PtScrollbar

Gamma/Photon: Using Gamma™ with the Photon microGUIŽ, Version 4.0
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# `PtScrollbar`

`PtScrollbar` -- A sliding handle for navigating a scroll area.

## Synopsis

    class PtScrollbar PtBasic
    {
        increment;          // long  (Pt_ARG_INCREMENT)
        maximum;            // integer  (Pt_ARG_MAXIMUM)
        min_slider_size;    // integer  (Pt_ARG_MIN_SLIDER_SIZE)
        minimum;            // integer  (Pt_ARG_MINIMUM)
        orientation;        // flags  (Pt_ARG_ORIENTATION)
        page_increment;     // integer  (Pt_ARG_PAGE_INCREMENT)
        scroll_position;    // integer  (Pt_ARG_SCROLL_POSITION)
        scrollbar_flags;    // flag  (Pt_ARG_SCROLLBAR_FLAGS)
        slider_size;        // integer  (Pt_ARG_SLIDER_SIZE)
    }

## Base Classes

`PtWidget` <-- `PtBasic` <-- `PtScrollbar`

## Description

This widget is a vertical or horizontal scrollbar with a handle that slides in a trough to set and show the position of the scroll area over the virtual area of a `PtScrollArea` widget. The scrollbar has arrow buttons at either end to move the handle.

The scrollbar trough represents a range of values, which is divided into integer increments. These increments are the unit of measure for the size, position, and movement of the handle. The number of increments is determined by the difference between the `maximum` and `minimum` variables.

| For additional information, please refer to PtScrollbar in the Photon documentation.

## Instance Variables

increment

  A number specifying the number of increments to move the handle when an arrow button is pressed. Default is `1`.

maximum

  An integer specifying the highest increment number, at the end of the scrollbar range. Default is `19`. The total number of increments is calculated by subtracting the `minimum` value from this value.

min_slider_size

  An integer specifying the minimum size (in pixels) that the handle is allowed to become. Default is 5 pixels.

minimum

  An integer specifying the lowest increment number, at the beginning of the scrollbar range. Default is `0`. The total number of increments is calculated by subtracting this value from the `maximum` value.

orientation

  This instance variable determines the horizontal/vertical orientation of the scrollbar, and may have one of the following values:

  Constant | Description
  --- | ---
  `Pt_HORIZONTAL` | The scrollbar is oriented horizontally.
  `Pt_VERTICAL` | The scrollbar is oriented vertically. This is the default.

page_increment

  An integer that specifies the number of increments the handle moves when the trough is clicked. Default is `-1`, which causes the handle to move the distance of its own length.

scroll_position

  An integer specifying the position of the top of the handle in the range.

scrollbar_flags

  This instance variable specifies several scrollbar characteristics, and may be a combination of zero or more of the following flags:

  Constant | Description
  --- | ---
  `Pt_SCROLLBAR_HORIZONTAL` | Change the scrollbar from vertical to horizontal.
  `Pt_SCROLLBAR_SHOW_ARROWS` | Show arrow buttons at both ends of the scrollbar.
  `Pt_SCROLLBAR_INVERTED` | Invert the scrolling mechanism: max/min or left/right.
  `Pt_SCROLLBAR_FOCUSED` | Render the scrollbar as if it had focus, even when it doesn't.

slider_size

  An integer specifying the number of increments to size the handle. Default is `20`.

## Callbacks

The following callbacks are associated with this widget:

Callback | Description
--- | ---
`Pt_CB_SCROLL_MOVE` | This callback is generated when the scroll position changes.

## Associated Classes

`PtScrollbarCallback`, `PtCallbackInfo`

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`PtScrollArea` | Up | `PtSeparator`

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