to stderr.
*/
void DumpRetainedLayerTree();
#endif
/******* PRIVATE METHODS to FrameLayerBuilder.cpp ********/
/* These are only in the public section because they need
* to be called by file-scope helper functions in FrameLayerBuilder.cpp.
*/
/**
* Record aItem as a display item that is rendered by aLayer.
*/
void AddLayerDisplayItem(Layer* aLayer,
nsDisplayItem* aItem,
LayerState aLayerState);
/**
* Record aItem as a display item that is rendered by the ThebesLayer
* aLayer, with aClipRect, where aContainerLayerFrame is the frame
* for the container layer this ThebesItem belongs to.
* aItem must have an underlying frame.
*/
struct Clip;
void AddThebesDisplayItem(ThebesLayer* aLayer,
nsDisplayItem* aItem,
const Clip& aClip,
nsIFrame* aContainerLayerFrame,
LayerState aLayerState);
/**
* Given a frame and a display item key that uniquely identifies a
* display item for the frame, find the layer that was last used to
* render that display item. Returns null if there is no such layer.
* This could be a dedicated layer for the display item, or a ThebesLayer
* that renders many display items.
*/
Layer* GetOldLayerFor(nsIFrame* aFrame, PRUint32 aDisplayItemKey);
/**
* A useful hashtable iteration function that removes the
* DisplayItemData property for the frame, clears its
* NS_FRAME_HAS_CONTAINER_LAYER bit and returns PL_DHASH_REMOVE.
* aClosure is ignored.
*/
static PLDHashOperator RemoveDisplayItemDataForFrame(nsPtrHashKey<nsIFrame>* aEntry,
void* aClosure)
{
return UpdateDisplayItemDataForFrame(aEntry, nsnull);
}
/**
* Try to determine whether the ThebesLayer aLayer paints an opaque
* single color everywhere it's visible in aRect.
* If successful, return that color, otherwise return NS_RGBA(0,0,0,0).
*/
nscolor FindOpaqueColorCovering(nsDisplayListBuilder* aBuilder,
ThebesLayer* aLayer, const nsRect& aRect);
/**
* Destroy any stored DisplayItemDataProperty for aFrame.
*/
static void DestroyDisplayItemDataFor(nsIFrame* aFrame)
{
aFrame->Properties().Delete(DisplayItemDataProperty());
}
LayerManager* GetRetainingLayerManager() { return mRetainingManager; }
/**
* Returns true if the given item (which we assume here is
* background-attachment:fixed) needs to be repainted as we scroll in its
* document.
* Returns false if it doesn't need to be repainted because the layer system
* is ensuring its fixed-ness for us.
*/
static PRBool NeedToInvalidateFixedDisplayItem(nsDisplayListBuilder* aBuilder,
nsDisplayItem* aItem);
/**
* Returns true if the given display item was rendered directly
* into a retained layer.
* Returns false if it was rendered into a temporary layer manager and then
* into a retained layer.
*/
static PRBool HasRetainedLayerFor(nsIFrame* aFrame, PRUint32 aDisplayItemKey);
/**
* Save transform that was in aLayer when we last painted. It must be an integer
* translation.
*/
void SaveLastPaintOffset(ThebesLayer* aLayer);
/**
* Get the translation transform that was in aLayer when we last painted. It's either
* the transform saved by SaveLastPaintTransform, or else the transform
* that's currently in the layer (which must be an integer translation).
*/
nsIntPoint GetLastPaintOffset(ThebesLayer* aLayer);
/**
* Clip represents the intersection of an optional rectangle with a
* list of rounded rectangles.
*/
struct Clip {
struct RoundedRect {
nsRect mRect;
// Indices into mRadii are the NS_CORNER_* constants in nsStyleConsts.h
nscoord mRadii[8];
bool operator==(const RoundedRect& aOther) const {
if (!mRect.IsEqualInterior(aOther.mRect)) {
return false;
}
NS_FOR_CSS_HALF_CORNERS(corner) {
if (mRadii[corner] != aOther.mRadii[corner]) {
return false;
}
}
return true;
}
bool operator!=(const RoundedRect& aOther) const {
return !(*this == aOther);
}
};
nsRect mClipRect;
nsTArray<RoundedRect> mRoundedClipRects;
PRPackedBool mHaveClipRect;
Clip() : mHaveClipRect(PR_FALSE) {}
// Construct as the intersection of aOther and aClipItem.
Clip(const Clip& aOther, nsDisplayItem* aClipItem);
// Apply this |Clip| to the given gfxContext. Any saving of state
// or clearing of other clips must be done by the caller.
void ApplyTo(gfxContext* aContext, nsPresContext* aPresContext);
// Return a rectangle contained in the intersection of aRect with this
// clip region. Tries to return the largest possible rectangle, but may
// not succeed.
nsRect ApproximateIntersect(const nsRect& aRect) const;
// Returns false if aRect is definitely not clipped by a rounded corner in
// this clip. Returns true if aRect is clipped by a rounded corner in this
// clip or it can not be quickly determined that it is not clipped by a
// rounded corner in this clip.
bool IsRectClippedByRoundedCorner(const nsRect& aRect) const;
// Intersection of all rects in this clip ignoring any rounded corners.
nsRect NonRoundedIntersection() const;
// Gets rid of any rounded corners in this clip.
void RemoveRoundedCorners();
bool operator==(const Clip& aOther) const {
return mHaveClipRect == aOther.mHaveClipRect &&
(!mHaveClipRect || mClipRect.IsEqualInterior(aOther.mClipRect)) &&
mRoundedClipRects == aOther.mRoundedClipRects;
}
bool operator!=(const Clip& aOther) const {
return !(*this == aOther);
}
};
protected:
/**
* We store an array of these for each frame that is associated with
* one or more retained layers. Each DisplayItemData records the layer
* used to render one of the frame's display items.
