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POUnable to Generate png Image from Html 5 Canvas
 

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  1. POUnable to Generate png Image from Html 5 Canvas
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    <p>I've drawn a gradient image with a Bezier Curve on a HTML 5 Canvas like this:</p> <pre><code>var canvas = $('#canvas1')[0]; if (canvas.getContext) { var context = canvas.getContext('2d'); var gradient = context.createLinearGradient(0, 0, 0, 100); gradient.addColorStop(0, 'rgba(193,193,193,1)'); gradient.addColorStop(.20, 'rgba(160,160,160,1)'); gradient.addColorStop(.5, 'rgba(102,102,102,1)'); gradient.addColorStop(.7, 'rgba(91,91,91,1)'); gradient.addColorStop(.97, 'rgba(160,160,160,1)'); gradient.addColorStop(1, 'rgba(193,193,193,1)'); context.fillStyle = gradient; context.fillRect(0, 0, 500, 100); var gradient1 = context.createLinearGradient(0, 0, 0, 100); gradient1.addColorStop(0, '#a1a1a1'); gradient1.addColorStop(.5, '#717171'); gradient1.addColorStop(1, '#a1a1a1'); context.beginPath(); context.moveTo(0, 0); context.bezierCurveTo(0, 0, 20, 50, 0, 100); context.lineWidth = 1; //context.strokeStyle = 'black'; // line color //context.stroke(); context.fillStyle = gradient1; context.fill(); context.closePath(); } </code></pre> <p>Now I want to save this image on HDD, for this I have formed this request:</p> <pre><code>var canvas = $('#canvas1')[0]; if (canvas.getContext) { var context = canvas.getContext('2d'); $.ajax({ url: '/Html5/Export', type: 'POST', data: 'img=' + escape(canvas.toDataURL("image/png")), success: function (data) { alert('data exported'); } }); } </code></pre> <p>On this server side, I've written this code (ASP.NET C#):</p> <pre><code>[HttpPost] public ActionResult Export() { string img = Request.Params["img"]; ConvertThis(img); return Content("true"); } public void ConvertThis(string ImageText) { if (ImageText.Length &gt; 0) { ImageText = ImageText.Substring(ImageText.IndexOf(",") + 1); Byte[] bitmapData; bitmapData = Convert.FromBase64String(ImageText); System.IO.File.WriteAllBytes(@"c:\logs\random.png", bitmapData); } } </code></pre> <p>But the image generated on the server side is totally different from the image drawn on the Html5 Canvas <img src="https://i.stack.imgur.com/gbbcG.png" alt="Server Image">.</p> <p>What am I doing wrong here..</p>
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    1. USNitin Agarwal
    1. USNitin Agarwal
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      1. POUnable to Generate png Image from Html 5 Canvas
      1. USjozecuervo
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      1. POUnable to Generate png Image from Html 5 Canvas
      1. USstephenwil
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    1. COIn what way is it different?
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    2. COIt is just a transparent image with nothing in it.. Actually I have attached that image in this code. Just before the last line of question there is an image which is generated through this program.
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      1. USNitin Agarwal
 

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