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Puzzle 17
The DEVMODE Is in the Details |
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The Win32API.txt file provided with visual studio includes the following declaration for the DocumentProperties function: |
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Declare Function DocumentProperties Lib "winspool.drv" Alias _
"DocumentPropertiesA" (ByVal hwnd As Long, ByVal hPrinter As Long, _
ByVal pDeviceName As String, pDevModeOutput As DEVMODE, _
pDevModeInput As DEVMODE, ByVal fMode As Long) As Long |
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My Win32 API book defines it as follows: |
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Declare Function DocumentProperties Lib "winspool.drv" Alias _
"DocumentPropertiesA" (ByVal hwnd As Long, ByVal hPrinter As Long, _
ByVal pDeviceName As String, ByVal pDevModeOutput As Long, ByVal _
pDevModeInput As Long, ByVal fMode As Long) As Long |
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where both pDevModeOutput and pDevModeInput are defined as pointers to DEVMODE data structures. |
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The C declaration is as follows: |
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LONG DocumentProperties(
HWND hWnd, // handle to window that displays dialog box
HANDLE hPrinter, // handle to printer object
LPTSTR pDeviceName, // pointer to device name
PDEVMODE pDevModeOutput, // pointer to modified device mode
// structure
PDEVMODE pDevModeInput, // pointer to original device mode structure
DWORD fMode // mode flag
); |
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If you've read Tutorial 4, ''How DLL Calls Work: Inside a Stack Frame," you know that declaring the parameter As DEVMODE (as shown in win32api.txt) will, in fact, pass a pointer to a DEVMODE structure. Why would the declaration in |
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