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