System camera to take pictures

1. Call the system camera to take a picture

package com.android.myapplication;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Point;
import android.graphics.drawable.BitmapDrawable;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Display;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;
import android.widget.LinearLayout;

import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

    private ImageView iv1;
    private File imgFile;
    private LinearLayout ll;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate (savedInstanceState);
        supportRequestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        iv1 = (ImageView) findViewById(R.id.iv1);
        ll = (LinearLayout) findViewById(R.id.ll);
    }

    //Get the photo by taking a photo of the system
    public void sys_capture(View view) {
        startActivityForResult(new Intent(MediaStore.ACTION_IMAGE_CAPTURE), 0);
    }

    //Get the original image taken by the system
    public void orig_capture(View view) {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        //image name
        String pic_name = "IMG_" + new SimpleDateFormat("yyyyMMdd_hhmmssSSS").format(new Date()) + ".jpg";
        //image save path
        String pic_dir = Environment.getExternalStorageDirectory().getAbsolutePath()
                + File.separator + "MyPicture";
        File file = new File(pic_dir);
        if(!file.exists()){
            file.mkdirs();
        }
        //image file
        imgFile = new File(
                pic_dir+ File.separator + pic_name);
        Uri imgFileUri = Uri.fromFile (imgFile);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imgFileUri);//Specify the location where the picture is saved after the system takes a picture
        startActivityForResult(intent, 1);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (RESULT_OK == resultCode) {
            switch (requestCode) {
                case 0: {
                    Bundle bundle = data.getExtras();//Get the container in the intent
                    Bitmap bitmap = (Bitmap) bundle.get("data");//This picture is the compressed picture of the system
                    iv1.setImageBitmap (bitmap);
                    break;
                }
                case 1: {
                    Bitmap bitmap = getFitBitMap();
                    ll.setBackground(new BitmapDrawable(getResources(),bitmap));
                    break;
                }
            }
        }
    }

    /**
     * Suppose the size of the photo taken is 100x50 and the size I display needs is 50x40
     * You need to reduce the original image by half to display it completely, that is, the value of the compression ratio inSampleSize is 2
     * The ratio of the original image to the displayed image width: 100/50=2
     * The ratio of the original image to the displayed image height: 50/40=1.25
     * Then the compression ratio inSampleSize=the maximum aspect ratio is 2
     * @return
     */
    private Bitmap getFitBitMap() {
        //1. Get the image width and height
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;//Do not encode and decode pictures, only get picture properties
        BitmapFactory.decodeFile(imgFile.getAbsolutePath(), options);
        int imgWidth = options.outWidth;
        int imgHeight = options.outHeight;
        Log.e("===", "" + imgWidth + "---" + imgHeight);
        //2. Get the screen width and height
        Display defaultDisplay = getWindowManager().getDefaultDisplay();
        Point outSize = new Point();
        defaultDisplay.getSize(outSize);
        int screenWidth = outSize.x;
        int screenHeight = outSize.y;
        Log.e("===", "" + screenWidth + "---" + screenHeight);
        //3. Calculate the compression rate
        int widthRatio = (int) Math.ceil(imgWidth / screenWidth);//ceil means to round up the integer, that is, if the fractional part is not 0, the result is the integer part plus 1
        int heightRatio = (int) Math.ceil(imgHeight / screenHeight);
        int fitInSampleSize = Math.max(widthRatio, heightRatio);
        //4. Compress the image according to the compression rate
        options.inSampleSize = fitInSampleSize;
        options.inJustDecodeBounds = false;
        Bitmap fitBitmap = BitmapFactory.decodeFile(imgFile.getAbsolutePath(), options);
        return fitBitmap;
    }


}