*/
class DisplayItemData {
public:
DisplayItemData(Layer* aLayer, PRUint32 aKey, LayerState aLayerState)
: mLayer(aLayer), mDisplayItemKey(aKey), mLayerState(aLayerState) {}
nsRefPtr<Layer> mLayer;
PRUint32 mDisplayItemKey;
LayerState mLayerState;
};
static void InternalDestroyDisplayItemData(nsIFrame* aFrame,
void* aPropertyValue,
PRBool aRemoveFromFramesWithLayers);
static void DestroyDisplayItemData(nsIFrame* aFrame, void* aPropertyValue);
/**
* For DisplayItemDataProperty, the property value *is* an
* nsTArray<DisplayItemData>, not a pointer to an array. This works
* because sizeof(nsTArray<T>) == sizeof(void*).
*/
NS_DECLARE_FRAME_PROPERTY_WITH_FRAME_IN_DTOR(DisplayItemDataProperty,
DestroyDisplayItemData)
/**
* We accumulate DisplayItemData elements in a hashtable during
* the paint process, and store them in the frame property only when
* paint is complete. This is the hashentry for that hashtable.
*/
class DisplayItemDataEntry : public nsPtrHashKey<nsIFrame> {
public:
DisplayItemDataEntry(const nsIFrame *key) : nsPtrHashKey<nsIFrame>(key) {}
DisplayItemDataEntry(const DisplayItemDataEntry &toCopy) :
nsPtrHashKey<nsIFrame>(toCopy.mKey), mData(toCopy.mData)
{
NS_ERROR("Should never be called, since we ALLOW_MEMMOVE");
}
PRBool HasNonEmptyContainerLayer();
nsTArray<DisplayItemData> mData;
enum { ALLOW_MEMMOVE = PR_TRUE };
};
/**
* We store one of these for each display item associated with a
* ThebesLayer, in a hashtable that maps each ThebesLayer to an array
* of ClippedDisplayItems. (ThebesLayerItemsEntry is the hash entry
* for that hashtable.)
* These are only stored during the paint process, so that the
* DrawThebesLayer callback can figure out which items to draw for the
* ThebesLayer.
* mItem always has an underlying frame.
*/
struct ClippedDisplayItem {
ClippedDisplayItem(nsDisplayItem* aItem, const Clip& aClip)
: mItem(aItem), mClip(aClip)
{
}
nsDisplayItem* mItem;
Clip mClip;
PRPackedBool mInactiveLayer;
};
/**
* We accumulate ClippedDisplayItem elements in a hashtable during
* the paint process. This is the hashentry for that hashtable.
*/
class ThebesLayerItemsEntry : public nsPtrHashKey<ThebesLayer> {
public:
ThebesLayerItemsEntry(const ThebesLayer *key) :
nsPtrHashKey<ThebesLayer>(key), mContainerLayerFrame(nsnull),
mHasExplicitLastPaintOffset(PR_FALSE) {}
ThebesLayerItemsEntry(const ThebesLayerItemsEntry &toCopy) :
nsPtrHashKey<ThebesLayer>(toCopy.mKey), mItems(toCopy.mItems)
{
NS_ERROR("Should never be called, since we ALLOW_MEMMOVE");
}
nsTArray<ClippedDisplayItem> mItems;
nsIFrame* mContainerLayerFrame;
// The translation set on this ThebesLayer before we started updating the
// layer tree.
nsIntPoint mLastPaintOffset;
PRPackedBool mHasExplicitLastPaintOffset;
enum { ALLOW_MEMMOVE = PR_TRUE };
};
void RemoveThebesItemsForLayerSubtree(Layer* aLayer);
static PLDHashOperator UpdateDisplayItemDataForFrame(nsPtrHashKey<nsIFrame>* aEntry,
void* aUserArg);
static PLDHashOperator StoreNewDisplayItemData(DisplayItemDataEntry* aEntry,
void* aUserArg);
/**
* Returns true if the DOM has been modified since we started painting,
* in which case we should bail out and not paint anymore. This should
* never happen, but plugins can trigger it in some cases.
*/
PRBool CheckDOMModified();
/**
* The layer manager belonging to the widget that is being retained
* across paints.
*/
LayerManager* mRetainingManager;
/**
* The root prescontext for the display list builder reference frame
*/
nsRootPresContext* mRootPresContext;
/**
* A map from frames to a list of (display item key, layer) pairs that
* describes what layers various parts of the frame are assigned to.
*/
nsTHashtable<DisplayItemDataEntry> mNewDisplayItemData;
/**
* A map from ThebesLayers to the list of display items (plus
* clipping data) to be rendered in the layer.
*/
nsTHashtable<ThebesLayerItemsEntry> mThebesLayerItems;
/**
* Saved generation counter so we can detect DOM changes.
*/
PRUint32 mInitialDOMGeneration;
/**
* Set to true if we have detected and reported DOM modification during
* the current paint.
*/
PRPackedBool mDetectedDOMModification;
/**
* Indicates that the entire layer tree should be rerendered
* during this paint.
*/
PRPackedBool mInvalidateAllLayers;
};
}
#endif /* FRAMELAYERBUILDER_H_ */