This function loads a thumbnail from the file specified by a file handle.
Declaration:
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AT_ERRCOUNT ACCUAPI IG_load_thumbnail_FD( AT_INT fd, LONG lOffset, LPHIGEAR lphIGear ); |
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Arguments:
| Name | Type | Description |
| fd | AT_INT | Handle of the open file containing the image from which to load the thumbnail. This handle can be obtained from Microsoft Windows functions such as CreateFile(), and cast to AT_INT for passing to the function parameter. FILE pointers returned by functions such as fopen(), and file handles returned by functions such as _sopen_s() are not supported. |
| lOffset | LONG | Offset in file at which file image begins. |
| lphIGear | LPHIGEAR | Pointer to a HIGEAR variable to receive the handle. |
Return Value:
Returns 0 if successful. Otherwise, returns the number of ImageGear errors that occurred during this function call.Supported Raster Image Formats:
All pixel formats supported by ImageGear Professional.
Sample:
None
Example:
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HIGEAR hIGear1 = 0; /* handle ret'd by IG_load_FD */ HIGEAR hIGear2 = 0; /* handle for thumbnail */ HANDLE fd; /* DOS File Descriptor */ LONG lOffset; /* offset to image in file */ UINT nPageNum; /* will be 0 for this call */ AT_ERRCOUNT nErrcount; /* to test for errors */ fd = CreateFile(_T("picture.bmp"), GENERIC_READ, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); if(fd != INVALID_HANDLE_VALUE) { nPageNum = 0; /* not a multi-page file */ lOffset = 0; /* access file from start */ /* Load image, and obtain its HIGEAR handle: */ nErrcount = IG_load_FD((AT_INT)fd, lOffset, nPageNum, 0, &hIGear1 ); CloseHandle(fd); if(nErrcount == 0) { nErrcount = IG_load_thumbnail_FD((AT_INT)fd, lOffset, &hIGear2 ); } //... // Destroy images if(IG_image_is_valid(hIGear1)) { IG_image_delete(hIGear1); } if(IG_image_is_valid(hIGear2)) { IG_image_delete(hIGear2); } } |
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Remarks:
The handle of the resulting image is returned to the HIGEAR variable pointed to by argument lphIGear. See also functions IG_load_thumbnail, and IG_save_thumbnail_set.