Jamba Views / Scrollbar

Scrollbar

 Scrollbar

Generic scrollbar which handles scrolling and (optional) zooming via handles. The scrollbar is driven by 2 parameters which can be tied to Vst or Jmb parameters:

  • offsetPercent which represents the position of the scrollbar as a percent (0 means completely left (resp. top), 1 means completely right (resp. bottom))
  • zoomPercent which represents the size of the scrollbar as a percent (0 means completely zoomed out (hence the scrollbar is full), 1 means completely zoomed in (hence the scrollbar is at its minimum size)).

In addition to the attributes exposed by CustomView, this class exposes the following attributes:

Attribute Description
orientation scrollbar orientation (horizontal or vertical)
offset-percent-tag id for the parameter tied to offset percent
zoom-percent-tag id for the parameter tied to zoom percent
margin Amount of space (in pixels) to draw around the full scrollbar (includes handles)
scrollbar-color the color of the scrollbar itself (the rectangle)
scrollbar-min-size Minimum size for the scrollbar (in pixels). If -1 it will be auto-computed.
scrollbar-gutter-spacing Spacing (in pixels) between the scrollbar and zoom handles (only drawn when zoom handles)
zoom-handles-color Zoom handles color
zoom-handles-size Zoom handles size. If -1 it will be auto-computed. Set to 0 to disable handles entirely.
shift-drag-factor Defines how much to slow down (if less than 1) or accelerate (if more than 1) when shift is held when dragging.
enable-zoom-double-click true to allow zooming on double click on the scrollbar

The image above shows an example of a scrollbar tied to 2 vst parameters which control the offset and zoom level of the display.

Note

Since Jamba 7.5.0, the scrollbar can now be vertical or horizontal.

Example

The XML defining the scrollbar, tied to 2 parameters (Param_LCDHistoryOffset and Param_LCDZoomFactorX) (Source)

<view back-color="~ BlackCColor" class="VAC6V::LCDScrollbar" custom-view-tag="CV_LCDScrollbar" enable-zoom-double-click="true" margin="3,2.5,3,2.5" offset-percent-tag="Param_LCDHistoryOffset" origin="72, 235" scrollbar-color="LevelStateOk" scrollbar-gutter-spacing="1" scrollbar-min-size="-1" shift-drag-factor="1" size="256, 16" zoom-handles-color="LevelStateOk" zoom-handles-size="-1" zoom-percent-tag="Param_LCDZoomFactorX"/>

The 2 vst params are defined this way (Percent is just an alias to a float) (Source)

VstParam<Percent> fZoomFactorXParam;
// ... #34
VstParam<Percent> fLCDHistoryOffsetParam;

The vst params are initialized this way (Source)

fZoomFactorXParam =
  vst<LCDZoomFactorXParamConverter>(EVAC6ParamID::kLCDZoomFactorX, STR16 ("Zoom Level"))
    .defaultValue(DEFAULT_ZOOM_FACTOR_X)
    .shortTitle(STR16 ("Zoom Lvl"))
    .precision(1)
    .add();
// ... #120
fLCDHistoryOffsetParam =
  vst<LCDHistoryOffsetParamConverter>(EVAC6ParamID::kLCDHistoryOffset, STR16 ("Graph Scroll"))
    .defaultValue(MAX_HISTORY_OFFSET) // all the way to the right
    .flags(0) // state is not saved
    .precision(0)
    .transient()
    .add();