Snapshot.h revision dbc26d2ba13f80a7590c57de2d80530d96832969 
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), fbo(0), invisible(false) {
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), fbo(s->fbo),
57            invisible(s->invisible), viewport(s->viewport), height(s->height) {
58        if (saveFlags & SkCanvas::kMatrix_SaveFlag) {
59            mTransformRoot.load(*s->transform);
60            transform = &mTransformRoot;
61        } else {
62            transform = s->transform;
63        }
64
65        if (saveFlags & SkCanvas::kClip_SaveFlag) {
66            mClipRectRoot.set(*s->clipRect);
67            clipRect = &mClipRectRoot;
68        } else {
69            clipRect = s->clipRect;
70        }
71
72        if ((s->flags & Snapshot::kFlagClipSet) &&
73                !(s->flags & Snapshot::kFlagDirtyLocalClip)) {
74            mLocalClip.set(s->mLocalClip);
75        } else {
76            flags |= Snapshot::kFlagDirtyLocalClip;
77        }
78    }
79
80    /**
81     * Various flags set on #flags.
82     */
83    enum Flags {
84        /**
85         * Indicates that the clip region was modified. When this
86         * snapshot is restored so must the clip.
87         */
88        kFlagClipSet = 0x1,
89        /**
90         * Indicates that this snapshot was created when saving
91         * a new layer.
92         */
93        kFlagIsLayer = 0x2,
94        /**
95         * Indicates that this snapshot is a special type of layer
96         * backed by an FBO. This flag only makes sense when the
97         * flag kFlagIsLayer is also set.
98         */
99        kFlagIsFboLayer = 0x4,
100        /**
101         * Indicates that the local clip should be recomputed.
102         */
103        kFlagDirtyLocalClip = 0x8,
104        /**
105         * Indicates that this snapshot has changed the ortho matrix.
106         */
107        kFlagDirtyOrtho = 0x10,
108    };
109
110    /**
111     * Modifies the current clip with the new clip rectangle and
112     * the specified operation. The specified rectangle is transformed
113     * by this snapshot's trasnformation.
114     */
115    bool clip(float left, float top, float right, float bottom,
116            SkRegion::Op op = SkRegion::kIntersect_Op) {
117        Rect r(left, top, right, bottom);
118        transform->mapRect(r);
119        return clipTransformed(r, op);
120    }
121
122    /**
123     * Modifies the current clip with the new clip rectangle and
124     * the specified operation. The specified rectangle is considered
125     * already transformed.
126     */
127    bool clipTransformed(const Rect& r, SkRegion::Op op = SkRegion::kIntersect_Op) {
128        bool clipped = false;
129
130        // NOTE: The unimplemented operations require support for regions
131        // Supporting regions would require using a stencil buffer instead
132        // of the scissor. The stencil buffer itself is not too expensive
133        // (memory cost excluded) but on fillrate limited devices, managing
134        // the stencil might have a negative impact on the framerate.
135        switch (op) {
136            case SkRegion::kDifference_Op:
137                break;
138            case SkRegion::kIntersect_Op:
139                clipped = clipRect->intersect(r);
140                break;
141            case SkRegion::kUnion_Op:
142                clipped = clipRect->unionWith(r);
143                break;
144            case SkRegion::kXOR_Op:
145                break;
146            case SkRegion::kReverseDifference_Op:
147                break;
148            case SkRegion::kReplace_Op:
149                clipRect->set(r);
150                clipped = true;
151                break;
152        }
153
154        if (clipped) {
155            clipRect->snapToPixelBoundaries();
156            flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
157        }
158
159        return clipped;
160    }
161
162    /**
163     * Sets the current clip.
164     */
165    void setClip(float left, float top, float right, float bottom) {
166        clipRect->set(left, top, right, bottom);
167        flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
168    }
169
170    const Rect& getLocalClip() {
171        if (flags & Snapshot::kFlagDirtyLocalClip) {
172            mat4 inverse;
173            inverse.loadInverse(*transform);
174
175            mLocalClip.set(*clipRect);
176            inverse.mapRect(mLocalClip);
177
178            flags &= ~Snapshot::kFlagDirtyLocalClip;
179        }
180        return mLocalClip;
181    }
182
183    void resetTransform(float x, float y, float z) {
184        transform = &mTransformRoot;
185        transform->loadTranslate(x, y, z);
186    }
187
188    void resetClip(float left, float top, float right, float bottom) {
189        clipRect = &mClipRectRoot;
190        clipRect->set(left, top, right, bottom);
191        flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
192    }
193
194    /**
195     * Dirty flags.
196     */
197    int flags;
198
199    /**
200     * Previous snapshot.
201     */
202    sp<Snapshot> previous;
203
204    /**
205     * Only set when the flag kFlagIsLayer is set.
206     */
207    Layer* layer;
208
209    /**
210     * Only set when the flag kFlagIsFboLayer is set.
211     */
212    GLuint fbo;
213
214    /**
215     * Indicates that this snapshot is invisible and nothing should be drawn
216     * inside it.
217     */
218    bool invisible;
219
220    /**
221     * Current viewport.
222     */
223    Rect viewport;
224
225    /**
226     * Height of the framebuffer the snapshot is rendering into.
227     */
228    int height;
229
230    /**
231     * Contains the previous ortho matrix.
232     */
233    mat4 orthoMatrix;
234
235    /**
236     * Local transformation. Holds the current translation, scale and
237     * rotation values.
238     */
239    mat4* transform;
240
241    /**
242     * Current clip region. The clip is stored in canvas-space coordinates,
243     * (screen-space coordinates in the regular case.)
244     */
245    Rect* clipRect;
246
247private:
248    mat4 mTransformRoot;
249    Rect mClipRectRoot;
250    Rect mLocalClip;
251
252}; // class Snapshot
253
254}; // namespace uirenderer
255}; // namespace android
256
257#endif // ANDROID_UI_SNAPSHOT_H
258