How to make circle shape on android activity screen programmatically on button click with canvas.

In this tutorial we are using Android’s Canvas class to draw round shape circle on activity screen. This process is completely dynamically. So here is the complete step by step tutorial for Create Draw 2D round shape circle on using Canvas in android example.

How to Create Draw 2D round shape circle on using Canvas in android example.

Code for MainActivity.java file.

 package com.draw2dcirclecanvas_android_examples.com;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {

 ImageView imageview;
 Button button;
 Bitmap bitmap;
 Canvas canvas;
 Paint paint;
 int CanvasRadius; 
 int CanvasPadding = 7;
 int height, width;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 
 imageview = (ImageView)findViewById(R.id.imageView1);
 button = (Button)findViewById(R.id.button1);
 
 
 button.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View view) {
 
 CreateBitmap();

 CreateCanvas();
 
 CanvasRadius = Math.min(canvas.getWidth(),canvas.getHeight()/2);

 CreatePaint();
 
 canvas.drawCircle(
 canvas.getWidth() / 2,
 canvas.getHeight() / 2,
 CanvasRadius - CanvasPadding,
 paint 
 );

 
 imageview.setImageBitmap(bitmap);
 }
 });
 
 }

 public void CreateBitmap(){
 
 bitmap = Bitmap.createBitmap(
 400,
 250,
 Bitmap.Config.RGB_565
 );
 
 }
 
 public void CreateCanvas(){
 
 canvas = new Canvas(bitmap);

 canvas.drawColor(Color.CYAN);
 
 }
 
 public void CreatePaint(){
 
 paint = new Paint();
 
 paint.setStyle(Paint.Style.FILL);
 
 paint.setColor(Color.BLUE);
 
 paint.setAntiAlias(true);
 
 }
}

Code for activity_main.xml layout file.

 <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.draw2dcirclecanvas_android_examples.com.MainActivity" >

 <ImageView
 android:id="@+id/imageView1"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_alignParentTop="true"
 android:layout_centerHorizontal="true"
 
 />

 <Button
 android:id="@+id/button1"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_centerHorizontal="true"
 android:layout_centerVertical="true"
 android:text="Click here to Create Draw 2D circle on using Canvas in android"
 />

</RelativeLayout>

Screenshot: