CanvasState.h revision 6b109c74982033d4a220cd10a0eab8b024b351c9 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_HWUI_CANVAS_STATE_H
18#define ANDROID_HWUI_CANVAS_STATE_H
19
20#include <SkMatrix.h>
21#include <SkPath.h>
22#include <SkRegion.h>
23
24#include "Snapshot.h"
25
26namespace android {
27namespace uirenderer {
28
29/**
30 * Abstract base class for any class containing CanvasState.
31 * Defines three mandatory callbacks.
32 */
33class CanvasStateClient {
34public:
35    CanvasStateClient() { }
36    virtual ~CanvasStateClient() { }
37
38    /**
39     * Callback allowing embedder to take actions in the middle of a
40     * setViewport() call.
41     */
42    virtual void onViewportInitialized() = 0;
43
44    /**
45     * Callback allowing embedder to take actions in the middle of a
46     * restore() call.  May be called several times sequentially.
47     */
48    virtual void onSnapshotRestored(const Snapshot& removed, const Snapshot& restored) = 0;
49
50    /**
51     * Allows subclasses to control what value is stored in snapshot's
52     * fbo field in * initializeSaveStack.
53     */
54    virtual GLuint getTargetFbo() const = 0;
55
56}; // class CanvasStateClient
57
58/**
59 * Implements Canvas state methods on behalf of Renderers.
60 *
61 * Manages the Snapshot stack, implementing matrix, save/restore, and clipping methods in the
62 * Renderer interface. Drawing and recording classes that include a CanvasState will have
63 * different use cases:
64 *
65 * Drawing subclasses (i.e. OpenGLRenderer) can query attributes (such as transform) or hook into
66 * changes (e.g. save/restore) with minimal surface area for manipulating the stack itself.
67 *
68 * Recording subclasses (i.e. DisplayListRenderer) can both record and pass through state operations
69 * to CanvasState, so that not only will querying operations work (getClip/Matrix), but so
70 * that quickRejection can also be used.
71 */
72
73class ANDROID_API CanvasState {
74public:
75    CanvasState(CanvasStateClient& renderer);
76    ~CanvasState();
77
78    /**
79     * Initializes the first snapshot, computing the projection matrix,
80     * and stores the dimensions of the render target.
81     */
82    void initializeSaveStack(float clipLeft, float clipTop, float clipRight, float clipBottom,
83            const Vector3& lightCenter);
84
85    void setViewport(int width, int height);
86
87    bool hasRectToRectTransform() const {
88        return CC_LIKELY(currentTransform()->rectToRect());
89    }
90
91    // Save (layer)
92    int getSaveCount() const { return mSaveCount; }
93    int save(int flags);
94    void restore();
95    void restoreToCount(int saveCount);
96
97    // Save/Restore without side-effects
98    int saveSnapshot(int flags);
99    void restoreSnapshot();
100
101    // Matrix
102    void getMatrix(SkMatrix* outMatrix) const;
103    void translate(float dx, float dy, float dz = 0.0f);
104    void rotate(float degrees);
105    void scale(float sx, float sy);
106    void skew(float sx, float sy);
107
108    void setMatrix(const SkMatrix& matrix);
109    void setMatrix(const Matrix4& matrix); // internal only convenience method
110    void concatMatrix(const SkMatrix& matrix);
111    void concatMatrix(const Matrix4& matrix); // internal only convenience method
112
113    // Clip
114    const Rect& getLocalClipBounds() const { return mSnapshot->getLocalClip(); }
115    const Rect& getRenderTargetClipBounds() const { return mSnapshot->getRenderTargetClip(); }
116
117    bool quickRejectConservative(float left, float top, float right, float bottom) const;
118
119    bool clipRect(float left, float top, float right, float bottom, SkRegion::Op op);
120    bool clipPath(const SkPath* path, SkRegion::Op op);
121    bool clipRegion(const SkRegion* region, SkRegion::Op op);
122
123    /**
124     * Sets a "clipping outline", which is independent from the regular clip.
125     * Currently only supports rectangles or rounded rectangles; passing in a
126     * more complicated outline fails silently. Replaces any previous clipping
127     * outline.
128     */
129    void setClippingOutline(LinearAllocator& allocator, const Outline* outline);
130    void setClippingRoundRect(LinearAllocator& allocator,
131            const Rect& rect, float radius, bool highPriority = true);
132
133    /**
134     * Returns true if drawing in the rectangle (left, top, right, bottom)
135     * will be clipped out. Is conservative: might return false when subpixel-
136     * perfect tests would return true.
137     */
138    bool calculateQuickRejectForScissor(float left, float top, float right, float bottom,
139            bool* clipRequired, bool* roundRectClipRequired, bool snapOut) const;
140
141    void setDirtyClip(bool opaque) { mDirtyClip = opaque; }
142    bool getDirtyClip() const { return mDirtyClip; }
143
144    void scaleAlpha(float alpha) { mSnapshot->alpha *= alpha; }
145    void setEmpty(bool value) { mSnapshot->empty = value; }
146    void setInvisible(bool value) { mSnapshot->invisible = value; }
147
148    inline const mat4* currentTransform() const { return currentSnapshot()->transform; }
149    inline const Rect& currentClipRect() const { return currentSnapshot()->getClipRect(); }
150    inline Region* currentRegion() const { return currentSnapshot()->region; }
151    inline int currentFlags() const { return currentSnapshot()->flags; }
152    const Vector3& currentLightCenter() const { return currentSnapshot()->getRelativeLightCenter(); }
153    inline bool currentlyIgnored() const { return currentSnapshot()->isIgnored(); }
154    int getViewportWidth() const { return currentSnapshot()->getViewportWidth(); }
155    int getViewportHeight() const { return currentSnapshot()->getViewportHeight(); }
156    int getWidth() { return mWidth; }
157    int getHeight() { return mHeight; }
158
159    inline const Snapshot* currentSnapshot() const {
160        return mSnapshot != nullptr ? mSnapshot.get() : mFirstSnapshot.get();
161    }
162    inline Snapshot* writableSnapshot() { return mSnapshot.get(); }
163    inline const Snapshot* firstSnapshot() const { return mFirstSnapshot.get(); }
164
165private:
166    /// No default constructor - must supply a CanvasStateClient (mCanvas).
167    CanvasState();
168
169    /// indicates that the clip has been changed since the last time it was consumed
170    bool mDirtyClip;
171
172    /// Dimensions of the drawing surface
173    int mWidth, mHeight;
174
175    /// Number of saved states
176    int mSaveCount;
177
178    /// Base state
179    sp<Snapshot> mFirstSnapshot;
180
181    /// Host providing callbacks
182    CanvasStateClient& mCanvas;
183
184    /// Current state
185    sp<Snapshot> mSnapshot;
186
187}; // class CanvasState
188
189}; // namespace uirenderer
190}; // namespace android
191
192#endif // ANDROID_HWUI_CANVAS_STATE_H
193