Javascript 如何将画布保存为png图像?
我有一个画布元素,其中有一个图形,我想创建一个按钮,当单击该按钮时,它会将图像保存为png文件。所以它应该打开“保存、打开、关闭”对话框 我是用这个代码做的Javascript 如何将画布保存为png图像?,javascript,html,canvas,png,save-image,Javascript,Html,Canvas,Png,Save Image,我有一个画布元素,其中有一个图形,我想创建一个按钮,当单击该按钮时,它会将图像保存为png文件。所以它应该打开“保存、打开、关闭”对话框 我是用这个代码做的 var canvas = document.getElementById("myCanvas"); window.open(canvas.toDataURL("image/png")); 但当我在IE9中进行测试时,会打开一个新窗口,显示“网页无法显示” 其网址为: data:image/png;b
var canvas = document.getElementById("myCanvas");
window.open(canvas.toDataURL("image/png"));
但当我在IE9中进行测试时,会打开一个新窗口,显示“网页无法显示”
其网址为:
data:image/png;base64,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
有人知道如何解决这个问题吗?试试这个:
var canvas = document.getElementById("alpha");
var dataURL = canvas.toDataURL("image/png");
var newTab = window.open('about:blank','image from canvas');
newTab.document.write("<img src='" + dataURL + "' alt='from canvas'/>");
应该能在这里帮助你
var canvas = document.getElementById("my-canvas");
// draw to canvas...
canvas.toBlob(function(blob) {
saveAs(blob, "pretty image.png");
});
我可能发现了一种更好的方法,可以不强迫用户右键单击并“将图像另存为”。实时将画布base64代码绘制到链接的
href
中,并对其进行修改,以便自动开始下载。我不知道它是否与浏览器兼容,但是
您可以将
包装在您想要的任何内容周围。我使用此解决方案设置文件名:
HTML:
试试这个:
jQuery('body').after('<a id="Download" target="_blank">Click Here</a>');
var canvas = document.getElementById('canvasID');
var ctx = canvas.getContext('2d');
document.getElementById('Download').addEventListener('click', function() {
downloadCanvas(this, 'canvas', 'test.png');
}, false);
function downloadCanvas(link, canvasId, filename) {
link.href = document.getElementById(canvasId).toDataURL();
link.Download = filename;
}
jQuery('body')。在('Click Here')之后;
var canvas=document.getElementById('canvasID');
var ctx=canvas.getContext('2d');
document.getElementById('Download').addEventListener('click',function(){
下载画布(这是“canvas”、“test.png”);
},假);
函数downloadCanvas(链接、canvasId、文件名){
link.href=document.getElementById(canvasId.toDataURL();
link.Download=文件名;
}
您可以将此代码放在firefox或chrom的控制台中,在上面的脚本中更改画布标记ID后,在控制台中运行此脚本
执行此代码后,您将在html页面底部看到文本“单击此处”的链接。单击此链接并在“保存图像”的新窗口中将画布图形作为PNG图像打开 我遇到了这个问题,这是没有任何外部或附加脚本库的最佳解决方案: 在Javascript标记或文件中创建此函数: 我们在此假设画布是您的画布:
function download(){
var download = document.getElementById("download");
var image = document.getElementById("canvas").toDataURL("image/png")
.replace("image/png", "image/octet-stream");
download.setAttribute("href", image);
}
在HTML的正文部分指定按钮:
<a id="download" download="image.png"><button type="button" onClick="download()">Download</button></a>
下载
这是工作和下载链接看起来像一个按钮。在Firefox和Chrome中测试。提交一个表单,其中包含一个输入值为canvas toDataURL('image/png'),例如 //JAVASCRIPT
var canvas = document.getElementById("canvas");
var url = canvas.toDataUrl('image/png');
将url的值插入表单元素上的隐藏输入
//PHP
var canvasId=chart.id+'-canvas';
var canvasdownloaddid=chart.id+'-下载画布';
var canvasHtml=Ext.String.format(“”,
拉瓦西德,
chart.getWidth(),
chart.getHeight(),
canvasDownloadId);
var canvascelement=reportBuilder.add({html:canvasHtml});
var canvas=document.getElementById(canvasId);
var canvasDownload=document.getElementById(canvasDownloadId);
canvasDownload.href=chart.getImage().data;
canvasDownload.download='chart';
canvassdownload.click();
完整的HTML代码。剪切并粘贴到新的.HTML文件中:
包含两个示例:
#保存画布测试
说明:
如何从HTML页面保存画布李>
如何保存动态创建的画布
保存画布(动态生成的画布)
保存画布(HTML代码中的画布)
var obj=新的MyTestCodeClass();
