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
19import android.annotation.NonNull;
20import android.annotation.Nullable;
21
22import libcore.util.NativeAllocationRegistry;
23
24/**
25 * Shader is the based class for objects that return horizontal spans of colors
26 * during drawing. A subclass of Shader is installed in a Paint calling
27 * paint.setShader(shader). After that any object (other than a bitmap) that is
28 * drawn with that paint will get its color(s) from the shader.
29 */
30public class Shader {
31
32    private static class NoImagePreloadHolder {
33        public static final NativeAllocationRegistry sRegistry = new NativeAllocationRegistry(
34                Shader.class.getClassLoader(), nativeGetFinalizer(), 50);
35    }
36
37    /**
38     * @deprecated Use subclass constructors directly instead.
39     */
40    @Deprecated
41    public Shader() {}
42
43    /**
44     * Current native shader instance. Created and updated lazily when {@link #getNativeInstance()}
45     * is called - otherwise may be out of date with java setters/properties.
46     */
47    private long mNativeInstance;
48    // Runnable to do immediate destruction
49    private Runnable mCleaner;
50
51    /**
52     * Current matrix - always set to null if local matrix is identity.
53     */
54    private Matrix mLocalMatrix;
55
56    public enum TileMode {
57        /**
58         * replicate the edge color if the shader draws outside of its
59         * original bounds
60         */
61        CLAMP   (0),
62        /**
63         * repeat the shader's image horizontally and vertically
64         */
65        REPEAT  (1),
66        /**
67         * repeat the shader's image horizontally and vertically, alternating
68         * mirror images so that adjacent images always seam
69         */
70        MIRROR  (2);
71
72        TileMode(int nativeInt) {
73            this.nativeInt = nativeInt;
74        }
75        final int nativeInt;
76    }
77
78    /**
79     * Return true if the shader has a non-identity local matrix.
80     * @param localM Set to the local matrix of the shader, if the shader's matrix is non-null.
81     * @return true if the shader has a non-identity local matrix
82     */
83    public boolean getLocalMatrix(@NonNull Matrix localM) {
84        if (mLocalMatrix != null) {
85            localM.set(mLocalMatrix);
86            return true; // presence of mLocalMatrix means it's not identity
87        }
88        return false;
89    }
90
91    /**
92     * Set the shader's local matrix. Passing null will reset the shader's
93     * matrix to identity. If the matrix has scale value as 0, the drawing
94     * result is undefined.
95     *
96     * @param localM The shader's new local matrix, or null to specify identity
97     */
98    public void setLocalMatrix(@Nullable Matrix localM) {
99        if (localM == null || localM.isIdentity()) {
100            if (mLocalMatrix != null) {
101                mLocalMatrix = null;
102                discardNativeInstance();
103            }
104        } else {
105            if (mLocalMatrix == null) {
106                mLocalMatrix = new Matrix(localM);
107                discardNativeInstance();
108            } else if (!mLocalMatrix.equals(localM)) {
109                mLocalMatrix.set(localM);
110                discardNativeInstance();
111            }
112        }
113    }
114
115    long createNativeInstance(long nativeMatrix) {
116        return 0;
117    }
118
119    /** @hide */
120    protected final void discardNativeInstance() {
121        if (mNativeInstance != 0) {
122            mCleaner.run();
123            mCleaner = null;
124            mNativeInstance = 0;
125        }
126    }
127
128    /**
129     * Callback for subclasses to call {@link #discardNativeInstance()} if the most recently
130     * constructed native instance is no longer valid.
131     * @hide
132     */
133    protected void verifyNativeInstance() {
134    }
135
136    /**
137     * @hide
138     */
139    protected Shader copy() {
140        final Shader copy = new Shader();
141        copyLocalMatrix(copy);
142        return copy;
143    }
144
145    /**
146     * @hide
147     */
148    protected void copyLocalMatrix(Shader dest) {
149        dest.mLocalMatrix.set(mLocalMatrix);
150    }
151
152    /**
153     * @hide
154     */
155    public final long getNativeInstance() {
156        // verify mNativeInstance is valid
157        verifyNativeInstance();
158
159        if (mNativeInstance == 0) {
160            mNativeInstance = createNativeInstance(mLocalMatrix == null
161                    ? 0 : mLocalMatrix.native_instance);
162            mCleaner = NoImagePreloadHolder.sRegistry.registerNativeAllocation(
163                    this, mNativeInstance);
164        }
165        return mNativeInstance;
166    }
167
168    private static native long nativeGetFinalizer();
169
170}
171
172