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LFile::LoadBitmapResize

Summary

Loads an image file into the class object's associated bitmap, resizing the bitmap as it loads, to the desired width, height, and bits per pixel. The file can be in any supported image file format and bits per pixel, whether compressed or uncompressed.

Syntax

#include "ltwrappr.h"

virtual L_INT LFile::LoadBitmapResize(nDestWidth, nDestHeight, nDestBits, uFlags, nOrder, pLoadOptions, pFileInfo)

Parameters

L_INT nDestWidth

New width of the image.

L_INT nDestHeight

New height of the image.

L_INT nDestBits

Resulting bitmap pixel depth. The following are valid values:

Value	Meaning
0	Keep the original file's pixel depth (Do not convert). A special note about loading 12 and 16-bit grayscale images.
1 to 8	The specified bits per pixel in the resultant bitmap
12	12 bits per pixel in the resultant bitmap.
16	16 bits per pixel in the resultant bitmap
24	24 bits per pixel in the resultant bitmap
32	32 bits per pixel in the resultant bitmap
48	48 bits per pixel in the resultant bitmap
64	64 bits per pixel in the resultant bitmap

L_UINT32 uFlags

Flag that indicates the type of resizing to use. Possible values are:

Value	Meaning
SIZE_NORMAL	[0x0] Normal resizing.
SIZE_RESAMPLE	[0x2] Linear interpolation resizing.
SIZE_BICUBIC	[0x4] Bicubic interpolation resizing.

L_INT nOrder

Color order for 16-, 24-, 32-, 48-, and 64-bit bitmaps. If the resultant bitmap is less than 16 bits per pixel, this will have no effect since palletized images have no order. The following are valid values:

Value	Meaning
ORDER_RGB	[0] Red, green, and blue color order in memory
ORDER_BGR	[1] Blue, green, and red color order in memory
ORDER_GRAY	[2] 12 or 16-bit grayscale image. 12 and 16-bit grayscale images are only supported in the Document/Medical toolkits.
ORDER_RGBORGRAY	[3] Load the image as red, green, blue OR as a 12 or 16-bit grayscale image. 12 and 16-bit grayscale images are supported in the Document/Medical toolkits only.
ORDER_BGRORGRAY	[4] Load the image as blue, green, red OR as a 12 or 16-bit grayscale image. 12 and 16-bit grayscale images are supported in the Document/Medical toolkits only.

pLOADFILEOPTION pLoadOptions

Pointer to a LOADFILEOPTION structure that contains optional extended load options. Pass NULL to use the default load options.

pFILEINFO pFileInfo

Pointer to a FILEINFO structure. This structure may contain file information used in loading an image, or it may be updated with information about the file being loaded.

If nothing is known about the file, pass NULL for this parameter, or declare a variable of type FILEINFO and set the FILEINFO.Flags to 0, then pass the address of the FILEINFO structure in this parameter. In this case, if the address of a FILEINFO structure is passed, the FILEINFO structure will be updated with the results of LFile::GetInfo.

If only the file type is known, set pFileInfo.Format to the file type and set pFileInfo.Flags to FILEINFO_FORMATVALID. This can also be done if LFile::GetInfo has been called previously, but values that affect the size of the image loaded have been changed (for example, by calling LFileSettings::SetPCDResolution or LFileSettings::SetWMFResolution). In this case the FILEINFO structure pointed to by pFileInfo will be updated with the results of LFile::GetInfo.

If LFile::GetInfo has been called prior to calling this function, and no changes have been made to the contents of the structure filled by LFile::GetInfo, then the address of the filled FILEINFO structure can be passed for this parameter. In this case, the FILEINFO.Flags member should be set to FILEINFO_INFOVALID. The LFile::GetInfo function will set the FILEINFO.Flags to FILEINFO_INFOVALID. In this case the load will be faster since this function does not have to query the file filters for the file type.

Note: Local variables are not initialized (since they are placed on the stack). So if you have a FILEINFO structure as a local variable, the value of its Flags parameter is undefined, possibly having FILEINFO_INFOVALID or FILEINFO_FORMATVALID set. That is why it is important to initialize FILEINFO.Flags before passing the address of the FILEINFO structure to the function.

Returns

Value	Meaning
SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

This function resizes a file as it loads, to the desired width, height, and bits per pixel. Note that the original file is not completely loaded into memory. This function is ideal for sampling large images (i.e. generating a thumbnail) without the memory overhead of loading the large file itself.

For supported formats, refer to Files To Be Included With Your Application.

Note: You should never pass an uninitialized FILEINFO structure to this function.

Required DLLs and Libraries

LTFIL
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Example

This sample loads and resizes an image to 400 pixels high.
The width of the bitmap is determined by the aspect ratio.
Bicubic interpolation is used in the resize.
The bitmap is loaded at the original bits per pixel.

L_INT LFile__LoadBitmapResizeExample(LFile & LeadFile, LBitmapBase & Bitmap, L_TCHAR * pszFile) 
{ 
   L_INT nRet; 
 
   LeadFile.SetBitmap(&Bitmap); 
 
   LeadFile.SetFileName(pszFile); 
 
   nRet = LeadFile.LoadBitmapResize(0, 400, 0, SIZE_BICUBIC, ORDER_BGR, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   return SUCCESS; 
 
}