TransparentColor Property

Gets or sets the transparent color used when painting this image.

Syntax

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

public RasterColor TransparentColor {get; set;}

'Declaration
 
Public Property TransparentColor As RasterColor

'Usage
 
Dim instance As RasterImage
Dim value As RasterColor
 
instance.TransparentColor = value
 
value = instance.TransparentColor

public RasterColor TransparentColor {get; set;}

 get_TransparentColor();
 set_TransparentColor(value);

public:
property RasterColor TransparentColor {
   RasterColor get();
   void set (    RasterColor value);
}

Property Value

The transparent color used when painting this image.

Remarks

The TransparentColor of a RasterImage is used when the Transparent property value is set to true.

Note, transparent paint does not work with RasterPaintEngine.Gdi. For more information, refer to Leadtools.Drawing.RasterPaintProperties.

If this RasterImage has a BitsPerPixel value of 8 or less, then the image has a palette. For palettized images, the value of the TransparentColor can be an RGB value or a palette index.

To set a palette index as the transparent color, use the RasterColor.FromPaletteIndex method.

If the color passed is a true RGB value(The value of see RasterColor.IsPaletteIndex is false and the image has a palette, then this RasterImage object will call GetTrueColorValue on the TransparentColor to translate it into the nearest palette index entry before using it to determine the actual transparent color in the image when painting.

For more information, refer to PNG Files and Transparency.

Example

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

Public Sub TransparentColorExample()
      Dim codecs As RasterCodecs = New RasterCodecs()

      Dim srcFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")
      Dim destFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1_Transparent.gif")

      ' Load the image
      Dim image As RasterImage = codecs.Load(srcFileName)

      ' Change the image's palette to be Red and Blue
      Dim redBluePalette As RasterColor() = New RasterColor(1) {}
      redBluePalette(0) = RasterColor.FromKnownColor(RasterKnownColor.Red)
      redBluePalette(1) = RasterColor.FromKnownColor(RasterKnownColor.Blue)
      image.SetPalette(redBluePalette, 0, 2)

      ' make red the transparent color
      image.Transparent = True
      image.TransparentColor = redBluePalette(0)

      ' Save the image
      codecs.Save(image, destFileName, RasterImageFormat.Gif, 8)

      ' Now load Ocr1_Transparent.gif in Internet Explorer.
      ' Notice how red is treated as a transparent color.
      ' You should get Blue text on a white background
      '    (if IE's background color is white).

      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 TransparentColorExample()
   {
      RasterCodecs codecs = new RasterCodecs();

      string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif");
      string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1_Transparent.gif");

      // Load the image
      RasterImage image = codecs.Load(srcFileName);

      // Change the image's palette to be Red and Blue
      RasterColor[] redBluePalette = new RasterColor[2];
      redBluePalette[0] = RasterColor.FromKnownColor(RasterKnownColor.Red);
      redBluePalette[1] = RasterColor.FromKnownColor(RasterKnownColor.Blue);
      image.SetPalette(redBluePalette, 0, 2);

      // make red the transparent color
      image.Transparent = true;
      image.TransparentColor = redBluePalette[0];

      // Save the image
      codecs.Save(image, destFileName, RasterImageFormat.Gif, 8);

      // Now load Ocr1_Transparent.gif in Internet Explorer.
      // Notice how red is treated as a transparent color.
      // You should get Blue text on a white background
      //    (if IE's background color is white).

