/*
 * Canvas2Image v0.1
 * Copyright (c) 2008 Jacob Seidelin, jseidelin@nihilogic.dk
 * MIT License [http://www.opensource.org/licenses/mit-license.php]
 */

/*
* utilisé par Rosette pour impression corpus
*/

var Canvas2Image = (function() {

	// check if we have canvas support
	var bHasCanvas = false;
	var oCanvas = document.createElement("canvas");
	if (oCanvas.getContext("2d")) {
		bHasCanvas = true;
	}

	// no canvas, bail out.
	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;name=aaa";
//	var strDownloadMime = "image/octet-stream";

	// ok, we're good
	var readCanvasData = function(oCanvas) {
		var iWidth = parseInt(oCanvas.width);
		var iHeight = parseInt(oCanvas.height);
		return oCanvas.getContext("2d").getImageData(0,0,iWidth,iHeight);
	}

	// base64 encodes either a string or an array of charcodes
	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);
	}

	// creates a base64 encoded string containing BMP data
	// takes an imagedata object as argument
	var createBMP = function(oData) {
		var aHeader = [];
	
		var iWidth = oData.width;
		var iHeight = oData.height;

		aHeader.push(0x42); // magic 1
		aHeader.push(0x4D); 
	
		var iFileSize = iWidth*iHeight*3 + 54; // total header size = 54 bytes
		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); // reserved
		aHeader.push(0);
		aHeader.push(0); // reserved
		aHeader.push(0);

		aHeader.push(54); // dataoffset
		aHeader.push(0);
		aHeader.push(0);
		aHeader.push(0);

		var aInfoHeader = [];
		aInfoHeader.push(40); // info header size
		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); // num of planes
		aInfoHeader.push(0);
	
		aInfoHeader.push(24); // num of bits per pixel
		aInfoHeader.push(0);
	
		aInfoHeader.push(0); // compression = none
		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);	// these bytes not used
		}
	
		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;
	}


	// sends the generated file to the client
	var saveFile = function(strData)
		{
f=window.open( 'about:blank', 'azaza' );
f.document.write('<img src="' + strData + '">');
alert( "l'image a été téléchargée sur votre micro-ordinateur. Renommez le fichier téléchargé en remplaçant l'extension .part par .png ou .jpg" );
		}

	var makeDataURI = function(strData, strMime) {
		return "data:" + strMime + ";base64," + strData;
	}

	// generates a <img> object containing the imagedata
	var makeImageObject = function(strSource)
		{
		f=window.open( 'about:blank', 'azaza' );
		f.focus();
		f.document.write('<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><link href="assets/rosette.ico" rel="SHORTCUT ICON"><head></head>');
		f.document.write('<body><img id="lImg" name="azerty">');
		f.document.write('<br><hr><br><span style="font-weight:bold">Clique droit sur l\'image pour l\'enregistrer</span></body></html>');
		f.document.close();
		f.document.getElementById('lImg').src = strSource;
		return f.document.getElementById('lImg');
		}

	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 not, return false
			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;
		}
	};

})();