Pinchzoom on TextView

Pinch Zoom TextView

	<?xml version="1.0" encoding="utf-8"?>
	<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
	xmlns:app="http://schemas.android.com/apk/res-auto"
	xmlns:tools="http://schemas.android.com/tools"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	tools:context=".DiffViewActivity">
	<Button
	android:id="@+id/button6"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_marginStart="8dp"
	android:layout_marginLeft="8dp"
	android:layout_marginTop="8dp"
	android:layout_marginEnd="8dp"
	android:layout_marginRight="8dp"
	android:text="Button"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toTopOf="parent" />
	<TextView
	android:id="@+id/mytv"
	android:layout_width="fill_parent"
	android:layout_height="wrap_content"
	android:layout_alignParentLeft="true"
	android:layout_alignParentTop="true"
	android:layout_marginStart="8dp"
	android:layout_marginLeft="8dp"
	android:layout_marginTop="16dp"
	android:layout_marginEnd="8dp"
	android:layout_marginRight="8dp"
	android:text="This is my sample text for pinch zoom demo, you can zoom in and out using
	pinch zoom, thanks"
	app:layout_constraintEnd_toStartOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toBottomOf="@+id/button6" />
	<TextView
	android:id="@+id/txt_size"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_marginStart="8dp"
	android:layout_marginLeft="8dp"
	android:layout_marginTop="16dp"
	android:layout_marginEnd="8dp"
	android:layout_marginRight="8dp"
	android:text="Hello how are you? I am fine."
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toBottomOf="@+id/mytv" />
	</android.support.constraint.ConstraintLayout>

view raw pinch_zoom.xml hosted with ❤ by GitHub

	package com.arham.csdevbin.all_android_concept;
	import android.support.v7.app.AppCompatActivity;
	import android.os.Bundle;
	import android.text.Spannable;
	import android.text.SpannableString;
	import android.text.style.RelativeSizeSpan;
	import android.view.MotionEvent;
	import android.view.View;
	import android.widget.TextView;
	public class DiffViewActivity extends AppCompatActivity implements View.OnTouchListener {
	final static float STEP = 200;
	TextView mytv;
	float mRatio = 1.0f;
	int mBaseDist;
	float mBaseRatio;
	float fontsize = 13;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.activity_diff_view);
	mytv = (TextView) findViewById(R.id.mytv);
	mytv.setTextSize(mRatio + 13);
	TextView textView = (TextView) findViewById(R.id.txt_size);
	Spannable span = new SpannableString(textView.getText());
	span.setSpan(new RelativeSizeSpan(0.8f), 12, 20, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
	textView.setText(span);
	}
	public boolean onTouchEvent(MotionEvent event) {
	if (event.getPointerCount() == 2) {
	int action = event.getAction();
	int pureaction = action & MotionEvent.ACTION_MASK;
	if (pureaction == MotionEvent.ACTION_POINTER_DOWN) {
	mBaseDist = getDistance(event);
	mBaseRatio = mRatio;
	} else {
	float delta = (getDistance(event) - mBaseDist) / STEP;
	float multi = (float) Math.pow(2, delta);
	mRatio = Math.min(1024.0f, Math.max(0.1f, mBaseRatio * multi));
	mytv.setTextSize(mRatio + 13);
	}
	}
	return true;
	}
	int getDistance(MotionEvent event) {
	int dx = (int) (event.getX(0) - event.getX(1));
	int dy = (int) (event.getY(0) - event.getY(1));
	return (int) (Math.sqrt(dx * dx + dy * dy));
	}
	public boolean onTouch(View v, MotionEvent event) {
	return false;
	}
	}

view raw Pinch_zoom.java hosted with ❤ by GitHub