Snapshot.h revision d55a86120dd1e8ebcc6906c9ffd463f7460348da 
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 <SkXfermode.h>
24
25#include <utils/RefBase.h>
26
27#include "Matrix.h"
28#include "Rect.h"
29
30namespace android {
31namespace uirenderer {
32
33/**
34 * A snapshot holds information about the current state of the rendering
35 * surface. A snapshot is usually created whenever the user calls save()
36 * and discarded when the user calls restore(). Once a snapshot is created,
37 * it can hold information for deferred rendering.
38 *
39 * Each snapshot has a link to a previous snapshot, indicating the previous
40 * state of the renderer.
41 */
42class Snapshot: public LightRefBase<Snapshot> {
43public:
44    Snapshot() {
45    }
46
47    /**
48     * Copies the specified snapshot. Only the transform and clip rectangle
49     * are copied. The layer information is set to 0 and the transform is
50     * assumed to be dirty. The specified snapshot is stored as the previous
51     * snapshot.
52     */
53    Snapshot(const sp<Snapshot> s):
54            transform(s->transform),
55            clipRect(s->clipRect),
56            flags(kFlagDirtyTransform),
57            previous(s),
58            layer(0.0f, 0.0f, 0.0f, 0.0f),
59            texture(0),
60            fbo(0),
61            alpha(255) {
62    }
63
64    /**
65     * Various flags set on #flags.
66     */
67    enum Flags {
68        /**
69         * Indicates that the clip region was modified. When this
70         * snapshot is restored so must the clip.
71         */
72        kFlagClipSet = 0x1,
73        /**
74         * Indicates that the snapshot holds new transform
75         * information.
76         */
77        kFlagDirtyTransform = 0x2,
78        /**
79         * Indicates that this snapshot was created when saving
80         * a new layer.
81         */
82        kFlagIsLayer = 0x4,
83    };
84
85    /**
86     * Returns the current clip region mapped by the current transform.
87     */
88    const Rect& getMappedClip() {
89        if (flags & kFlagDirtyTransform) {
90            flags &= ~kFlagDirtyTransform;
91            mappedClip.set(clipRect);
92            transform.mapRect(mappedClip);
93        }
94        return mappedClip;
95    }
96
97    /**
98     * Local transformation. Holds the current translation, scale and
99     * rotation values.
100     */
101    mat4 transform;
102
103    /**
104     * Current clip region.
105     */
106    Rect clipRect;
107
108    /**
109     * Dirty flags.
110     */
111    int flags;
112
113    /**
114     * Previous snapshot.
115     */
116    sp<Snapshot> previous;
117
118    /**
119     * Coordinates of the layer corresponding to this snapshot.
120     * Only set when the flag kFlagIsLayer is set.
121     */
122    Rect layer;
123    /**
124     * Name of the texture used to render the layer.
125     * Only set when the flag kFlagIsLayer is set.
126     */
127    GLuint texture;
128    /**
129     * Name of the FBO used to render the layer.
130     * Only set when the flag kFlagIsLayer is set.
131     */
132    GLuint fbo;
133    /**
134     * Opacity of the layer.
135     * Only set when the flag kFlagIsLayer is set.
136     */
137    float alpha;
138    /**
139     * Blending mode of the layer.
140     * Only set when the flag kFlagIsLayer is set.
141     */
142    SkXfermode::Mode mode;
143
144private:
145    // Clipping rectangle mapped with the transform
146    Rect mappedClip;
147}; // class Snapshot
148
149}; // namespace uirenderer
150}; // namespace android
151
152#endif // ANDROID_UI_SNAPSHOT_H
153