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      1 /*
      2  * Copyright (C) 2007 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 /** A subclass of shader that returns the composition of two other shaders, combined by
     20     an {@link android.graphics.Xfermode} subclass.
     21 */
     22 public class ComposeShader extends Shader {
     23 
     24     private static final int TYPE_XFERMODE = 1;
     25     private static final int TYPE_PORTERDUFFMODE = 2;
     26 
     27     /**
     28      * Type of the ComposeShader: can be either TYPE_XFERMODE or TYPE_PORTERDUFFMODE
     29      */
     30     private int mType;
     31 
     32     private Xfermode mXferMode;
     33     private PorterDuff.Mode mPorterDuffMode;
     34 
     35     /**
     36      * Hold onto the shaders to avoid GC.
     37      */
     38     @SuppressWarnings({"UnusedDeclaration"})
     39     private final Shader mShaderA;
     40     @SuppressWarnings({"UnusedDeclaration"})
     41     private final Shader mShaderB;
     42 
     43     /** Create a new compose shader, given shaders A, B, and a combining mode.
     44         When the mode is applied, it will be given the result from shader A as its
     45         "dst", and the result from shader B as its "src".
     46         @param shaderA  The colors from this shader are seen as the "dst" by the mode
     47         @param shaderB  The colors from this shader are seen as the "src" by the mode
     48         @param mode     The mode that combines the colors from the two shaders. If mode
     49                         is null, then SRC_OVER is assumed.
     50     */
     51     public ComposeShader(Shader shaderA, Shader shaderB, Xfermode mode) {
     52         mType = TYPE_XFERMODE;
     53         mShaderA = shaderA;
     54         mShaderB = shaderB;
     55         mXferMode = mode;
     56         init(nativeCreate1(shaderA.getNativeInstance(), shaderB.getNativeInstance(),
     57                 (mode != null) ? mode.native_instance : 0));
     58     }
     59 
     60     /** Create a new compose shader, given shaders A, B, and a combining PorterDuff mode.
     61         When the mode is applied, it will be given the result from shader A as its
     62         "dst", and the result from shader B as its "src".
     63         @param shaderA  The colors from this shader are seen as the "dst" by the mode
     64         @param shaderB  The colors from this shader are seen as the "src" by the mode
     65         @param mode     The PorterDuff mode that combines the colors from the two shaders.
     66     */
     67     public ComposeShader(Shader shaderA, Shader shaderB, PorterDuff.Mode mode) {
     68         mType = TYPE_PORTERDUFFMODE;
     69         mShaderA = shaderA;
     70         mShaderB = shaderB;
     71         mPorterDuffMode = mode;
     72         init(nativeCreate2(shaderA.getNativeInstance(), shaderB.getNativeInstance(),
     73                 mode.nativeInt));
     74     }
     75 
     76     /**
     77      * @hide
     78      */
     79     @Override
     80     protected Shader copy() {
     81         final ComposeShader copy;
     82         switch (mType) {
     83             case TYPE_XFERMODE:
     84                 copy = new ComposeShader(mShaderA.copy(), mShaderB.copy(), mXferMode);
     85                 break;
     86             case TYPE_PORTERDUFFMODE:
     87                 copy = new ComposeShader(mShaderA.copy(), mShaderB.copy(), mPorterDuffMode);
     88                 break;
     89             default:
     90                 throw new IllegalArgumentException(
     91                         "ComposeShader should be created with either Xfermode or PorterDuffMode");
     92         }
     93         copyLocalMatrix(copy);
     94         return copy;
     95     }
     96 
     97     private static native long nativeCreate1(long native_shaderA, long native_shaderB,
     98             long native_mode);
     99     private static native long nativeCreate2(long native_shaderA, long native_shaderB,
    100             int porterDuffMode);
    101 }
    102