# Class `wibox.container.scroll`

### Info:

- Copyright: 2015 Uli Schlachter
- Author: Uli Schlachter (based on ideas from Saleur Geoffrey)

## Functions

scroll.step_functions.linear_increase (elapsed, size, _, speed, extra_space) | A step function that scrolls the widget in an increasing direction with constant speed.
scroll.step_functions.linear_decrease (elapsed, size, _, speed, extra_space) | A step function that scrolls the widget in an decreasing direction with constant speed.
scroll.step_functions.linear_back_and_forth (elapsed, size, visible_size, speed) | A step function that scrolls the widget to its end and back to its beginning, then back to its end, etc.
scroll.step_functions.nonlinear_back_and_forth (elapsed, size, visible_size, speed) | A step function that scrolls the widget to its end and back to its beginning, then back to its end, etc.
scroll.step_functions.waiting_nonlinear_back_and_forth (elapsed, size, visible_size, speed) | A step function that scrolls the widget to its end and back to its beginning, then back to its end, etc.

## Object properties

wibox.container.scroll.widget | The widget to be scrolled.
wibox.container.scroll.forced_height | Force a widget height.
wibox.container.scroll.forced_width | Force a widget width.
wibox.container.scroll.opacity | The widget opacity (transparency).
wibox.container.scroll.visible | The widget visibility.

## Signals

widget::layout_changed | When the layout (size) change.
widget::redraw_needed | When the widget content changed.
button::press | When a mouse button is pressed over the widget.
button::release | When a mouse button is released over the widget.
mouse::enter | When the mouse enter a widget.
mouse::leave | When the mouse leave a widget.

## Tables

wibox.container.scroll.step_functions | A selection of step functions

## Methods

wibox.container.scroll:pause () | Pause the scrolling animation.
wibox.container.scroll:continue () | Continue the scrolling animation.
wibox.container.scroll:reset_scrolling () | Reset the scrolling state to its initial condition.
wibox.container.scroll:set_direction (dir) | Set the direction in which this widget scroll.
wibox.container.scroll:get_children () | Get the number of children element
wibox.container.scroll:set_children (children) | Replace the layout children This layout only accept one children, all others will be ignored
wibox.container.scroll:set_expand (expand) | Specify the expand mode that is used for extra space.
wibox.container.scroll:set_fps (fps) | Set the number of frames per second that this widget should draw.
wibox.container.scroll:set_extra_space (extra_space) | Set the amount of extra space that should be included in the scrolling.
wibox.container.scroll:set_speed (speed) | Set the speed of the scrolling animation.
wibox.container.scroll:set_max_size (max_size) | Set the maximum size of this widget in the direction set by set_direction.
wibox.container.scroll:set_step_function (step_function) | Set the step function that determines the exact behaviour of the scrolling animation.
wibox.container.scroll:set_space_for_scrolling (space_for_scrolling) | Set an upper limit for the space for scrolling.
wibox.container.scroll:horizontal ([widget[, fps=20[, speed=10[, extra_space=0[, expand=false[, max_size[, step_function=step_functions.linear_increase[, space_for_scrolling=2^1024]]]]]]]]) | Get a new horizontal scrolling container.
wibox.container.scroll:vertical ([widget[, fps=20[, speed=10[, extra_space=0[, expand=false[, max_size[, step_function=step_functions.linear_increase[, space_for_scrolling=2^1024]]]]]]]]) | Get a new vertical scrolling container.
wibox.container.scroll:index (widget[, recursive[, ...]]) | Get a widex index.
wibox.container.scroll:get_all_children () | Get all direct and indirect children widgets.
wibox.container.scroll:setup (args) | Set a declarative widget hierarchy description.
wibox.container.scroll:buttons (_buttons) | Set/get a widget's buttons.
wibox.container.scroll:emit_signal_recursive (signal_name, ...) | Emit a signal and ensure all parent widgets in the hierarchies also forward the signal.
wibox.container.scroll:disconnect_signal (name, func) | Disconnect to a signal.
wibox.container.scroll:emit_signal (name, ...) | Emit a signal.
wibox.container.scroll:connect_signal (name, func) | Connect to a signal.
wibox.container.scroll:weak_connect_signal (name, func) | Connect to a signal weakly.

