Class pv.Behavior.zoom
Extends
pv.Behavior.
Implements interactive zooming using mousewheel events. Register this
behavior on panels to allow zooming. This behavior can be used in tandem with
pv.Behavior.pan to allow both panning and zooming:
.event("mousedown", pv.Behavior.pan())
.event("mousewheel", pv.Behavior.zoom())
The zoom behavior currently supports only mousewheel events; support for
keyboard shortcuts and gesture events to improve accessibility may be added
in the future.
The implementation of this behavior relies on the panel's transform property, which specifies a matrix transformation that is applied to child marks. Note that the transform property only affects the panel's children, but not the panel itself; therefore the panel's fill and stroke will not change when the contents are zoomed. The built-in support for transforms only supports uniform scaling and translates, which is sufficient for panning and zooming. Note that this is not a strict geometric transformation, as the lineWidth property is scale-aware: strokes are drawn at constant size independent of scale.
Panels have transparent fill styles by default; this means that panels may not receive mousewheel events to zoom. To fix this problem, either given the panel a visible fill style (such as "white"), or set the events property to "all" such that the panel receives events despite its transparent fill.
The zoom behavior has optional support for bounding. If enabled, the user
will not be able to zoom out farther than the initial bounds. This feature is
designed to work in conjunction with the pan behavior.
Defined in: Zoom.js.
| Constructor Attributes | Constructor Name and Description |
|---|---|
|
pv.Behavior.zoom(speed)
Returns a new zoom behavior to be registered on mousewheel events.
|
| Method Attributes | Method Name and Description |
|---|---|
|
bound(x)
Sets or gets the bound parameter.
|
- Parameters:
- {number} speed
Note: enabling bounding after zooming has already occurred will not immediately reset the transform. Bounding should be enabled before the zoom behavior is applied.
- Parameters:
- {boolean} x Optional
- the new bound parameter.
- Returns:
- {pv.Behavior.zoom} this, or the current bound parameter.