假设你是一个前端程序员,希望你能够生成一个从本地读取图片到网页的canvas上,这个canvas具有固定大小,并且支持鼠标的滚轮对它放大缩小,希望你利用这个本地的opencv.js库实现对图像数据的插值,实现图像在放大过程中,像素也放大,保证清晰度,你能给出一个完整的示例吗
时间: 2023-06-17 17:05:22 浏览: 48
当然可以,以下是一个完整的示例代码:
HTML代码:
```html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图片缩放</title>
<script async src="./opencv.js" onload="onOpenCvReady();" type="text/javascript"></script>
</head>
<body>
<canvas id="canvas" width="800" height="600" onmousewheel="onMouseWheel(event)"></canvas>
<input type="file" id="fileInput" accept="image/*" onchange="onFileSelected(event)">
</body>
</html>
```
JavaScript代码:
```javascript
let imgData;
let srcMat;
let dstMat;
let scaleFactor = 1.0;
function onOpenCvReady() {
document.getElementById('fileInput').disabled = false;
}
function onMouseWheel(event) {
event.preventDefault();
scaleFactor += event.deltaY * -0.01;
scaleFactor = Math.max(0.1, scaleFactor);
scaleFactor = Math.min(scaleFactor, 5.0);
updateImage();
}
function onFileSelected(event) {
const file = event.target.files[0];
const reader = new FileReader();
reader.onload = function(event) {
const img = new Image();
img.onload = function() {
const canvas = document.createElement('canvas');
const ctx = canvas.getContext('2d');
canvas.width = img.width;
canvas.height = img.height;
ctx.drawImage(img, 0, 0);
imgData = ctx.getImageData(0, 0, img.width, img.height);
srcMat = cv.matFromImageData(imgData);
dstMat = new cv.Mat();
updateImage();
}
img.src = event.target.result;
}
reader.readAsDataURL(file);
}
function updateImage() {
cv.resize(srcMat, dstMat, new cv.Size(srcMat.cols * scaleFactor, srcMat.rows * scaleFactor), 0, 0, cv.INTER_LINEAR);
const dstData = new Uint8ClampedArray(dstMat.data);
const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
canvas.width = dstMat.cols;
canvas.height = dstMat.rows;
ctx.putImageData(new ImageData(dstData, dstMat.cols, dstMat.rows), 0, 0);
}
```
以上代码实现了从本地读取图片到网页的canvas上,并支持鼠标的滚轮对它放大缩小。在放大过程中,使用了opencv.js库实现对图像数据的插值,保证了图像在放大过程中像素也放大,保证清晰度。
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