tkVScrollBar

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tkVScrollBar

Draws a vertical scrollbar that you size, feed a range, and listen to.

tkVScrollBar is a flat vertical track with a flat thumb and no arrow buttons. You tell it the total, the page and the position; it tells you when the user drags, pages or wheels it. It does not scroll anything itself, so use it beside content you already draw: a list, a canvas, a preview. For a panel that scrolls child content for you, see tkScrollPanel.

It is a thin module over tkScrollBar, which describes the behaviour both bars share: paging and auto-repeat, the minimum thumb, the wheel, theme colours and the porting notes. tkVScrollBar_SetDividerColor is its own: a one-pixel line down the bar's left edge, separating it from the content.

Importing

#import "vendor/tkControls/tkVScrollBar"

using tkVScrollBar
using tkHost

The module imports tkScrollBar, tkHost and tkTheme publicly.

Example

A bar down the right edge of a content widget, which forwards its own wheel to the bar.

dim shared as TK_WIDGET ptr gVS

sub VS_Scroll( byval hSB as TK_WIDGET ptr, byval newPos as integer )
    gTopLine = newPos              ' the user moved the bar: redraw the content from here
    tkHost_Invalidate( gHost )
end sub

function Content_Proc( byval w as TK_WIDGET ptr, byval m as TK_MSG ptr ) as boolean
    if m->msg = TKM_MOUSEWHEEL then
        tkVScrollBar_HandleWheelDelta( gVS, cint( m->wheelY * 120 ) )
        return true
    end if
    return false
end function

gVS = tkVScrollBar_Create( tkHost_Root( gHost ), 1002 )
tkWidget_SetPos( gVS, pw - tkHost_Scale( gHost, TKVSCROLL_DEFAULT_WIDTH ), 0, _
                 tkHost_Scale( gHost, TKVSCROLL_DEFAULT_WIDTH ), ph )
tkVScrollBar_SetRange( gVS, nLines, nVisibleLines, 0 )
tkVScrollBar_SetScrollCallback( gVS, @VS_Scroll )

tkVScrollBar_SetRange and tkVScrollBar_SetPos are silent; only the user's actions call the scroll callback.

Coming from PsVScrollBar

PsVScrollBar_* → tkVScrollBar_* and CVSCROLL_* → TKVSCROLL_*; the callback type names are unchanged and the handle is TK_WIDGET ptr. The rest of the differences are listed on tkScrollBar. PsVScrollBar remains the behaviour reference.

Public declarations

Every public name the module declares, as the source declares it. Signatures are exact; type bodies keep their field comments and drop the rest.

Constants

const TKVSCROLL_REPEAT_DELAY = TKSCROLL_REPEAT_DELAY
const TKVSCROLL_REPEAT_MS = TKSCROLL_REPEAT_MS
const TKVSCROLL_MIN_THUMB = TKSCROLL_MIN_THUMB
const TKVSCROLL_DEFAULT_WIDTH = TKSCROLL_DEFAULT_THICKNESS

Types

type TKVSCROLLBAR_PAINTINFO as TKSCROLLBAR_PAINTINFO
type VScrollPaintCallbackSub as tkScrollPaintSub
type VScrollCallbackSub as tkScrollNotifySub

Procedures

function tkVScrollBar_Create( byval hParent as TK_WIDGET ptr, byval CtrlID as integer ) as TK_WIDGET ptr
sub tkVScrollBar_SetRange( byval hSB as TK_WIDGET ptr, byval nTotal as integer, byval nPage as integer, byval nPosition as integer )
function tkVScrollBar_GetPos( byval hSB as TK_WIDGET ptr ) as integer
sub tkVScrollBar_SetPos( byval hSB as TK_WIDGET ptr, byval nPosition as integer )
function tkVScrollBar_HandleWheelDelta( byval hSB as TK_WIDGET ptr, byval nDelta as integer ) as boolean
sub tkVScrollBar_SetWheelStep( byval hSB as TK_WIDGET ptr, byval nUnitsPerNotch as integer )
function tkVScrollBar_GetWheelStep( byval hSB as TK_WIDGET ptr ) as integer
function tkVScrollBar_NeedsThumb( byval hSB as TK_WIDGET ptr ) as boolean
function tkVScrollBar_IsDragging( byval hSB as TK_WIDGET ptr ) as boolean
function tkVScrollBar_GetThumbRect( byval hSB as TK_WIDGET ptr ) as TKRECT
sub tkVScrollBar_SetColors( byval hSB as TK_WIDGET ptr, byval backclr as ulong, byval foreclr as ulong, byval foreclrhot as ulong )
sub tkVScrollBar_SetDividerColor( byval hSB as TK_WIDGET ptr, byval clr as ulong, byval bShow as boolean = true )
function tkVScrollBar_GetDividerColor( byval hSB as TK_WIDGET ptr ) as ulong
sub tkVScrollBar_ApplyTheme( byval hSB as TK_WIDGET ptr, byref t as TKTHEME_COLORS )
sub tkVScrollBar_UnpinColors( byval hSB as TK_WIDGET ptr )
sub tkVScrollBar_SetPaintCallback( byval hSB as TK_WIDGET ptr, byval usersub as VScrollPaintCallbackSub )
sub tkVScrollBar_SetScrollCallback( byval hSB as TK_WIDGET ptr, byval usersub as VScrollCallbackSub )

See also

• tkControls
• tkApp, tkHost
• PsVScrollBar, the PsControls control