圖片在PictureBox中旋轉

Question

正如問題所暗示的，當我將圖片加載到pictureBox（使用對話框）時，它不會以其原始外觀出現。在此屏幕拍攝中，左側的圖像是我加載到pictureBox（右側）中的圖像。

試圖知道是什麼導致這種情況我使用Paint應用繪製圖像，並使用Windows照片查看器旋轉它，旋轉後的圖像按原樣加載（旋轉），也就是說，一些圖片加載正常，其他圖片旋轉！我不明白爲什麼？！

Answer 1

沒有原始圖像數據，無法確定發生了什麼。但很明顯，在某些情況下，涉及圖像處理的某些軟件使用EXIF方向屬性來旋轉圖像，而不是實際修改圖像數據本身。這可能是照片查看器或某些其他處理照片的工具。

這裏是代碼，你可以用它來檢測圖像的方向，記錄在相機的EXIF數據拍的圖片：

static ImageOrientation GetOrientation(this Image image) 
{ 
    PropertyItem pi = SafeGetPropertyItem(image, 0x112); 

    if (pi == null || pi.Type != 3) 
    { 
     return ImageOrientation.Original; 
    } 

    return (ImageOrientation)BitConverter.ToInt16(pi.Value, 0); 
} 

// A file without the desired EXIF property record will throw ArgumentException. 
static PropertyItem SafeGetPropertyItem(Image image, int propid) 
{ 
    try 
    { 
     return image.GetPropertyItem(propid); 
    } 
    catch (ArgumentException) 
    { 
     return null; 
    } 
} 

其中：

/// <summary> 
/// Possible EXIF orientation values describing clockwise 
/// rotation of the captured image due to camera orientation. 
/// </summary> 
/// <remarks>Reverse/undo these transformations to display an image correctly</remarks> 
public enum ImageOrientation 
{ 
    /// <summary> 
    /// Image is correctly oriented 
    /// </summary> 
    Original = 1, 
    /// <summary> 
    /// Image has been mirrored horizontally 
    /// </summary> 
    MirrorOriginal = 2, 
    /// <summary> 
    /// Image has been rotated 180 degrees 
    /// </summary> 
    Half = 3, 
    /// <summary> 
    /// Image has been mirrored horizontally and rotated 180 degrees 
    /// </summary> 
    MirrorHalf = 4, 
    /// <summary> 
    /// Image has been mirrored horizontally and rotated 270 degrees clockwise 
    /// </summary> 
    MirrorThreeQuarter = 5, 
    /// <summary> 
    /// Image has been rotated 270 degrees clockwise 
    /// </summary> 
    ThreeQuarter = 6, 
    /// <summary> 
    /// Image has been mirrored horizontally and rotated 90 degrees clockwise. 
    /// </summary> 
    MirrorOneQuarter = 7, 
    /// <summary> 
    /// Image has been rotated 90 degrees clockwise. 
    /// </summary> 
    OneQuarter = 8 
} 

的GetOrientation()上面的方法是作爲擴展方法編寫的，但當然，您可以將其稱爲純靜態方法。無論採用哪種方式，只需將它剛剛從文件打開的Bitmap對象傳遞給它，它將返回存儲在文件中的EXIF方向（如果有的話）。

有了這個，你可以根據你的需要旋轉圖像。

Answer 2

當您在Windows照片查看器中查看圖像時，如果它具有Exif方向數據，它將自動更正圖像方向。 PictureBox沒有內置的對這種功能的支持。您可以創建自定義PictureBox其正確，即使他們有方向的數據顯示圖片：

using System.Linq; 
using System.Windows.Forms; 
using System.Drawing; 
using System.ComponentModel; 

public class MyPictureBox : PictureBox 
{ 
    private void CorrectExifOrientation(Image image) 
    { 
     if (image == null) return; 
     int orientationId = 0x0112; 
     if (image.PropertyIdList.Contains(orientationId)) 
     { 
      var orientation = (int)image.GetPropertyItem(orientationId).Value[0]; 
      var rotateFlip = RotateFlipType.RotateNoneFlipNone; 
      switch (orientation) 
      { 
       case 1: rotateFlip = RotateFlipType.RotateNoneFlipNone; break; 
       case 2: rotateFlip = RotateFlipType.RotateNoneFlipX; break; 
       case 3: rotateFlip = RotateFlipType.Rotate180FlipNone; break; 
       case 4: rotateFlip = RotateFlipType.Rotate180FlipX; break; 
       case 5: rotateFlip = RotateFlipType.Rotate90FlipX; break; 
       case 6: rotateFlip = RotateFlipType.Rotate90FlipNone; break; 
       case 7: rotateFlip = RotateFlipType.Rotate270FlipX; break; 
       case 8: rotateFlip = RotateFlipType.Rotate270FlipNone; break; 
       default: rotateFlip = RotateFlipType.RotateNoneFlipNone; break; 
      } 
      if (rotateFlip != RotateFlipType.RotateNoneFlipNone) 
      { 
       image.RotateFlip(rotateFlip); 
       image.RemovePropertyItem(orientationId); 
      } 
     } 
    } 
    [Localizable(true)] 
    [Bindable(true)] 
    public new Image Image 
    { 
     get { return base.Image; } 
     set { base.Image = value; CorrectExifOrientation(value); } 
    } 
}