## Functions

Methods

scroll.step_functions.linear_increase (elapsed, size, _, speed, extra_space)
  A step function that scrolls the widget in an increasing direction with constant speed.
  - elapsed
  - size
  - _
  - speed
  - extra_space
scroll.step_functions.linear_decrease (elapsed, size, _, speed, extra_space)
  A step function that scrolls the widget in an decreasing direction with constant speed.
  - elapsed
  - size
  - _
  - speed
  - extra_space
scroll.step_functions.linear_back_and_forth (elapsed, size, visible_size, speed)
  A step function that scrolls the widget to its end and back to its beginning, then back to its end, etc. The speed is constant.
  - elapsed
  - size
  - visible_size
  - speed
scroll.step_functions.nonlinear_back_and_forth (elapsed, size, visible_size, speed)
  A step function that scrolls the widget to its end and back to its beginning, then back to its end, etc. The speed is null at the ends and maximal in the middle.
  - elapsed
  - size
  - visible_size
  - speed
scroll.step_functions.waiting_nonlinear_back_and_forth (elapsed, size, visible_size, speed)
  A step function that scrolls the widget to its end and back to its beginning, then back to its end, etc. The speed is null at the ends and maximal in the middle. At both ends the widget stands still for a moment.
  - elapsed
  - size
  - visible_size
  - speed

## Object properties

wibox.container.scroll.widget
  The widget to be scrolled.

  ### Type:

  - widget widget The widget
wibox.container.scroll.forced_height
  Force a widget height.

  ### Type:

  - height number or nil The height (`nil` for automatic)
wibox.container.scroll.forced_width
  Force a widget width.

  ### Type:

  - width number or nil The width (`nil` for automatic)
wibox.container.scroll.opacity
  The widget opacity (transparency).

  ### Type:

  - opacity number The opacity (between 0 and 1) (default 1)
wibox.container.scroll.visible
  The widget visibility.

  ### Type:

  - boolean

## Signals

widget::layout_changed
  When the layout (size) change. This signal is emitted when the previous results of `:layout()` and `:fit()` are no longer valid. Unless this signal is emitted, `:layout()` and `:fit()` must return the same result when called with the same arguments.

  ### See also:

  widget::redraw_needed
widget::redraw_needed
  When the widget content changed. This signal is emitted when the content of the widget changes. The widget will be redrawn, it is not re-layouted. Put differently, it is assumed that `:layout()` and `:fit()` would still return the same results as before.

  ### See also:

  widget::layout_changed
button::press
  When a mouse button is pressed over the widget.

  ### Arguments:

  - lx number The horizontal position relative to the (0,0) position in the widget.
  - ly number The vertical position relative to the (0,0) position in the widget.
  - button number The button number.
  - mods table The modifiers (mod4, mod1 (alt), Control, Shift)
  - find_widgets_result The entry from the result of wibox.drawable:find_widgets for the position that the mouse hit.
    - drawable wibox.drawable The drawable containing the widget.
    - widget widget The widget being displayed.
    - hierarchy wibox.hierarchy The hierarchy managing the widget's geometry.
    - x number An approximation of the X position that the widget is visible at on the surface.
    - y number An approximation of the Y position that the widget is visible at on the surface.
    - width number An approximation of the width that the widget is visible at on the surface.
    - height number An approximation of the height that the widget is visible at on the surface.
    - widget_width number The exact width of the widget in its local coordinate system.
    - widget_height number The exact height of the widget in its local coordinate system.

  ### See also:

  mouse
button::release
  When a mouse button is released over the widget.

  ### Arguments:

  - lx number The horizontal position relative to the (0,0) position in the widget.
  - ly number The vertical position relative to the (0,0) position in the widget.
  - button number The button number.
  - mods table The modifiers (mod4, mod1 (alt), Control, Shift)
  - find_widgets_result The entry from the result of wibox.drawable:find_widgets for the position that the mouse hit.
    - drawable wibox.drawable The drawable containing the widget.
    - widget widget The widget being displayed.
    - hierarchy wibox.hierarchy The hierarchy managing the widget's geometry.
    - x number An approximation of the X position that the widget is visible at on the surface.
    - y number An approximation of the Y position that the widget is visible at on the surface.
    - width number An approximation of the width that the widget is visible at on the surface.
    - height number An approximation of the height that the widget is visible at on the surface.
    - widget_width number The exact width of the widget in its local coordinate system.
    - widget_height number The exact height of the widget in its local coordinate system.

