Image Tint API Worker

addEventListener('fetch', event => {
    event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) {
    // Get the image URL from the query string
    const url = new URL(request.url);
    const imageUrl = url.searchParams.get('url');

    // Fetch the original image
    const response = await fetch(imageUrl);
    const blob = await response.blob();

    // Create a canvas and draw the original image on it
    const img = new Image();
    img.src = URL.createObjectURL(blob);
    const canvas = document.createElement('canvas');
    canvas.width = img.width;
    canvas.height = img.height;
    const ctx = canvas.getContext('2d');
    ctx.drawImage(img, 0, 0);

    // Generate a random color tint
    const r = Math.floor(Math.random() * 256);
    const g = Math.floor(Math.random() * 256);
    const b = Math.floor(Math.random() * 256);
    const tint = `rgb(${r}, ${g}, ${b})`;

    // Draw a transparent rect to cover the entire canvas, then set the
    // composite operation to "source-atop" so that only the tinted areas
    // are visible
    ctx.fillStyle = tint;
    ctx.globalCompositeOperation = 'source-atop';
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    // Convert the canvas to a blob and return it as the response
    const tintedBlob = await new Promise((resolve) => {
        canvas.toBlob(resolve, 'image/png');
    });
    const tintedResponse = new Response(tintedBlob);
    tintedResponse.headers.set('Content-Type', 'image/png');
    tintedResponse.headers.set('Content-Disposition', 'inline');
    return tintedResponse
}