GetTrueColorValue Method

Gets the true (RGB) value of the specified color based on the current image palette.

Syntax

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

public RasterColor GetTrueColorValue( 
   RasterColor color
)

'Declaration
 
Public Function GetTrueColorValue( _
   ByVal color As RasterColor _
) As RasterColor

'Usage
 
Dim instance As RasterImage
Dim color As RasterColor
Dim value As RasterColor
 
value = instance.GetTrueColorValue(color)

public RasterColor GetTrueColorValue( 
   RasterColor color
)

 function Leadtools.RasterImage.GetTrueColorValue( 
   color 
)

public:
RasterColor GetTrueColorValue( 
   RasterColor color
)

Parameters

color: a RasterColor that specifies the source color

Return Value

A RasterColor that is guaranteed to be a true color (has RGB value)

Remarks

Use this method to translate a color that is really a palette index (the value of the RasterColor.IsPaletteIndex property is true) to a true RGB color value

The apposite of this method is TranslateColor(RasterImage,Int32).

Example

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

Public Sub CreateTransparentGifExample()
      ' Create a 24 bpp image, we will draw on it first then convert it to 8 bpp
      Dim imageWidth As Integer = 256
      Dim imageHeight As Integer = 256
      Dim image As New RasterImage( _
         RasterMemoryFlags.Conventional, _
         imageWidth, _
         imageHeight, _
         24, _
         RasterByteOrder.Bgr, _
         RasterViewPerspective.BottomLeft, _
         Nothing, _
         IntPtr.Zero, _
         0)
      ' Fill this image with magenta color and draw some random ellipses on top
      Dim hdc As IntPtr = RasterImagePainter.CreateLeadDC(image)
      Dim g As Graphics = Graphics.FromHdc(hdc)

      g.FillRectangle(Brushes.Magenta, 0, 0, imageWidth, imageHeight)

      Const ellipseWidth As Integer = 40
      Const ellipseHeight As Integer = 40

      Dim r As New Random()

      For i As Integer = 0 To 39
         Dim x As Integer = r.Next(imageWidth - ellipseWidth)
         Dim y As Integer = r.Next(imageHeight - ellipseHeight)

         Dim clr As Color = Color.FromArgb(r.Next(256), r.Next(256), r.Next(256))
         Dim brush As New SolidBrush(clr)
         g.FillEllipse(brush, x, y, ellipseWidth, ellipseHeight)
         brush.Dispose()
      Next

      g.Dispose()
      RasterImagePainter.DeleteLeadDC(hdc)

      ' Convert this image to 8 bits/pixel
      Dim cmd As New ColorResolutionCommand( _
         ColorResolutionCommandMode.InPlace, _
         8, _
         RasterByteOrder.Rgb, _
         RasterDitheringMethod.None, _
         ColorResolutionCommandPaletteFlags.Optimized, _
         Nothing)
      cmd.Run(image)

      ' Find the Magenta color and set it as the transparent color
      Dim transparentColor As RasterColor = RasterColor.FromKnownColor(RasterKnownColor.Magenta)

      ' Get the true color used for Magenta inside this image (a palette index)
      transparentColor = image.TranslateColor(image, transparentColor)

      image.Transparent = True
      image.TransparentColor = transparentColor

      ' Initialize the RasterCodecs object
      Dim codecs As New RasterCodecs()

      ' Save this image as GIF
      Dim fileName As String = Path.Combine(LEAD_VARS.ImagesDir, "TransparentEllipses.gif")
      codecs.Save(image, fileName, RasterImageFormat.Gif, 8)

      ' Clean up
      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 CreateTransparentGifExample()
   {
      // Create a 24 bpp image, we will draw on it first then convert it to 8 bpp
      int imageWidth = 256;
      int imageHeight = 256;
      RasterImage image = new RasterImage(
         RasterMemoryFlags.Conventional,
         imageWidth,
         imageHeight,
         24,
         RasterByteOrder.Bgr,
         RasterViewPerspective.BottomLeft,
         null,
         IntPtr.Zero,
         0);

      // Fill this image with magenta color and draw some random ellipses on top
      IntPtr hdc = RasterImagePainter.CreateLeadDC(image);
      Graphics g = Graphics.FromHdc(hdc);

      g.FillRectangle(Brushes.Magenta, 0, 0, imageWidth, imageHeight);

      const int ellipseWidth = 40;
      const int ellipseHeight = 40;

