69 lines
1.8 KiB
JavaScript
69 lines
1.8 KiB
JavaScript
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window.onload = main;
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var canvas;
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var dgl_input;
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var rgnlum;
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var rgncon;
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var rgnsat;
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var img;
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var ratio;
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var topmargin;
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var leftmargin;
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var ctx;
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function main() {
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console.log("JS Loaded");
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canvas = document.getElementById("canvastp1");
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dgl_input = document.getElementById('files');
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dgl_input.addEventListener('change', handleFileSelect, false);
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console.log("Event Listener added");
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ctx = canvas.getContext('2d');
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setRnglum();
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setRngcon();
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setRngsat();
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}
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function setRnglum() {
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rgnlum = document.getElementById('rgnlum');
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rgnlum.oninput = updateFilters;
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}
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function setRngcon() {
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rgncon = document.getElementById('rgncon');
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rgncon.oninput = updateFilters;
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}
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function setRngsat() {
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rgnsat = document.getElementById('rgnsat');
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rgnsat.oninput = updateFilters;
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}
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function updateFilters() {
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ctx.filter =
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'brightness(' + rgnlum.value + '%)' +
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' contrast(' + rgncon.value + '%)' +
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' saturate(' + rgnsat.value + '%)';
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ctx.drawImage(img, 0, 0,
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img.width, img.height,
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leftmargin, topmargin,
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img.width * ratio, img.height * ratio);
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}
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function handleFileSelect(e) {
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var ctx = canvas.getContext('2d');
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img = new Image;
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img.onload = function() {
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ctx.clearRect(0, 0, canvas.width, canvas.height);
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var hRatio = canvas.width / img.width;
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var vRatio = canvas.height / img.height;
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ratio = Math.min(hRatio, vRatio);
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topmargin = (canvas.height - img.height * ratio) / 2;
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leftmargin = (canvas.width - img.width * ratio) / 2;
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ctx.drawImage(img, 0, 0,
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img.width, img.height,
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leftmargin, topmargin,
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img.width * ratio, img.height * ratio);
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};
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img.src = URL.createObjectURL(e.target.files[0]);
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}
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