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      */
getWidth()41     public final float getWidth() {
42         return mWidth;
43     }
44 
45     /**
46      * Returns the height of the Shape.
47      */
getHeight()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      */
draw(Canvas canvas, Paint paint)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      */
resize(float width, float height)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      */
hasAlpha()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      */
onResize(float width, float height)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      */
getOutline(@onNull Outline outline)112     public void getOutline(@NonNull Outline outline) {}
113 
114     @Override
clone()115     public Shape clone() throws CloneNotSupportedException {
116         return (Shape) super.clone();
117     }
118 }
119