      Random r = new Random();

      for(int i = 0; i < 40; i++)
      {
         int x = r.Next(imageWidth - ellipseWidth);
         int y = r.Next(imageHeight - ellipseHeight);

         Color clr = Color.FromArgb(r.Next(256), r.Next(256), r.Next(256));
         Brush brush = new SolidBrush(clr);
         g.FillEllipse(brush, x, y, ellipseWidth, ellipseHeight);
         brush.Dispose();
      }

      g.Dispose();
      RasterImagePainter.DeleteLeadDC(hdc);

      // Convert this image to 8 bits/pixel
      ColorResolutionCommand cmd = new ColorResolutionCommand(
         ColorResolutionCommandMode.InPlace,
         8,
         RasterByteOrder.Rgb,
         RasterDitheringMethod.None,
         ColorResolutionCommandPaletteFlags.Optimized,
         null);
      cmd.Run(image);

      // Find the Magenta color and set it as the transparent color
      RasterColor transparentColor = RasterColor.FromKnownColor(RasterKnownColor.Magenta);

      // Get the true color used for Magenta inside this image (a palette index)
      transparentColor = image.TranslateColor(image, transparentColor);

      image.Transparent = true;
      image.TransparentColor = transparentColor;

      // Initialize the RasterCodecs object
      RasterCodecs codecs = new RasterCodecs();

      // Save this image as GIF
      string fileName = Path.Combine(LEAD_VARS.ImagesDir,"TransparentEllipses.gif");
      codecs.Save(image, fileName, RasterImageFormat.Gif, 8);

      // Clean up
      image.Dispose();
      codecs.Dispose();
   }

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

[TestMethod]
public async Task CreateTransparentGifExample()
{
   // Create a 24 bpp image, we will draw on it first then convert it to 8 bpp
   int imageWidth = 256;
   int imageHeight = 256;
   RasterImage image = new RasterImage(
      RasterMemoryFlags.Conventional,
      imageWidth,
      imageHeight,
      24,
      RasterByteOrder.Bgr,
      RasterViewPerspective.BottomLeft,
      null);
   // Fill this image with magenta color
   FillCommand fillCmd = new FillCommand(RasterColorHelper.FromKnownColor(RasterKnownColor.Magenta));
   fillCmd.Run(image);
   RasterRegionXForm xform = new RasterRegionXForm();
   xform.ViewPerspective = RasterViewPerspective.TopLeft;
   xform.XOffset = 0;
   xform.YOffset = 0;
   xform.XScalarDenominator = 1;
   xform.XScalarNumerator = 1;
   xform.YScalarDenominator = 1;
   xform.YScalarNumerator = 1;
   image.AddRectangleToRegion(xform, LeadRectHelper.Create(0, 0, 100, 100), RasterRegionCombineMode.Set);
   FillCommand fillRgnCmd = new FillCommand(RasterColorHelper.FromKnownColor(RasterKnownColor.Black));
   fillRgnCmd.Run(image);

   // Convert this image to 8 bits/pixel
   ColorResolutionCommand colorResCmd = new ColorResolutionCommand(
      ColorResolutionCommandMode.InPlace,
      8,
      RasterByteOrder.Rgb,
      RasterDitheringMethod.None,
      ColorResolutionCommandPaletteFlags.Optimized,
      null);
   colorResCmd.Run(image);

   // Find the Magenta color and set it as the transparent color
   RasterColor transparentColor = RasterColorHelper.FromKnownColor(RasterKnownColor.Magenta);

   // Get the true color used for Magenta inside this image (a palette index)
   transparentColor = image.TranslateColor(image, transparentColor);

   image.Transparent = true;
   image.TransparentColor = transparentColor;

   // Initialize the RasterCodecs object
   RasterCodecs codecs = new RasterCodecs();

   // Save this image as GIF
   StorageFile saveFile = await Tools.AppLocalFolder.CreateFileAsync("TransparentEllipses.gif");
   ILeadStream saveStream = LeadStreamFactory.Create(saveFile);
   await codecs.SaveAsync(image, saveStream, RasterImageFormat.Gif, 8);

   // Clean up
   image.Dispose();
   codecs.Dispose();
}

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
TranslateColor(RasterImage,Int32) Method
Implementing Animation