android_translation_layer/src/api-impl/android/util/DisplayMetrics.java

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.util;

import android.view.Display;

/**
 * A structure describing general information about a display, such as its
 * size, density, and font scaling.
 * <p>To access the DisplayMetrics members, initialize an object like this:</p>
 * <pre> DisplayMetrics metrics = new DisplayMetrics();
 * getWindowManager().getDefaultDisplay().getMetrics(metrics);</pre>
 */
public class DisplayMetrics {
	/**
	 * Standard quantized DPI for low-density screens.
	 */
	public static final int DENSITY_LOW = 120;

	/**
	 * Standard quantized DPI for medium-density screens.
	 */
	public static final int DENSITY_MEDIUM = 160;

	/**
	 * This is a secondary density, added for some common screen configurations.
	 * It is recommended that applications not generally target this as a first
	 * class density -- that is, don't supply specific graphics for this
	 * density, instead allow the platform to scale from other densities
	 * (typically {@link #DENSITY_HIGH}) as
	 * appropriate.  In most cases (such as using bitmaps in
	 * {@link android.graphics.drawable.Drawable}) the platform
	 * can perform this scaling at load time, so the only cost is some slight
	 * startup runtime overhead.
	 *
	 * <p>This density was original introduced to correspond with a
	 * 720p TV screen: the density for 1080p televisions is
	 * {@link #DENSITY_XHIGH}, and the value here provides the same UI
	 * size for a TV running at 720p.  It has also found use in 7" tablets,
	 * when these devices have 1280x720 displays.
	 */
	public static final int DENSITY_TV = 213;

	/**
	 * Standard quantized DPI for high-density screens.
	 */
	public static final int DENSITY_HIGH = 240;

	/**
	 * Standard quantized DPI for extra-high-density screens.
	 */
	public static final int DENSITY_XHIGH = 320;

	/**
	 * Intermediate density for screens that sit somewhere between
	 * {@link #DENSITY_XHIGH} (320dpi) and {@link #DENSITY_XXHIGH} (480 dpi).
	 * This is not a density that applications should target, instead relying
	 * on the system to scale their {@link #DENSITY_XXHIGH} assets for them.
	 */
	public static final int DENSITY_400 = 400;

	/**
	 * Standard quantized DPI for extra-extra-high-density screens.  Applications
	 * should not generally worry about this density; relying on XHIGH graphics
	 * being scaled up to it should be sufficient for almost all cases.
	 */
	public static final int DENSITY_XXHIGH = 480;

	/**
	 * Standard quantized DPI for extra-extra-extra-high-density screens.  Applications
	 * should not generally worry about this density; relying on XHIGH graphics
	 * being scaled up to it should be sufficient for almost all cases.  A typical
	 * use of this density would be 4K television screens -- 3840x2160, which
	 * is 2x a traditional HD 1920x1080 screen which runs at DENSITY_XHIGH.
	 */
	public static final int DENSITY_XXXHIGH = 640;

	/**
	 * The reference density used throughout the system.
	 */
	public static final int DENSITY_DEFAULT = DENSITY_MEDIUM;

	/**
	 * Scaling factor to convert a density in DPI units to the density scale.
	 * @hide
	 */
	public static final float DENSITY_DEFAULT_SCALE = 1.0f / DENSITY_DEFAULT;

	/**
	 * The device's density.
	 * @hide because eventually this should be able to change while
	 * running, so shouldn't be a constant.
	 * @deprecated There is no longer a static density; you can find the
	 * density for a display in {@link #densityDpi}.
	 */
	@Deprecated
	public static int DENSITY_DEVICE = getDeviceDensity();

	/**
	 * The absolute width of the display in pixels.
	 */
	public int widthPixels;
	/**
	 * The absolute height of the display in pixels.
	 */
	public int heightPixels;
	/**
	 * The logical density of the display.  This is a scaling factor for the
	 * Density Independent Pixel unit, where one DIP is one pixel on an
	 * approximately 160 dpi screen (for example a 240x320, 1.5"x2" screen),
	 * providing the baseline of the system's display. Thus on a 160dpi screen
	 * this density value will be 1; on a 120 dpi screen it would be .75; etc.
	 *
	 * <p>This value does not exactly follow the real screen size (as given by
	 * {@link #xdpi} and {@link #ydpi}, but rather is used to scale the size of
	 * the overall UI in steps based on gross changes in the display dpi.  For
	 * example, a 240x320 screen will have a density of 1 even if its width is
	 * 1.8", 1.3", etc. However, if the screen resolution is increased to
	 * 320x480 but the screen size remained 1.5"x2" then the density would be
	 * increased (probably to 1.5).
	 *
	 * @see #DENSITY_DEFAULT
	 */
	public float density;
	/**
	 * The screen density expressed as dots-per-inch.  May be either
	 * {@link #DENSITY_LOW}, {@link #DENSITY_MEDIUM}, or {@link #DENSITY_HIGH}.
	 */
	public int densityDpi;
	/**
	 * A scaling factor for fonts displayed on the display.  This is the same
	 * as {@link #density}, except that it may be adjusted in smaller
	 * increments at runtime based on a user preference for the font size.
	 */
	public float scaledDensity;
	/**
	 * The exact physical pixels per inch of the screen in the X dimension.
	 */
	public float xdpi;
	/**
	 * The exact physical pixels per inch of the screen in the Y dimension.
	 */
	public float ydpi;

