在Angular中,可以使用exif-js
库来获取图像的方向信息。以下是一个示例解决方法:
exif-js
库:npm install exif-js --save
exif-js
库:import * as EXIF from 'exif-js';
detectImageOrientation(imageUrl: string): void {
const image = new Image();
image.src = imageUrl;
image.onload = () => {
EXIF.getData(image, () => {
const orientation = EXIF.getTag(image, 'Orientation');
console.log('Image orientation:', orientation);
this.rotateImage(image, orientation);
});
};
}
rotateImage(image: HTMLImageElement, orientation: number): void {
const canvas = document.createElement('canvas');
const ctx = canvas.getContext('2d');
if (orientation && [5, 6, 7, 8].includes(orientation)) {
canvas.width = image.height;
canvas.height = image.width;
} else {
canvas.width = image.width;
canvas.height = image.height;
}
switch (orientation) {
case 2:
ctx.transform(-1, 0, 0, 1, image.width, 0);
break;
case 3:
ctx.transform(-1, 0, 0, -1, image.width, image.height);
break;
case 4:
ctx.transform(1, 0, 0, -1, 0, image.height);
break;
case 5:
ctx.transform(0, 1, 1, 0, 0, 0);
break;
case 6:
ctx.transform(0, 1, -1, 0, image.height, 0);
break;
case 7:
ctx.transform(0, -1, -1, 0, image.height, image.width);
break;
case 8:
ctx.transform(0, -1, 1, 0, 0, image.width);
break;
default:
break;
}
ctx.drawImage(image, 0, 0);
const rotatedImageUrl = canvas.toDataURL('image/jpeg');
console.log('Rotated image URL:', rotatedImageUrl);
}
detectImageOrientation
方法,并传入图像的URL:this.detectImageOrientation('path/to/image.jpg');
在控制台中,你将看到图像方向的值和旋转后的图像URL。
请注意,这个示例假设图像已经加载完成。如果需要从数据库中获取图像,你可以使用Angular的HTTP模块来获取图像,并在获取成功后传递给detectImageOrientation
方法。