函数MyTestCodeClass(){
//公开披露的职能:
this.SAVE_CANVAS=保存_CANVAS;
//:私人:
var_画布;
var\u canvas\u id=“id\u OF\u DYNAMIC\u canvas”;
var\u name\u hash\u计数器=0;
//:创建画布:
(函数_构造函数(){
var D=文件;
var CE=D.createElement.bind(D);
_画布=CE(“画布”);
_画布宽度=300;
_帆布。高度=300;
_canvas.id=\u canvas\u id;
})();
//:保存画布之前,请将其填充为
//:我们可以看到它。用于演示代码。
函数_fillCanvas(输入_canvas,r,g,b){
var ctx=input_canvas.getContext(“2d”);
var c=输入值;
ctx.fillStyle=“rgb(“+r+”、“+g+”、“+b+”);
ctx.fillRect(0,0,c.宽度,c.高度);
}
//:保存画布。如果提供了可选的\u id,
//:将从DOM中保存画布。如果不是,
//:将保存动态创建的画布。
函数保存\u画布(可选\u id){
var c=\u getCanvas(可选的\u id);
//:调试代码:来自DOM的彩色画布
//:绿色,内部画布红色。
if(可选的_id){
_(c,0255,0);
}否则{
_填充画布(c,255,0,0);
}
_(c);
}
//:如果提供了可选的\u id,则获取画布
//:从DOM。否则,动态获取内部
//:已创建画布。
函数\u getCanvas(可选\u id){
var c=null;//:画布。
if(可选的类型_id==“字符串”){
var id=可选的_id;
var d=文件;
var c=d.getElementById(id);
}否则{
c=_画布;
}
返回c;
}
函数_saveCanvas(画布){
如果(!window){alert(“[window\u IS\u NULL]”;}
//:我们想给这个窗口一个独特的
//:名称以便我们可以多次保存
//:无需关闭上一个
//:窗户。
_name_hash_counter++;
var NHC=_name_hash_计数器;
var URL='about:blank';
变量名称='UNIQUE_WINDOW_ID'+NHC;
var w=window.open(URL、名称);
如果(!w){alert([w_IS_NULL]”;}
//:创建页面内容,
//:然后设置互动程序。顺序很重要。
var DW=“”;
DW+=”;
w、 文件编写(DW);
w、 document.title=“NHC”+NHC;
}
}//:末班
要容纳所有三点:
- 钮扣
- 将图像另存为png文件
- 打开保存,打开,关闭di
jQuery('body').after('<a id="Download" target="_blank">Click Here</a>'); var canvas = document.getElementById('canvasID'); var ctx = canvas.getContext('2d'); document.getElementById('Download').addEventListener('click', function() { downloadCanvas(this, 'canvas', 'test.png'); }, false); function downloadCanvas(link, canvasId, filename) { link.href = document.getElementById(canvasId).toDataURL(); link.Download = filename; }
function download(){ var download = document.getElementById("download"); var image = document.getElementById("canvas").toDataURL("image/png") .replace("image/png", "image/octet-stream"); download.setAttribute("href", image); }
<a id="download" download="image.png"><button type="button" onClick="download()">Download</button></a>
var canvas = document.getElementById("canvas"); var url = canvas.toDataUrl('image/png');
$data = $_POST['photo']; $data = str_replace('data:image/png;base64,', '', $data); $data = base64_decode($data); file_put_contents("i". rand(0, 50).".png", $data);
var canvasId = chart.id + '-canvas'; var canvasDownloadId = chart.id + '-download-canvas'; var canvasHtml = Ext.String.format('<canvas id="{0}" width="{1}" height="{2}"></canvas><a id="{3}"/>', canvasId, chart.getWidth(), chart.getHeight(), canvasDownloadId); var canvasElement = reportBuilder.add({ html: canvasHtml }); var canvas = document.getElementById(canvasId); var canvasDownload = document.getElementById(canvasDownloadId); canvasDownload.href = chart.getImage().data; canvasDownload.download = 'chart'; canvasDownload.click();
