opencv.js Uncaught DOMException: Failed to execute 'getImageData' on 'CanvasRenderingContext2D': The source width is 0.

This error occurs when the width of the source image used in the getImageData method of the CanvasRenderingContext2D is zero.

The getImageData method is used to retrieve the pixel data of a specified rectangle from a canvas. It requires valid source dimensions in order to fetch the image data.

To fix this error, ensure that you provide valid dimensions for the source image that you are trying to retrieve the data from. This can be done by checking if the image has been properly loaded and its dimensions are not zero.

Here's an example of how to handle this error:

const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('2d');
const image = new Image();

image.onload = function() {
  // Checking if the image has valid dimensions
  if (image.naturalWidth !== 0 && image.naturalHeight !== 0) {
    // Set the canvas dimensions to match the image dimensions
    canvas.width = image.naturalWidth;
    canvas.height = image.naturalHeight;

    // Draw the image onto the canvas
    ctx.drawImage(image, 0, 0);

    // Now you can safely use `getImageData`
    const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
    // Rest of your code...
  } else {
    console.error('Image dimensions are zero.');
  }
};

image.src = 'path/to/your/image.jpg';

In this example, we first check if the image has valid dimensions (naturalWidth and naturalHeight are not zero) before trying to fetch the pixel data using getImageData. If the dimensions are zero, an error message is logged to the console. Otherwise, the image is drawn onto the canvas and then the pixel data can be retrieved with getImageData.