L_LoadMemory
#include "l_bitmap.h"
L_INT EXT_FUNCTION L_LoadMemory(pBuffer, pBitmap, uStructSize, nBitsPerPixel, nOrder, uFlags, pfnCallback, pUserData, nBufferSize, pLoadOptions, pFileInfo)
/* pointer to the file in memory to be loaded */ | |
pBITMAPHANDLE pBitmap; |
/* pointer to the bitmap handle */ |
L_UINT uStructSize; |
/* size in bytes, of the structure pointed to by pBitmap */ |
L_INT nBitsPerPixel; |
/* resulting bitmap pixel depth */ |
L_INT nOrder; |
/* desired color order */ |
L_UINT uFlags; |
/* flags that determine function behavior */ |
FILEREADCALLBACK pfnCallback; |
/* optional callback function */ |
/* pointer to more parameters for the callback */ | |
L_INT32 nBufferSize; |
/* size of the file in memory (in bytes) */ |
pLOADFILEOPTION pLoadOptions; |
/* pointer to optional extended load options */ |
pFILEINFO pFileInfo; |
/* pointer to a structure */ |
Loads any supported file from memory using a callback function.
Parameter |
Description |
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pBuffer |
Pointer to the file in memory to be loaded. |
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pBitmap |
Pointer to the bitmap handle referencing the bitmap to be filled with image data. |
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uStructSize |
Size in bytes, of the structure pointed to by pBitmap, for versioning. Use sizeof(BITMAPHANDLE). |
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nBitsPerPixel |
Resulting bitmap pixel depth. The following are valid values: |
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Value |
Meaning |
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0 |
Keep the original file's pixel depth (Do not convert). A special note about loading 12 and 16-bit grayscale images. |
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1 to 8 |
The specified bits per pixel in the resultant bitmap |
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12 |
12 bits per pixel in the resultant bitmap. |
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16 |
16 bits per pixel in the resultant bitmap |
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24 |
24 bits per pixel in the resultant bitmap |
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32 |
32 bits per pixel in the resultant bitmap |
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48 |
48 bits per pixel in the resultant bitmap |
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64 |
64 bits per pixel in the resultant bitmap |
nOrder |
The desired color order. Possible values are: |
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Value |
Meaning |
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ORDER_RGB |
[0] Red-green-blue order. |
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ORDER_BGR |
[1] Blue-green-red order. |
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ORDER_GRAY |
[2] 12 or 16-bit grayscale image. 12 and 16-bit grayscale images are only supported in the Document/Medical Imaging editions . |
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0 |
The data is 8 bits per pixel or less. |
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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 Imaging editions only. |
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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 Imaging editions only. |
|
ORDER_ROMM |
[5] ROMM order. ROMM only supports 24 and 48-bit images. |
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ORDER_BGRORGRAYORROMM |
[6] Load the image as red, green, blue OR as a 12 or 16-bit grayscale image OR as ROMM. 12 and 16-bit grayscale images are supported in the Document/Medical Imaging editions only. ROMM only supports 24 and 48-bit color images. |
uFlags |
Binary flags that determine the behavior of L_LoadMemory. You can specify one or more of the following values: |
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Value |
Meaning |
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LOADFILE_ALLOCATE |
[0x0001] The function allocates memory for the specified bitmap. |
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LOADFILE_STORE |
[0x0002] The function loads data into the specified bitmap. (This takes place in addition to the actions of your callback function.) |
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LOADFILE_FIXEDPALETTE |
[0x0004] This flag will force a palletized image to be dithered to a fixed palette. |
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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.) |
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LOADFILE_ALLPAGES |
[0x0010] The function loads all pages of a multi-page file. Use this flag only if you are creating a bitmap list using the L_AppendPlayback function. |
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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. |
pfnCallback |
Optional callback function for additional processing. |
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If you do not provide a callback function, use NULL as the value of this parameter. |
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If you do provide a callback function, use the function pointer as the value of this parameter. |
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The callback function must adhere to the function prototype described in FILEREADCALLBACK Function. |
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pUserData |
Void pointer that you can use to pass one or more additional parameters that the callback function needs. |
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To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID L_FAR *. The callback function, which receives the address in its own pUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure. |
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If the additional parameters are not needed, you can pass NULL in this parameter. |
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nBufferSize |
Size of the file in memory (in bytes). |
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pLoadOptions |
Pointer to optional extended load options. Pass NULL to use the default load options. |
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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. |
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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. |
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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. |
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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. |
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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
SUCCESS |
The function was successful. |
< 1 |
An error occurred. Refer to Return Codes. |
Comments
Support for 12 and 16-bit grayscale images is only available in the Document/Medical Imaging editions .
The callback function can display the image to the screen, write to a file, or do other useful things.
