ColorDrawable.java revision b798689749c64baba81f02e10cf2157c747d6b46 
1/*
2 * Copyright (C) 2008 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;
18
19import android.graphics.*;
20import android.content.res.Resources;
21import android.content.res.TypedArray;
22import android.util.AttributeSet;
23import org.xmlpull.v1.XmlPullParser;
24import org.xmlpull.v1.XmlPullParserException;
25
26import java.io.IOException;
27
28/**
29 * A specialized Drawable that fills the Canvas with a specified color,
30 * with respect to the clip region. Note that a ColorDrawable ignores the ColorFilter.
31 * It also ignores the Bounds, meaning it will draw everywhere in the current clip,
32 * even if setBounds(...) was called with a smaller area.
33 *
34 * <p>It can be defined in an XML file with the <code>&lt;color></code> element.</p>
35 *
36 * @attr ref android.R.styleable#ColorDrawable_color
37 */
38public class ColorDrawable extends Drawable {
39    private ColorState mState;
40
41    /**
42     * Creates a new black ColorDrawable.
43     */
44    public ColorDrawable() {
45        this(null);
46    }
47
48    /**
49     * Creates a new ColorDrawable with the specified color.
50     *
51     * @param color The color to draw.
52     */
53    public ColorDrawable(int color) {
54        this(null);
55        mState.mBaseColor = mState.mUseColor = color;
56    }
57
58    private ColorDrawable(ColorState state) {
59        mState = new ColorState(state);
60    }
61
62    @Override
63    public int getChangingConfigurations() {
64        return super.getChangingConfigurations() | mState.mChangingConfigurations;
65    }
66
67    @Override
68    public void draw(Canvas canvas) {
69        canvas.drawColor(mState.mUseColor);
70    }
71
72    /**
73     * Returns the alpha value of this drawable's color.
74     *
75     * @return A value between 0 and 255.
76     */
77    public int getAlpha() {
78        return mState.mUseColor >>> 24;
79    }
80
81    /**
82     * Sets the color's alpha value.
83     *
84     * @param alpha The alpha value to set, between 0 and 255.
85     */
86    public void setAlpha(int alpha) {
87        alpha += alpha >> 7;   // make it 0..256
88        int baseAlpha = mState.mBaseColor >>> 24;
89        int useAlpha = baseAlpha * alpha >> 8;
90        mState.mUseColor = (mState.mBaseColor << 8 >>> 8) | (useAlpha << 24);
91    }
92
93    /**
94     * Setting a color filter on a ColorDrawable has no effect.
95     *
96     * @param colorFilter Ignore.
97     */
98    public void setColorFilter(ColorFilter colorFilter) {
99    }
100
101    public int getOpacity() {
102        switch (mState.mUseColor >>> 24) {
103            case 255:
104                return PixelFormat.OPAQUE;
105            case 0:
106                return PixelFormat.TRANSPARENT;
107        }
108        return PixelFormat.TRANSLUCENT;
109    }
110
111    @Override
112    public void inflate(Resources r, XmlPullParser parser, AttributeSet attrs)
113            throws XmlPullParserException, IOException {
114        super.inflate(r, parser, attrs);
115
116        TypedArray a = r.obtainAttributes(attrs, com.android.internal.R.styleable.ColorDrawable);
117
118        int color = mState.mBaseColor;
119        color = a.getColor(com.android.internal.R.styleable.ColorDrawable_color, color);
120        mState.mBaseColor = mState.mUseColor = color;
121
122        a.recycle();
123    }
124
125    @Override
126    public ConstantState getConstantState() {
127        mState.mChangingConfigurations = super.getChangingConfigurations();
128        return mState;
129    }
130
131    final static class ColorState extends ConstantState {
132        int mBaseColor; // initial color. never changes
133        int mUseColor;  // basecolor modulated by setAlpha()
134        int mChangingConfigurations;
135
136        ColorState(ColorState state) {
137            if (state != null) {
138                mBaseColor = state.mBaseColor;
139                mUseColor = state.mUseColor;
140            }
141        }
142
143        @Override
144        public Drawable newDrawable() {
145            return new ColorDrawable(this);
146        }
147
148        @Override
149        public int getChangingConfigurations() {
150            return mChangingConfigurations;
151        }
152    }
153}
154