amos-tool/lib/dom/canvas2img.js

amos ui tool

"use strict";

var utils = require("./../utils"), $support = {}, support = function() {
  if (utils.isEmpty($support)) {
    var e = document.createElement("canvas"), t = e.getContext("2d");
    $support = {
      canvas: !!t,
      imageData: !!t.getImageData,
      dataURL: !!e.toDataURL,
      btoa: !!window.btoa
    };
  }
  return $support;
}, downloadMime = "image/octet-stream";

function scaleCanvas(e, t, a) {
  var n = e.width, r = e.height;
  null == t && (t = n), null == a && (a = r);
  var o = document.createElement("canvas"), g = o.getContext("2d");
  return o.width = t, o.height = a, g.drawImage(e, 0, 0, n, r, 0, 0, t, a), o;
}

function getDataURL(e, t, a, n) {
  return (e = scaleCanvas(e, a, n)).toDataURL(t);
}

function getBlob(e, t, a) {
  var n = a.type || "image/png", r = a.width, o = a.height, g = a.encoderOptions || 1;
  return (e = scaleCanvas(e, r, o)).toBlob(t, n, g);
}

function saveFile(e) {
  document.location.href = e;
}

function genImage(e) {
  var t = document.createElement("img");
  return t.src = e, t;
}

function fixType(e) {
  return "image/" + (e = e.toLowerCase().replace(/jpg/i, "jpeg")).match(/png|jpeg|bmp|gif/)[0];
}

function encodeData(e) {
  if (!window.btoa) throw new Error("btoa undefined");
  var t = "";
  if ("string" == typeof e) t = e; else for (var a = 0; a < e.length; a++) t += String.fromCharCode(e[a]);
  return btoa(t);
}

function getImageData(e) {
  var t = e.width, a = e.height;
  return e.getContext("2d").getImageData(0, 0, t, a);
}

function makeURI(e, t) {
  return "data:" + t + ";base64," + e;
}

var genBitmapImage = function(e) {
  var t = e.width, a = e.height, n = t * a * 3, r = n + 54, o = [ 66, 77, 255 & r, r >> 8 & 255, r >> 16 & 255, r >> 24 & 255, 0, 0, 0, 0, 54, 0, 0, 0 ], g = [ 40, 0, 0, 0, 255 & t, t >> 8 & 255, t >> 16 & 255, t >> 24 & 255, 255 & a, a >> 8 & 255, a >> 16 & 255, a >> 24 & 255, 1, 0, 24, 0, 0, 0, 0, 0, 255 & n, n >> 8 & 255, n >> 16 & 255, n >> 24 & 255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ], i = (4 - 3 * t % 4) % 4, s = e.data, u = "", c = t << 2, m = a, v = String.fromCharCode;
  do {
    for (var p = c * (m - 1), f = "", d = 0; d < t; d++) {
      var l = d << 2;
      f += v(s[p + l + 2]) + v(s[p + l + 1]) + v(s[p + l]);
    }
    for (var I = 0; I < i; I++) f += String.fromCharCode(0);
    u += f;
  } while (--m);
  return encodeData(o.concat(g)) + encodeData(u);
}, saveAsImage = function(e, t, a, n) {
  if (support().canvas && support().dataURL) if ("string" == typeof e && (e = document.getElementById(e)), 
  null == n && (n = "png"), n = fixType(n), /bmp/.test(n)) {
    var r = getImageData(scaleCanvas(e, t, a));
    saveFile(makeURI(genBitmapImage(r), downloadMime));
  } else {
    saveFile(getDataURL(e, n, t, a).replace(n, downloadMime));
  }
}, convert2Image = function(e, t, a, n) {
  if (support().canvas && support().dataURL) {
    if ("string" == typeof e && (e = document.getElementById(e)), null == n && (n = "png"), 
    n = fixType(n), /bmp/.test(n)) {
      var r = getImageData(scaleCanvas(e, t, a));
      return genImage(makeURI(genBitmapImage(r), "image/bmp"));
    }
    return genImage(getDataURL(e, n, t, a));
  }
};

module.exports = {
  saveAsImage: saveAsImage,
  saveAsPNG: function(e, t, a) {
    return saveAsImage(e, t, a, "png");
  },
  saveAsJPEG: function(e, t, a) {
    return saveAsImage(e, t, a, "jpeg");
  },
  saveAsGIF: function(e, t, a) {
    return saveAsImage(e, t, a, "gif");
  },
  saveAsBMP: function(e, t, a) {
    return saveAsImage(e, t, a, "bmp");
  },
  convert2Image: convert2Image,
  convert2data: getDataURL,
  convert2Blob: getBlob,
  convert2PNG: function(e, t, a) {
    return convert2Image(e, t, a, "png");
  },
  convert2JPEG: function(e, t, a) {
    return convert2Image(e, t, a, "jpeg");
  },
  convert2GIF: function(e, t, a) {
    return convert2Image(e, t, a, "gif");
  },
  convert2BMP: function(e, t, a) {
    return convert2Image(e, t, a, "bmp");
  }
};