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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.drawable.shapes;
     18 
     19 import android.annotation.NonNull;
     20 import android.graphics.Canvas;
     21 import android.graphics.Outline;
     22 import android.graphics.Paint;
     23 
     24 /**
     25  * Defines a generic graphical "shape."
     26  * <p>
     27  * Any Shape can be drawn to a Canvas with its own draw() method, but more
     28  * graphical control is available if you instead pass it to a
     29  * {@link android.graphics.drawable.ShapeDrawable}.
     30  * <p>
     31  * Custom Shape classes must implement {@link #clone()} and return an instance
     32  * of the custom Shape class.
     33  */
     34 public abstract class Shape implements Cloneable {
     35     private float mWidth;
     36     private float mHeight;
     37 
     38     /**
     39      * Returns the width of the Shape.
     40      */
     41     public final float getWidth() {
     42         return mWidth;
     43     }
     44 
     45     /**
     46      * Returns the height of the Shape.
     47      */
     48     public final float getHeight() {
     49         return mHeight;
     50     }
     51 
     52     /**
     53      * Draws this shape into the provided Canvas, with the provided Paint.
     54      * <p>
     55      * Before calling this, you must call {@link #resize(float,float)}.
     56      *
     57      * @param canvas the Canvas within which this shape should be drawn
     58      * @param paint  the Paint object that defines this shape's characteristics
     59      */
     60     public abstract void draw(Canvas canvas, Paint paint);
     61 
     62     /**
     63      * Resizes the dimensions of this shape.
     64      * <p>
     65      * Must be called before {@link #draw(Canvas,Paint)}.
     66      *
     67      * @param width the width of the shape (in pixels)
     68      * @param height the height of the shape (in pixels)
     69      */
     70     public final void resize(float width, float height) {
     71         if (width < 0) {
     72             width = 0;
     73         }
     74         if (height < 0) {
     75             height =0;
     76         }
     77         if (mWidth != width || mHeight != height) {
     78             mWidth = width;
     79             mHeight = height;
     80             onResize(width, height);
     81         }
     82     }
     83 
     84     /**
     85      * Checks whether the Shape is opaque.
     86      * <p>
     87      * Default impl returns {@code true}. Override if your subclass can be
     88      * opaque.
     89      *
     90      * @return true if any part of the drawable is <em>not</em> opaque.
     91      */
     92     public boolean hasAlpha() {
     93         return true;
     94     }
     95 
     96     /**
     97      * Callback method called when {@link #resize(float,float)} is executed.
     98      *
     99      * @param width the new width of the Shape
    100      * @param height the new height of the Shape
    101      */
    102     protected void onResize(float width, float height) {}
    103 
    104     /**
    105      * Computes the Outline of the shape and return it in the supplied Outline
    106      * parameter. The default implementation does nothing and {@code outline}
    107      * is not changed.
    108      *
    109      * @param outline the Outline to be populated with the result. Must be
    110      *                non-{@code null}.
    111      */
    112     public void getOutline(@NonNull Outline outline) {}
    113 
    114     @Override
    115     public Shape clone() throws CloneNotSupportedException {
    116         return (Shape) super.clone();
    117     }
    118 }
    119