js固定比例裁剪图片

function cropImageToAspectRatio(image, width, height, aspectRatio) {
    const canvas = document.createElement('canvas');
    const ctx = canvas.getContext('2d');

    let cropWidth, cropHeight;
    if (width / height > aspectRatio) {
        cropHeight = height;
        cropWidth = height * aspectRatio;
    } else {
        cropWidth = width;
        cropHeight = width / aspectRatio;
    }

    const x = (width - cropWidth) / 2;
    const y = (height - cropHeight) / 2;

    canvas.width = width;
    canvas.height = height;
    ctx.drawImage(image, x, y, cropWidth, cropHeight, 0, 0, width, height);

    return canvas.toDataURL('image/jpeg');
}

// 使用示例
const img = new Image();
img.src = 'path/to/your/image.jpg';
img.onload = () => {
    const croppedImage = cropImageToAspectRatio(img, 300, 300, 1); // 16:9 aspect ratio
    document.body.appendChild(document.createElement('img')).src = croppedImage;
};