AutoLISP
Developer's Guide > Working with
Programmable Dialog Boxes > Managing Dialog
Boxes > Handling
Tiles >
Handling Sliders
When you handle actions and callbacks from sliders, your application should check the reason code that it receives along with the callback. This is not required, but it is a good idea because it can reduce processing.
A callback occurs when an increment boundary on a slider is crossed. For example, if the slider is defined with a minimum value of 0, a maximum value of 10, and both small and big increments of 1, a callback is issued 10 times as the user traverses from one end of the slider to the other.
The following function shows the basic scheme of a function to handle a slider. It is called from an action expression associated with the slider tile. The slider_info tile used by the function displays the slider's current value in decimal form. Often such a tile is an edit box as well, which gives users the choice of either manipulating the slider or entering its value directly. If a user enters a value in slider_info, your edit box callback should update the value of the slider as follows:
(action_tile
"myslider"
"(slider_action $value $reason)"
)
(action_tile
"slider_info"
"(ebox_action $value $reason)"
)
.
.
.
(defun slider_action(val why)
(if (or (= why 2) (= why 1)) ; Check reason code.
(set_tile "slider_info" val) ; Show interim result.
)
)
(defun ebox_action(val why)
(if (or (= why 2) (= why 1)) ; Check reason code.
( set_tile "myslider" val) ; Show interim result.
)
)