Shader.java revision ffa84e008c712ceffa09d6b89a49882c88b3cca5 
1/*
2 * Copyright (C) 2006 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
17package android.graphics;
18
19/**
20 * Shader is the based class for objects that return horizontal spans of colors
21 * during drawing. A subclass of Shader is installed in a Paint calling
22 * paint.setShader(shader). After that any object (other than a bitmap) that is
23 * drawn with that paint will get its color(s) from the shader.
24 */
25public class Shader {
26    /**
27     * This is set by subclasses, but don't make it public.
28     */
29    private long native_instance;
30
31    /**
32     * Initialization step that should be called by subclasses in their
33     * constructors. Calling again may result in memory leaks.
34     * @hide
35     */
36    protected void init(long ni) {
37        native_instance = ni;
38    }
39
40    private Matrix mLocalMatrix;
41
42    public enum TileMode {
43        /**
44         * replicate the edge color if the shader draws outside of its
45         * original bounds
46         */
47        CLAMP   (0),
48        /**
49         * repeat the shader's image horizontally and vertically
50         */
51        REPEAT  (1),
52        /**
53         * repeat the shader's image horizontally and vertically, alternating
54         * mirror images so that adjacent images always seam
55         */
56        MIRROR  (2);
57
58        TileMode(int nativeInt) {
59            this.nativeInt = nativeInt;
60        }
61        final int nativeInt;
62    }
63
64    /**
65     * Return true if the shader has a non-identity local matrix.
66     * @param localM If not null, it is set to the shader's local matrix.
67     * @return true if the shader has a non-identity local matrix
68     */
69    public boolean getLocalMatrix(Matrix localM) {
70        if (mLocalMatrix != null) {
71            localM.set(mLocalMatrix);
72            return !mLocalMatrix.isIdentity();
73        }
74        return false;
75    }
76
77    /**
78     * Set the shader's local matrix. Passing null will reset the shader's
79     * matrix to identity.
80     *
81     * @param localM The shader's new local matrix, or null to specify identity
82     */
83    public void setLocalMatrix(Matrix localM) {
84        mLocalMatrix = localM;
85        nativeSetLocalMatrix(native_instance, localM == null ? 0 : localM.native_instance);
86    }
87
88    protected void finalize() throws Throwable {
89        try {
90            super.finalize();
91        } finally {
92            nativeDestructor(native_instance);
93            native_instance = 0;  // Other finalizers can still call us.
94        }
95    }
96
97    /**
98     * @hide
99     */
100    protected Shader copy() {
101        final Shader copy = new Shader();
102        copyLocalMatrix(copy);
103        return copy;
104    }
105
106    /**
107     * @hide
108     */
109    protected void copyLocalMatrix(Shader dest) {
110        if (mLocalMatrix != null) {
111            final Matrix lm = new Matrix();
112            getLocalMatrix(lm);
113            dest.setLocalMatrix(lm);
114        } else {
115            dest.setLocalMatrix(null);
116        }
117    }
118
119    /* package */ long getNativeInstance() {
120        return native_instance;
121    }
122
123    private static native void nativeDestructor(long native_shader);
124    private static native void nativeSetLocalMatrix(long native_shader, long matrix_instance);
125}
126