[ALLY] "Circonfine" - or how to skin a cat

From: ven::telia::com at: 28-Oct-2000 2:50

Hello allies!

Check out this one! It's the result of some hard hours trying to make a
round boundary for GUI-making (I'm not really a die-hard programmer).
I think it turned out pretty good. Now we can make these neat volume-
knobs for MP3-skins or whatever comes first..

Any comments are welcome..

--
Magnus Lundström

-- Attached file included as plaintext by Listar --
-- File: circonfine.r

rebol[]

circonfine: func [
    {Return the correct offset to keep circular area in-bounds.}
    offset [pair!] "Initial offset"
	origin [pair!] "Area offset"
    asize [pair!] "Size of area"
	size [pair!] "Size of object to confine"
][

    origin: origin + (asize / 2) - (size / 2)

	offset: offset - origin
    rmax: to-integer (asize/x / 2) - (size/x / 2)
    r: square-root ((power offset/x 2) + (power offset/y 2))
	if r > rmax [offset/x: to-integer offset/x * (rmax / r)
                     offset/y: to-integer offset/y * (rmax / r)]
	offset: offset + origin
    offset
]

;--------- example -----------

circle: make face [
    offset: 100x100
    size: 100x100
    color: 175.185.188
    effect: [gradcol 1x1 200.200.200 0.0.0 oval 0.0.0 key]
	edge: make edge [size: 0x0]
]

dragger: make face [
	size: 28x28
    offset: circle/offset + (circle/size / 2) - 14x14
	color: -1
	edge: make edge [size: 0x0]
    effect: [gradcol -1x-1 255.255.255 0.0.0 oval 0.0.0 key]
	feel: make feel [
		engage: func [face action event index][
			either none? face/data [
				face/data: event/offset
			][

    face/offset: circonfine face/offset + (event/offset - face/data) circle/offset circle/size 
    dragger/size
				show face
			]
			if action = 'up [face/data: none]
		]
	]
]

fence: make face [
	offset: 0x0
	size: 300x300
	color: 50.100.150
	pane: [circle dragger]
]

view fence

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