Start Method

Summary

Sets up information for the ResizeBuffer method.

Syntax

Objective-C

C++/CLI

Python

public void Start( 
   RasterImage image, 
   int width, 
   int height, 
   int bitsPerPixel, 
   RasterByteOrder order, 
   RasterDitheringMethod ditheringMethod, 
   RasterSizeFlags sizeFlags, 
   RasterColor[] palette 
)

- (BOOL)startResize:(LTRasterImage *)image width:(NSInteger)width height:(NSInteger)height bitsPerPixel:(NSInteger)bitsPerPixel order:(LTRasterByteOrder)order ditheringMethod:(LTRasterDitheringMethod)ditheringMethod sizeFlags:(LTRasterSizeFlags)sizeFlags palette:(NSArray<LTRasterColor *> *)palette callback:(void (^ __nullable)(LTRasterImageResizeData *, BOOL *))callback error:(NSError **)error;

public: 
void Start(  
   RasterImage^ image, 
   int width, 
   int height, 
   int bitsPerPixel, 
   RasterByteOrder order, 
   RasterDitheringMethod ditheringMethod, 
   RasterSizeFlags sizeFlags, 
   array<RasterColor>^ palette 
)

def Start(self,image,width,height,bitsPerPixel,order,ditheringMethod,sizeFlags,] palette):

Parameters

image
Image to be resized.

width
New width of the image data.

height
New height of the image data.

bitsPerPixel
Output bits per pixel. Use 0 for 8-bit grayscale. Possible values are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 24, 32, 48 and 64.

order
Output color order.

ditheringMethod
Flags that indicate the type of dithering, if bitsPerPixel is not the same as the source image.

sizeFlags
Flags that indicate the type of resizing.

palette
The palette to dither to if bitsPerPixel is less than or equal to 8. Pass a null reference to dither to the fixed palette or if no palette is required.

Remarks ditheringMethod is used when dithering is needed to produce the output bits per pixel. The interpolation usually requires that the input data be converted to 24-bit or 48-bit and then back to the desired bits per pixel. So some dithering might be required if the output bits/pixel are less than or equal to 8.

The Start method starts the resizing process. This will be followed by calls to ResizeBuffer to retrieve the resized data and by a call to Stop, to end the resize process and clean up any allocated resources.

Example

using Leadtools; 
using Leadtools.Codecs; 
 
 
public void RasterImageResizeExample() 
{ 
	string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); 
	string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_RasterImageResize.bmp"); 
 
	using (RasterCodecs codecs = new RasterCodecs()) 
	{ 
		// Load the source image 
		using (RasterImage srcImage = codecs.Load(srcFileName)) 
		{ 
			// We will resize to half the original size 
			int destWidth = srcImage.Width / 2; 
			int destHeight = srcImage.Height / 2; 
 
			// Create the destination image 
			using (RasterImage destImage = new RasterImage( 
			   RasterMemoryFlags.Conventional, 
			   destWidth, 
			   destHeight, 
			   srcImage.BitsPerPixel, 
			   srcImage.Order, 
			   srcImage.ViewPerspective, 
			   srcImage.GetPalette(), 
			   IntPtr.Zero, 
			   0)) 
			{ 
				RasterImageResize resize = new RasterImageResize(); 
 
				// Add Event Handler 
				resize.Resize += new EventHandler<RasterImageResizeEventArgs>(resize_Resize); 
 
				byte[] buffer = new byte[destImage.BytesPerLine]; 
 
				// Start the resize process 
				resize.Start( 
				   srcImage, 
				   destWidth, 
				   destHeight, 
				   srcImage.BitsPerPixel, 
				   srcImage.Order, 
				   srcImage.DitheringMethod, 
				   RasterSizeFlags.None, 
				   srcImage.GetPalette()); 
 
				destImage.Access(); 
				// get the rows for the resized image, one by one 
				for (int row = 0; row < destImage.Height; row++) 
				{ 
					resize.ResizeBuffer(row, 0, buffer, 0, destImage.BytesPerLine); 
					destImage.SetRow(row, buffer, 0, destImage.BytesPerLine); 
				} 
				destImage.Release(); 
				resize.Stop(); 
 
				// Save the destination image 
				codecs.Save(destImage, destFileName, RasterImageFormat.Bmp, 24); 
			} 
		} 
	} 
} 
 
private void resize_Resize(object sender, RasterImageResizeEventArgs e) 
{ 
	// e.Row should ALWAYS be less than e.Image.Height 
	if (e.Row >= e.Image.Height) 
	{ 
		e.Cancel = true; // abort the resize 
		return; 
	} 
 
	byte[] buffer = new byte[e.Bytes]; 
	e.Image.Access(); 
	e.Image.GetRowColumn(e.Row, e.Column, buffer, 0, e.Bytes); 
	e.Image.Release(); 
	Marshal.Copy(buffer, 0, e.Buffer, e.Bytes); 
	Console.WriteLine("{0}, {1}", e.Row, e.Column); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms

Reference

RasterImageResize Class

RasterImageResize Members

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Help Version 22.0.2023.5.16

Leadtools Assembly

Introduction

Getting Started

Namespaces

Leadtools Namespace

Leadtools.ImageProcessing Namespace

Assemblies