[REBOL] Re: Scroll text area?

From: agem:crosswinds at: 6-Jul-2001 22:31

RE: [REBOL] Scroll text area?

[hijim--pronet--net] wrote:
>
> Volker showed me how to move the cursor position, but can I scroll the text
> in the text area? All I want is page up and down and top and end of file to
> be displayed with buttons. There must be a way to scroll the display.
>
> Anyone?
>
[rebol []
    protect-system
    ???: func ['word value] [
        print [mold :word mold type? :value ":" mold :value]
        word :value]

    {Hi Jim. lets look at}

    source scroll-para

    [;the source:
        scroll-para: func [tf sf /local tmp] [
            if none? tf/para [exit]
            tmp: min 0x0 tf/size - (size-text tf) - 0x30
            either sf/size/x > sf/size/y [tf/para/scroll/x: sf/data * first tmp] [
                tf/para/scroll/y: sf/data * second tmp]
            show tf
        ]
    ]

    {this nice function is usually used like}
    context [
        view center-face layout [
            title "simple slider"
            across
            my-slider: slider 16x480 [scroll-para my-area my-slider]
            my-area: area para [] 640x480 (read first request-file)
        ]
    ]

    {for the hand-made way, we see 'tf/para/scroll/y and 'size-text tf
the first lets you set a position for your text, the 'size-text
gives you the size of the full text.
this is used to make scrolling relativ there.
its nice to play with it.}

    {but we have a slider! it can do the work!
set 'my-slider/data between 0 .. 1}

    context [
        view center-face layout [
            title "we jump!"
            across
            button "1/2" [
                my-slider/data: 0.5
                scroll-para my-area my-slider
                show [my-slider]
            ]
            return
            my-slider: slider 16x480 [scroll-para my-area my-slider]
            my-area: area para [] 640x480 (read first request-file)
        ]
    ]

    {so we can set slider & cursor together, now we have to
do something with pages.
has vid something ready? hm.
http://www.cs.unm.edu/~whip/objview.r is always a nice tool.
(on jeffs reb), but it does not work to look in 'system/view here?!
trick 2: to get an overview for faces i use
}
    layout [my-area: area do [probe my-area/feel]]

    {and we see somewhere
  key [edit-text face event get in face 'action]
'edit-text ? grumbling.
must be somewhere..
trick 3: to get an overview of objects:}

    probe first system/view ;this one is where you find caret and that
    probe first system/view/vid
    probe first system/view/vid/vid-feel ; no..
    {well, long not looked at. /view 1.2 now..}
    help ctx-
    probe first ctx-text ;lalala :)
    {but psst! its a function! do not wake!}
    probe get in ctx-text 'edit-text ;not probe ctx-text/edit-text !
    { AHA!
      set-caret: [view*/caret: offset-to-caret face tmp]
        page-up: [
            tmp/y: tmp/y - face/size/y
            if not head? view*/line-info/start set-caret
        ]
        page-down: [
            tmp/y: tmp/y + face/size/y
            if not tail? offset-to-caret face tmp set-caret
        ]

but then it gets complicated.. nono.
i calculate a bit myself:
}
    context [
        face: none
        view center-face layout [
            title "page-jumper"
            across
            button "down" [
                my-slider/data: my-slider/data +
                (my-area/size/y / second size-text my-area)
                scroll-para my-area my-slider
                show [my-slider]
            ]
            button "up" [
                my-slider/data: my-slider/data -
                (my-area/size/y / second size-text my-area)
                scroll-para my-area my-slider
                show [my-slider]
            ]
            return
            my-slider: slider 16x480 [scroll-para my-area my-slider]
            my-area: area para [] 640x480 (read first request-file)
        ]
    ]

    {seems, i misunderstood something. it jumps only part of pages.
needs more work..
}
]
;-) Volker

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