Retrieving Mouse States

There are various ways of retrieving mouse states in CVI. The mouse control events return the coordinates of the mouse. When you have an EVENT_LEFT_CLICK, EVENT_RIGHT_CLICK, EVENT_LEFT_DOUBLE_CLICK or EVENT_RIGHT_DOUBLE_CLICK then the callback functions eventData1 and eventData2 parameters contain the current location of the mouse. This is useful, for example, when you want to display a pop-up menu in your program whenever you right click on a control.

There are also two functions in CVI that are useful in getting the state of the mouse.

• The GetGlobalMouseState function obtains information about the state of the mouse cursor where the X and Y coordinates are set to the position of the mouse relative to the top, left corner of the screen.
• The GetRelativeMouseState function obtains information about the state of the mouse cursor where the X and Y coordinates are set to the position of the mouse relative to the top and left coordinates of the control specified.

If Control ID of 0 is passed in the above functions, the coordinate information is relative to the top and left coordinates of the panel specified, excluding the frame and title bar. The coordinates return even if the mouse is not over the control or the panel.

Another useful function is the SetMouseCursor function, which is available in the User Interface Library. This function allows you to change the style of the cursor. For example, you can display the cursor as a cross hair, box, pointing finger, or hour glass.

Reader Comments | Submit a comment »