There are several internal formats used in the ImageGear library to represent an image, and there are groups of functions that allow you to convert it to an Xlib-compatible DDB (Pixmap) file, and back to its original format. Creating a DDB displays an image on a pixmap (not on a window). All display-related parameters are used in a DDB display the same way that they are used for displaying an image in a window.
Use the IG_dspl_DDB_create() function to create a pixmap object from a HIGEAR image function. This function accepts a HIGEAR image and the pixmap’s width and height as input, and returns a pixmap object as output. You can optionally remove the source HIGEAR object after creating the object.
To draw a pixmap, use either the standard Xlib functions or ImageGear’s IG_dspl_DDB_draw() function.
The following are segments from the Filters sample that demonstrate how an image is loaded (dlg_open.c):
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| AT_ERRCOUNT dlgOpenLoadPage(LPCHAR lpFileName, UINT nPage, LPHIGEAR lphIGear) { int fd; AT_ERRCOUNT nErrCount; LPVOID lpPrivate; LPFNIG_ERRSTACK_ADD lpCBFunc; LPFNIG_ERRSTACK_CLEAR lpCBFunc2; fd = open( (char*)lpFileName, O_RDONLY ); if( fd>0 ) { IG_err_callback_get( &lpPrivate, &lpCBFunc, &lpCBFunc2 ); IG_err_callback_set( NULL, NULL, NULL ); IG_err_callback_set( lpPrivate, lpCBFunc, lpCBFunc2 ); nErrCount = IG_load_FD( fd, 0, nPage, 0, lphIGear ); close( fd ); }else { nErrCount = 1; *lphIGear = (HIGEAR)NULL; } return nErrCount; } |
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and converted to a pixmap and back to HIGEAR (filters.c):
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| void mnuView_callback( Widget w, XtPointer data, XtPointer call_data ) { AT_DIMENSION width, height; int item_no = (int)data; switch( item_no ) { ... case 2: /* To Pixmap */ IG_image_dimensions_get( hIGear, &width, &height, NULL ); IG_dspl_DDB_create( hIGear, IG_GRP_DEFAULT, NULL, width, height, TRUE, &hPixmap, &hPalette ); hIGear = (HIGEAR)NULL; ImageViewUpdate(); break; case 3: /* From Pixmap */ IG_dspl_DDB_import( NULL, hPixmap, hPalette, &hIGear ); ImageViewUpdate(); break; ... }} |
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and how to draw a pixmap (filters.c):
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void wndDrawImage_callback( Widget w, XtPointer data, XtPointer call_data ) |
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