FromPaletteIndex Method

Summary

Creates a new RasterColor object that is an index into a palette

Syntax

C++/CLI

Python

public static RasterColor FromPaletteIndex( 
   int index 
)

public: 
static RasterColor FromPaletteIndex(  
   int index 
)

def FromPaletteIndex(self,index):

Parameters

index
The index value

Return Value

A new RasterColor object that is an index into a palette.

Remarks

A RasterColor object can be a true RGB color or an index value into the palette of an image.

If the value of IsPaletteIndex is true, then this color does not contain a true RGB value, instead, the value stored is an index into the palette of an image. To get the index value, use ToRgb.

If the value of IsPaletteIndex is false, then this color contains a true RGB value.

Use this method to create a color that is a palette index.

Example

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.Drawing; 
 
 
// WIN32 API 
const int LOGPIXELSY = 90; 
 
[DllImport("gdi32")] 
extern static int GetDeviceCaps(IntPtr hdc, int nIndex); 
 
[DllImport("kernel32")] 
extern static int MulDiv(int nNumber, int nNumerator, int nDenominator); 
 
		public void AnimatedGIFExample() 
{ 
	// The GIF file will contain 4 frames 
	const int frameCount = 4; 
 
	// Each frame is 128 by 128 pixels (the GIF file will have double that size) 
	const int frameWidth = 128; 
	const int frameHeight = 128; 
 
	// Background colors 
	RasterColor[] backColor = 
	{ 
	new RasterColor(0xFF, 0x00, 0x00), 
	new RasterColor(0x00, 0xFF, 0x00), 
	new RasterColor(0x00, 0x00, 0xFF), 
	new RasterColor(0xFF, 0xFF, 0x00) 
 }; 
 
	// Foreground colors 
	RasterColor[] foreColor = 
	{ 
	new RasterColor(0xFF, 0xFF, 0x00), 
	new RasterColor(0xFF, 0x00, 0x00), 
	new RasterColor(0x00, 0xFF, 0x00), 
	new RasterColor(0xFF, 0x00, 0x00) 
 }; 
 
	// Delay in milliseconds 
	int[] delay = 
	{ 
	1000, 
	1000, 
	1000, 
	1000 
 }; 
 
	// Left and top, we want the frames to move to each corner 
	LeadPoint[] offset = 
	{ 
	new LeadPoint(0, 0), 
	new LeadPoint(frameWidth, 0), 
	new LeadPoint(frameWidth, frameHeight), 
	new LeadPoint(0, frameHeight), 
 }; 
 
	RasterImageAnimationDisposalMethod[] disposalMethod = 
	{ 
	RasterImageAnimationDisposalMethod.RestoreBackground, 
	RasterImageAnimationDisposalMethod.RestoreBackground, 
	RasterImageAnimationDisposalMethod.RestoreBackground, 
	RasterImageAnimationDisposalMethod.RestoreBackground 
 }; 
 
	RasterColor backgroundColor = RasterColor.FromKnownColor(RasterKnownColor.Yellow); 
 
	RasterImage image = null; 
	Font font = null; 
	StringFormat stringFormat = null; 
 
	// Create the frames 
	for (int frame = 0; frame < frameCount; frame++) 
	{ 
            RasterImage frameImage = new RasterImage( 
               RasterMemoryFlags.Conventional, 
               frameWidth, 
               frameHeight, 
               24, 
               RasterByteOrder.Bgr, 
               RasterViewPerspective.BottomLeft, 
               null, 
               IntPtr.Zero, 
               0) 
            { 
 
               // Set the frame properties 
               AnimationDelay = delay[frame], 
               AnimationOffset = offset[frame], 
               AnimationDisposalMethod = disposalMethod[frame], 
 
               // Background is white 
               AnimationBackground = backgroundColor 
            }; 
 
            // Draw the number of the frame on its surface 
            IntPtr hdc = RasterImagePainter.CreateLeadDC(frameImage); 
		Graphics g = Graphics.FromHdc(hdc); 
		Rectangle rc = new Rectangle(0, 0, frameWidth, frameHeight); 
 
		Brush brush = new SolidBrush(RasterColorConverter.ToColor(backColor[frame])); 
		g.FillRectangle(brush, rc); 
		brush.Dispose(); 
 
		if (font == null) 
		{ 
			int fontHeight = MulDiv(72, GetDeviceCaps(hdc, LOGPIXELSY), 72); 
			font = new Font("Consolas", fontHeight); 
 
               stringFormat = new StringFormat 
               { 
                  Alignment = StringAlignment.Center, 
                  LineAlignment = StringAlignment.Center 
               }; 
            } 
 
		string str = string.Format("{0}", frame + 1); 
 
		brush = new SolidBrush(RasterColorConverter.ToColor(foreColor[frame])); 
		g.DrawString(str, font, brush, rc, stringFormat); 
		brush.Dispose(); 
 
		g.Dispose(); 
		RasterImagePainter.DeleteLeadDC(hdc); 
 
		if (image == null) 
			image = frameImage; 
		else 
			image.AddPage(frameImage); 
	} 
 
	font.Dispose(); 
	stringFormat.Dispose(); 
 
	// Setup the global image properties 
	image.AnimationGlobalSize = new LeadSize(frameWidth * 2, frameHeight * 2); 
	image.AnimationGlobalLoop = 0; 
	image.AnimationGlobalBackground = backgroundColor; 
 
	// Convert this image to 8 bits/pixel 
	ColorResolutionCommand cmd = new ColorResolutionCommand( 
	   ColorResolutionCommandMode.AllPages, 
	   8, 
	   RasterByteOrder.Rgb, 
	   RasterDitheringMethod.None, 
	   ColorResolutionCommandPaletteFlags.Optimized, 
	   null); 
	cmd.Run(image); 
 
	RasterCodecs codecs = new RasterCodecs(); 
 
	// Setup the GIF save options 
	RasterColor[] animationPalette = image.GetPalette(); 
	codecs.Options.Gif.Save.SetAnimationPalette(animationPalette); 
	codecs.Options.Gif.Save.UseAnimationPalette = true; 
 
	// The GIF Animation width & height, loop and background are 
	// pulled automatically from the image 
 
	// Save the file 
	string fileName = Path.Combine(LEAD_VARS.ImagesDir, "AnimatedGifFile.gif"); 
	codecs.Save(image, fileName, RasterImageFormat.Gif, 8, 1, image.PageCount, 1, CodecsSavePageMode.Overwrite); 
 
	image.Dispose(); 
 
	codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms

Reference

RasterColor Structure

RasterColor Members

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Help Version 22.0.2023.5.16