index.js

'use strict'

const KOCReturn = require('koc-common-return/index')
const ImageMagick = require('gm').subClass({imageMagick: true})

const KOCImage = {
  Ratio: (Path) => {
    return new Promise((resolve) => {
      ImageMagick(Path).size((err, value) => {
        const retValue = KOCReturn.Value()
        if (err) {
          retValue.hasError = true
          retValue.message = err.message
          retValue.returnObject = err
          return resolve(retValue)
        }
        retValue.returnObject = value.width / value.height
        retValue.PutValue('Width', value.width)
        retValue.PutValue('Height', value.height)
        resolve(retValue)
      })
    })
  },
  Resize: (mode, source, target, width, height) => {
    return new Promise((resolve) => {
      const retValue = KOCReturn.Value()
      let Image = ImageMagick(source)
      if (!Image) {
        retValue.hasError = true
        retValue.message = '没有找到图片文件'
        return resolve(retValue)
      }
      height = (height && height > 0) ? height : null
      Image.size((err, value) => {
        if (err) {
          retValue.hasError = true
          retValue.message = err.message
          return resolve(retValue)
        }
        let x = 0, y = 0, ow = value.width, oh = value.height, tw = width, th = height
        const Ratio = {
          Width: value.width,
          Height: value.height,
          Original: value.width / value.height,
          This: -1
        }
        switch (mode) {
          case 'W'://固定宽
          case 'H'://固定高
          case 'W_H'://最大宽,最大高(比例)
            Image.resize(tw, th)
            Ratio.This = tw / th
            break
          default://固定宽,固定高
            Image.resize(tw, th, '!')
            Ratio.This = tw / th
            break
          case 'Cut_Middle'://裁剪(中)(按比例放大or缩小)
            if (!width || !height) {
              Image.resize(tw, th)
              Ratio.This = tw / th
              break
            }
            th = oh * tw / ow
            if (height > th) {
              tw = tw * height / th
              th = height
            }
            Image = Image.resize(tw, th).crop(width, height, (tw - width) / 2, (th - height) / 2)
            Ratio.This = width / height
            break
          case 'Cut_Top'://裁剪(顶)(按比例放大or缩小)
            if (!width || !height) {
              Image.resize(tw, th)
              Ratio.This = tw / th
              break
            }
            th = oh * tw / ow
            if (height > th) {
              tw = tw * height / th
              th = height
            }
            Image = Image.resize(tw, th).crop(width, height, (tw - width) / 2, 0)
            Ratio.This = width / height
            break
          case 'Cut_Bottom'://裁剪(顶)(按比例放大or缩小)
            if (!width || !height) {
              Image.resize(tw, th)
              Ratio.This = tw / th
              break
            }
            th = oh * tw / ow
            if (height > th) {
              tw = tw * height / th
              th = height
            }
            Image = Image.resize(tw, th).crop(width, height, (tw - width) / 2, th - height)
            Ratio.This = width / height
            break
          case 'W_HMaxCut'://固定宽，最大高裁剪(顶)
            if (!height) {
              Image.resize(tw, th)
              Ratio.This = tw / th
              break
            }
            th = oh * width / ow
            Image = Image.resize(tw, th)
            Ratio.This = tw / th
            if (th > height) {
              Image = Image.crop(tw, height, x, y)
              Ratio.This = tw / height
            }
            break
          case 'W_HMaxCut_Middle'://固定宽，最大高裁剪(中)
            if (!height) {
              Image.resize(tw, th)
              Ratio.This = tw / th
              break
            }
            th = oh * width / ow
            Image = Image.resize(tw, th)
            Ratio.This = tw / th
            if (th > height) {
              y = (th - height) / 2
              Image = Image.crop(tw, height, x, y)
              Ratio.This = tw / height
            }
            break
          case 'H_WMaxCut'://固定高，最大宽裁剪(顶)
            if (!width) {
              Image.resize(tw, th)
              Ratio.This = tw / th
              break
            }
            tw = ow * height / oh
            Image = Image.resize(tw, th)
            Ratio.This = tw / th
            if (tw > width) {
              Image = Image.crop(width, th, x, y)
              Ratio.This = width / th
            }
            break
          case 'H_WMaxCut_Middle'://固定高，最大宽裁剪(顶)
            if (!width) {
              Image.resize(tw, th)
              Ratio.This = tw / th
              break
            }
            tw = ow * height / oh
            Image = Image.resize(tw, th)
            Ratio.This = tw / th
            if (tw > width) {
              x = (tw - width) / 2
              Image = Image.crop(width, th, x, y)
              Ratio.This = width / th
            }
            break
        }
        if (typeof target !== 'string') {
          target = 'JPG'
        }
        if (['JPG', 'PNG'].includes(target)) {
          Image.toBuffer(target, (err, buffer) => {
            if (err) {
              retValue.hasError = true
              retValue.message = err.message
              return resolve(retValue)
            }
            retValue.returnObject = buffer
            retValue.PutValue('Ratio', Ratio)
            resolve(retValue)
          })
        } else {
          Image.write(target, (err) => {
            if (err) {
              retValue.hasError = true
              retValue.message = err.message
              return resolve(retValue)
            }
            retValue.returnObject = Ratio
            retValue.PutValue('Ratio', Ratio)
            resolve(retValue)
          })
        }
      })
    })
  }
}

module.exports = KOCImage