ChangeViewPerspective Method

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

public void ChangeViewPerspective( 
   RasterViewPerspective viewPerspective
)

'Declaration
 
Public Sub ChangeViewPerspective( _
   ByVal viewPerspective As RasterViewPerspective _
)

'Usage
 
Dim instance As RasterImage
Dim viewPerspective As RasterViewPerspective
 
instance.ChangeViewPerspective(viewPerspective)

public void ChangeViewPerspective( 
   RasterViewPerspective viewPerspective
)

 function Leadtools.RasterImage.ChangeViewPerspective( 
   viewPerspective 
)

public:
void ChangeViewPerspective( 
   RasterViewPerspective viewPerspective
)

Parameters

viewPerspective: Desired view perspective.

The ViewPerspective is the arrangement of pixels in the image. This method references image coordinates, which are often different from the display coordinates of an image.

Use this method to change the data and the ViewPerspective to simplify calculations that involve image coordinates. This method does not affect the image display. For more information, refer to Accounting for View Perspective.

The following values for viewPerspective are supported in (Document/Medical only) only:

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Public Sub GetRowCompressedExample()
      Dim codecs As RasterCodecs = New RasterCodecs()
      ' Load the bitmap, at 1 bit per pixel, compressed
      codecs.Options.Load.Compressed = True
      Dim image As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "OCR1.TIF"), 1, CodecsLoadByteOrder.Bgr, 1, 1)

      ' This example does not work with rotated view perspectives.
      If (image.ViewPerspective <> RasterViewPerspective.TopLeft) OrElse (image.ViewPerspective <> RasterViewPerspective.BottomLeft) Then
         image.ChangeViewPerspective(RasterViewPerspective.TopLeft)
      End If

      ' Adjust the YOffset if the view perspective is bottom left.
      Dim nRow As Integer = 500 ' first row to get.
      Dim nYSize As Integer = 500 ' number of rows to get.

      If image.ViewPerspective = RasterViewPerspective.BottomLeft Then
         nRow = image.Height - nRow - nYSize
      End If

      ' Allocate the buffers.
      Dim pBuffer As Byte() = New Byte(Convert.ToInt32((((image.Width + 31) And Not (31)) / 8)) * nYSize - 1) {} ' Buffer to hold the expanded row.
      Dim pRunBuffer As System.UInt16() = New System.UInt16(((image.Width + 3) * 2) * nYSize - 1) {} ' Buffer to hold the compressed row.

      If image.IsGlobalMemory Then
         image.Access()
      End If
      ' Get the top nRow lines.
      image.GetRowCompressed(Nothing, pRunBuffer, 0, nRow, nYSize)
      ' Expand the compressed data.
      RasterRleCompressor.ExpandRows(pRunBuffer, pBuffer, 0, image.Width, nYSize)
      ' Invert the data.

      Dim n As Integer = 0
      Do While n < (image.BytesPerLine * nYSize)
         pBuffer(n) = pBuffer(n) Xor Convert.ToByte(&HFF)
         n += 1
      Loop


      ' Compress the inverted data.
      RasterRleCompressor.CompressRows(pRunBuffer, pBuffer, 0, image.Width, nYSize)

      ' Put the inverted, compressed data back into the image.
      image.SetRowCompressed(Nothing, pRunBuffer, 0, nRow, nYSize)

      If image.IsGlobalMemory Then
         image.Release()
      End If

      codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1_getrowcompresed.BMP"), RasterImageFormat.Bmp, 0)

      image.Dispose()
      codecs.Dispose()
   End Sub

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class

public void GetRowCompressedExample()
   {
      RasterCodecs codecs = new RasterCodecs();
      // Load the bitmap, at 1 bit per pixel, compressed
      codecs.Options.Load.Compressed = true;
      RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "OCR1.TIF"), 1, Leadtools.Codecs.CodecsLoadByteOrder.Bgr, 1, 1);

      // This example does not work with rotated view perspectives.
      if((image.ViewPerspective != RasterViewPerspective.TopLeft) || (image.ViewPerspective != RasterViewPerspective.BottomLeft))
         image.ChangeViewPerspective(RasterViewPerspective.TopLeft);

      // Adjust the YOffset if the view perspective is bottom left.
      int nRow = 500; // first row to get.
      int nYSize = 500; // number of rows to get.

      if(image.ViewPerspective == RasterViewPerspective.BottomLeft)
         nRow = image.Height - nRow - nYSize;

      // Allocate the buffers.
      byte[] pBuffer = new byte[Convert.ToInt32((((image.Width + 31) & ~(31)) / 8)) * nYSize]; // Buffer to hold the expanded row.
      ushort[] pRunBuffer = new ushort[((image.Width + 3) * 2) * nYSize]; // Buffer to hold the compressed row.

      if(image.IsGlobalMemory)
         image.Access();
      // Get the top nRow lines.
      image.GetRowCompressed(null, pRunBuffer, 0, nRow, nYSize);
      // Expand the compressed data.
      RasterRleCompressor.ExpandRows(pRunBuffer, pBuffer, 0, image.Width, nYSize);
      // Invert the data.

      for(int n = 0; n < (image.BytesPerLine * nYSize); n++)
         pBuffer[n] ^= 0xff;


      // Compress the inverted data.
      RasterRleCompressor.CompressRows(pRunBuffer, pBuffer, 0, image.Width, nYSize);

      // Put the inverted, compressed data back into the image.
      image.SetRowCompressed(null, pRunBuffer, 0, nRow, nYSize);

      if(image.IsGlobalMemory)
         image.Release();

      codecs.Save(image,Path.Combine(LEAD_VARS.ImagesDir,"IMAGE1_getrowcompresed.BMP"), RasterImageFormat.Bmp, 0);

      image.Dispose();
      codecs.Dispose();
   }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

RasterImage Class
RasterImage Members