求救 ..为什么使用 html2canvas 转化的 canvas 不能调用 toDataURL 方法?????????

[u011141772]

我先用 html2canvas 把dom转化成 canvas

//将dom树转换为canvas
	function print_body() {
		var test = $('div.helloworld');
		html2canvas(test, {
			onrendered : function(canvas) {
				document.body.appendChild(canvas);
			}
		});
		alert(test)
//然后调用下载的方法
 download_canvas(test);
}

//将canvas画板导出
	function download_canvas(oCanvas) {

		var bMouseIsDown = false;
		//var oCanvas = document.getElementById("thecanvas");

		oCanvas.onmousedown = function(e) {
			bMouseIsDown = true;
			iLastX = e.clientX
					- oCanvas.offsetLeft
					+ (window.pageXOffset || document.body.scrollLeft || document.documentElement.scrollLeft);
			iLastY = e.clientY
					- oCanvas.offsetTop
					+ (window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop);
		}
		oCanvas.onmouseup = function() {
			bMouseIsDown = false;
			iLastX = -1;
			iLastY = -1;
		}
		oCanvas.onmousemove = function(e) {
			if (bMouseIsDown) {
				var iX = e.clientX
						- oCanvas.offsetLeft
						+ (window.pageXOffset || document.body.scrollLeft || document.documentElement.scrollLeft);
				var iY = e.clientY
						- oCanvas.offsetTop
						+ (window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop);
				iLastX = iX;
				iLastY = iY;
			}
		}

		function showDownloadText() {
			document.getElementById("buttoncontainer").style.display = "none";
			document.getElementById("textdownload").style.display = "block";
		}

		function hideDownloadText() {
			document.getElementById("buttoncontainer").style.display = "block";
			document.getElementById("textdownload").style.display = "none";
		}

		function convertCanvas(strType) {
			if (strType == "JPEG") {
				var oImg = Canvas2Image.saveAsJPEG(oCanvas, true);
			}
			if (!oImg) {
				alert("Sorry, this browser is not capable of saving " + strType
						+ " files!");
				return false;
			}

			oImg.id = "canvasimage";

			oImg.style.border = oCanvas.style.border;
			oCanvas.parentNode.replaceChild(oImg, oCanvas);

			showDownloadText();
		}

		saveCanvas(oCanvas, "JPEG");//在这里报错 说 无法找到 toDataURL 方法 
		function saveCanvas(pCanvas, strType) {
			var bRes = false;
			if (strType == "JPEG") {
				bRes = Canvas2Image.saveAsJPEG(oCanvas);
			}
			if (!bRes) {
				alert("Sorry, this browser is not capable of saving " + strType
						+ " files!");
				return false;
			}
		}
}

之前我写好了一个 canvas 然后直接调用下载方法就可以 正常下载 为什么 html2canvas 生成的canvas 就不能调用呢

[u011141772]

求 版主 showbo 解答啊

[u011141772]

[functionsub]

难道你就没发现你传进去的实际参数是一个jquery对象么？

function print_body() {
        var test = $('div.helloworld');
        html2canvas(test, {
            onrendered : function(canvas) {
                document.body.appendChild(canvas);
                //canvas生成之后，然后调用下载的方法
                download_canvas(canvas);
            }
        });
}

应该这样吧

[u011141772]

引用 3 楼 functionsub 的回复:

难道你就没发现你传进去的实际参数是一个jquery对象么？

function print_body() {
        var test = $('div.helloworld');
        html2canvas(test, {
            onrendered : function(canvas) {
                document.body.appendChild(canvas);
                //canvas生成之后，然后调用下载的方法
                download_canvas(canvas);
            }
        });
}

应该这样吧

给大神跪了 leader说我粗心 。。果然是这样