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* Copyright (C) 2015 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#ifndef CLIPAREA_H
#define CLIPAREA_H
#include "Matrix.h"
#include "Rect.h"
#include "utils/Pair.h"
#include <SkRegion.h>
namespace android {
namespace uirenderer {
class LinearAllocator;
Rect transformAndCalculateBounds(const Rect& r, const Matrix4& transform);
class TransformedRectangle {
TransformedRectangle(const Rect& bounds, const Matrix4& transform);
bool canSimplyIntersectWith(const TransformedRectangle& other) const;
void intersectWith(const TransformedRectangle& other);
bool isEmpty() const;
const Rect& getBounds() const {
return mBounds;
Rect transformedBounds() const {
Rect transformedBounds(transformAndCalculateBounds(mBounds, mTransform));
return transformedBounds;
const Matrix4& getTransform() const {
return mTransform;
void transform(const Matrix4& transform) {
Matrix4 t;
t.loadMultiply(transform, mTransform);
mTransform = t;
Rect mBounds;
Matrix4 mTransform;
class RectangleList {
bool isEmpty() const;
int getTransformedRectanglesCount() const;
const TransformedRectangle& getTransformedRectangle(int i) const;
void setEmpty();
void set(const Rect& bounds, const Matrix4& transform);
bool intersectWith(const Rect& bounds, const Matrix4& transform);
void transform(const Matrix4& transform);
SkRegion convertToRegion(const SkRegion& clip) const;
Rect calculateBounds() const;
enum {
kMaxTransformedRectangles = 5
int mTransformedRectanglesCount;
TransformedRectangle mTransformedRectangles[kMaxTransformedRectangles];
enum class ClipMode {
// region and path - intersected. if either is empty, don't use
struct ClipBase {
ClipBase(ClipMode mode)
: mode(mode) {}
ClipBase(const Rect& rect)
: mode(ClipMode::Rectangle)
, rect(rect) {}
const ClipMode mode;
bool intersectWithRoot = false;
// Bounds of the clipping area, used to define the scissor, and define which
// portion of the stencil is updated/used
Rect rect;
void dump() const;
struct ClipRect : ClipBase {
ClipRect(const Rect& rect)
: ClipBase(rect) {}
struct ClipRectList : ClipBase {
ClipRectList(const RectangleList& rectList)
: ClipBase(ClipMode::RectangleList)
, rectList(rectList) {}
RectangleList rectList;
struct ClipRegion : ClipBase {
ClipRegion(const SkRegion& region)
: ClipBase(ClipMode::Region)
, region(region) {}
: ClipBase(ClipMode::Region) {}
SkRegion region;
class ClipArea {
void setViewportDimensions(int width, int height);
bool isEmpty() const {
return mClipRect.isEmpty();
void setEmpty();
void setClip(float left, float top, float right, float bottom);
void clipRectWithTransform(const Rect& r, const mat4* transform,
SkRegion::Op op);
void clipRegion(const SkRegion& region, SkRegion::Op op);
void clipPathWithTransform(const SkPath& path, const mat4* transform,
SkRegion::Op op);
const Rect& getClipRect() const {
return mClipRect;
const SkRegion& getClipRegion() const {
return mClipRegion;
const RectangleList& getRectangleList() const {
return mRectangleList;
bool isRegion() const {
return ClipMode::Region == mMode;
bool isSimple() const {
return mMode == ClipMode::Rectangle;
bool isRectangleList() const {
return mMode == ClipMode::RectangleList;
WARN_UNUSED_RESULT const ClipBase* serializeClip(LinearAllocator& allocator);
WARN_UNUSED_RESULT const ClipBase* serializeIntersectedClip(LinearAllocator& allocator,
const ClipBase* recordedClip, const Matrix4& recordedClipTransform);
void applyClip(const ClipBase* recordedClip, const Matrix4& recordedClipTransform);
static void applyTransformToRegion(const Matrix4& transform, SkRegion* region);
void enterRectangleMode();
void rectangleModeClipRectWithTransform(const Rect& r, const mat4* transform, SkRegion::Op op);
void enterRectangleListMode();
void rectangleListModeClipRectWithTransform(const Rect& r,
const mat4* transform, SkRegion::Op op);
void enterRegionModeFromRectangleMode();
void enterRegionModeFromRectangleListMode();
void enterRegionMode();
void regionModeClipRectWithTransform(const Rect& r, const mat4* transform,
SkRegion::Op op);
void ensureClipRegion();
void onClipRegionUpdated();
// Called by every state modifying public method.
void onClipUpdated() {
mPostViewportClipObserved = true;
mLastSerialization = nullptr;
mLastResolutionResult = nullptr;
SkRegion createViewportRegion() {
return SkRegion(mViewportBounds.toSkIRect());
void regionFromPath(const SkPath& path, SkRegion& pathAsRegion) {
// TODO: this should not mask every path to the viewport - this makes it impossible to use
// paths to clip to larger areas (which is valid e.g. with SkRegion::kReplace_Op)
pathAsRegion.setPath(path, createViewportRegion());
ClipMode mMode;
bool mPostViewportClipObserved = false;
bool mReplaceOpObserved = false;
* If mLastSerialization is non-null, it represents an already serialized copy
* of the current clip state. If null, it has not been computed.
const ClipBase* mLastSerialization = nullptr;
* This pair of pointers is a single entry cache of most recently seen
const ClipBase* mLastResolutionResult = nullptr;
const ClipBase* mLastResolutionClip = nullptr;
Matrix4 mLastResolutionTransform;
Rect mViewportBounds;
Rect mClipRect;
SkRegion mClipRegion;
RectangleList mRectangleList;
} /* namespace uirenderer */
} /* namespace android */
#endif /* CLIPAREA_H_ */