In This Topic ▼

LMemoryFile::LoadMemory

Summary

Loads any supported file from memory.

Syntax

#include "ltwrappr.h"

virtual L_INT LMemoryFile::LoadMemory(LMemoryBuffer, nBitsPerPixel=0, nOrder=ORDER_BGRORGRAY, uFlags=LOADFILE_ALLOCATE|LOADFILE_STORE, pLoadFileOption=NULL, pFileInfo = NULL)

Parameters

LBuffer& LMemoryBuffer

A LEAD buffer into which the file in memory will be loaded.

L_INT nBitsPerPixel

Resulting bitmap pixel depth. Possible values are:

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_INT nOrder

The desired color order. Possible values are:

Value	Meaning
ORDER_RGB	[0] Red-green-blue order.
ORDER_BGR	[1] Blue-green-red order.
ORDER_GRAY	[2] 12 or 16-bit grayscale image. 12 and 16-bit grayscale images are only supported in Document/Medical toolkits.
0	The data is 8 bits per pixel or less.
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.

L_UINT uFlags

Binary flags that determine the behavior of LMemoryFile::LoadMemory. You can specify one or more of the following values:

LOADFILE_ALLOCATE	[0x0001] The function allocates memory for the specified bitmap.
LOADFILE_STORE	[0x0002] The function loads data into the specified bitmap. (This takes place in addition to the actions of your callback function.)
LOADFILE_FIXEDPALETTE	[0x0004] This flag will force a palletized image to be dithered to a fixed palette.
LOADFILE_NOINTERLACE	[0x0008] The function passes image data in the order that is displayed, regardless of how it is stored in the file. (Set this flag if your program does not handle interlaced file formats.)
LOADFILE_ALLPAGES	[0x0010] The function loads all pages of a multipage file. Use this flag only if you are creating a bitmap list using the LPlayBack::Append function.
LOADFILE_COMPRESSED	[0x0040] (Document/Medical only) If possible, load the file as a 1-bit RLE-compressed image. For more information, refer to Speeding Up 1-Bit Documents.

pLOADFILEOPTION pLoadFileOption

Pointer to 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).

Some file formats do not contain a well-defined file signature. This is especially true for document file formats (TXT, PST, etc). LEADTOOLS can still detect the file format using the filename extension (ex. ".PST"). However, when loading files from memory the filename extension is not available. To provide this function with a filename extension, set pFileInfo.Name to the image file's name with extension and pFileInfo.Flags to FILEINFO_NAMEVALID when loading from memory.

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.

Returns

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

Comments

This function supports the LMemoryFile::LoadMemoryCallBack virtual function.

Support for 12 and 16-bit grayscale images is only available in the Document/Medical toolkits.

Before calling this function, you may need to get or set file information, such as the page number of a multipage file. Refer to Getting and Setting File Information.

Notes:

This function does not support Kodak PhotoCD (PCD) or Kodak FlashPix (FPX) files.
More options are available in the LOADFILEOPTION structure.

The LMemoryBuffer parameter is passed by reference, and is a required parameter.

This function cannot be used in combination with the Redirect input / output functions.

Notes:

For information on loading and saving large TIFF files faster, refer to Loading and Saving Large TIFF/BigTIFF Files.
You should never pass an uninitialized FILEINFO structure to this function.

Required DLLs and Libraries

LTFIL
File format DLLs
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.

Example

// define user LMemoryFile class to override its CallBacks 
class LUserMemoryFileLM : public LMemoryFile 
{ 
   public: 
      LUserMemoryFileLM() ; 
      virtual ~LUserMemoryFileLM() ; 
      virtual L_INT LoadMemoryCallBack(pFILEINFO pFileInfo, 
                                       LBitmapBase * pLBitmap, 
                                       LBuffer * pLBuffer, 
                                       L_UINT uFlags, 
                                       L_INT nRow, 
                                       L_INT nLines); 
}; 
 
LUserMemoryFileLM::LUserMemoryFileLM() 
{ 
} 
 
LUserMemoryFileLM::~LUserMemoryFileLM() 
{ 
} 
 
L_INT LUserMemoryFileLM::LoadMemoryCallBack(pFILEINFO pFileInfo, 
                                          LBitmapBase * pLBitmap, 
                                          LBuffer * pLBuffer, 
                                          L_UINT uFlags, 
                                          L_INT nRow, 
                                          L_INT nLines) 
{ 
   UNREFERENCED_PARAMETER(pFileInfo); 
   UNREFERENCED_PARAMETER(pLBitmap); 
   UNREFERENCED_PARAMETER(pLBuffer); 
   UNREFERENCED_PARAMETER(uFlags); 
   UNREFERENCED_PARAMETER(nRow); 
   UNREFERENCED_PARAMETER(nLines); 
 
   return SUCCESS ; 
} 
 
L_INT LMemoryFile__LoadMemoryExample(LBitmapBase& LeadBitmap) 
{ 
   L_INT nRet; 
   LUserMemoryFileLM userLeadMemFile ; 
   LBuffer LeadMemBuffer ; 
   FILEINFO FileInfo; 
 
   if (userLeadMemFile.IsValid() == FALSE) 
      userLeadMemFile.SetBitmap(&LeadBitmap) ; 
 
   userLeadMemFile.EnableCallBack(TRUE) ; 
 
   nRet = userLeadMemFile.Save(&LeadMemBuffer,FILE_LEAD,24,QS, NULL) ; 
   if(nRet != SUCCESS) 
      return nRet; 
 
   nRet = userLeadMemFile.GetInfo (LeadMemBuffer,&FileInfo, sizeof(FILEINFO), NULL) ; 
   if(nRet != SUCCESS) 
      return nRet; 
 
   nRet = LeadBitmap.Free(); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   nRet = LeadBitmap.Initialize(FileInfo.Width, FileInfo.Height, FileInfo.BitsPerPixel) ; 
   if(nRet != SUCCESS) 
      return nRet; 
 
   nRet = userLeadMemFile.LoadMemory( LeadMemBuffer, 0, ORDER_BGR, LOADFILE_ALLOCATE | LOADFILE_STORE, NULL) ; 
   if(nRet != SUCCESS) 
      return nRet; 
 
   return SUCCESS ; 
}