Snapshot.h revision f28daffda50042c1b7cbfeb34b4d47741c6e21a8 
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_HWUI_SNAPSHOT_H
18#define ANDROID_HWUI_SNAPSHOT_H
19
20#include <GLES2/gl2.h>
21#include <GLES2/gl2ext.h>
22
23#include <utils/RefBase.h>
24#include <ui/Region.h>
25
26#include <SkCanvas.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), empty(false) {
47        transform = &mTransformRoot;
48        clipRect = &mClipRectRoot;
49        region = NULL;
50    }
51
52    /**
53     * Copies the specified snapshot/ The specified snapshot is stored as
54     * the previous snapshot.
55     */
56    Snapshot(const sp<Snapshot>& s, int saveFlags):
57            flags(0), previous(s), layer(NULL), fbo(s->fbo),
58            invisible(s->invisible), empty(false), viewport(s->viewport), height(s->height) {
59        if (saveFlags & SkCanvas::kMatrix_SaveFlag) {
60            mTransformRoot.load(*s->transform);
61            transform = &mTransformRoot;
62        } else {
63            transform = s->transform;
64        }
65
66        if (saveFlags & SkCanvas::kClip_SaveFlag) {
67            mClipRectRoot.set(*s->clipRect);
68            clipRect = &mClipRectRoot;
69        } else {
70            clipRect = s->clipRect;
71        }
72
73        if ((s->flags & Snapshot::kFlagClipSet) &&
74                !(s->flags & Snapshot::kFlagDirtyLocalClip)) {
75            mLocalClip.set(s->mLocalClip);
76        } else {
77            flags |= Snapshot::kFlagDirtyLocalClip;
78        }
79
80        if (s->flags & Snapshot::kFlagFboTarget) {
81            flags |= Snapshot::kFlagFboTarget;
82            region = s->region;
83        } else {
84            region = NULL;
85        }
86    }
87
88    /**
89     * Various flags set on #flags.
90     */
91    enum Flags {
92        /**
93         * Indicates that the clip region was modified. When this
94         * snapshot is restored so must the clip.
95         */
96        kFlagClipSet = 0x1,
97        /**
98         * Indicates that this snapshot was created when saving
99         * a new layer.
100         */
101        kFlagIsLayer = 0x2,
102        /**
103         * Indicates that this snapshot is a special type of layer
104         * backed by an FBO. This flag only makes sense when the
105         * flag kFlagIsLayer is also set.
106         */
107        kFlagIsFboLayer = 0x4,
108        /**
109         * Indicates that the local clip should be recomputed.
110         */
111        kFlagDirtyLocalClip = 0x8,
112        /**
113         * Indicates that this snapshot has changed the ortho matrix.
114         */
115        kFlagDirtyOrtho = 0x10,
116        /**
117         * Indicates that this snapshot or an ancestor snapshot is
118         * an FBO layer.
119         */
120        kFlagFboTarget = 0x20
121    };
122
123    /**
124     * Modifies the current clip with the new clip rectangle and
125     * the specified operation. The specified rectangle is transformed
126     * by this snapshot's trasnformation.
127     */
128    bool clip(float left, float top, float right, float bottom,
129            SkRegion::Op op = SkRegion::kIntersect_Op) {
130        Rect r(left, top, right, bottom);
131        transform->mapRect(r);
132        return clipTransformed(r, op);
133    }
134
135    /**
136     * Modifies the current clip with the new clip rectangle and
137     * the specified operation. The specified rectangle is considered
138     * already transformed.
139     */
140    bool clipTransformed(const Rect& r, SkRegion::Op op = SkRegion::kIntersect_Op) {
141        bool clipped = false;
142
143        // NOTE: The unimplemented operations require support for regions
144        // Supporting regions would require using a stencil buffer instead
145        // of the scissor. The stencil buffer itself is not too expensive
146        // (memory cost excluded) but on fillrate limited devices, managing
147        // the stencil might have a negative impact on the framerate.
148        switch (op) {
149            case SkRegion::kDifference_Op:
150                break;
151            case SkRegion::kIntersect_Op:
152                clipped = clipRect->intersect(r);
153                if (!clipped) {
154                    clipRect->setEmpty();
155                    clipped = true;
156                }
157                break;
158            case SkRegion::kUnion_Op:
159                clipped = clipRect->unionWith(r);
160                break;
161            case SkRegion::kXOR_Op:
162                break;
163            case SkRegion::kReverseDifference_Op:
164                break;
165            case SkRegion::kReplace_Op:
166                clipRect->set(r);
167                clipped = true;
168                break;
169        }
170
171        if (clipped) {
172            flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
173        }
174
175        return clipped;
176    }
177
178    /**
179     * Sets the current clip.
180     */
181    void setClip(float left, float top, float right, float bottom) {
182        clipRect->set(left, top, right, bottom);
183        flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
184    }
185
186    const Rect& getLocalClip() {
187        if (flags & Snapshot::kFlagDirtyLocalClip) {
188            mat4 inverse;
189            inverse.loadInverse(*transform);
190
191            mLocalClip.set(*clipRect);
192            inverse.mapRect(mLocalClip);
193
194            flags &= ~Snapshot::kFlagDirtyLocalClip;
195        }
196        return mLocalClip;
197    }
198
199    void resetTransform(float x, float y, float z) {
200        transform = &mTransformRoot;
201        transform->loadTranslate(x, y, z);
202    }
203
204    void resetClip(float left, float top, float right, float bottom) {
205        clipRect = &mClipRectRoot;
206        clipRect->set(left, top, right, bottom);
207        flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
208    }
209
210    bool isIgnored() const {
211        return invisible || empty;
212    }
213
214    /**
215     * Dirty flags.
216     */
217    int flags;
218
219    /**
220     * Previous snapshot.
221     */
222    sp<Snapshot> previous;
223
224    /**
225     * Only set when the flag kFlagIsLayer is set.
226     */
227    Layer* layer;
228
229    /**
230     * Only set when the flag kFlagIsFboLayer is set.
231     */
232    GLuint fbo;
233
234    /**
235     * Indicates that this snapshot is invisible and nothing should be drawn
236     * inside it. This flag is set only when the layer clips drawing to its
237     * bounds and is passed to subsequent snapshots.
238     */
239    bool invisible;
240
241    /**
242     * If set to true, the layer will not be composited. This is similar to
243     * invisible but this flag is not passed to subsequent snapshots.
244     */
245    bool empty;
246
247    /**
248     * Current viewport.
249     */
250    Rect viewport;
251
252    /**
253     * Height of the framebuffer the snapshot is rendering into.
254     */
255    int height;
256
257    /**
258     * Contains the previous ortho matrix.
259     */
260    mat4 orthoMatrix;
261
262    /**
263     * Local transformation. Holds the current translation, scale and
264     * rotation values.
265     */
266    mat4* transform;
267
268    /**
269     * Current clip region. The clip is stored in canvas-space coordinates,
270     * (screen-space coordinates in the regular case.)
271     */
272    Rect* clipRect;
273
274    /**
275     * The ancestor layer's dirty region.
276     */
277    Region* region;
278
279private:
280    mat4 mTransformRoot;
281    Rect mClipRectRoot;
282    Rect mLocalClip;
283
284}; // class Snapshot
285
286}; // namespace uirenderer
287}; // namespace android
288
289#endif // ANDROID_HWUI_SNAPSHOT_H
290