DisplayMetrics.java revision e5fb328825995aa33b5b7ecf8b5bee2b17f81715 
1/*
2 * Copyright (C) 2006 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.util;
18
19import android.content.res.CompatibilityInfo;
20import android.content.res.Configuration;
21import android.os.*;
22
23
24/**
25 * A structure describing general information about a display, such as its
26 * size, density, and font scaling.
27 */
28public class DisplayMetrics {
29    /**
30     * The reference density used throughout the system.
31     *
32     * @hide Pending API council approval
33     */
34    public static final int DEFAULT_DENSITY = 160;
35
36    /**
37     * The device's density.
38     * @hide
39     */
40    public static final int DEVICE_DENSITY = SystemProperties.getInt("ro.sf.lcd_density",
41            DEFAULT_DENSITY);
42
43    /**
44     * The absolute width of the display in pixels.
45     */
46    public int widthPixels;
47    /**
48     * The absolute height of the display in pixels.
49     */
50    public int heightPixels;
51    /**
52     * The logical density of the display.  This is a scaling factor for the
53     * Density Independent Pixel unit, where one DIP is one pixel on an
54     * approximately 160 dpi screen (for example a 240x320, 1.5"x2" screen),
55     * providing the baseline of the system's display. Thus on a 160dpi screen
56     * this density value will be 1; on a 106 dpi screen it would be .75; etc.
57     *
58     * <p>This value does not exactly follow the real screen size (as given by
59     * {@link #xdpi} and {@link #ydpi}, but rather is used to scale the size of
60     * the overall UI in steps based on gross changes in the display dpi.  For
61     * example, a 240x320 screen will have a density of 1 even if its width is
62     * 1.8", 1.3", etc. However, if the screen resolution is increased to
63     * 320x480 but the screen size remained 1.5"x2" then the density would be
64     * increased (probably to 1.5).
65     *
66     * @see #DEFAULT_DENSITY
67     */
68    public float density;
69    /**
70     * A scaling factor for fonts displayed on the display.  This is the same
71     * as {@link #density}, except that it may be adjusted in smaller
72     * increments at runtime based on a user preference for the font size.
73     */
74    public float scaledDensity;
75    /**
76     * The exact physical pixels per inch of the screen in the X dimension.
77     */
78    public float xdpi;
79    /**
80     * The exact physical pixels per inch of the screen in the Y dimension.
81     */
82    public float ydpi;
83
84    public DisplayMetrics() {
85    }
86
87    public void setTo(DisplayMetrics o) {
88        widthPixels = o.widthPixels;
89        heightPixels = o.heightPixels;
90        density = o.density;
91        scaledDensity = o.scaledDensity;
92        xdpi = o.xdpi;
93        ydpi = o.ydpi;
94    }
95
96    public void setToDefaults() {
97        widthPixels = 0;
98        heightPixels = 0;
99        density = DEVICE_DENSITY / (float) DEFAULT_DENSITY;
100        scaledDensity = density;
101        xdpi = DEVICE_DENSITY;
102        ydpi = DEVICE_DENSITY;
103    }
104
105    /**
106     * Update the display metrics based on the compatibility info and orientation
107     * {@hide}
108     */
109    public void updateMetrics(CompatibilityInfo compatibilityInfo, int orientation) {
110        if (compatibilityInfo.mScalingRequired) {
111            float invertedRatio = compatibilityInfo.mApplicationInvertedScale;
112            density *= invertedRatio;
113            scaledDensity *= invertedRatio;
114            xdpi *= invertedRatio;
115            ydpi *= invertedRatio;
116            widthPixels *= invertedRatio;
117            heightPixels *= invertedRatio;
118        }
119        if (!compatibilityInfo.mConfiguredExpandable) {
120            // Note: this assume that configuration is updated before calling
121            // updateMetrics method.
122            int defaultWidth;
123            int defaultHeight;
124            switch (orientation) {
125                case Configuration.ORIENTATION_LANDSCAPE: {
126                    defaultWidth = (int)(CompatibilityInfo.DEFAULT_PORTRAIT_HEIGHT * density);
127                    defaultHeight = (int)(CompatibilityInfo.DEFAULT_PORTRAIT_WIDTH * density);
128                    break;
129                }
130                case Configuration.ORIENTATION_PORTRAIT:
131                case Configuration.ORIENTATION_SQUARE:
132                default: {
133                    defaultWidth = (int)(CompatibilityInfo.DEFAULT_PORTRAIT_WIDTH * density);
134                    defaultHeight = (int)(CompatibilityInfo.DEFAULT_PORTRAIT_HEIGHT * density);
135                    break;
136                }
137                case Configuration.ORIENTATION_UNDEFINED: {
138                    // don't change
139                    return;
140                }
141            }
142
143            if (defaultWidth == widthPixels && defaultHeight == heightPixels) {
144                // the screen size is same as expected size. make it expandable
145                compatibilityInfo.mExpandable = true;
146            } else {
147                compatibilityInfo.mExpandable = false;
148                // adjust the size only when the device's screen is bigger.
149                if (defaultWidth < widthPixels) {
150                    widthPixels = defaultWidth;
151                }
152                if (defaultHeight < heightPixels) {
153                    heightPixels = defaultHeight;
154                }
155            }
156        }
157    }
158
159    public String toString() {
160        return "DisplayMetrics{density=" + density + ", width=" + widthPixels +
161            ", height=" + heightPixels + ", scaledDensity=" + scaledDensity +
162            ", xdpi=" + xdpi + ", ydpi=" + ydpi + "}";
163    }
164}
165