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