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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<style type=''>
html {
font-family: helvetica, sans-serif;
}
canvas, img {
margin: 10px;
border: 1px solid grey;
}
.example {
display: inline-block;
width: 280px;
margin-top: 50px;
margin-right: 50px;
}
.title {
text-align: center;
}
.description {
width: 100%;
}
.description div {
display: inline-block;
text-align: center;
font-size: 13px;
}
.description .source {
width: 100px;
}
.description .target {
width: 130px;
}
.example-title {
text-align: center;
font-size: 16px;
}
.error {
color: red;
}
</style>
<body>
<h1 class="title">DrawImage canvas to canvas</h1>
</body>
<script type="text/javascript">
var smoothingEnabled = false;
var examplesNum = 0;
var imageSource = {
width: 100,
height: 100
};
var destCanvas = {
width: 100,
height: 100
};
// 2 arguments, the dest origin is 0,0
// The source canvas will copied to the 0,0 position of the destination canvas
drawImage(0, 0);
// 2 arguments, the dest origin is not 0,0
// The source canvas will copied to the 25, 25 position of the destination canvas
drawImage(25, 25);
// 4 arguments, the source origin is not 0,0, the dest size is provided
// The source canvas will copied to the 50, 50 position of the destination canvas and
// on an area of 50x50 pixels
drawImage(50, 50, 50, 50);
// 4 arguments, the dest origin is not 0,0 and the dest size is provided but
// does not match the size of the source. The image will be distorted
// The source canvas will copied to the 50,50 position of the destination canvas
// and it will be shrunk to a and area of 25x25
drawImage(50, 50, 25, 25);
// The source canvas will copied to the 50,50 position of the destination canvas
// over an area of 50x25 pixels
// The copied image will be distorted along the x axis
drawImage(50, 50, 50, 25);
// 8 arguments, both destination and source origins are 0, 0
// An area of 25x25 pixels of the source image will be copied to
// an area of 25x25 pixels of the destination canvas
drawImage(0, 0, 25, 25, 0, 0, 25, 25);
// 8 arguments the destination origin is not 0,0
// An area of 25x25 pixels of the source image will be copied to
// an area of 25x25 pixels of the destination canvas in the position 25,25
drawImage(0, 0, 25, 25, 25, 25, 25, 25);
// The source rectangle overflows the source image
// The source area is clipped to fit the source image
// and the destination are is clipped in the same proportion
drawImage(25, 25, 50, 50, 0, 0, 50, 50);
// The destination rectangle has negative width and height
// An exception is raised and nothing is drawn
drawImage(25, 25, 50, 50, 0, 0, -100, -100);
// The destination rectangle is larger thant the destination canvas
// When the destination rectangle is outside the destination image (the scratch bitmap), the pixels
// that land outside the scratch bitmap are discarded, as if the destination was an infinite canvas
// whose rendering was clipped to the dimensions of the scratch bitmap.
drawImage(0, 0, 50, 50, 0, 0, 200, 200);
// The source rectangle is larger than the source canvas
// The source area is clipped to fit the source image
// and the destination are is clipped in the same proportion
drawImage(0, 0, 100, 100, 0, 0, 50, 50);
// Negative coorditanes of the source rectangle
// The source area is clipped to fit the source image
// and the destination are is clipped in the same proportion
drawImage(-25, -25, 50, 50, 0, 0, 50, 50);
// Example with non squared origin and source canvases
imageSource = {
width: 100,
height: 50
};
destCanvas = {
width: 100,
height: 50
};
//drawImage(0, 0);
function renderExample(title) {
var container = document.createElement('div');
container.id = 'example' + examplesNum++;
container.setAttribute('class', 'example');
var h2 = document.createElement('h2');
h2.textContent = title;
h2.setAttribute('class', 'example-title');
container.appendChild(h2);
var div1 = document.createElement('div');
var canvas1 = document.createElement('canvas');
var img = document.createElement('img');
img.src = 'rust-0.png';
div1.appendChild(img);
div1.appendChild(canvas1);
container.appendChild(div1);
var div2 = document.createElement('div');
div2.setAttribute('class', 'description');
var source = document.createElement('div');
source.textContent = ' Source (' + imageSource.width + ',' + imageSource.height + ')';
source.setAttribute('class', 'source');
var arrow = document.createElement('div');
arrow.textContent = ' -> ';
arrow.setAttribute('class', 'arrow');
var target = document.createElement('div');
target.textContent = 'Target (' + destCanvas.width + ',' + destCanvas.height + ')';
target.setAttribute('class', 'target');
div2.appendChild(source);
div2.appendChild(arrow);
div2.appendChild(target);
container.appendChild(div2);
return container;
}
function drawImage() {
var args = Array.prototype.slice.call(arguments);
var div = renderExample('drawImage(' + args.toString() + ')');
var canvas = div.querySelectorAll('canvas')[0];
var img = div.querySelectorAll('img')[0];
img.width = imageSource.width;
img.height = imageSource.height;
canvas.width = destCanvas.width;
canvas.height = destCanvas.height;
var ctx = canvas.getContext('2d');
ctx.fillStyle = "#FF0000";
ctx.fillRect(0, 0, destCanvas.width, destCanvas.height);
ctx.imageSmoothingEnabled = smoothingEnabled;
args.unshift(img);
try {
ctx.drawImage.apply(ctx, args);
}
catch(err) {
var title = div.querySelector('.example-title');
var error = document.createElement('h2');
error.setAttribute('class', 'example-title error');
div.insertBefore(error, title);
error.textContent += "Call Failed: " + err.message;
}
document.body.appendChild(div);
}
</script>
</body>
</html>
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