Nodejs GM drawLine()函数用法介绍

drawLine()函数是GraphicsMagick库中的内置函数, 用于绘制具有指定坐标的线。成功时该函数返回真实值。

语法如下：

drawLine( x0, y0, x1, y1 )

参数：该函数接受上述和以下所述的四个参数：

• x0：此参数存储初始点的x坐标值。
• y0：此参数存储初始点的y坐标值。
• x1：此参数存储最终点的x坐标值。
• y1：此参数存储终点的y坐标值。

返回值：此函数返回GraphicsMagick对象。

原始图片：

示例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' );
});

输出如下：

示例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' );
});

输出如下：

参考：

• http://www.graphicsmagick.org/GraphicsMagick.html#details-draw
• https://www.npmjs.com/package/gm

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