ColorDrawable.java revision f013e1afd1e68af5e3b868c26a653bbfb39538f8 
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 ColorDrawable is a specialized drawable that fills the Canvas with a specified color,
30 * and 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 */
34public class ColorDrawable extends Drawable {
35    private ColorState mState;
36
37    /**
38     * Creates a new black ColorDrawable.
39     */
40    public ColorDrawable() {
41        this(null);
42    }
43
44    /**
45     * Creates a new ColorDrawable with the specified color.
46     *
47     * @param color The color to draw.
48     */
49    public ColorDrawable(int color) {
50        this(null);
51        mState.mBaseColor = mState.mUseColor = color;
52    }
53
54    private ColorDrawable(ColorState state) {
55        mState = new ColorState(state);
56    }
57
58    @Override
59    public int getChangingConfigurations() {
60        return super.getChangingConfigurations() | mState.mChangingConfigurations;
61    }
62
63    @Override
64    public void draw(Canvas canvas) {
65        canvas.drawColor(mState.mUseColor);
66    }
67
68    /**
69     * Returns the alpha value of this drawable's color.
70     *
71     * @return A value between 0 and 255.
72     */
73    public int getAlpha() {
74        return mState.mUseColor >>> 24;
75    }
76
77    /**
78     * Sets the color's alpha value.
79     *
80     * @param alpha The alpha value to set, between 0 and 255.
81     */
82    public void setAlpha(int alpha) {
83        alpha += alpha >> 7;   // make it 0..256
84        int baseAlpha = mState.mBaseColor >>> 24;
85        int useAlpha = baseAlpha * alpha >> 8;
86        mState.mUseColor = (mState.mBaseColor << 8 >>> 8) | (useAlpha << 24);
87    }
88
89    /**
90     * Setting a color filter on a ColorDrawable has no effect.
91     *
92     * @param colorFilter Ignore.
93     */
94    public void setColorFilter(ColorFilter colorFilter) {
95    }
96
97    public int getOpacity() {
98        switch (mState.mUseColor >>> 24) {
99            case 255:
100                return PixelFormat.OPAQUE;
101            case 0:
102                return PixelFormat.TRANSPARENT;
103        }
104        return PixelFormat.TRANSLUCENT;
105    }
106
107    @Override
108    public void inflate(Resources r, XmlPullParser parser, AttributeSet attrs)
109            throws XmlPullParserException, IOException {
110        super.inflate(r, parser, attrs);
111
112        TypedArray a = r.obtainAttributes(attrs, com.android.internal.R.styleable.ColorDrawable);
113
114        int color = mState.mBaseColor;
115        color = a.getColor(com.android.internal.R.styleable.ColorDrawable_color, color);
116        mState.mBaseColor = mState.mUseColor = color;
117
118        a.recycle();
119    }
120
121    @Override
122    public ConstantState getConstantState() {
123        mState.mChangingConfigurations = super.getChangingConfigurations();
124        return mState;
125    }
126
127    final static class ColorState extends ConstantState {
128        int mBaseColor; // initial color. never changes
129        int mUseColor;  // basecolor modulated by setAlpha()
130        int mChangingConfigurations;
131
132        ColorState(ColorState state) {
133            if (state != null) {
134                mBaseColor = state.mBaseColor;
135                mUseColor = state.mUseColor;
136            }
137        }
138
139        @Override
140        public Drawable newDrawable() {
141            return new ColorDrawable(this);
142        }
143
144        @Override
145        public int getChangingConfigurations() {
146            return mChangingConfigurations;
147        }
148    }
149}
150