📜  Node.js GMnegative()函数

📅  最后修改于: 2022-05-13 01:56:25.547000             🧑  作者: Mango

Node.js GMnegative()函数

negative()函数是 GraphicsMagick 库中的一个内置函数,用于将每个像素替换为其补色。该函数在成功时返回真值。
句法:

negative()

参数:此函数不接受任何参数。
返回值:此函数返回 GraphicsMagick 对象。
示例 1:

javascript
// Include gm library
var gm = require('gm');
  
// Import the image
gm('1.png')
  
// Invoke Negative function
.negative()
  
// Process and Write the image
.write("negative1.png", function (err) {
  if (!err) console.log('done');
});


javascript
// 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)
  
// Call to drawText Function
.drawText(100, 280, "GeeksforGeeks!")
  
// Invoke borderColor() function
// and set border color to green
.borderColor("Green")
  
// Invoke border function
.border(62, 32)
  
// Invoke negative function
.negative()
  
// Process and write the image 
.write("negative2.png", function (err) {
  if (!err) console.log('done');
});


javascript
// Include gm library
var gm = require('gm');
gm('1.png')
  
// Include another image
.composite('operator-noise-multiplicative1.png')
  
// Shift the image using geometry function
.geometry('+10+50')
  
// Invoke compose function with 'plus' Argument
.compose('plus')
  
// Include another image
.composite('randomThreshold1.png')
  
// Shift the image using geometry function
.geometry('+20+70')
  
// Invoke compose function with 'plus' argument
.compose('plus')
  
// Invoke negative function
.negative()
  
// Process and write the image
.write('negative3.png', function(err) {
    if(!err) console.log("Written composite image.");
});


输出:

示例 2:

javascript

// 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)
  
// Call to drawText Function
.drawText(100, 280, "GeeksforGeeks!")
  
// Invoke borderColor() function
// and set border color to green
.borderColor("Green")
  
// Invoke border function
.border(62, 32)
  
// Invoke negative function
.negative()
  
// Process and write the image 
.write("negative2.png", function (err) {
  if (!err) console.log('done');
});

输出:

示例 3:

javascript

// Include gm library
var gm = require('gm');
gm('1.png')
  
// Include another image
.composite('operator-noise-multiplicative1.png')
  
// Shift the image using geometry function
.geometry('+10+50')
  
// Invoke compose function with 'plus' Argument
.compose('plus')
  
// Include another image
.composite('randomThreshold1.png')
  
// Shift the image using geometry function
.geometry('+20+70')
  
// Invoke compose function with 'plus' argument
.compose('plus')
  
// Invoke negative function
.negative()
  
// Process and write the image
.write('negative3.png', function(err) {
    if(!err) console.log("Written composite image.");
});

输出:

参考:

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