Class: ScrollBar

• Inheritance
• Description
• Related information
• Class protocol
  • style changes
• Instance protocol
  • accessing
  • accessing-behavior
  • accessing-components
  • accessing-look
  • change & update
  • events
  • focus handling
  • forced scroll
  • initialization
  • native widget support
  • private
  • private-scrollview interface
  • queries

Inheritance:

   Object
   |
   +--GraphicsMedium
      |
      +--DisplaySurface
         |
         +--SimpleView
            |
            +--ScrollBar
               |
               +--HorizontalScrollBar
               |
               +--SteppingSlider

Package:

stx:libwidg

Category:

Views-Interactors

Version:

rev: 1.100 date: 2018/11/09 23:27:09

user: cg

file: ScrollBar.st directory: libwidg

module: stx stc-classLibrary: libwidg

Author:

Claus Gittinger

Description:

this class implements vertical scrollbars with scroller and
2 step-scroll buttons. when moved or stepped, it performs a
predefined action.

The action is specified by:                 the block to be evaluated for step-up
    aScrollBar scrollUpAction:aBlock
    (scrollLeftAction for hor-Scrollbars)

    aScrollBar scrollDownAction:aBlock      the block to be evaluated for step-down
    (scrollRightAction for hor-Scrollbars)

    aScrollbar scrollAction:aBlock          the block to be evaluated for scroll
                                            passing percentage as argument.

Scrollbars can scroll synchronous (i.e. every movement is notified immediately via the
scrollAction) or asynchronous (i.e. only one notification takes place at the end of the movement).
The choice is up to the user of the scrollbar (typically, views which are complicated to redraw,
will set it to asynchronous.)

Most often scrollbars are used hidden with ScrollableView or HVScrollableView (i.e. you
don't have to care for all the details).

The scrollBars and scrollers protocols have been made similar enough to
allow transparent use of either a scroller or a scrollBar in applications.

Related information:

    Scroller
    Slider
    ScrollableView

Class protocol:

 updateStyleCache

extract values from the styleSheet and cache them in class variables

Instance protocol:

 thumbHeight

return height of thumb in percent

 thumbHeight: newHeight

set height of thumb in percent

 thumbOrigin

return position of (top of) thumb in percent

 thumbOrigin: newOrigin

set position of (top of) thumb in percent

 thumbOrigin: newOrigin thumbHeight: newHeight

set origin and height of thumb (both in percent)

 asynchronousOperation

 beAsynchronous

set asynchronous-mode - scroll action is performed after movement
of scroller when mouse-button is finally released (no tracking).
This is forwarded to the scroller here.

 beSynchronous

set synchronous-mode - scroll action is performed for every movement
of scroller (tracking).
This is forwarded to the scroller here.

 isSynchronous

return true if the scroll-mode is synchronous.
If true, the scroll action is performed for every movement of the thumb (tracking).
If false, the scroll action is only performed at the end.

 scrollAction: aBlock

set the action, aBlock to be performed when the scroller is moved.
This is forwarded to the scroller here.

 scrollDownAction

return the action which is performed on scroll-down.
(vertical scrollBars)

 scrollDownAction: aBlock

set the action, aBlock to be performed when the down-button is pressed.
(for vertical scrollBars)

 scrollLeftAction

return the action which is performed on scroll-left
(for horizontal scrollBars)

 scrollLeftAction: aBlock

set the action to be performed on scroll-left.
(for horizontal scrollBars)

 scrollRightAction

return the action which is performed on scroll-right.
(for horizontal scrollBars)

 scrollRightAction: aBlock

set the action to be performed on scroll-right.
(for horizontal scrollBars)

 scrollUpAction

return the action which is performed on scroll-up.
(for vertical scrollBars)

 scrollUpAction: aBlock

set the action, aBlock to be performed when the up-button is pressed.
(for vertical scrollBars)

 synchronousOperation

 downButton

return the down-button
(Please: only use this direct access for special applications)

 thumb

return the thumb (i.e. the scroller subview)
(Please: only use this direct access for special applications)

 upButton

return the up-button
(Please: only use this direct access for special applications)

 allViewBackground: something if: condition

blocked for all scrollBars (I want my own background)

usage example(s):

^ super allViewBackground:something

 orientation

for ST-80 compatibility, answer this query

 orientation: aSymbol

set the orientation; either #horizontal or #vertical

 thumbColor: aColor

set the thumbs color

 upButtonLabel: label1 downButtonLabel: label2

set the labels shown in the buttons.
Because of the fixed button sizes, this only makes sense with
single-character strings or small bitmaps.

usage example(s):

also possible : |v| v := ScrollableView for:EditTextView. v scrolledView contents:('/etc/passwd' asFilename contentsOfEntireFile). v scrollBar upButtonLabel:'u' downButtonLabel:'d'. v open

 update: something with: aParameter from: changedObject

 keyPress: key x: x y: y

(comment from inherited method)
a key has been pressed. If there are components,
pass it to the corresponding one.
Otherwise, forward it to the superview, if there is any.

 sizeChanged: how

when my size changes, I have to resize/reposition the subviews.
Also, if I became too small, hide thumb/buttons.