var Canvas2Image = (function () {
var bHasCanvas = false;
var oCanvas = document.createElement("canvas");
if (oCanvas.getContext("2d")) {
bHasCanvas = true;
}
if (!bHasCanvas) {
return {
saveAsBMP: function () {},
saveAsPNG: function () {},
saveAsJPEG: function () {}
}
}
var bHasImageData = !! (oCanvas.getContext("2d").getImageData);
var bHasDataURL = !! (oCanvas.toDataURL);
var bHasBase64 = !! (window.btoa);
var strDownloadMime = "image/octet-stream";
var readCanvasData = function (oCanvas) {
var iWidth = parseInt(oCanvas.width);
var iHeight = parseInt(oCanvas.height);
return oCanvas.getContext("2d").getImageData(0, 0, iWidth, iHeight);
}
var encodeData = function (data) {
var strData = "";
if (typeof data == "string") {
strData = data;
} else {
var aData = data;
for (var i = 0; i < aData.length; i++) {
strData += String.fromCharCode(aData[i]);
}
}
return btoa(strData);
}
var createBMP = function (oData) {
var aHeader = [];
var iWidth = oData.width;
var iHeight = oData.height;
aHeader.push(0x42);
aHeader.push(0x4D);
var iFileSize = iWidth * iHeight * 3 + 54;
aHeader.push(iFileSize % 256);
iFileSize = Math.floor(iFileSize / 256);
aHeader.push(iFileSize % 256);
iFileSize = Math.floor(iFileSize / 256);
aHeader.push(iFileSize % 256);
iFileSize = Math.floor(iFileSize / 256);
aHeader.push(iFileSize % 256);
aHeader.push(0);
aHeader.push(0);
aHeader.push(0);
aHeader.push(0);
aHeader.push(54);
aHeader.push(0);
aHeader.push(0);
aHeader.push(0);
var aInfoHeader = [];
aInfoHeader.push(40);
aInfoHeader.push(0);
aInfoHeader.push(0);
aInfoHeader.push(0);
var iImageWidth = iWidth;
aInfoHeader.push(iImageWidth % 256);
iImageWidth = Math.floor(iImageWidth / 256);
aInfoHeader.push(iImageWidth % 256);
iImageWidth = Math.floor(iImageWidth / 256);
aInfoHeader.push(iImageWidth % 256);
iImageWidth = Math.floor(iImageWidth / 256);
aInfoHeader.push(iImageWidth % 256);
var iImageHeight = iHeight;
aInfoHeader.push(iImageHeight % 256);
iImageHeight = Math.floor(iImageHeight / 256);
aInfoHeader.push(iImageHeight % 256);
iImageHeight = Math.floor(iImageHeight / 256);
aInfoHeader.push(iImageHeight % 256);
iImageHeight = Math.floor(iImageHeight / 256);
aInfoHeader.push(iImageHeight % 256);
aInfoHeader.push(1);
aInfoHeader.push(0);
aInfoHeader.push(24);
aInfoHeader.push(0);
aInfoHeader.push(0);
aInfoHeader.push(0);
aInfoHeader.push(0);
aInfoHeader.push(0);
var iDataSize = iWidth * iHeight * 3;
aInfoHeader.push(iDataSize % 256);
iDataSize = Math.floor(iDataSize / 256);
aInfoHeader.push(iDataSize % 256);
iDataSize = Math.floor(iDataSize / 256);
aInfoHeader.push(iDataSize % 256);
iDataSize = Math.floor(iDataSize / 256);
aInfoHeader.push(iDataSize % 256);
for (var i = 0; i < 16; i++) {
aInfoHeader.push(0);
}
var iPadding = (4 - ((iWidth * 3) % 4)) % 4;
var aImgData = oData.data;
var strPixelData = "";
var y = iHeight;
do {
var iOffsetY = iWidth * (y - 1) * 4;
var strPixelRow = "";
for (var x = 0; x < iWidth; x++) {
var iOffsetX = 4 * x;
strPixelRow += String.fromCharCode(aImgData[iOffsetY + iOffsetX + 2]);
strPixelRow += String.fromCharCode(aImgData[iOffsetY + iOffsetX + 1]);
strPixelRow += String.fromCharCode(aImgData[iOffsetY + iOffsetX]);
}
for (var c = 0; c < iPadding; c++) {
strPixelRow += String.fromCharCode(0);
}
strPixelData += strPixelRow;
} while (--y);
var strEncoded = encodeData(aHeader.concat(aInfoHeader)) + encodeData(strPixelData);
return strEncoded;
}
var saveFile = function (strData) {
document.location.href = strData;
}
var makeDataURI = function (strData, strMime) {
return "data:" + strMime + ";base64," + strData;
}
var makeImageObject = function (strSource) {
var oImgElement = document.createElement("img");
oImgElement.src = strSource;
return oImgElement;
}
var scaleCanvas = function (oCanvas, iWidth, iHeight) {
if (iWidth && iHeight) {
var oSaveCanvas = document.createElement("canvas");
oSaveCanvas.width = iWidth;
oSaveCanvas.height = iHeight;
oSaveCanvas.style.width = iWidth + "px";
oSaveCanvas.style.height = iHeight + "px";
var oSaveCtx = oSaveCanvas.getContext("2d");
oSaveCtx.drawImage(oCanvas, 0, 0, oCanvas.width, oCanvas.height, 0, 0, iWidth, iHeight);
return oSaveCanvas;
}
return oCanvas;
}
return {
saveAsPNG: function (oCanvas, bReturnImg, iWidth, iHeight) {
if (!bHasDataURL) {
return false;
}
var oScaledCanvas = scaleCanvas(oCanvas, iWidth, iHeight);
var strData = oScaledCanvas.toDataURL("image/png");
if (bReturnImg) {
return makeImageObject(strData);
} else {
saveFile(strData.replace("image/png", strDownloadMime));
}
return true;
},
saveAsJPEG: function (oCanvas, bReturnImg, iWidth, iHeight) {
if (!bHasDataURL) {
return false;
}
var oScaledCanvas = scaleCanvas(oCanvas, iWidth, iHeight);
var strMime = "image/jpeg";
var strData = oScaledCanvas.toDataURL(strMime);
if (strData.indexOf(strMime) != 5) {
return false;
}
if (bReturnImg) {
return makeImageObject(strData);
} else {
saveFile(strData.replace(strMime, strDownloadMime));
}
return true;
},
saveAsBMP: function (oCanvas, bReturnImg, iWidth, iHeight) {
if (!(bHasImageData && bHasBase64)) {
return false;
}
var oScaledCanvas = scaleCanvas(oCanvas, iWidth, iHeight);
var oData = readCanvasData(oScaledCanvas);
var strImgData = createBMP(oData);
if (bReturnImg) {
return makeImageObject(makeDataURI(strImgData, "image/bmp"));
} else {
saveFile(makeDataURI(strImgData, strDownloadMime));
}
return true;
}
};
})();