OpenGPSActivity.java

package com.wuxiaolong.androidsamples;

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.DisplayMetrics;
import android.util.Log;
import android.widget.ImageView;

public class OpenGPSActivity extends AppCompatActivity {
    ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_open_gps);
        imageView = (ImageView) findViewById(R.id.imageView);
//        imageView.setBackgroundResource(R.mipmap.about_us);
        DisplayMetrics displayMetrics = this.getResources().getDisplayMetrics();
        imageView.setImageBitmap(decodeSampledBitmapFromResource(getResources(), R.mipmap.dog, displayMetrics.widthPixels, displayMetrics.heightPixels));

    }

    public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId, int reqWidth, int reqHeight) {

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
        Log.d("wxl", "calculateInSampleSize(options, reqWidth, reqHeight)=" + calculateInSampleSize(options, reqWidth, reqHeight));
        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(res, resId, options);
    }

    public static int calculateInSampleSize(
            BitmapFactory.Options options, int reqWidth, int reqHeight) {
        // Raw height and width of image
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        Log.d("wxl", "height=" + height);
        Log.d("wxl", "width=" + width);
        if (height > reqHeight || width > reqWidth) {

            final int halfHeight = height / 2;
            final int halfWidth = width / 2;

            // Calculate the largest inSampleSize value that is a power of 2 and keeps both
            // height and width larger than the requested height and width.
            while ((halfHeight / inSampleSize) > reqHeight
                    && (halfWidth / inSampleSize) > reqWidth) {
                inSampleSize *= 2;
            }

        }

        return inSampleSize;
    }

}