Stencil.h revision 5a4690bf26932c0d6940e4af8516d920e09ae81a 
1/*
2 * Copyright (C) 2012 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_STENCIL_H
18#define ANDROID_HWUI_STENCIL_H
19
20#include <GLES2/gl2.h>
21
22#include <cutils/compiler.h>
23
24namespace android {
25namespace uirenderer {
26
27///////////////////////////////////////////////////////////////////////////////
28// Stencil buffer management
29///////////////////////////////////////////////////////////////////////////////
30
31class ANDROID_API Stencil {
32public:
33    Stencil();
34
35    /**
36     * Returns the desired size for the stencil buffer. If the returned value
37     * is 0, then no stencil buffer is required.
38     */
39    ANDROID_API static uint8_t getStencilSize();
40
41    static GLenum getLayerStencilFormat();
42
43    /**
44     * Clears the stencil buffer.
45     */
46    void clear();
47
48    /**
49     * Enables stencil test. When the stencil test is enabled the stencil buffer is not written
50     * into. An increment threshold of zero causes the stencil to use a constant reference value
51     * and GL_EQUAL for the test. A non-zero increment threshold causes the stencil to use that
52     * value as the reference value and GL_EQUAL for the test.
53     */
54    void enableTest(int incrementThreshold);
55
56    /**
57     * Enables stencil write. When stencil write is enabled, the stencil
58     * test always succeeds and the value 0x1 is written in the stencil
59     * buffer for each fragment. An increment threshold of zero causes the stencil to use a constant
60     * reference value and GL_EQUAL for the test. A non-zero increment threshold causes the stencil
61     * to use that value as the reference value and GL_EQUAL for the test.
62     */
63    void enableWrite(int incrementThreshold);
64
65    /**
66     * The test passes only when equal to the specified value.
67     */
68    void enableDebugTest(GLint value, bool greater = false);
69
70    /**
71     * Used for debugging. The stencil test always passes and increments.
72     */
73    void enableDebugWrite();
74
75    /**
76     * Disables stencil test and write.
77     */
78    void disable();
79
80    /**
81     * Indicates whether either test or write is enabled.
82     */
83    bool isEnabled() {
84        return mState != kDisabled;
85    }
86
87    /**
88     * Indicates whether testing only is enabled.
89     */
90    bool isTestEnabled() {
91        return mState == kTest;
92    }
93
94    bool isWriteEnabled() {
95        return mState == kWrite;
96    }
97
98    void dump();
99
100private:
101    void enable();
102
103    enum StencilState {
104        kDisabled,
105        kTest,
106        kWrite
107    };
108
109    StencilState mState;
110
111}; // class Stencil
112
113}; // namespace uirenderer
114}; // namespace android
115
116#endif // ANDROID_HWUI_STENCIL_H
117