在Windows phone實際項目中,可能需要使用者從相冊中選擇圖檔然後進行相應的處理。但是不知道大家有沒有發現這樣一種情況,就是手機裡看是豎着的,但是上傳到微網誌或者哪裡的時候确實橫着的。一種情況是你拿手機豎着拍照得話,照片就是橫着的,雖然在手機裡看是豎着的。(可能有點抽象,遇到此情況的同學應該深有感觸)
那麼我們在用戶端中應該如何處理這種情況呢?一種想法是擷取圖檔的角度,如果是90°,就把照片翻轉過來,再進行相應的操作。那這樣就涉及到2個問題
1. 如何擷取相冊中照片的角度
2. 如何翻轉已有的照片(流、或者Bitmap或者WriteableBitmap)
檢視了系統的API,并沒有對相片的角度提供支援,但是我們可以使用ExifLib開源庫去做。
下述的方法就是擷取選取圖檔的角度的
///
/// get angle of photo
/// photo stream
/// photo name
/// angle of the photo
public static int GetAngle(Stream stream, string filename)
{
ExifLib.ExifOrientation _orientation;
int _angle = 0;
stream.Position = 0;
JpegInfo info = ExifReader.ReadJpeg(stream, filename);
if (info!=null)
_orientation = info.Orientation;
switch (info.Orientation)
case ExifOrientation.TopLeft:
case ExifOrientation.Undefined:
_angle = 0;
break;
case ExifOrientation.TopRight:
_angle = 90;
case ExifOrientation.BottomRight:
_angle = 180;
case ExifOrientation.BottomLeft:
_angle = 270;
}
return _angle;
擷取到角度後,如果角度是90°,即是反的,我們需要将其糾正過來,可以使用如下的方法:
private Stream RotateStream(Stream stream, int angle)
if (angle % 90 != 0 || angle < 0) throw new ArgumentException();
if (angle % 360 == 0) return stream;
BitmapImage bitmap = new BitmapImage();
bitmap.SetSource(stream);
WriteableBitmap wbSource = new WriteableBitmap(bitmap);
WriteableBitmap wbTarget = null;
if (angle % 180 == 0)
wbTarget = new WriteableBitmap(wbSource.PixelWidth, wbSource.PixelHeight);
else
wbTarget = new WriteableBitmap(wbSource.PixelHeight, wbSource.PixelWidth);
for (int x = 0; x < wbSource.PixelWidth; x++)
for (int y = 0; y < wbSource.PixelHeight; y++)
switch (angle % 360)
case 90:
wbTarget.Pixels[(wbSource.PixelHeight - y - 1) + x * wbTarget.PixelWidth] = wbSource.Pixels[x + y * wbSource.PixelWidth];
case 180:
wbTarget.Pixels[(wbSource.PixelWidth - x - 1) + (wbSource.PixelHeight - y - 1) * wbSource.PixelWidth] = wbSource.Pixels[x + y * wbSource.PixelWidth];
case 270:
wbTarget.Pixels[y + (wbSource.PixelWidth - x - 1) * wbTarget.PixelWidth] = wbSource.Pixels[x + y * wbSource.PixelWidth];
MemoryStream targetStream = new MemoryStream();
wbTarget.SaveJpeg(targetStream, wbTarget.PixelWidth, wbTarget.PixelHeight, 0, 100);
return targetStream;
本文轉自 wws5201985 51CTO部落格,原文連結:http://blog.51cto.com/wws5201985/751291,如需轉載請自行聯系原作者