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Updated: Wednesday, February 10, 2021

ttk_intro (1t)


ttk_intro - Introduction to the Tk theme engine


Please see following description for synopsis


ttk::intro(1t)                 Tk Themed Widget                 ttk::intro(1t)


       ttk::intro - Introduction to the Tk theme engine

       The  Tk themed widget set is based on a revised and enhanced version of
       TIP #48 (http://tip.tcl.tk/48) specified style engine.  The  main  con-
       cepts  are  described  below.   The  basic  idea is to separate, to the
       extent possible, the code implementing a  widget's  behavior  from  the
       code  implementing its appearance.  Widget class bindings are primarily
       responsible for maintaining the widget state  and  invoking  callbacks;
       all  aspects  of the widget's appearance are controlled by the style of
       the widget (i.e. the style of the elements of the widget).

       A theme is a collection of elements and styles that determine the  look
       and feel of the widget set.  Themes can be used to:

       o      isolate platform differences (X11 vs. classic Windows vs. XP vs.
              Aqua ...)

       o      adapt to display limitations (low-color, grayscale,  monochrome,
              tiny screens)

       o      accessibility (high contrast, large type)

       o      application suite branding

       o      blend in with the rest of the desktop (Gnome, KDE, Java)

       o      and, of course: eye candy.

       An  element  displays  an  individual part of a widget.  For example, a
       vertical scrollbar  widget  contains  uparrow,  downarrow,  trough  and
       slider elements.

       Element  names  use  a recursive dotted notation.  For example, uparrow
       identifies a generic arrow  element,  and  Scrollbar.uparrow  and  Com-
       bobox.uparrow  identify  widget-specific elements.  When looking for an
       element, the style engine looks for the specific name first, and if  an
       element  of  that  name  is  not found it looks for generic elements by
       stripping off successive leading components of the element name.

       Like widgets, elements have options which specify what to  display  and
       how  to  display  it.   For example, the text element (which displays a
       text string) has -text, -font,  -foreground,  -background,  -underline,
       and -width options.  The value of an element option is taken from:

       o      an option of the same name and type in the widget containing the

       o      a dynamic setting specified by style map and the current state;

       o      the default setting specified by style configure; or

       o      the element's built-in default value for the option.

       A layout specifies which elements make up a widget  and  how  they  are
       arranged.   The  layout  engine  uses  a simplified version of the pack
       algorithm: starting with an initial cavity equal to  the  size  of  the
       widget,  elements  are  allocated  a parcel within the cavity along the
       side specified by the  -side  option,  and  placed  within  the  parcel
       according  to  the -sticky option.  For example, the layout for a hori-
       zontal scrollbar is:

              ttk::style layout Horizontal.TScrollbar {
                  Scrollbar.trough -children {
                Scrollbar.leftarrow -side left -sticky w
                Scrollbar.rightarrow -side right -sticky e
                Scrollbar.thumb -side left -expand true -sticky ew

       By default, the layout for a widget is the  same  as  its  class  name.
       Some  widgets may override this (for example, the ttk::scrollbar widget
       chooses different layouts based on the -orient option).

       In standard Tk, many widgets have a -state option which (in most cases)
       is  either normal or disabled.  Some widgets support additional states,
       such as the entry widget which has a readonly  state  and  the  various
       flavors of buttons which have active state.

       The  themed Tk widgets generalizes this idea: every widget has a bitmap
       of independent state flags.  Widget state flags  include  active,  dis-
       abled,  pressed,  focus, etc., (see ttk::widget(n) for the full list of
       state flags).

       Instead of a -state option, every widget now has a state widget command
       which  is  used  to set or query the state.  A state specification is a
       list of symbolic state  names  indicating  which  bits  are  set,  each
       optionally  prefixed  with an exclamation point indicating that the bit
       is cleared instead.

       For example, the class bindings for the ttk::button widget are:

              bind TButton <Enter>{ %W state active }
              bind TButton <Leave>{ %W state !active }
              bind TButton <ButtonPress-1>{ %W state pressed }
              bind TButton <Button1-Leave>{ %W state !pressed }
              bind TButton <Button1-Enter>{ %W state pressed }
              bind TButton <ButtonRelease-1>\
                  { %W instate {pressed} { %W state !pressed ; %W invoke } }

       This specifies that the widget becomes active when the  pointer  enters
       the  widget, and inactive when it leaves.  Similarly it becomes pressed
       when the mouse button is pressed, and  !pressed  on  the  ButtonRelease
       event.  In addition, the button unpresses if pointer is dragged outside
       the widget while Button-1 is held down, and represses if  it's  dragged
       back  in.   Finally,  when  the  mouse button is released, the widget's
       -command is invoked, but only if the button is currently in the pressed
       state.   (The  actual  bindings  are a little more complicated than the
       above, but not by much).

       Each widget is associated with a style, which specifies values for ele-
       ment options.  Style names use a recursive dotted notation like layouts
       and elements; by default, widgets use the class name to look up a style
       in the current theme.  For example:

              ttk::style configure TButton \
                -background #d9d9d9 \
                -foreground black \
                -relief raised \

       Many  elements are displayed differently depending on the widget state.
       For example, buttons have a different background when they are  active,
       a  different  foreground  when  disabled,  and  a different relief when
       pressed.  The style map command specifies dynamic option settings for a
       particular style:

              ttk::style map TButton \
                -background [list disabled #d9d9d9  active #ececec] \
                -foreground [list disabled #a3a3a3] \
                -relief [list {pressed !disabled} sunken] \

       See attributes(7) for descriptions of the following attributes:

       |Availability   | runtime/tk-8     |
       |Stability      | Uncommitted      |
       ttk::widget(n), ttk::style(n)

       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source        was        downloaded        from         https://source-

       Further information about this software can be found on the open source
       community website at https://www.tcl.tk/.

Tk                                    8.5                       ttk::intro(1t)