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( _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) {
 // ...
});