我试图从手机上传图片到我的网络服务,但是当我上传图片时发现图片方向丢失了。在上传之前,我需要做些什么来确保图片以正确的方向上传吗?
我还在其他地方找到了Objective-C代码来旋转图片,然后我将其转换为C#,但每次使用旋转方法时,图片就会变成黑色,也就是什么都不显示。
我附上我的代码供您参考,如果有人能告诉我我做错了什么,我会非常感激。谢谢!
我还在其他地方找到了Objective-C代码来旋转图片,然后我将其转换为C#,但每次使用旋转方法时,图片就会变成黑色,也就是什么都不显示。
我附上我的代码供您参考,如果有人能告诉我我做错了什么,我会非常感激。谢谢!
public static UIImage RotateImage(this UIImage image)
{
UIImage imageToReturn = null;
if(image.Orientation == UIImageOrientation.Up)
{
imageToReturn = image;
}
else
{
CGAffineTransform transform = CGAffineTransform.MakeIdentity();
switch (image.Orientation) {
case UIImageOrientation.Down:
case UIImageOrientation.DownMirrored:
transform.Translate(image.Size.Width, image.Size.Height);
transform.Rotate((float)Math.PI);
break;
case UIImageOrientation.Left:
case UIImageOrientation.LeftMirrored:
transform.Translate(image.Size.Width, 0);
transform.Rotate((float)Math.PI/2);
break;
case UIImageOrientation.Right:
case UIImageOrientation.RightMirrored:
transform.Translate(0, image.Size.Height);
transform.Rotate((float)-Math.PI/2);
break;
case UIImageOrientation.Up:
case UIImageOrientation.UpMirrored:
break;
}
switch (image.Orientation) {
case UIImageOrientation.UpMirrored:
case UIImageOrientation.DownMirrored:
transform.Translate(image.Size.Width, 0);
transform.Scale(-1, 1);
break;
case UIImageOrientation.LeftMirrored:
case UIImageOrientation.RightMirrored:
transform.Translate(image.Size.Height, 0);
transform.Scale(-1, 1);
break;
case UIImageOrientation.Up:
case UIImageOrientation.Down:
case UIImageOrientation.Left:
case UIImageOrientation.Right:
break;
}
//now draw image
using(var context = new CGBitmapContext(IntPtr.Zero,
(int)image.Size.Width,
(int)image.Size.Height,
image.CGImage.BitsPerComponent,
image.CGImage.BytesPerRow,
image.CGImage.ColorSpace,
image.CGImage.BitmapInfo)){
context.ConcatCTM(transform);
switch (image.Orientation)
{
case UIImageOrientation.Left:
case UIImageOrientation.LeftMirrored:
case UIImageOrientation.Right:
case UIImageOrientation.RightMirrored:
// Grr...
context.DrawImage(new RectangleF(PointF.Empty,new SizeF(image.Size.Height, image.Size.Width)), image.CGImage);
break;
default:
context.DrawImage(new RectangleF(PointF.Empty, new SizeF(image.Size.Width, image.Size.Height)), image.CGImage);
break;
}
using(var imageRef = context.ToImage())
{
imageToReturn = new UIImage(imageRef);
}
}
}
return imageToReturn;
}