<!DOCTYPE HTML > <html lang="en"> <head> <meta charset="UTF-8"> <title> #SAVE_CANVAS_TEST# </title> <meta name ="author" content="John Mark Isaac Madison" > <!-- EMAIL: J4M4I5M7 -[AT]- Hotmail.com --> </head> <body> <div id="about_the_code"> Illustrates: <ol> <li>How to save a canvas from HTML page. </li> <li>How to save a dynamically created canvas.</li> </ol> </div> <canvas id="DOM_CANVAS" width ="300" height="300" ></canvas> <div id="controls"> <button type="button" style="width:300px;" onclick="obj.SAVE_CANVAS()"> SAVE_CANVAS ( Dynamically Made Canvas ) </button> <button type="button" style="width:300px;" onclick="obj.SAVE_CANVAS('DOM_CANVAS')"> SAVE_CANVAS ( Canvas In HTML Code ) </button> </div> <script> var obj = new MyTestCodeClass(); function MyTestCodeClass(){ //Publically exposed functions: this.SAVE_CANVAS = SAVE_CANVAS; //:Private: var _canvas; var _canvas_id = "ID_OF_DYNAMIC_CANVAS"; var _name_hash_counter = 0; //:Create Canvas: (function _constructor(){ var D = document; var CE = D.createElement.bind(D); _canvas = CE("canvas"); _canvas.width = 300; _canvas.height= 300; _canvas.id = _canvas_id; })(); //:Before saving the canvas, fill it so //:we can see it. For demonstration of code. function _fillCanvas(input_canvas, r,g,b){ var ctx = input_canvas.getContext("2d"); var c = input_canvas; ctx.fillStyle = "rgb("+r+","+g+","+b+")"; ctx.fillRect(0, 0, c.width, c.height); } //:Saves canvas. If optional_id supplied, //:will save canvas off the DOM. If not, //:will save the dynamically created canvas. function SAVE_CANVAS(optional_id){ var c = _getCanvas( optional_id ); //:Debug Code: Color canvas from DOM //:green, internal canvas red. if( optional_id ){ _fillCanvas(c,0,255,0); }else{ _fillCanvas(c,255,0,0); } _saveCanvas( c ); } //:If optional_id supplied, get canvas //:from DOM. Else, get internal dynamically //:created canvas. function _getCanvas( optional_id ){ var c = null; //:canvas. if( typeof optional_id == "string"){ var id = optional_id; var d = document; var c = d.getElementById( id ); }else{ c = _canvas; } return c; } function _saveCanvas( canvas ){ if(!window){ alert("[WINDOW_IS_NULL]"); } //:We want to give the window a unique //:name so that we can save multiple times //:without having to close previous //:windows. _name_hash_counter++ ; var NHC = _name_hash_counter ; var URL = 'about:blank' ; var name= 'UNIQUE_WINDOW_ID' + NHC; var w=window.open( URL, name ) ; if(!w){ alert("[W_IS_NULL]");} //:Create the page contents, //:THEN set the tile. Order Matters. var DW = "" ; DW += "<img src='" ; DW += canvas.toDataURL("image/png"); DW += "' alt='from canvas'/>" ; w.document.write(DW) ; w.document.title = "NHC"+NHC ; } }//:end class </script> </body> <!-- In IE: Script cannot be outside of body. --> </html>
function DownloadCanvasAsImage(){ let downloadLink = document.createElement('a'); downloadLink.setAttribute('download', 'CanvasAsImage.png'); let canvas = document.getElementById('myCanvas'); let dataURL = canvas.toDataURL('image/png'); let url = dataURL.replace(/^data:image\/png/,'data:application/octet-stream'); downloadLink.setAttribute('href', url); downloadLink.click(); }
function DownloadCanvasAsImage(){ let downloadLink = document.createElement('a'); downloadLink.setAttribute('download', 'CanvasAsImage.png'); let canvas = document.getElementById('myCanvas'); canvas.toBlob(function(blob) { let url = URL.createObjectURL(blob); downloadLink.setAttribute('href', url); downloadLink.click(); }); }
function prepDownload(a, canvas, name) { a.download = name a.href = canvas.toDataURL() }
<a href="#" onclick="prepDownload(this, document.getElementById('canvasId'), 'imgName.png')">Download</a> <canvas id="canvasId"></canvas>