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.hardware.display.DisplayManager;
24import android.os.AsyncTask;
25import android.os.RemoteException;
26import android.os.UserHandle;
27import android.util.DisplayMetrics;
28import android.util.Log;
29import android.util.MathUtils;
30import android.view.Display;
31import android.view.IWindowManager;
32import android.view.WindowManagerGlobal;
33
34import java.util.Arrays;
35
36/**
37 * Utility methods for working with display density.
38 */
39public class DisplayDensityUtils {
40    private static final String LOG_TAG = "DisplayDensityUtils";
41
42    /** Minimum increment between density scales. */
43    private static final float MIN_SCALE_INTERVAL = 0.09f;
44
45    /** Minimum density scale. This is available on all devices. */
46    private static final float MIN_SCALE = 0.85f;
47
48    /** Maximum density scale. The actual scale used depends on the device. */
49    private static final float MAX_SCALE = 1.50f;
50
51    /** Summary used for "default" scale. */
52    public static final int SUMMARY_DEFAULT = R.string.screen_zoom_summary_default;
53
54    /** Summary used for "custom" scale. */
55    private static final int SUMMARY_CUSTOM = R.string.screen_zoom_summary_custom;
56
57    /**
58     * Summaries for scales smaller than "default" in order of smallest to
59     * largest.
60     */
61    private static final int[] SUMMARIES_SMALLER = new int[] {
62            R.string.screen_zoom_summary_small
63    };
64
65    /**
66     * Summaries for scales larger than "default" in order of smallest to
67     * largest.
68     */
69    private static final int[] SUMMARIES_LARGER = new int[] {
70            R.string.screen_zoom_summary_large,
71            R.string.screen_zoom_summary_very_large,
72            R.string.screen_zoom_summary_extremely_large,
73    };
74
75    /**
76     * Minimum allowed screen dimension, corresponds to resource qualifiers
77     * "small" or "sw320dp". This value must be at least the minimum screen
78     * size required by the CDD so that we meet developer expectations.
79     */
80    private static final int MIN_DIMENSION_DP = 320;
81
82    private final String[] mEntries;
83    private final int[] mValues;
84
85    private final int mDefaultDensity;
86    private final int mCurrentIndex;
87
88    public DisplayDensityUtils(Context context) {
89        final int defaultDensity = DisplayDensityUtils.getDefaultDisplayDensity(
90                Display.DEFAULT_DISPLAY);
91        if (defaultDensity <= 0) {
92            mEntries = null;
93            mValues = null;
94            mDefaultDensity = 0;
95            mCurrentIndex = -1;
96            return;
97        }
98
99        final Resources res = context.getResources();
100        final DisplayMetrics metrics = new DisplayMetrics();
101        context.getDisplay().getRealMetrics(metrics);
102
103        final int currentDensity = metrics.densityDpi;
104        int currentDensityIndex = -1;
105
106        // Compute number of "larger" and "smaller" scales for this display.
107        final int minDimensionPx = Math.min(metrics.widthPixels, metrics.heightPixels);
108        final int maxDensity = DisplayMetrics.DENSITY_MEDIUM * minDimensionPx / MIN_DIMENSION_DP;
109        final float maxScale = Math.min(MAX_SCALE, maxDensity / (float) defaultDensity);
110        final float minScale = MIN_SCALE;
111        final int numLarger = (int) MathUtils.constrain((maxScale - 1) / MIN_SCALE_INTERVAL,
112                0, SUMMARIES_LARGER.length);
113        final int numSmaller = (int) MathUtils.constrain((1 - minScale) / MIN_SCALE_INTERVAL,
114                0, SUMMARIES_SMALLER.length);
115
116        String[] entries = new String[1 + numSmaller + numLarger];
117        int[] values = new int[entries.length];
118        int curIndex = 0;
119
120        if (numSmaller > 0) {
121            final float interval = (1 - minScale) / numSmaller;
122            for (int i = numSmaller - 1; i >= 0; i--) {
123                // Round down to a multiple of 2 by truncating the low bit.
124                final int density = ((int) (defaultDensity * (1 - (i + 1) * interval))) & ~1;
125                if (currentDensity == density) {
126                    currentDensityIndex = curIndex;
127                }
128                entries[curIndex] = res.getString(SUMMARIES_SMALLER[i]);
129                values[curIndex] = density;
130                curIndex++;
131            }
132        }
133
134        if (currentDensity == defaultDensity) {
135            currentDensityIndex = curIndex;
136        }
137        values[curIndex] = defaultDensity;
138        entries[curIndex] = res.getString(SUMMARY_DEFAULT);
139        curIndex++;
140
141        if (numLarger > 0) {
142            final float interval = (maxScale - 1) / numLarger;
143            for (int i = 0; i < numLarger; i++) {
144                // Round down to a multiple of 2 by truncating the low bit.
145                final int density = ((int) (defaultDensity * (1 + (i + 1) * interval))) & ~1;
146                if (currentDensity == density) {
147                    currentDensityIndex = curIndex;
148                }
149                values[curIndex] = density;
150                entries[curIndex] = res.getString(SUMMARIES_LARGER[i]);
151                curIndex++;
152            }
153        }
154
155        final int displayIndex;
156        if (currentDensityIndex >= 0) {
157            displayIndex = currentDensityIndex;
158        } else {
159            // We don't understand the current density. Must have been set by
160            // someone else. Make room for another entry...
161            int newLength = values.length + 1;
162            values = Arrays.copyOf(values, newLength);
163            values[curIndex] = currentDensity;
164
165            entries = Arrays.copyOf(entries, newLength);
166            entries[curIndex] = res.getString(SUMMARY_CUSTOM, currentDensity);
167
168            displayIndex = curIndex;
169        }
170
171        mDefaultDensity = defaultDensity;
172        mCurrentIndex = displayIndex;
173        mEntries = entries;
174        mValues = values;
175    }
176
177    public String[] getEntries() {
178        return mEntries;
179    }
180
181    public int[] getValues() {
182        return mValues;
183    }
184
185    public int getCurrentIndex() {
186        return mCurrentIndex;
187    }
188
189    public int getDefaultDensity() {
190        return mDefaultDensity;
191    }
192
193    /**
194     * Returns the default density for the specified display.
195     *
196     * @param displayId the identifier of the display
197     * @return the default density of the specified display, or {@code -1} if
198     *         the display does not exist or the density could not be obtained
199     */
200    private static int getDefaultDisplayDensity(int displayId) {
201       try {
202           final IWindowManager wm = WindowManagerGlobal.getWindowManagerService();
203           return wm.getInitialDisplayDensity(displayId);
204       } catch (RemoteException exc) {
205           return -1;
206       }
207    }
208
209    /**
210     * Asynchronously applies display density changes to the specified display.
211     * <p>
212     * The change will be applied to the user specified by the value of
213     * {@link UserHandle#myUserId()} at the time the method is called.
214     *
215     * @param displayId the identifier of the display to modify
216     */
217    public static void clearForcedDisplayDensity(final int displayId) {
218        final int userId = UserHandle.myUserId();
219        AsyncTask.execute(() -> {
220            try {
221                final IWindowManager wm = WindowManagerGlobal.getWindowManagerService();
222                wm.clearForcedDisplayDensityForUser(displayId, userId);
223            } catch (RemoteException exc) {
224                Log.w(LOG_TAG, "Unable to clear forced display density setting");
225            }
226        });
227    }
228
229    /**
230     * Asynchronously applies display density changes to the specified display.
231     * <p>
232     * The change will be applied to the user specified by the value of
233     * {@link UserHandle#myUserId()} at the time the method is called.
234     *
235     * @param displayId the identifier of the display to modify
236     * @param density the density to force for the specified display
237     */
238    public static void setForcedDisplayDensity(final int displayId, final int density) {
239        final int userId = UserHandle.myUserId();
240        AsyncTask.execute(() -> {
241            try {
242                final IWindowManager wm = WindowManagerGlobal.getWindowManagerService();
243                wm.setForcedDisplayDensityForUser(displayId, density, userId);
244            } catch (RemoteException exc) {
245                Log.w(LOG_TAG, "Unable to save forced display density setting");
246            }
247        });
248    }
249}
250