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      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 
     17 package 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  */
     25 public 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         }
     94     }
     95 
     96     /**
     97      * @hide
     98      */
     99     protected Shader copy() {
    100         final Shader copy = new Shader();
    101         copyLocalMatrix(copy);
    102         return copy;
    103     }
    104 
    105     /**
    106      * @hide
    107      */
    108     protected void copyLocalMatrix(Shader dest) {
    109         if (mLocalMatrix != null) {
    110             final Matrix lm = new Matrix();
    111             getLocalMatrix(lm);
    112             dest.setLocalMatrix(lm);
    113         } else {
    114             dest.setLocalMatrix(null);
    115         }
    116     }
    117 
    118     /* package */ long getNativeInstance() {
    119         return native_instance;
    120     }
    121 
    122     private static native void nativeDestructor(long native_shader);
    123     private static native void nativeSetLocalMatrix(long native_shader, long matrix_instance);
    124 }
    125