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 * <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 */
34public 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