Learn How to Draw Line Using Canvas in Android

Introduction

This article explains how to draw a line using a canvas in Android.

In this I have drawn two lines that intersect each other. To draw these intersecting lines you need to first extend the view class that provides the onDraw() method where you will write code to draw lines. You will call the drawline() method of the canvas class to draw the lines. The setColor() method will be provided by the Paint class to set the colors of both the lines.

Step 1

Create the project like this:



Step 2

XML 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:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    android:paddingBottom="@dimen/activity_vertical_margin"

    tools:context=".MainActivity">

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="Draw Lines"

            android:layout_centerHorizontal="true"

            android:textSize="20dp"

            android:textStyle="bold"/>

 

</RelativeLayout>

Step 3

Create a Java class file and write this:

package com.logacat;

import android.os.Bundle;

import android.app.Activity;

import android.util.Log;

import android.view.Menu; 

import android.app.Activity;

import android.graphics.Color;

import android.os.Bundle;

 

public class MainActivity extends Activity {

    DrawLine drawLine;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        drawLine = new DrawLine(this);

        drawLine.setBackgroundColor(Color.CYAN);

        setContentView(drawLine);

    }

}

Step 4

Create another Java class file and write this:
 

package com.logacat;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.view.View;

 

class DrawLine extends View {

    Paint paint = new Paint();

    public DrawLine(Context context) {

        super(context);

        paint.setColor(Color.BLACK);

    }

    @Override

    public void onDraw(Canvas canvas) {

        canvas.drawLine(50, 100, 600, 600, paint);

        canvas.drawLine(50, 550, 770, 0, paint);

    }

 

}

Step 5

Android manifest.xml file
 

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.logacat"

    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"

        android:theme="@style/AppTheme" >

        <activity

            android:name="com.logacat.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>

Step 6