1/*
2 * Copyright (C) 2015 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 com.android.settingslib.display;
18
19import com.android.settingslib.R;
20
21import android.content.Context;
22import android.content.res.Resources;
23import android.os.AsyncTask;
24import android.os.RemoteException;
25import android.util.DisplayMetrics;
26import android.util.Log;
27import android.util.MathUtils;
28import android.view.Display;
29import android.view.IWindowManager;
30import android.view.WindowManagerGlobal;
31
32import java.util.Arrays;
33
34/**
35 * Utility methods for working with display density.
36 */
37public class DisplayDensityUtils {
38    private static final String LOG_TAG = "DisplayDensityUtils";
39
40    /** Minimum increment between density scales. */
41    private static final float MIN_SCALE_INTERVAL = 0.09f;
42
43    /** Minimum density scale. This is available on all devices. */
44    private static final float MIN_SCALE = 0.85f;
45
46    /** Maximum density scale. The actual scale used depends on the device. */
47    private static final float MAX_SCALE = 1.50f;
48
49    /** Summary used for "default" scale. */
50    public static final int SUMMARY_DEFAULT = R.string.screen_zoom_summary_default;
51
52    /** Summary used for "custom" scale. */
53    private static final int SUMMARY_CUSTOM = R.string.screen_zoom_summary_custom;
54
55    /**
56     * Summaries for scales smaller than "default" in order of smallest to
57     * largest.
58     */
59    private static final int[] SUMMARIES_SMALLER = new int[] {
60            R.string.screen_zoom_summary_small
61    };
62
63    /**
64     * Summaries for scales larger than "default" in order of smallest to
65     * largest.
66     */
67    private static final int[] SUMMARIES_LARGER = new int[] {
68            R.string.screen_zoom_summary_large,
69            R.string.screen_zoom_summary_very_large,
70            R.string.screen_zoom_summary_extremely_large,
71    };
72
73    /**
74     * Minimum allowed screen dimension, corresponds to resource qualifiers
75     * "small" or "sw320dp". This value must be at least the minimum screen
76     * size required by the CDD so that we meet developer expectations.
77     */
78    private static final int MIN_DIMENSION_DP = 320;
79
80    private final String[] mEntries;
81    private final int[] mValues;
82
83    private final int mDefaultDensity;
84    private final int mCurrentIndex;
85
86    public DisplayDensityUtils(Context context) {
87        final int defaultDensity = DisplayDensityUtils.getDefaultDisplayDensity(
88                Display.DEFAULT_DISPLAY);
89        if (defaultDensity <= 0) {
90            mEntries = null;
91            mValues = null;
92            mDefaultDensity = 0;
93            mCurrentIndex = -1;
94            return;
95        }
96
97        final Resources res = context.getResources();
98        final DisplayMetrics metrics = res.getDisplayMetrics();
99        final int currentDensity = metrics.densityDpi;
100        int currentDensityIndex = -1;
101
102        // Compute number of "larger" and "smaller" scales for this display.
103        final int minDimensionPx = Math.min(metrics.widthPixels, metrics.heightPixels);
104        final int maxDensity = DisplayMetrics.DENSITY_MEDIUM * minDimensionPx / MIN_DIMENSION_DP;
105        final float maxScale = Math.min(MAX_SCALE, maxDensity / (float) defaultDensity);
106        final float minScale = MIN_SCALE;
107        final int numLarger = (int) MathUtils.constrain((maxScale - 1) / MIN_SCALE_INTERVAL,
108                0, SUMMARIES_LARGER.length);
109        final int numSmaller = (int) MathUtils.constrain((1 - minScale) / MIN_SCALE_INTERVAL,
110                0, SUMMARIES_SMALLER.length);
111
112        String[] entries = new String[1 + numSmaller + numLarger];
113        int[] values = new int[entries.length];
114        int curIndex = 0;
115
116        if (numSmaller > 0) {
117            final float interval = (1 - minScale) / numSmaller;
118            for (int i = numSmaller - 1; i >= 0; i--) {
119                // Round down to a multiple of 2 by truncating the low bit.
