Snapshot.h revision 5cbbce535744b89df5ecea95de21ee3733298260 
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 "Matrix.h"
26#include "Rect.h"
27
28namespace android {
29namespace uirenderer {
30
31/**
32 * A snapshot holds information about the current state of the rendering
33 * surface. A snapshot is usually created whenever the user calls save()
34 * and discarded when the user calls restore(). Once a snapshot is created,
35 * it can hold information for deferred rendering.
36 *
37 * Each snapshot has a link to a previous snapshot, indicating the previous
38 * state of the renderer.
39 */
40class Snapshot: public LightRefBase<Snapshot> {
41public:
42    Snapshot() {
43    }
44
45    /**
46     * Copies the specified snapshot. Only the transform and clip rectangle
47     * are copied. The layer information is set to 0 and the transform is
48     * assumed to be dirty. The specified snapshot is stored as the previous
49     * snapshot.
50     */
51    Snapshot(const sp<Snapshot> s):
52            transform(s->transform),
53            clipRect(s->clipRect),
54            flags(kFlagDirtyTransform),
55            previous(s),
56            layer(0.0f, 0.0f, 0.0f, 0.0f),
57            texture(0),
58            fbo(0),
59            alpha(255) {
60    }
61
62    /**
63     * Various flags set on #flags.
64     */
65    enum Flags {
66        /**
67         * Indicates that the clip region was modified. When this
68         * snapshot is restored so must the clip.
69         */
70        kFlagClipSet = 0x1,
71        /**
72         * Indicates that the snapshot holds new transform
73         * information.
74         */
75        kFlagDirtyTransform = 0x2,
76        /**
77         * Indicates that this snapshot was created when saving
78         * a new layer.
79         */
80        kFlagIsLayer = 0x4,
81    };
82
83    /**
84     * Returns the current clip region mapped by the current transform.
85     */
86    const Rect& getMappedClip() {
87        if (flags & kFlagDirtyTransform) {
88            flags &= ~kFlagDirtyTransform;
89            mappedClip.set(clipRect);
90            transform.mapRect(mappedClip);
91        }
92        return mappedClip;
93    }
94
95    /**
96     * Local transformation. Holds the current translation, scale and
97     * rotation values.
98     */
99    mat4 transform;
100
101    /**
102     * Current clip region.
103     */
104    Rect clipRect;
105
106    /**
107     * Dirty flags.
108     */
109    int flags;
110
111    /**
112     * Previous snapshot.
113     */
114    sp<Snapshot> previous;
115
116    /**
117     * Coordinates of the layer corresponding to this snapshot.
118     * Only set when the flag kFlagIsLayer is set.
119     */
120    Rect layer;
121    /**
122     * Name of the texture used to render the layer.
123     * Only set when the flag kFlagIsLayer is set.
124     */
125    GLuint texture;
126    /**
127     * Name of the FBO used to render the layer.
128     * Only set when the flag kFlagIsLayer is set.
129     */
130    GLuint fbo;
131    /**
132     * Opacity of the layer.
133     * Only set when the flag kFlagIsLayer is set.
134     */
135    float alpha;
136
137private:
138    // Clipping rectangle mapped with the transform
139    Rect mappedClip;
140}; // class Snapshot
141
142}; // namespace uirenderer
143}; // namespace android
144
145#endif // ANDROID_UI_SNAPSHOT_H
146