Custom View Example in Android

Project Structure :

 

 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <com.rajeshvijayakumar.view.CustomViewEx
        android:id="@+id/custom_view"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />

</RelativeLayout>

CustomViewEx.java

package com.rajeshvijayakumar.view;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class CustomViewEx extends View {
    private PointF point;
    private Paint paint;

    public CustomViewEx(Context context) {
        this(context, null);
    }

    public CustomViewEx(Context context, AttributeSet attrs) {
        super(context, attrs);
        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (point != null) {
            int radius = 50;
                paint.setColor(Color.GREEN);
                canvas.drawCircle(point.x, point.y, radius, paint);
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {

        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            point = new PointF(event.getX(), event.getY());
            break;
        case MotionEvent.ACTION_UP:
            point = null;
            break;
        case MotionEvent.ACTION_MOVE:
            point = new PointF(event.getX(), event.getY());
            break;
        }
        invalidate();
        return true;
    }
}

MainActivity.java

 package com.example.custom_view_example;

import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity {

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

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.custom_view_example"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="7"
        android:targetSdkVersion="16" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name="com.example.custom_view_example.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Output :

 Source Code : Download this Example Here