	/**
	 * The reported display width prior to any compatibility mode scaling
	 * being applied.
	 * @hide
	 */
	public int noncompatWidthPixels;
	/**
	 * The reported display height prior to any compatibility mode scaling
	 * being applied.
	 * @hide
	 */
	public int noncompatHeightPixels;
	/**
	 * The reported display density prior to any compatibility mode scaling
	 * being applied.
	 * @hide
	 */
	public float noncompatDensity;
	/**
	 * The reported display density prior to any compatibility mode scaling
	 * being applied.
	 * @hide
	 */
	public int noncompatDensityDpi;
	/**
	 * The reported scaled density prior to any compatibility mode scaling
	 * being applied.
	 * @hide
	 */
	public float noncompatScaledDensity;
	/**
	 * The reported display xdpi prior to any compatibility mode scaling
	 * being applied.
	 * @hide
	 */
	public float noncompatXdpi;
	/**
	 * The reported display ydpi prior to any compatibility mode scaling
	 * being applied.
	 * @hide
	 */
	public float noncompatYdpi;

	public DisplayMetrics() {
		setToDefaults();
	}

	public void setTo(DisplayMetrics o) {
		widthPixels = o.widthPixels;
		heightPixels = o.heightPixels;
		density = o.density;
		densityDpi = o.densityDpi;
		scaledDensity = o.scaledDensity;
		xdpi = o.xdpi;
		ydpi = o.ydpi;
		noncompatWidthPixels = o.noncompatWidthPixels;
		noncompatHeightPixels = o.noncompatHeightPixels;
		noncompatDensity = o.noncompatDensity;
		noncompatDensityDpi = o.noncompatDensityDpi;
		noncompatScaledDensity = o.noncompatScaledDensity;
		noncompatXdpi = o.noncompatXdpi;
		noncompatYdpi = o.noncompatYdpi;
	}

	public void setToDefaults() {
		widthPixels = Display.window_width;
		heightPixels = Display.window_height;
		density = DENSITY_DEVICE / (float)DENSITY_DEFAULT;
		densityDpi = DENSITY_DEVICE;
		scaledDensity = density;
		xdpi = DENSITY_DEVICE;
		ydpi = DENSITY_DEVICE;
		noncompatWidthPixels = widthPixels;
		noncompatHeightPixels = heightPixels;
		noncompatDensity = density;
		noncompatDensityDpi = densityDpi;
		noncompatScaledDensity = scaledDensity;
		noncompatXdpi = xdpi;
		noncompatYdpi = ydpi;
	}

	@Override
	public boolean equals(Object o) {
		return o instanceof DisplayMetrics && equals((DisplayMetrics)o);
	}

	/**
	 * Returns true if these display metrics equal the other display metrics.
	 *
	 * @param other The display metrics with which to compare.
	 * @return True if the display metrics are equal.
	 */
	public boolean equals(DisplayMetrics other) {
		return equalsPhysical(other) && scaledDensity == other.scaledDensity && noncompatScaledDensity == other.noncompatScaledDensity;
	}

	/**
	 * Returns true if the physical aspects of the two display metrics
	 * are equal.  This ignores the scaled density, which is a logical
	 * attribute based on the current desired font size.
	 *
	 * @param other The display metrics with which to compare.
	 * @return True if the display metrics are equal.
	 * @hide
	 */
	public boolean equalsPhysical(DisplayMetrics other) {
		return other != null && widthPixels == other.widthPixels && heightPixels == other.heightPixels && density == other.density && densityDpi == other.densityDpi && xdpi == other.xdpi && ydpi == other.ydpi && noncompatWidthPixels == other.noncompatWidthPixels && noncompatHeightPixels == other.noncompatHeightPixels && noncompatDensity == other.noncompatDensity && noncompatDensityDpi == other.noncompatDensityDpi && noncompatXdpi == other.noncompatXdpi && noncompatYdpi == other.noncompatYdpi;
	}

	@Override
	public int hashCode() {
		return widthPixels * heightPixels * densityDpi;
	}

	@Override
	public String toString() {
		return "DisplayMetrics{density=" + density + ", width=" + widthPixels +
		    ", height=" + heightPixels + ", scaledDensity=" + scaledDensity +
		    ", xdpi=" + xdpi + ", ydpi=" + ydpi + "}";
	}

	private static int getDeviceDensity() {
		// qemu.sf.lcd_density can be used to override ro.sf.lcd_density
		// when running in the emulator, allowing for dynamic configurations.
		// The reason for this is that ro.sf.lcd_density is write-once and is
		// set by the init process when it parses build.prop before anything else.
		return DENSITY_DEFAULT;
	}
}