Shape.java revision 6beeb75723cec42603b47664bce794a2b97d7bac 
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
17package android.graphics.drawable.shapes;
18
19import android.annotation.NonNull;
20import android.graphics.Canvas;
21import android.graphics.Outline;
22import android.graphics.Paint;
23
24/**
25 * Defines a generic graphical "shape."
26 * Any Shape can be drawn to a Canvas with its own draw() method,
27 * but more graphical control is available if you instead pass
28 * it to a {@link android.graphics.drawable.ShapeDrawable}.
29 */
30public abstract class Shape implements Cloneable {
31    private float mWidth;
32    private float mHeight;
33
34    /**
35     * Returns the width of the Shape.
36     */
37    public final float getWidth() {
38        return mWidth;
39    }
40
41    /**
42     * Returns the height of the Shape.
43     */
44    public final float getHeight() {
45        return mHeight;
46    }
47
48    /**
49     * Draw this shape into the provided Canvas, with the provided Paint.
50     * Before calling this, you must call {@link #resize(float,float)}.
51     *
52     * @param canvas the Canvas within which this shape should be drawn
53     * @param paint  the Paint object that defines this shape's characteristics
54     */
55    public abstract void draw(Canvas canvas, Paint paint);
56
57    /**
58     * Resizes the dimensions of this shape.
59     * Must be called before {@link #draw(Canvas,Paint)}.
60     *
61     * @param width the width of the shape (in pixels)
62     * @param height the height of the shape (in pixels)
63     */
64    public final void resize(float width, float height) {
65        if (width < 0) {
66            width = 0;
67        }
68        if (height < 0) {
69            height =0;
70        }
71        if (mWidth != width || mHeight != height) {
72            mWidth = width;
73            mHeight = height;
74            onResize(width, height);
75        }
76    }
77
78    /**
79     * Checks whether the Shape is opaque.
80     * Default impl returns true. Override if your subclass can be opaque.
81     *
82     * @return true if any part of the drawable is <em>not</em> opaque.
83     */
84    public boolean hasAlpha() {
85        return true;
86    }
87
88    /**
89     * Callback method called when {@link #resize(float,float)} is executed.
90     *
91     * @param width the new width of the Shape
92     * @param height the new height of the Shape
93     */
94    protected void onResize(float width, float height) {}
95
96    /**
97     * Compute the Outline of the shape and return it in the supplied Outline
98     * parameter. The default implementation does nothing and {@code outline} is not changed.
99     *
100     * @param outline The Outline to be populated with the result. Should not be null.
101     */
102    public void getOutline(@NonNull Outline outline) {}
103
104    @Override
105    public Shape clone() throws CloneNotSupportedException {
106        return (Shape) super.clone();
107    }
108
109}
110