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
   |
   +--GraphicsContext
      |
      +--DeviceGraphicsContext
         |
         +--GraphicsMedium
            |
            +--DisplaySurface
               |
               +--SimpleView
                  |
                  +--ScrollBar
                     |
                     +--HorizontalScrollBar
                     |
                     +--SteppingSlider

Package:

stx:libwidg

Category:

Views-Interactors

Version:

rev: 1.88 date: 2009/10/24 14:00:20

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 syncronous (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
dont 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

** This is an obsolete interface - do not use it (it may vanish in future versions) **

 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

** This is an obsolete interface - do not use it (it may vanish in future versions) **

 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)

 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.

 update: something with: aParameter from: changedObject

 keyPress: key x: x y: y

 realize

 sizeChanged: how

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

 wantsFocusWithButtonPress

no, do not catch the keyboard focus on button click

 pageDown

page down/right

 pageUp

page up/left

 scrollToBeginning

to top

 scrollToEnd

to end

 createElements

private: create my elements

 defaultExtent

compute my extent from sub-components

 initStyle

setup viewStyle specifics

 initialize

setup; create the 2 buttons and a scroller

 reinitialize

 setElementPositions

position sub-components

 beNativeWidget

 makeElementsInvisible

when using native widget, my elements are not visible.
(they are not destroyed, to keep a place for their attributes,
and to allow future dynamic switching and snapshot restore on
a non-native system)

 nativeWindowType

return a symbol describing my native window type
(may be used internally by the device as a native window creation hint)

 updateNativeWidget

 changeVisibilityOf: aComponent to: aBoolean

 enableDisableButtons

only used with styles which disable their buttons if the
thumb is at either end. Check where the thumb is and enable/disable
as appropriate.

 setThumbFor: aView

adjust thumb for aView
(i.e. adjust thumbs origin & size for views size & views contents).
This is forwarded to the scroller here.

 setThumbHeightFor: aView

adjust thumbs height for aViews size & contents.
This is forwarded to the scroller here.

 setThumbOriginFor: aView

adjust thumbs origin for aViews size & contents.
This is forwarded to the scroller here.

 isMiniScroller

 isScrolling

true, if thumb is being moved (by user)

 preferredExtent

compute my extent from sub-components