Snapshot.h revision d2a1ff003b9b1212c9ab4b5f679b5b097720a359 
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            flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
156        }
157
158        return clipped;
159    }
160
161    /**
162     * Sets the current clip.
163     */
164    void setClip(float left, float top, float right, float bottom) {
165        clipRect->set(left, top, right, bottom);
166        flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
167    }
168
169    const Rect& getLocalClip() {
170        if (flags & Snapshot::kFlagDirtyLocalClip) {
171            mat4 inverse;
172            inverse.loadInverse(*transform);
173
174            mLocalClip.set(*clipRect);
175            inverse.mapRect(mLocalClip);
176
177            flags &= ~Snapshot::kFlagDirtyLocalClip;
178        }
179        return mLocalClip;
180    }
181
182    void resetTransform(float x, float y, float z) {
183        transform = &mTransformRoot;
184        transform->loadTranslate(x, y, z);
185    }
186
187    void resetClip(float left, float top, float right, float bottom) {
188        clipRect = &mClipRectRoot;
189        clipRect->set(left, top, right, bottom);
190        flags |= Snapshot::kFlagClipSet | Snapshot::kFlagDirtyLocalClip;
191    }
192
193    /**
194     * Dirty flags.
195     */
196    int flags;
197
198    /**
199     * Previous snapshot.
200     */
201    sp<Snapshot> previous;
202
203    /**
204     * Only set when the flag kFlagIsLayer is set.
205     */
206    Layer* layer;
207
208    /**
209     * Only set when the flag kFlagIsFboLayer is set.
210     */
211    GLuint fbo;
212
213    /**
214     * Indicates that this snapshot is invisible and nothing should be drawn
215     * inside it.
216     */
217    bool invisible;
218
219    /**
220     * Current viewport.
221     */
222    Rect viewport;
223
224    /**
225     * Height of the framebuffer the snapshot is rendering into.
226     */
227    int height;
228
229    /**
230     * Contains the previous ortho matrix.
231     */
232    mat4 orthoMatrix;
233
234    /**
235     * Local transformation. Holds the current translation, scale and
236     * rotation values.
237     */
238    mat4* transform;
239
240    /**
241     * Current clip region. The clip is stored in canvas-space coordinates,
242     * (screen-space coordinates in the regular case.)
243     */
244    Rect* clipRect;
245
246private:
247    mat4 mTransformRoot;
248    Rect mClipRectRoot;
249    Rect mLocalClip;
250
251}; // class Snapshot
252
253}; // namespace uirenderer
254}; // namespace android
255
256#endif // ANDROID_UI_SNAPSHOT_H
257