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Node.js GraphicsMagick: A Beginner’s Guide to the drawLine() Function

Posted on by Thao Nguyen

The drawLine() function is a built-in function in the GraphicsMagick library that is used to draw a line with specified coordinates. If successful, the function returns the true value.

The syntax is as follows:

drawLine( x0, y0, x1, y1 )

Parameters: This function accepts the four parameters described above and below:

  • x0: This parameter stores the x-coordinate value of the initial point.
  • y0: This parameter stores the y-coordinate value of the initial point.
  • x1: This parameter stores the x-coordinate value of the final point.
  • y1: This parameter stores the y-coordinate value of the endpoint.

Return Value: This function returns a GraphicsMagick object.

Example 1:

//Include gm library
var gm = require( 'gm' ).subClass({imageMagick: true });
  
//Import the image
gm( '1.png' )
  
//Set the color for the stroke
.stroke( "#000000" , 20)
  
//Invoke drawLine function with x0 as 100, //y0 as 45, x1 as 100, y1 as 89, r0 as 50
//and r1 as 40
.drawLine(100, 30, 400, 80)
  
//Process and write the image 
.write( "drawLine1.png" , function (err) {
   if (!err) console.log( 'done' );
});

Example 2:

//Include gm library
var gm = require( 'gm' );
  
//Import the image
gm(600, 300, 'white' )
  
//set the color for the stroke
.stroke( "green" , 3)
  
//Set the font 
.font( "Helvetica.ttf" , 60)
  
//Invoke drawLine function with
//x0 as 100, y0 as 45, x1 as 100, //y1 as 200
.drawLine(100, 45, 100, 200)
  
//Invoke drawLine function with
//x0 as 100, y0 as 45, x1 as 500, //y1 as 45
.drawLine(100, 45, 500, 45)
  
//Invoke drawLine function with
//x0 as 500, y0 as 45, x1 as 500, //y1 as 200
.drawLine(500, 45, 500, 200)
  
//Call to drawText Function
.drawText(100, 280, "lsbin!" )
  
//Process and write the image 
.write( "drawLine1.png" , function (err) {
   if (!err) console.log( 'done' );
});
Thao Nguyen