120                final int density = ((int) (defaultDensity * (1 - (i + 1) * interval))) & ~1;
121                if (currentDensity == density) {
122                    currentDensityIndex = curIndex;
123                }
124                entries[curIndex] = res.getString(SUMMARIES_SMALLER[i]);
125                values[curIndex] = density;
126                curIndex++;
127            }
128        }
129
130        if (currentDensity == defaultDensity) {
131            currentDensityIndex = curIndex;
132        }
133        values[curIndex] = defaultDensity;
134        entries[curIndex] = res.getString(SUMMARY_DEFAULT);
135        curIndex++;
136
137        if (numLarger > 0) {
138            final float interval = (maxScale - 1) / numLarger;
139            for (int i = 0; i < numLarger; i++) {
140                // Round down to a multiple of 2 by truncating the low bit.
141                final int density = ((int) (defaultDensity * (1 + (i + 1) * interval))) & ~1;
142                if (currentDensity == density) {
143                    currentDensityIndex = curIndex;
144                }
145                values[curIndex] = density;
146                entries[curIndex] = res.getString(SUMMARIES_LARGER[i]);
147                curIndex++;
148            }
149        }
150
151        final int displayIndex;
152        if (currentDensityIndex >= 0) {
153            displayIndex = currentDensityIndex;
154        } else {
155            // We don't understand the current density. Must have been set by
156            // someone else. Make room for another entry...
157            int newLength = values.length + 1;
158            values = Arrays.copyOf(values, newLength);
159            values[curIndex] = currentDensity;
160
161            entries = Arrays.copyOf(entries, newLength);
162            entries[curIndex] = res.getString(SUMMARY_CUSTOM, currentDensity);
163
164            displayIndex = curIndex;
165        }
166
167        mDefaultDensity = defaultDensity;
168        mCurrentIndex = displayIndex;
169        mEntries = entries;
170        mValues = values;
171    }
172
173    public String[] getEntries() {
174        return mEntries;
175    }
176
177    public int[] getValues() {
178        return mValues;
179    }
180
181    public int getCurrentIndex() {
182        return mCurrentIndex;
183    }
184
185    public int getDefaultDensity() {
186        return mDefaultDensity;
187    }
188
189    /**
190     * Returns the default density for the specified display.
191     *
192     * @param displayId the identifier of the display
193     * @return the default density of the specified display, or {@code -1} if
194     *         the display does not exist or the density could not be obtained
195     */
196    private static int getDefaultDisplayDensity(int displayId) {
197       try {
198           final IWindowManager wm = WindowManagerGlobal.getWindowManagerService();
199           return wm.getInitialDisplayDensity(displayId);
200       } catch (RemoteException exc) {
201           return -1;
202       }
203    }
204
205    /**
206     * Asynchronously applies display density changes to the specified display.
207     *
208     * @param displayId the identifier of the display to modify
209     */
210    public static void clearForcedDisplayDensity(final int displayId) {
211        AsyncTask.execute(new Runnable() {
212            @Override
213            public void run() {
214                try {
215                    final IWindowManager wm = WindowManagerGlobal.getWindowManagerService();
216                    wm.clearForcedDisplayDensity(displayId);
217                } catch (RemoteException exc) {
218                    Log.w(LOG_TAG, "Unable to clear forced display density setting");
219                }
220            }
221        });
222    }
223
224    /**
225     * Asynchronously applies display density changes to the specified display.
226     *
227     * @param displayId the identifier of the display to modify
228     * @param density the density to force for the specified display
229     */
230    public static void setForcedDisplayDensity(final int displayId, final int density) {
231        AsyncTask.execute(new Runnable() {
232            @Override
233            public void run() {
234                try {
235                    final IWindowManager wm = WindowManagerGlobal.getWindowManagerService();
236                    wm.setForcedDisplayDensity(displayId, density);
237                } catch (RemoteException exc) {
238                    Log.w(LOG_TAG, "Unable to save forced display density setting");
239                }
240            }
241        });
242    }
243}
244