ViewUtils.java

package com.marshalchen.common.uimodule.smoothswitch;

import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.View;

public class ViewUtils {
    private static int width;
    private static int height;

    public static void init(Context context) {
        Resources res = context.getResources();
        DisplayMetrics metrics = res.getDisplayMetrics();
        width = metrics.widthPixels;
        height = metrics.heightPixels;
    }

    public static int getScreenWidth() {
        return width;
    };

    public static int getScreenHeight() {
        return height;
    };

    /**
     * change dip value to pixel value for certain screen size
     * 
     * @param dipValue
     * @param context
     * @return
     */
    public static int getPixels(int dipValue, Context context) {
        int result = 0;
        Resources res = context.getResources();
        result = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dipValue, res.getDisplayMetrics());
        return result;
    }

    /**
     * change View to Bitmap Object
     * 
     * @param v
     * @return
     */
    public static Bitmap loadBitmapFromView(View v) {
        if (v == null) {
            return null;
        }
        Bitmap screenshot;
        screenshot = Bitmap.createBitmap(v.getWidth(), v.getHeight(), Config.ARGB_8888);
        Canvas c = new Canvas(screenshot);
        c.translate(-v.getScrollX(), -v.getScrollY());
        v.draw(c);
        return screenshot;
    }

    /**
     * compute sample size you want
     * 
     * @param options
     * @param minSideLength
     * @param maxNumOfPixels
     * @return
     */
    public static int computeSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) {
        int initialSize = computeInitialSampleSize(options, minSideLength, maxNumOfPixels);
        int roundedSize;
        if (initialSize <= 8) {
            roundedSize = 1;
            while (roundedSize < initialSize) {
                roundedSize <<= 1;
            }
        } else {
            roundedSize = (initialSize + 7) / 8 * 8;
        }
        return roundedSize;
    }

    /**
     * compute bitmap initial sample size
     * 
     * @param options
     * @param minSideLength
     * @param maxNumOfPixels
     * @return
     */
    private static int computeInitialSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) {
        double w = options.outWidth;
        double h = options.outHeight;
        int lowerBound = (maxNumOfPixels == -1) ? 1 : (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));
        int upperBound = (minSideLength == -1) ? 128 : (int) Math.min(Math.floor(w / minSideLength), Math.floor(h / minSideLength));
        if (upperBound < lowerBound) {
            // return the larger one when there is no overlapping zone.
            return lowerBound;
        }
        if ((maxNumOfPixels == -1) && (minSideLength == -1)) {
            return 1;
        } else if (minSideLength == -1) {
            return lowerBound;
        } else {
            return upperBound;
        }
    }

    public static int getStatusBarHeight(Activity context) {
        Rect rect = new Rect();
        context.getWindow().getDecorView().getWindowVisibleDisplayFrame(rect);
        return rect.top;
    }
}