关于JPG图片旋转问题,急急急!!!

引用 20 楼 ChrisAK 的回复:

VB6么..
LZ用GDI+的Flat API吧...
vb.net可以直接用GDI+了.
PS:GDI+ Flat API就是8L贴的东东.
不是很复杂.不过声明API和结构很麻烦囧.

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JPG图片旋转90度
'以下代码在bas#############
Private Type POINTAPI
X As Long
y As Long
End Type

Private Type Bitmap
bmType As Long
bmWidth As Long
bmHeight As Long
bmWidthBytes As Long
bmPlanes As Integer
bmBitsPixel As Integer
BmBits As Long
End Type
Private Declare Function GetObject Lib "gdi32" Alias "GetObjectA" (ByVal hObject As Long, ByVal nCount As Long, lpObject As Any) As Long
Private Declare Function GetTickCount Lib "kernel32" () As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hDC As Long, ByVal hObject As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function CreateCompatibleBitmap Lib "gdi32" (ByVal hDC As Long, ByVal nWidth As Long, ByVal nHeight As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function ReleaseDC Lib "user32" (ByVal hWnd As Long, ByVal hDC As Long) As Long
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal X As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Declare Function PlgBlt Lib "gdi32" (ByVal hdcDest As Long, lpPoint As POINTAPI, ByVal hdcSrc As Long, ByVal nXSrc As Long, ByVal nYSrc As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hbmMask As Long, ByVal xMask As Long, ByVal yMask As Long) As Long

Public Sub Rotate90(Pic As PictureBox)
Dim DefPoints(3) As POINTAPI
Dim MemDC As Long
Dim BHandle As Long
Dim OldObject As Long
Dim picINFO As Bitmap
Dim Width As Long, Height As Long, Temp As Long
Pic.AutoSize = True: Pic.AutoRedraw = True
GetObject Pic.Image, Len(picINFO), picINFO
Width = picINFO.bmWidth
Height = picINFO.bmHeight
MemDC = CreateCompatibleDC(Pic.hDC)
BHandle = CreateCompatibleBitmap(Pic.hDC, Width, Height)
OldObject = SelectObject(MemDC, BHandle)
BitBlt MemDC, 0, 0, Width, Height, Pic.hDC, 0, 0, vbSrcCopy
DefPoints(0).X = 0
DefPoints(0).y = Width
DefPoints(1).X = 0
DefPoints(1).y = 0
DefPoints(2).X = Height
DefPoints(2).y = Width
Pic.Move Pic.Left, Pic.Top, Pic.Height, Pic.Width
Set Pic.Picture = Nothing
PlgBlt Pic.hDC, DefPoints(0), MemDC, 0, 0, Width, Height, 0, 0, 0
SelectObject MemDC, OldObject
DeleteDC MemDC
DeleteObject BHandle
End Sub

'窗体代码#############
Private Sub Command1_Click()'旋转JPG图片90度
Dim t As Long
t = GetTickCount
Rotate90 Picture1
End Sub
Private Sub Command2_Click()'打开JPG图片
CommonDialog1.Filter = " *.jpg |*.jpg"
  CommonDialog1.ShowOpen
  If CommonDialog1.Filename <> "" Then
  Picture1.Picture = LoadPicture(CommonDialog1.Filename)
End Sub


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c++ 注意的是
一个要在使用gdi+之前调用gdiplusstartup
之后要gdiplusshutdown
图像格式不像托管的那样直接拿来就用

  CLSID jpgClsid;
  GetEncoderClsid(L"image/jpeg", &jpgClsid);
  CLSID pngClsid;
  GetEncoderClsid(L"image/png", &pngClsid);
   

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用c#写6行代码,c++估计在12行左右
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实际上，有两种选择：

1 利用 PictureBox 加载图片，获取像素后做旋转运算，然后可以直接保存为 .jpg 文件（不需要 .bmp 过度）。这样做的好处是，不必解析 .jpg 文件结构。

2 直接解析 .jpg 文件，取得像素，运算，结构成新的 .jpg 文件，写文件。这个需要熟悉 .jpg 的文件结构。
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不用转化为RGB。
JPG是压缩的YCbCr的数据，把JPG解码为YCbCr，然后旋转YCbCr,再编码为JPG，省去转化为RGB的时间，应该会快点。
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菜鸟来看看，呵呵
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http://www.92dotnet.com/index.aspx
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路过
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路过
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好复杂啊
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看看！
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我晕啊！！！以为自己可以了的。。。。人外有人啊
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我晕
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如果旋转的是90,180,270的话，应该不需要转换。我觉得JPG文件中，应该有方向的选项。

你可以自己试一下，把一个JPG文件用Windows来打开，下面有一个旋转按钮，可以以90度进行旋转，速度飞快。

你可以试一下，在转换前，与转换后，比较一下JPG文件究竟哪些内容发生了变化。
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我刚才试过，好象不行的，还是得编程。呵呵！
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我也想知道
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ding yixia //
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打酱油 ，
 看到好多牛人 
 VB 有点犯晕 ，对于新入行的程序员来讲 VB是个大问题！！！
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楼上的都搞错了，LZ问的是JPG旋转90度，这种特殊情况下不需要把JPG解压为BMP来处理，ACDSee是直接对JPG的数据来处理的，这种方法速度要快一个数量级，而且不会损失画质


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路过
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