This function will create a buffer and fill it with the actual image data. Once the buffer is full, the callback function is called.
Before calling this function, you may need to get or set file information, such as the page number of a multi-page file. Refer to Getting and Setting File Information.
This function cannot be used in combination with L_RedirectIO.
Note: |
This function does not support Kodak PhotoCD (PCD), Kodak FlashPix, or Microsoft FAX (AWD) files. |
Note: |
More options are available in the LOADFILEOPTION structure. |
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
Windows 95 / 98 / Me, Windows 2000 / XP, Windows CE.
See Also
Functions: |
L_SetExtFileOption,
L_LoadBitmapMemory, L_DecompressBitmapMemory,
L_DecompressMemory, L_SetWMFResolution,
L_SetLoadInfoCallback, L_DlgOpen,
L_CreatePanWindow, L_SetLoadResolution,
L_SetPCDResolution, |
Topics: |
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For a list of functions that utilize the LOADFILEOPTION or SAVEFILEOPTION structures, refer to Functions Utilizing the LOADFILEOPTION or SAVEFILEOPTION structures.
Example
For complete sample code, refer to the MEMORYCB example.
/****************************************************************************************
This example loads a temporary bitmap, saves it as a file in memory,
then loads the memory-resident file into the global bitmap handle
It uses L_LoadMemory with a callback function to implement a
paint-while-load feature. Refer to the FILEREADCALLBACK
function to see how the callback function paints the image data.
The sample code uses the following global declarations: */
HINSTANCE hInst; /* Current instance of the application, set by the InitInstance function */
RECT rClientSize; /* RECT for the client area */
RECT rLeadDest; /* Destination rectangle for painting */
RECT rLeadSource; /* Source rectangle for painting */
BITMAPHANDLE LeadBitmap; /* Bitmap handle to hold the loaded image */
FILEINFO FileInfo; /* LEAD File Information structure.*/
/* Structure used for the callback function's user data */
typedef struct tagIMAGECBPARM
{
HWND hwnd; /* Current window */
HDC hdc; /* Device context for the current window */
} IMAGECBPARM;
/****************************************************************************************/
void TestFunction(HWND hWnd)
{
BITMAPHANDLE TmpBitmap; /* Bitmap handle for the initial image */
HGLOBAL hFileInMemory; /* Memory handle */
L_UINT32 uMemSize; /* Size of the data in memory */
L_CHAR L_FAR *pData; /* Pointer to the data in memory */
static IMAGECBPARM UserData; /* Structure used for the callback function's user data */
FILEREADCALLBACK lpfnCallBack;
/* Load a bitmap at its own bits per pixel */
L_LoadBitmap (TEXT("image3.cmp"), &TmpBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
/* Save the image as a CMP file in memory */
L_SaveBitmapMemory(&hFileInMemory, &TmpBitmap, FILE_CMP, 24, QS, &uMemSize, NULL);
/* Free the temporary bitmap */
L_FreeBitmap(&TmpBitmap);
/* Get the pointer to the memory-resident file */
pData = (L_CHAR L_FAR *) GlobalLock (hFileInMemory);
/* Get the client area of the window. We assume that elsewhere in the program, the
L_FileInfo function has been used to update the FileInfo structure and that the
window dimensions have been adjusted to the bitmap's aspect ratio. */
GetClientRect(hWnd,&rClientSize);
/* Make the destination rectangle for painting the same as the client area */
rLeadDest = rClientSize;
/* Initialize the bitmap handle */
L_InitBitmap( &LeadBitmap, sizeof(BITMAPHANDLE), FileInfo.Width, FileInfo.Height, FileInfo.BitsPerPixel );
LeadBitmap.ViewPerspective = FileInfo.ViewPerspective;
/* Set the user data used for the callback in the L_LoadFile function */
UserData.hwnd = hWnd; /* Current window */
UserData.hdc = GetDC( hWnd ); /* Device context for the current window */
/* Set the callback function for the L_LoadFile function.*/
lpfnCallBack = (FILEREADCALLBACK) MakeProcInstance(
(FARPROC) LoadImageCB, hInst );
/* Load the file, calling lpfnCallBack to paint the bitmap. */
L_LoadMemory(pData,
&LeadBitmap, sizeof(BITMAPHANDLE),
0,
ORDER_BGR,
LOADFILE_ALLOCATE | LOADFILE_STORE,
lpfnCallBack,
&UserData,
uMemSize,
NULL, NULL);
FreeProcInstance ((FARPROC) lpfnCallBack);
/* Avoid an unnecessary repaint */
ValidateRect(hWnd, &rLeadDest);
/* Clean up */
GlobalUnlock (hFileInMemory);
GlobalFree (hFileInMemory);
return;
}