Snapshot.h revision f607bdc167f66b3e7003acaa4736ae46d78c1492 
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        switch (op) {
120            case SkRegion::kDifference_Op:
121                break;
122            case SkRegion::kIntersect_Op:
123                clipped = clipRect->intersect(r);
124                break;
125            case SkRegion::kUnion_Op:
126                clipped = clipRect->unionWith(r);
127                break;
128            case SkRegion::kXOR_Op:
129                break;
130            case SkRegion::kReverseDifference_Op:
131                break;
132            case SkRegion::kReplace_Op:
133                clipRect->set(r);
134                clipped = true;
135                break;
136        }
137
138        if (clipped) {
139            flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
140        }
141
142        return clipped;
143    }
144
145    /**
146     * Sets the current clip.
147     */
148    void setClip(float left, float top, float right, float bottom) {
149        clipRect->set(left, top, right, bottom);
150        flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
151    }
152
153    const Rect& getLocalClip() {
154        if (flags & Snapshot::kFlagDirtyLocalClip) {
155            mat4 inverse;
156            inverse.loadInverse(*transform);
157
158            mLocalClip.set(*clipRect);
159            inverse.mapRect(mLocalClip);
160
161            flags &= ~Snapshot::kFlagDirtyLocalClip;
162        }
163        return mLocalClip;
164    }
165
166    /**
167     * Dirty flags.
168     */
169    int flags;
170
171    /**
172     * Previous snapshot.
173     */
174    sp<Snapshot> previous;
175
176    /**
177     * Only set when the flag kFlagIsLayer is set.
178     */
179    Layer* layer;
180
181    /**
182     * Local transformation. Holds the current translation, scale and
183     * rotation values.
184     */
185    mat4* transform;
186
187    /**
188     * Current clip region. The clip is stored in canvas-space coordinates,
189     * (screen-space coordinates in the regular case.)
190     */
191    Rect* clipRect;
192
193private:
194    mat4 mTransformRoot;
195    Rect mClipRectRoot;
196    Rect mLocalClip;
197
198}; // class Snapshot
199
200}; // namespace uirenderer
201}; // namespace android
202
203#endif // ANDROID_UI_SNAPSHOT_H
204