Load photo and scale-down to suit ImageView

This example show how to load photo using Intent.ACTION_OPEN_DOCUMENT, and scale-down to suitable size, to display in ImageView.


MainActivity.java

package com.blogspot.android_er.androidimage;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.FileNotFoundException;

public class MainActivity extends AppCompatActivity {

    private static final int RQS_OPEN = 1;
    Button buttonOpen;
    ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        buttonOpen = (Button) findViewById(R.id.opendocument);
        buttonOpen.setOnClickListener(buttonOpenOnClickListener);

        imageView = (ImageView)findViewById(R.id.image);
    }

    View.OnClickListener buttonOpenOnClickListener =
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent intent = new Intent();
                    intent.setAction(Intent.ACTION_OPEN_DOCUMENT);
                    intent.addCategory(Intent.CATEGORY_OPENABLE);
                    intent.setType("image/*");
                    startActivityForResult(intent, RQS_OPEN);
                }
            };

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == RESULT_OK && requestCode == RQS_OPEN) {
            Uri dataUri = data.getData();
            int w = imageView.getWidth();
            int h = imageView.getHeight();
            Toast.makeText(MainActivity.this,
                    dataUri.toString() + "\n" +
                    w + " : " + h,
                    Toast.LENGTH_LONG).show();

            try {
                Bitmap bm = loadScaledBitmap(dataUri, w, h);
                imageView.setImageBitmap(bm);
                Toast.makeText(MainActivity.this,
                        bm.getWidth() + " x " + bm.getHeight(),
                        Toast.LENGTH_SHORT).show();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
                Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_LONG).show();
            }
        }
    }

    /*
    reference:
    Load scaled bitmap
    http://android-er.blogspot.com/2013/08/load-scaled-bitmap.html
     */
    private Bitmap loadScaledBitmap(Uri src, int req_w, int req_h) throws FileNotFoundException {

        Bitmap bm = null;

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(getBaseContext().getContentResolver().openInputStream(src),
                null, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, req_w, req_h);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        bm = BitmapFactory.decodeStream(
                getBaseContext().getContentResolver().openInputStream(src), null, options);

        return bm;
    }

    public 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;

        if (height > reqHeight || width > reqWidth) {

            // Calculate ratios of height and width to requested height and
            // width
            final int heightRatio = Math.round((float) height
                    / (float) reqHeight);
            final int widthRatio = Math.round((float) width / (float) reqWidth);

            // Choose the smallest ratio as inSampleSize value, this will
            // guarantee
            // a final image with both dimensions larger than or equal to the
            // requested height and width.
            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }

        return inSampleSize;
    }
}