轉換帆布爲PDF格式：黑色背景

Question

我想我的HTML畫布導出爲PDF和下載它，我做了一些搜索和下面的腳本正常工作與我：

<script language = "JAVASCRIPT"> 
var canvas = document.getElementById('mycanvas'); 

var context = canvas.getContext('2d'); 

// draw a blue cloud 
context.beginPath(); 
context.moveTo(170, 80); 
context.bezierCurveTo(130, 100, 130, 150, 230, 150); 
context.bezierCurveTo(250, 180, 320, 180, 340, 150); 
context.bezierCurveTo(420, 150, 420, 120, 390, 100); 
context.bezierCurveTo(430, 40, 370, 30, 340, 50); 
context.bezierCurveTo(320, 5, 250, 20, 250, 50); 
context.bezierCurveTo(200, 5, 150, 20, 170, 80); 
context.closePath(); 
context.lineWidth = 5; 
context.fillStyle = '#8ED6FF'; 
context.fill(); 
context.strokeStyle = '#0000ff'; 
context.stroke(); 

download.addEventListener("click", function() { 
// only jpeg is supported by jsPDF 
var imgData = canvas.toDataURL("image/jpeg", 1.0); 
var pdf = new jsPDF(); 

pdf.addImage(imgData, 'JPEG', 0, 0); 
var download = document.getElementById('download'); 

pdf.save("download.pdf"); 
}, false); 
</script> 

但我得到我的畫布與黑色背景！

我已經嘗試過其他的代碼和許多解決方案，我在互聯網上找到，我試圖改變canvas標籤的背景顏色，什麼事也沒有工作..

任何幫助嗎？

Answer 1

，而無需下載作爲JPEG的，嘗試下載一個PNG：

download.addEventListener("click", function() { 
// only jpeg is supported by jsPDF 
var imgData = canvas.toDataURL("image/png", 1.0); 
var pdf = new jsPDF(); 

pdf.addImage(imgData, 'PNG', 0, 0); 
var download = document.getElementById('download'); 

pdf.save("download.pdf"); 
}, false);