  ### See also:

  mouse
mouse::enter
  When the mouse enter a widget.

  ### Arguments:

  - find_widgets_result The entry from the result of wibox.drawable:find_widgets for the position that the mouse hit.
    - drawable wibox.drawable The drawable containing the widget.
    - widget widget The widget being displayed.
    - hierarchy wibox.hierarchy The hierarchy managing the widget's geometry.
    - x number An approximation of the X position that the widget is visible at on the surface.
    - y number An approximation of the Y position that the widget is visible at on the surface.
    - width number An approximation of the width that the widget is visible at on the surface.
    - height number An approximation of the height that the widget is visible at on the surface.
    - widget_width number The exact width of the widget in its local coordinate system.
    - widget_height number The exact height of the widget in its local coordinate system.

  ### See also:

  mouse
mouse::leave
  When the mouse leave a widget.

  ### Arguments:

  - find_widgets_result The entry from the result of wibox.drawable:find_widgets for the position that the mouse hit.
    - drawable wibox.drawable The drawable containing the widget.
    - widget widget The widget being displayed.
    - hierarchy wibox.hierarchy The hierarchy managing the widget's geometry.
    - x number An approximation of the X position that the widget is visible at on the surface.
    - y number An approximation of the Y position that the widget is visible at on the surface.
    - width number An approximation of the width that the widget is visible at on the surface.
    - height number An approximation of the height that the widget is visible at on the surface.
    - widget_width number The exact width of the widget in its local coordinate system.
    - widget_height number The exact height of the widget in its local coordinate system.

  ### See also:

  mouse

## Tables

wibox.container.scroll.step_functions
  A selection of step functions

  ### See also:

  set_step_function

## Methods

wibox.container.scroll:pause ()
  Pause the scrolling animation.

  ### See also:

  continue
wibox.container.scroll:continue ()
  Continue the scrolling animation.

  ### See also:

  pause
wibox.container.scroll:reset_scrolling ()
  Reset the scrolling state to its initial condition. For must scroll step functions, the effect of this function should be to display the widget without any scrolling applied. This function does not undo the effect of pause.
wibox.container.scroll:set_direction (dir)
  Set the direction in which this widget scroll.
  - dir Either "h" for horizontal scrolling or "v" for vertical scrolling
wibox.container.scroll:get_children ()
  Get the number of children element

  ### Returns:

  table The children
wibox.container.scroll:set_children (children)
  Replace the layout children This layout only accept one children, all others will be ignored
  - children table A table composed of valid widgets
wibox.container.scroll:set_expand (expand)
  Specify the expand mode that is used for extra space.
  - expand boolean If true, the widget is expanded to include the extra space. If false, the extra space is simply left empty.

  ### See also:

  set_extra_space
wibox.container.scroll:set_fps (fps)
  Set the number of frames per second that this widget should draw.
  - fps number The number of frames per second
wibox.container.scroll:set_extra_space (extra_space)
  Set the amount of extra space that should be included in the scrolling. This extra space will likely be left empty between repetitions of the widgets.
  - extra_space number The amount of extra space

  ### See also:

  set_expand
wibox.container.scroll:set_speed (speed)
  Set the speed of the scrolling animation. The exact meaning depends on the step function that is used, but for the simplest step functions, this will be in pixels per second.
  - speed number The speed for the animation
wibox.container.scroll:set_max_size (max_size)
  Set the maximum size of this widget in the direction set by set_direction. If the child widget is smaller than this size, no scrolling is done. If the child widget is larger, then only this size will be visible and the rest is made visible via scrolling.
  - max_size number The maximum size of this widget or nil for unlimited.
wibox.container.scroll:set_step_function (step_function)
  Set the step function that determines the exact behaviour of the scrolling animation. The step function is called with five arguments:
  - The time in seconds since the state of the animation
  - The size of the child widget
  - The size of the visible part of the widget
  - The speed of the animation. This should have a linear effect on this function's behaviour.
  - The extra space configured by set_extra_space. This was not yet added to the size of the child widget, but should likely be added to it in most cases.

