L_LoadBitmapResize

Summary

Loads an image file into a 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.

Note: More options are available in the LOADFILEOPTION structure.

Syntax

L_LTFIL_API L_INT L_LoadBitmapResize(pszFile, pSmallBitmap, uStructSize, nDestWidth, nDestHeight, nDestBits, uFlags, nOrder, pLoadOptions, pFileInfo)

Parameters

L_TCHAR* pszFile

Character string containing the name of the file to load.

pBITMAPHANDLE pSmallBitmap

Pointer to the bitmap handle referencing the target bitmap.

L_UINT uStructSize

Size in bytes, of the structure pointed to by pBitmap, for versioning. Use sizeof(BITMAPHANDLE).

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:

L_UINT uFlags

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

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:

pLOADFILEOPTION pLoadOptions

Pointer to a LOADFILEOPTION structure 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 L_FileInfo.

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 L_FileInfo has been called previously, but values that affect the size of the image loaded have been changed (for example, by calling L_SetPCDResolution or L_SetWMFResolution). In this case the FILEINFO structure pointed to by pFileInfo will be updated with the results of L_FileInfo.

If L_FileInfo has been called prior to calling this function, and no changes have been made to the contents of the structure filled by L_FileInfo, 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 L_FileInfo 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

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.

Platforms

Win32, x64, Linux.

See Also

Functions

• L_LoadFile
• L_LoadFileOffset
• L_ReadFileStamp
• L_SetLoadResolution
• L_SetPCDResolution
• L_SetWMFResolution
• L_SetLoadInfoCallback
• L_DlgOpen
• L_CreatePanWindow
• For Vector files:
• L_2DGetViewMode
• L2DGetViewPort
• L_2DSetViewMode
• L_2DSetViewPort

Topics

• Raster Image Functions: Loading Files
• Raster Image Functions: Redirecting Input and Output
• Raster Image Functions: Input and Output
• Loading and Saving Images
• Using a PanWindow

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 on the resize.
The bitmap is loaded at the original bits per pixel.

L_INT LoadBitmapResizeExample(pBITMAPHANDLE pSmallBitmap, L_TCHAR *pszFile) 
{ 
   L_INT nRet; 
   if(pSmallBitmap->Flags.Allocated) 
      L_FreeBitmap(pSmallBitmap); 
   nRet = L_LoadBitmapResize( 
                              pszFile,       // name of the file to load  
                              pSmallBitmap,  // pointer to the target bitmap handle  
                              sizeof(BITMAPHANDLE), 
                              0,             // new width of the image  
                              400,           // new height of the image  
                              0,             // new bits per pixel for the image  
                              SIZE_BICUBIC, 
                              ORDER_BGR,     // color order 
                              NULL,          // pointer to optional extended load options  
                              NULL           // pointer to a structure  
                              ); 
   return nRet; 
}