UpdateMetaFileResolution Method

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

public static IntPtr UpdateMetaFileResolution( 
   IntPtr emfHandle,
   int xResolution,
   int yResolution
)

'Declaration
 
Public Shared Function UpdateMetaFileResolution( _
   ByVal emfHandle As IntPtr, _
   ByVal xResolution As Integer, _
   ByVal yResolution As Integer _
) As IntPtr

'Usage
 
Dim emfHandle As IntPtr
Dim xResolution As Integer
Dim yResolution As Integer
Dim value As IntPtr
 
value = DocumentWriter.UpdateMetaFileResolution(emfHandle, xResolution, yResolution)

public static IntPtr UpdateMetaFileResolution( 
   IntPtr emfHandle,
   int xResolution,
   int yResolution
)

 function Leadtools.Forms.DocumentWriters.DocumentWriter.UpdateMetaFileResolution( 
   emfHandle ,
   xResolution ,
   yResolution 
)

public:
static IntPtr UpdateMetaFileResolution( 
   IntPtr emfHandle,
   int xResolution,
   int yResolution
)

Parameters

emfHandle: Handle to the source EMF
xResolution: New horizontal resolution
yResolution: New vertical resolution

Return Value

A handle to the modified Windows Enhanced Metafile (EMF).

This method is especially helpful in case you use the CreateEnhMetaFile Windows API when generating the EMF handle. For example, requirement is to create an EMF with 8.5 by 11 inches at 300 DPI. With CreateEnhMetaFile, the resolution of the generated EMF is the same as the resolution of the reference HDC. Since it is impractical to find an HDC with resolution equal to the desired one, you can use UpdateMetaFileResolution to accomplish this. Here is an example:

            const int resolution = 300;
            // Calculate the width in pixels:
            int widthInPixels = (int)(8.5 * resolution);
            int heightInPixels = (int)(11.0 * resolution);
            Win32.RECT rc = new Win32.RECT();
            rc.left = 0;
            rc.top = 0;
            rc.right = widthInPixels;
            rc.bottom = heightInPixels;
            IntPtr hdc = Win32.CreateEnhMetaFile(IntPtr.Zero, IntPtr.Zero, rc, IntPtr.Zero);
            IntPtr hEmfTemp = Win32.CloseEnhMetaFile(hdc);
            // hEmfTemp has the same resolution as the screen, change it to the desired one
            IntPtr hEmf;
            hEmf = DocumentWriter.UpdateMetaFileResolution(hEmfTemp, resolution, resolution);
            Win32.DeleteEnhMetaFile(hEmfTemp);
            // hEmf now is 8.5 by 11 at 300

If xResolution or yResolution is 0, then the original resolution of the EMF handle will be used. If either xResolution or yResolution is equal to -1, then the aspect ratio for original EMF handle will be maintained and the positive value for either xResolution or yResolution will be used as the resolution (DPI) value for the modified emf handle.

Note that xResolution and yResolution cannot be both less than zero.

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

Private Shared Sub ShowMetaFileDimension(ByVal hemf As IntPtr)
   ' Use System.Drawing.Imaging.Metafile to load the EMF and get its information
   Using mf As System.Drawing.Imaging.Metafile = New System.Drawing.Imaging.Metafile(hemf, False)
      Console.WriteLine("Size: {0} by {1} pixels", mf.Width, mf.Height)
      Console.WriteLine("Resolution: {0} by {1} pixels/inch", mf.HorizontalResolution, mf.VerticalResolution)
   End Using
End Sub
'' Windows API functions needed to load/delete an EMF
'<DllImport("gdi32.dll")> _
'Private Shared Function GetEnhMetaFile(ByVal lpszMetaFile As String) As IntPtr
'End Function

'<DllImport("gdi32.dll")> _
'Private Shared Function DeleteEnhMetaFile(ByVal hemf As IntPtr) As Boolean
'End Function

private static void ShowMetaFileDimension(IntPtr hemf)
   {
      // Use System.Drawing.Imaging.Metafile to load the EMF and get its information
      using (System.Drawing.Imaging.Metafile mf = new System.Drawing.Imaging.Metafile(hemf, false))
      {
         Console.WriteLine("Size: {0} by {1} pixels", mf.Width, mf.Height);
         Console.WriteLine("Resolution: {0} by {1} pixels/inch", mf.HorizontalResolution, mf.VerticalResolution);
      }
   }
   //// Windows API
   //[DllImport("gdi32")]
   //private extern static IntPtr GetEnhMetaFile(string lpszMetaFile);
   //[DllImport("gdi32")]
   //private extern static int DeleteEnhMetaFile(IntPtr hemf);

   private static void ChangeMetaFileResolutionExample()
   {
      // Load the original meta file
      IntPtr hemf = GetEnhMetaFile(Path.Combine(LEAD_VARS.ImagesDir,"Ocr1.emf"));

      // Show the dimension
      Console.WriteLine("Original EMF dimension:");
      ShowMetaFileDimension(hemf);

      // Change the resolution to be 200 by 200 dots/inch
      IntPtr hemfDest = DocumentWriter.UpdateMetaFileResolution(hemf, 200, 200);

      // No need for the original handle anymore
      DeleteEnhMetaFile(hemf);

      Console.WriteLine("New EMF dimension:");
      ShowMetaFileDimension(hemfDest);

      DeleteEnhMetaFile(hemfDest);
   }

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

DocumentWriter Class
DocumentWriter Members
DocumentWriter Class
DocumentFormat Enumeration
Programming with LEADTOOLS Document Writers
Files to be Included with Your Application
Unlocking Special LEAD Features