Pinch To Zoom In Android

we are going to create pinch to zoom IN/OUT in Android.

Step 1. For this we have created xml File as Follow.

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.gc.myapplication.MainActivity">
<TextView android:id="@+id/pinchZoom" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/pinch_title" />
<ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/pinchZoom" android:scaleType="matrix" android:src="@mipmap/amrit" android:maxHeight="100dp" android:id="@+id/pinchimage" android:maxWidth="50dp" android:contentDescription="@string/content_description" /></RelativeLayout>

Step 2. we have created Activity for Pinch Zoom IN/OUT.

package com.example.gc.myapplication;


import android.graphics.Matrix;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.widget.ImageView;


public class MainActivity extends AppCompatActivity {

    

    // ImageView imageView;
    ImageView imageView;
    Matrix matrix= new Matrix();
    Float scale=1f;
    ScaleGestureDetector sgd;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = (ImageView) findViewById(R.id.pinchimage);
        sgd = new ScaleGestureDetector(this,new scaleListener());
    }

    private class scaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener{

        @Override        public boolean onScale(ScaleGestureDetector detector) {
            scale =scale*detector.getScaleFactor();
            scale=Math.max(0.1f,Math.min(scale,5f));
            matrix.setScale(scale,scale);
            imageView.setImageMatrix(matrix);
            return true;
        }
    }

    public boolean onTouchEvent(MotionEvent event){
        sgd.onTouchEvent(event);
        return true;
    }


}