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

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

RasterImageExamples.prototype.TransparentColorExample = function ( )
{
   Tools.SetLicense ( ) ;
   with (Leadtools) {
      with (Leadtools.Codecs) {
         var codecs = new RasterCodecs();

         var srcFileName = "Assets\\Ocr1.tif";
         var destFileName = "Ocr1_Transparent.gif";
         var image;
         // Load the image
         return Tools.AppInstallFolder().getFileAsync(srcFileName).then(function (loadFile) {
            return codecs.loadAsync(LeadStreamFactory.create(loadFile))
         })
            .then(function (img) {
               image = img;
               // Change the image's palette to be Red and Blue
               var redBluePalette = [RasterColorHelper.fromKnownColor(RasterKnownColor.Red),
                  RasterColorHelper.fromKnownColor(RasterKnownColor.Blue)];
               image.setPalette(redBluePalette, 0, 2);

               // make red the transparent color
               image.transparent = true;
               image.transparentColor = redBluePalette[0];

               // Save the image
               return Tools.AppLocalFolder().createFileAsync(destFileName)
            })
            .then(function (saveFile) {
               var saveStream = LeadStreamFactory.create (saveFile);
               return codecs.saveAsync(image, saveStream, RasterImageFormat.gif, 8)
            })
            .then(function () {

               // Now load Ocr1_Transparent.gif in Internet Explorer.
               // Notice how red is treated as a transparent color.
               // You should get Blue text on a white background
               //    (if IE's background color is white).

               image.close();
               codecs.close();
            })
      }
   }
}

[TestMethod]
public async Task TransparentColorExample()
{
   RasterCodecs codecs = new RasterCodecs();
   string srcFileName = @"Assets\Ocr1.tif";
   string destFileName = @"Ocr1_Transparent.gif";

   // Load the image
   StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(srcFileName);
   RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile));

   // Change the image's palette to be Red and Blue
   RasterColor[] redBluePalette = { RasterColorHelper.FromKnownColor(RasterKnownColor.Red),
                                    RasterColorHelper.FromKnownColor(RasterKnownColor.Blue)};
   image.SetPalette(redBluePalette, 0, 2);

   // make red the transparent color
   image.Transparent = true;
   image.TransparentColor = redBluePalette[0];

   // Save the image
   StorageFile saveFile = await Tools.AppLocalFolder.CreateFileAsync(destFileName);
   ILeadStream saveStream = LeadStreamFactory.Create(saveFile);
   await codecs.SaveAsync(image, saveStream, RasterImageFormat.Gif, 8);

   // Now load Ocr1_Transparent.gif in Internet Explorer.
   // Notice how red is treated as a transparent color.
   // You should get Blue text on a white background
   //    (if IE's background color is white).

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

public void TransparentColorExample(RasterImage image, Stream destStream)
{
   // Change the image's palette to be Red and Blue
   RasterColor[] redBluePalette = new RasterColor[2];
   redBluePalette[0] = RasterColorConverter.FromColor(Colors.Red);
   redBluePalette[1] = RasterColorConverter.FromColor(Colors.Blue);
   image.SetPalette(redBluePalette, 0, 2);
   // make red the transparent color
   image.Transparent = true;
   image.TransparentColor = redBluePalette[0];

   // Save the image
   RasterCodecs codecs = new RasterCodecs();
   codecs.Save(image, destStream, RasterImageFormat.Gif, 8);

   // Now load Ocr1_Transparent.gif in Internet Explorer.
   // Notice how red is treated as a transparent color.
   // You should get Blue text on a white background
   //    (if IE's background color is white).

   image.Dispose();
}

Public Sub TransparentColorExample(ByVal image As RasterImage, ByVal destStream As Stream)
   ' Change the image's palette to be Red and Blue
   Dim redBluePalette As RasterColor() = New RasterColor(1){}
   redBluePalette(0) = RasterColorConverter.FromColor(Colors.Red)
   redBluePalette(1) = RasterColorConverter.FromColor(Colors.Blue)
   image.SetPalette(redBluePalette, 0, 2)
   ' make red the transparent color
   image.Transparent = True
   image.TransparentColor = redBluePalette(0)

   ' Save the image
   Dim codecs As RasterCodecs = New RasterCodecs()
   codecs.Save(image, destStream, RasterImageFormat.Gif, 8)

   ' Now load Ocr1_Transparent.gif in Internet Explorer.
   ' Notice how red is treated as a transparent color.
   ' You should get Blue text on a white background
   '    (if IE's background color is white).

   image.Dispose()
End Sub

Requirements

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