Last active
October 6, 2015 10:27
-
-
Save kotarou3/f5b918b01eb808ab1f18 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
<!DOCTYPE html> | |
<section> | |
<input type="file" id="input" /> | |
<input type="number" id="maxWidth" /> × <input type="number" id="maxHeight" /> | |
<button onclick="convert()">Convert</button> | |
</section> | |
<section><pre id="output"></pre></section> | |
<section><img id="outputImage"></pre></section> | |
<script type="application/javascript"> | |
function convert() { | |
var image = new Image; | |
image.onload = function () { | |
var width = image.width; | |
var height = image.height; | |
var maxWidth = parseInt(document.getElementById("maxWidth").value, 10) || Infinity; | |
var maxHeight = parseInt(document.getElementById("maxHeight").value, 10) || Infinity; | |
var scale = Math.max(1, height / maxHeight, width / maxWidth); | |
width /= scale; | |
height /= scale; | |
var canvas = document.createElement("canvas"); | |
canvas.width = width; | |
canvas.height = height; | |
canvas.getContext("2d").drawImage(image, 0, 0, width, height); | |
URL.revokeObjectURL(image.src); | |
var result = canvas.toDataURL("image/png"); | |
document.getElementById("output").textContent = result; | |
document.getElementById("outputImage").src = result; | |
}; | |
image.onerror = alert.bind(window, "Not an image!"); | |
image.src = URL.createObjectURL(document.getElementById("input").files[0]); | |
} | |
</script> |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment