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RetrieveDataFromImage Property

Summary

Gets or sets a value that indicates whether to automatically populate the scanline buffers in CodecsSaveImageEventArgs when using the RasterCodecs.SaveImage event.

Syntax
C#
VB
Java
Objective-C
C++
public bool RetrieveDataFromImage { get; set; } 
Public Property RetrieveDataFromImage As Boolean 
@property (nonatomic, assign) BOOL retrieveDataFromImage 
public boolean getRetrieveDataFromImage() 
public void setRetrieveDataFromImage(boolean value) 
public: 
property bool RetrieveDataFromImage { 
   bool get(); 
   void set (    bool ); 
} 

Property Value

true to automatically populate the scanline buffers in CodecsSaveImageEventArgs when using the RasterCodecs.SaveImage event, or false to make the user responsible for populating the scanline buffers. Default value is false.

Remarks

The Buffer property works as the input and output buffer containing the image data to save. If the value of RetrieveDataFromImage is set to false (the default), then the user is always responsible for providing the image data by setting in Buffer. If the value of RetrieveDataFromImage is set to true, then the RasterCodecs object will populate the Buffer prior to raising this event. The user can then inspect or modify the scanlines data or simple ignore it to save the original image data as is.

Notice that on either case, the user must provide the scanline data in the source image original format (stored in the Image property. The RasterCodecs object will then convert this data to the appropriate output format if needed, for example, if the user instructed the RasterCodecs object to save the image in a different file format than the original image.

Example

The following example shows how to use RetrieveDataFromImage to:

  1. Save the image without instructing RasterCodecs to automatically populate the data. Resulting in an output file with a blank image.
  2. Save the image while RasterCodecs to automatically populate the data. Resulting in a correct output image.
  3. Save the image with RasterCodecs automatically generating the data then manipulating it to generate an output file that is an invert of the original image.
C#
VB
using Leadtools; 
using Leadtools.Codecs; 
 
private int myMode; 
public void RetrieveDataFromImageExample() 
{ 
   using (RasterCodecs codecs = new RasterCodecs()) 
   { 
      string srcFile = Path.Combine(LEAD_VARS.ImagesDir, "Sample1.cmp"); 
      string blankFile = Path.Combine(LEAD_VARS.ImagesDir, "Sample1_Blank.bmp"); 
      string defaultFile = Path.Combine(LEAD_VARS.ImagesDir, "Sample1_Default.bmp"); 
      string invertedFile = Path.Combine(LEAD_VARS.ImagesDir, "Sample1_Inverted.bmp"); 
 
      // Load the source image 
      using (RasterImage image = codecs.Load(srcFile)) 
      { 
         // Subscribe to the SaveImage event 
         codecs.SaveImage += new EventHandler<CodecsSaveImageEventArgs>(codecs_SaveImage); 
 
         // First, set RetrieveDataFromImage to false and save 
         // This should generate a blank image 
         myMode = 0; 
         codecs.Options.Save.RetrieveDataFromImage = false; 
         codecs.Save(image, blankFile, RasterImageFormat.Bmp, 24); 
 
         // Next, set RetrieveDataFromImage to true but do not 
         // change the data, this should generate the correct image and is the equivalant 
         // to calling Save without subscribing to SaveImage 
         myMode = 1; 
         codecs.Options.Save.RetrieveDataFromImage = true; 
         codecs.Save(image, defaultFile, RasterImageFormat.Bmp, 24); 
 
         // Finally, leave RetrieveDataFromImage as true but change the data by inverting 
         // the scanlines, this should generate an inverted image 
         myMode = 2; 
         codecs.Save(image, invertedFile, RasterImageFormat.Bmp, 24); 
 
         codecs.SaveImage -= new EventHandler<CodecsSaveImageEventArgs>(codecs_SaveImage); 
      } 
   } 
} 
 
private void codecs_SaveImage(object sender, CodecsSaveImageEventArgs e) 
{ 
   // This example works with 24 bpp images only 
   Debug.Assert(e.Image.BitsPerPixel == 24); 
 
   switch (myMode) 
   { 
      case 0: 
         // Do not do anything 
         break; 
 
      case 1: 
         // Do not do anything 
         break; 
 
      case 2: 
         // Invert the image data 
         { 
            int scanlineLength = e.Image.BytesPerLine; 
            byte[] scanline = new byte[scanlineLength]; 
 
            // Loop through all the scanlines in the data 
            for (int y = 0; y < e.Lines; y++) 
            { 
               // Get this row 
               e.Buffer.GetData(y * scanlineLength, scanline, 0, scanlineLength); 
 
               // Process it by inverting every pixel data 
               for (int x = 0; x < scanlineLength; x++) 
               { 
                  scanline[x] = (byte)(255 - scanline[x]); 
               } 
 
               // Copy it back to the event buffer 
               e.Buffer.SetData(y * scanlineLength, scanline, 0, scanlineLength); 
            } 
         } 
         break; 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
 
Private myMode As Integer 
Public Sub RetrieveDataFromImageExample() 
 
   Using codecs As New RasterCodecs() 
      Dim srcFile As String = Path.Combine(LEAD_VARS.ImagesDir, "Sample1.cmp") 
      Dim blankFile As String = Path.Combine(LEAD_VARS.ImagesDir, "Sample1_Blank.bmp") 
      Dim defaultFile As String = Path.Combine(LEAD_VARS.ImagesDir, "Sample1_Default.bmp") 
      Dim invertedFile As String = Path.Combine(LEAD_VARS.ImagesDir, "Sample1_Inverted.bmp") 
 
      ' Load the source image 
      Using image As RasterImage = codecs.Load(srcFile) 
         ' Subscribe to the SaveImage event 
         AddHandler codecs.SaveImage, AddressOf codecs_SaveImage 
 
         ' First, set RetrieveDataFromImage to false and save 
         ' This should generate a blank image 
         myMode = 0 
         codecs.Options.Save.RetrieveDataFromImage = False 
         codecs.Save(image, blankFile, RasterImageFormat.Bmp, 24) 
 
         ' Next, set RetrieveDataFromImage to true but do not 
         ' change the data, this should generate the correct image and is the equivalant 
         ' to calling Save without subscribing to SaveImage 
         myMode = 1 
         codecs.Options.Save.RetrieveDataFromImage = True 
         codecs.Save(image, defaultFile, RasterImageFormat.Bmp, 24) 
 
         ' Finally, leave RetrieveDataFromImage as true but change the data by inverting 
         ' the scanlines, this should generate an inverted image 
         myMode = 2 
         codecs.Save(image, invertedFile, RasterImageFormat.Bmp, 24) 
 
         RemoveHandler codecs.SaveImage, AddressOf codecs_SaveImage 
      End Using 
   End Using 
 
End Sub 
 
Private Sub codecs_SaveImage(ByVal sender As Object, ByVal e As CodecsSaveImageEventArgs) 
   ' This example works with 24 bpp images only 
   Debug.Assert(e.Image.BitsPerPixel = 24) 
 
   Select Case myMode 
      Case 0 
         ' Do not do anything 
 
      Case 1 
         ' Do not do anything 
 
      Case 2 
         ' Invert the image data 
         Dim scanlineLength As Integer = e.Image.BytesPerLine 
         Dim scanline(scanlineLength - 1) As Byte 
 
         ' Loop through all the scanlines in the data 
         For y As Integer = 0 To e.Lines - 1 
            ' Get this row 
            e.Buffer.GetData(y * scanlineLength, scanline, 0, scanlineLength) 
 
            ' Process it by inverting every pixel data 
            For x As Integer = 0 To scanlineLength - 1 
               scanline(x) = CByte(255 - scanline(x)) 
            Next 
 
            ' Copy it back to the event buffer 
            e.Buffer.SetData(y * scanlineLength, scanline, 0, scanlineLength) 
         Next 
   End Select 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class 

Requirements

Target Platforms

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Leadtools.Codecs Assembly