root/ui/android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java

DEFINITIONS

1. JNINamespace
2. getDisplayHeight
3. getDisplayWidth
4. getPhysicalDisplayHeight
5. getPhysicalDisplayWidth
6. SuppressWarnings
7. getPixelFormat
8. getBitsPerPixel
9. SuppressWarnings
10. getBitsPerComponent
11. getDIPScale
12. getSmallestDIPWidth
13. updateNativeSharedDisplayInfo
14. getDisplay
15. create
16. nativeUpdateSharedDeviceDisplayInfo

// Copyright 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package org.chromium.ui.gfx;

import android.content.Context;
import android.graphics.PixelFormat;
import android.graphics.Point;
import android.os.Build;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.WindowManager;

import org.chromium.base.CalledByNative;
import org.chromium.base.JNINamespace;

/**
 * This class facilitates access to android information typically only
 * available using the Java SDK, including {@link Display} properties.
 *
 * Currently the information consists of very raw display information (height, width, DPI scale)
 * regarding the main display.
 */
@JNINamespace("gfx")
public class DeviceDisplayInfo {

    private final Context mAppContext;
    private final WindowManager mWinManager;
    private Point mTempPoint = new Point();
    private DisplayMetrics mTempMetrics = new DisplayMetrics();

    private DeviceDisplayInfo(Context context) {
        mAppContext = context.getApplicationContext();
        mWinManager = (WindowManager) mAppContext.getSystemService(Context.WINDOW_SERVICE);
    }

    /**
     * @return Display height in physical pixels.
     */
    @CalledByNative
    public int getDisplayHeight() {
        getDisplay().getSize(mTempPoint);
        return mTempPoint.y;
    }

    /**
     * @return Display width in physical pixels.
     */
    @CalledByNative
    public int getDisplayWidth() {
        getDisplay().getSize(mTempPoint);
        return mTempPoint.x;
    }

    /**
     * @return Real physical display height in physical pixels.
     */
    @CalledByNative
    public int getPhysicalDisplayHeight() {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
            return 0;
        }
        getDisplay().getRealSize(mTempPoint);
        return mTempPoint.y;
    }

    /**
     * @return Real physical display width in physical pixels.
     */
    @CalledByNative
    public int getPhysicalDisplayWidth() {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
            return 0;
        }
        getDisplay().getRealSize(mTempPoint);
        return mTempPoint.x;
    }

    @SuppressWarnings("deprecation")
    private int getPixelFormat() {
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
            return getDisplay().getPixelFormat();
        }
        // JellyBean MR1 and later always uses RGBA_8888.
        return PixelFormat.RGBA_8888;
    }

    /**
     * @return Bits per pixel.
     */
    @CalledByNative
    public int getBitsPerPixel() {
        int format = getPixelFormat();
        PixelFormat info = new PixelFormat();
        PixelFormat.getPixelFormatInfo(format, info);
        return info.bitsPerPixel;
    }

    /**
     * @return Bits per component.
     */
    @SuppressWarnings("deprecation")
    @CalledByNative
    public int getBitsPerComponent() {
        int format = getPixelFormat();
        switch (format) {
            case PixelFormat.RGBA_4444:
                return 4;

            case PixelFormat.RGBA_5551:
                return 5;

            case PixelFormat.RGBA_8888:
            case PixelFormat.RGBX_8888:
            case PixelFormat.RGB_888:
                return 8;

            case PixelFormat.RGB_332:
                return 2;

            case PixelFormat.RGB_565:
                return 5;

            // Non-RGB formats.
            case PixelFormat.A_8:
            case PixelFormat.LA_88:
            case PixelFormat.L_8:
                return 0;

            // Unknown format. Use 8 as a sensible default.
            default:
                return 8;
        }
    }

    /**
     * @return A scaling factor for the Density Independent Pixel unit. 1.0 is
     *         160dpi, 0.75 is 120dpi, 2.0 is 320dpi.
     */
    @CalledByNative
    public double getDIPScale() {
        getDisplay().getMetrics(mTempMetrics);
        return mTempMetrics.density;
    }

    /**
     * @return Smallest screen size in density-independent pixels that the
     *         application will see, regardless of orientation.
     */
    @CalledByNative
    private int getSmallestDIPWidth() {
        return mAppContext.getResources().getConfiguration().smallestScreenWidthDp;
    }

    /**
     * Inform the native implementation to update its cached representation of
     * the DeviceDisplayInfo values.
     */
    public void updateNativeSharedDisplayInfo() {
        nativeUpdateSharedDeviceDisplayInfo(
                getDisplayHeight(), getDisplayWidth(),
                getPhysicalDisplayHeight(), getPhysicalDisplayWidth(),
                getBitsPerPixel(), getBitsPerComponent(),
                getDIPScale(), getSmallestDIPWidth());
    }

    private Display getDisplay() {
        return mWinManager.getDefaultDisplay();
    }

    /**
     * Creates DeviceDisplayInfo for a given Context.
     *
     * @param context A context to use.
     * @return DeviceDisplayInfo associated with a given Context.
     */
    @CalledByNative
    public static DeviceDisplayInfo create(Context context) {
        return new DeviceDisplayInfo(context);
    }

    private native void nativeUpdateSharedDeviceDisplayInfo(
            int displayHeight, int displayWidth,
            int physicalDisplayHeight, int physicalDisplayWidth,
            int bitsPerPixel, int bitsPerComponent, double dipScale,
            int smallestDIPWidth);

}