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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 import android.annotation.NonNull;
     20 import android.annotation.Nullable;
     21 
     22 import 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  */
     30 public 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     45      * is called - otherwise may be out of date with java setters/properties.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