nodejs图片处理工具gm用法小结

npm install --save gm

var gm = require('gm')

var gm = require('gm').subClass({imageMagick: true})// 注意使用的区别

gm('img.png')
.size(function (err, size) {
 if (!err)
  console.log(size.width > size.height ? 'wider' : 'taller than you');
});

gm("img.png").resize(width)//保持宽高比
gm("img.png").resize(null, height)//保持宽高比
gm("img.png").resize(width, height, '!')//参数'!'用于忽略宽高比

gm("img.png").rotate(color, degrees)
gm("img.png").rotate('green', 45)

gm("img.png").crop(width, height, x, y)

gm()
 .in('-page', '+0+0')
 .in('bg.jpg')
 .in('-page', '+10+20') // location of smallIcon.jpg is x,y -> 10, 20
 .in('smallIcon.jpg')
 .mosaic()
 .write('tesOutput.jpg', function (err) {
  if (err) console.log(err);
 });

gm()
.command("composite") 
.in("-gravity", "center")
.in(change_image_url)
.in(base_image_url)
.write( output_file, function (err) {
 if (!err) 
  console.log(' hooray! ');
 else
  console.log(err);
});

gm("img.png").append(img [, img, ltr])
gm("img.png").append("another.jpg", "third.gif")//从上到下拼接
gm("img.png").append("another.jpg", "third.gif", true)//从左到右拼接

gm("img.png").drawText(10, 50, "from scratch")

gm(200, 400, "#ddff99f3")
.drawText(10, 50, "from scratch")
.write("/path/to/brandNewImg.jpg", function (err) {
 // ...
});