  The step function should return a single number. This number is the offset at which the widget is drawn and should be between 0 and `size+extra_space`.

  - step_function function A step function.

  ### See also:

  step_functions
wibox.container.scroll:set_space_for_scrolling (space_for_scrolling)
  Set an upper limit for the space for scrolling. This restricts the child widget's maximal size.
  - space_for_scrolling number The space for scrolling
wibox.container.scroll:horizontal ([widget[, fps=20[, speed=10[, extra_space=0[, expand=false[, max_size[, step_function=step_functions.linear_increase[, space_for_scrolling=2^1024]]]]]]]])
  Get a new horizontal scrolling container.
  - widget The widget that should be scrolled (optional)
  - fps The number of frames per second (default 20)
  - speed The speed of the animation (default 10)
  - extra_space The amount of extra space to include (default 0)
  - expand boolean Should the widget be expanded to include the extra space? (default false)
  - max_size The maximum size of the child widget (optional)
  - step_function The step function to be used (default step_functions.linear_increase)
  - space_for_scrolling The space for scrolling (default 2^1024)
wibox.container.scroll:vertical ([widget[, fps=20[, speed=10[, extra_space=0[, expand=false[, max_size[, step_function=step_functions.linear_increase[, space_for_scrolling=2^1024]]]]]]]])
  Get a new vertical scrolling container.
  - widget The widget that should be scrolled (optional)
  - fps The number of frames per second (default 20)
  - speed The speed of the animation (default 10)
  - extra_space The amount of extra space to include (default 0)
  - expand boolean Should the widget be expanded to include the extra space? (default false)
  - max_size The maximum size of the child widget (optional)
  - step_function The step function to be used (default step_functions.linear_increase)
  - space_for_scrolling The space for scrolling (default 2^1024)
wibox.container.scroll:index (widget[, recursive[, ...]])
  Get a widex index.
  - widget The widget to look for
  - recursive Also check sub-widgets (optional)
  - ... Aditional widgets to add at the end of the \"path\" (optional)

  ### Returns:

  1. The index
  2. The parent layout
  3. The path between \"self\" and \"widget\"
wibox.container.scroll:get_all_children ()
  Get all direct and indirect children widgets. This will scan all containers recursively to find widgets Warning: This method it prone to stack overflow id the widget, or any of its children, contain (directly or indirectly) itself.

  ### Returns:

  table The children
wibox.container.scroll:setup (args)
  Set a declarative widget hierarchy description. See The declarative layout system
  - args An array containing the widgets disposition
wibox.container.scroll:buttons (_buttons)
  Set/get a widget's buttons.
  - _buttons The table of buttons that should bind to the widget.
wibox.container.scroll:emit_signal_recursive (signal_name, ...)
  Emit a signal and ensure all parent widgets in the hierarchies also forward the signal. This is useful to track signals when there is a dynamic set of containers and layouts wrapping the widget.
  - signal_name string
  - ... Other arguments
wibox.container.scroll:disconnect_signal (name, func)
  Disconnect to a signal.
  - name string The name of the signal
  - func function The callback that should be disconnected
wibox.container.scroll:emit_signal (name, ...)
  Emit a signal.
  - name string The name of the signal
  - ... Extra arguments for the callback functions. Each connected function receives the object as first argument and then any extra arguments that are given to emit_signal()
wibox.container.scroll:connect_signal (name, func)
  Connect to a signal.
  - name string The name of the signal
  - func function The callback to call when the signal is emitted
wibox.container.scroll:weak_connect_signal (name, func)
  Connect to a signal weakly. This allows the callback function to be garbage collected and automatically disconnects the signal when that happens.

  Warning: Only use this function if you really, really, really know what you are doing.

  - name string The name of the signal
  - func function The callback to call when the signal is emitted

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