Compass Control

Environment: Compiled using VC6.0 Sp3 and tested using Win95/98 WinNT4.0 and Win 2000

This article introduces a simple "cylinder" type of compass control based from CStatic. This will allow the control to be used within a dialog using the MFC Class Wizard Dialog or as a static control within a window.

The compass project is a simple dialog based project incorporating the compass control. To illustrate the dynamics of the control, a Proportional, Integer, Derivative Control (PID control) algorithm has been implemented to command the compass control to a user specified heading. This gives the affect of a turning compass.

The compass control is easy to use and has two member functions to control the compass.

Use

From a Dialog

Before you begin, make sure that the compass control class is registered in the Class Wizard database.

1. In a dialog, inset a picture control.
2. Set the picture ID.
3. Create a member variable using the Class Wizard Dialog. Make sure that the category is Control and that Variable Type is CCompass.

CCompass::SetPos

UINT SetPos( int nPos )

Return Value

Returns the previous heading.

Parameters

Heading to set compass to. Any values are valid. If the position is less than 0 or greater than 360, then compass will reflect their reference angles.

Remarks

Use the SetPos method to set the compass heading. Normal compass headings range form 0 to 360 degrees. Other values greater than 360 or less than 0 degrees may be used. The compass control will reflect the reference angle.

CCompass::SetTicAlign

void SetTicAlign( WORD wAlign )

Parameters

wAlign

Sets the tic alignment. Where:

COMPASS_TIC_TOP - Aligns tics along top of compass



COMPASS_TIC_BOTTOM - Aligns tics along the bottom of compass



COMPASS_TIC_BOTH - Aligns tics on top and bottom of compass

Remarks

Use SetTicAlign to setup the alignment of degree tics on the compass.

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