Snapshot.h revision 3b3e457c270a4bc5fe3047e815b5867d99b36f8a 
1/*
2 * Copyright (C) 2010 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_UI_SNAPSHOT_H
18#define ANDROID_UI_SNAPSHOT_H
19
20#include <GLES2/gl2.h>
21#include <GLES2/gl2ext.h>
22
23#include <utils/RefBase.h>
24
25#include <SkCanvas.h>
26#include <SkRegion.h>
27
28#include "Layer.h"
29#include "Matrix.h"
30#include "Rect.h"
31
32namespace android {
33namespace uirenderer {
34
35/**
36 * A snapshot holds information about the current state of the rendering
37 * surface. A snapshot is usually created whenever the user calls save()
38 * and discarded when the user calls restore(). Once a snapshot is created,
39 * it can hold information for deferred rendering.
40 *
41 * Each snapshot has a link to a previous snapshot, indicating the previous
42 * state of the renderer.
43 */
44class Snapshot: public LightRefBase<Snapshot> {
45public:
46    Snapshot(): flags(0), previous(NULL), layer(NULL) {
47        transform = &mTransformRoot;
48        clipRect = &mClipRectRoot;
49    }
50
51    /**
52     * Copies the specified snapshot/ The specified snapshot is stored as
53     * the previous snapshot.
54     */
55    Snapshot(const sp<Snapshot>& s, int saveFlags):
56            flags(0), previous(s), layer(NULL) {
57        if (saveFlags & SkCanvas::kMatrix_SaveFlag) {
58            mTransformRoot.load(*s->transform);
59            transform = &mTransformRoot;
60        } else {
61            transform = s->transform;
62        }
63
64        if (saveFlags & SkCanvas::kClip_SaveFlag) {
65            mClipRectRoot.set(*s->clipRect);
66            clipRect = &mClipRectRoot;
67        } else {
68            clipRect = s->clipRect;
69        }
70
71        if ((s->flags & Snapshot::kFlagClipSet) &&
72                !(s->flags & Snapshot::kFlagDirtyLocalClip)) {
73            mLocalClip.set(s->mLocalClip);
74        } else {
75            flags |= Snapshot::kFlagDirtyLocalClip;
76        }
77    }
78
79    /**
80     * Various flags set on #flags.
81     */
82    enum Flags {
83        /**
84         * Indicates that the clip region was modified. When this
85         * snapshot is restored so must the clip.
86         */
87        kFlagClipSet = 0x1,
88        /**
89         * Indicates that this snapshot was created when saving
90         * a new layer.
91         */
92        kFlagIsLayer = 0x2,
93        /**
94         * Indicates that the local clip should be recomputed.
95         */
96        kFlagDirtyLocalClip = 0x4,
97    };
98
99    /**
100     * Modifies the current clip with the new clip rectangle and
101     * the specified operation. The specified rectangle is transformed
102     * by this snapshot's trasnformation.
103     */
104    bool clip(float left, float top, float right, float bottom,
105            SkRegion::Op op = SkRegion::kIntersect_Op) {
106        Rect r(left, top, right, bottom);
107        transform->mapRect(r);
108        return clipTransformed(r, op);
109    }
110
111    /**
112     * Modifies the current clip with the new clip rectangle and
113     * the specified operation. The specified rectangle is considered
114     * already transformed.
115     */
116    bool clipTransformed(const Rect& r, SkRegion::Op op = SkRegion::kIntersect_Op) {
117        bool clipped = false;
118
119        // NOTE: The unimplemented operations require support for regions
120        // Supporting regions would require using a stencil buffer instead
121        // of the scissor. The stencil buffer itself is not too expensive
122        // (memory cost excluded) but on fillrate limited devices, managing
123        // the stencil might have a negative impact on the framerate.
124        switch (op) {
125            case SkRegion::kDifference_Op:
126                break;
127            case SkRegion::kIntersect_Op:
128                clipped = clipRect->intersect(r);
129                break;
130            case SkRegion::kUnion_Op:
131                clipped = clipRect->unionWith(r);
132                break;
133            case SkRegion::kXOR_Op:
134                break;
135            case SkRegion::kReverseDifference_Op:
136                break;
137            case SkRegion::kReplace_Op:
138                clipRect->set(r);
139                clipped = true;
140                break;
141        }
142
143        if (clipped) {
144            clipRect->snapToPixelBoundaries();
145            flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
146        }
147
148        return clipped;
149    }
150
151    /**
152     * Sets the current clip.
153     */
154    void setClip(float left, float top, float right, float bottom) {
155        clipRect->set(left, top, right, bottom);
156        flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
157    }
158
159    const Rect& getLocalClip() {
160        if (flags & Snapshot::kFlagDirtyLocalClip) {
161            mat4 inverse;
162            inverse.loadInverse(*transform);
163
164            mLocalClip.set(*clipRect);
165            inverse.mapRect(mLocalClip);
166
167            flags &= ~Snapshot::kFlagDirtyLocalClip;
168        }
169        return mLocalClip;
170    }
171
172    /**
173     * Dirty flags.
174     */
175    int flags;
176
177    /**
178     * Previous snapshot.
179     */
180    sp<Snapshot> previous;
181
182    /**
183     * Only set when the flag kFlagIsLayer is set.
184     */
185    Layer* layer;
186
187    /**
188     * Local transformation. Holds the current translation, scale and
189     * rotation values.
190     */
191    mat4* transform;
192
193    /**
194     * Current clip region. The clip is stored in canvas-space coordinates,
195     * (screen-space coordinates in the regular case.)
196     */
197    Rect* clipRect;
198
199private:
200    mat4 mTransformRoot;
201    Rect mClipRectRoot;
202    Rect mLocalClip;
203
204}; // class Snapshot
205
206}; // namespace uirenderer
207}; // namespace android
208
209#endif // ANDROID_UI_SNAPSHOT_H
210