Member

Description

uStructSize

Size of this structure, in bytes. Use the sizeof operator to calculate this value.

pBitmap

Pointer to the bitmap handle that references the bitmap used for preview or processing.

bZoomToFit

Flag that indicates the initial zoom level for previewing the image. Possible values are:

Value

Meaning

TRUE

Set the initial zoom level to "Zoom to fit".

FALSE

Set the initial zoom level to "Normal (1:1)".

pFilter

Address of a variable to be updated with the spatial filter selected in the dialog. The Prewitt filter applies Prewitt edge detection. All pixels not on the detected edges are changed to black. (The usage is the same as Sobel, but the algorithm is different.) Choose the appropriate value for horizontal or vertical detection. Possible values are:

Value

FLT_PREWITT_HORZ

FLT_PREWITT_VERT

uDlgFlags

User interface flags for this dialog, which determine the layout and action of the dialog. Possible values are:

Value

Meaning

DLG_PREWITTFILTER_AUTOPROCESS

[0x00000001] process the image on OK. The pBitmap member of this structure should contain a valid bitmap.

DLG_PREWITTFILTER_SHOW_CONTEXTHELP

[0x00000002] dialog should contain a context sensitive help icon.

DLG_PREWITTFILTER_SHOW_PREVIEW

[0x00000004] show a preview of the image in the dialog. The pBitmap member of this structure should contain a valid bitmap.

DLG_PREWITTFILTER_SHOW_TOOL_ZOOMLEVEL

[0x00000008] show the "Zoom to fit" and "Zoom Normal" toolbar buttons. The DLG_PREWITTFILTER_SHOW_PREVIEW flag must be set in order to show these buttons.

pfnHelpCallback

Pointer to an optional help callback function. If you do not wish to provide help to this dialog, use NULL as the value of this parameter. To provide help to this dialog, use the function pointer as the value of this parameter. The callback function must adhere to the prototype described in LTCOMMDLGHELPCB.

pHelpCallBackUserData

Void pointer that you can use to pass one or more additional parameters that the callback function needs. 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 pHelpCallBackUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure. If the additional parameters are not needed, you can pass NULL in this parameter.