Rules for Tools/DragSlider()
long DragSlider(struct Window *window, struct Gadget *gadget,
long width, long (*routine)(), char vertical)
`struct Window *window'
Window for slider.
`struct Gadget *gadget'
Gadget that defines slider.
Slider button width.
Routine to draw button.
TRUE if vertical slider.
Use `DragSlider()' in conjunction with `DrawSlider()' to create
the sliders used extensively by the Bars&Pipes Tool control
windows. Each slider corresponds to an Intuition Boolean gadget
and the bounding box of the gadget describes the region the slider
may move within.
To drag the slider, call `DragSlider()', passing it the window to
draw in, the gadget, so it knows the dimensions of the slider, the
width of the button in pixels, a routine to draw the data in the
button, and a flag that is set if this is a vertical slider. When
the user finally releases the slider, `DragSlider()' returns the
final position of the slider. The final position is actually the
value returned by your draw routine, so you can tailor that
routine to return a value in the appropriate range.
`DragSlider()' calls your draw routine every time the mouse moves.
`DragSlider()' erases the button, so your routine need only redraw
the contents. Here's a sample routine that converts the slider
position into a number between 0 and 99, draws that number into
the knob, and returns it:
long dragroutine(rastport,x,y,position) struct RastPort *rastport;
/* RastPort to draw in. */
short x,y; /* Coordinates of button. *.
unsigned short position; /* The slider position. */
position = position / 655;
To use `DragSlider()', set up your window to receive Intuition
`MOUSEMOVE', `MOUSEBUTTONS', `GADGETDOWN' and `GADGETUP' events.
When the user clicks on your slider's Boolean gadget, respond to
the `GADGETDOWN' event with a call to `DragSlider()'. The
following example uses a horizontal slider 30 pixels wide:
newvalue = (*functions->DragSlider)(window,gadget,30,dragroutine,0);