Flickable
The Flickable
is a low-level element that is the base for scrollable
widgets, such as the ScrollView. When the viewport-width
or the
viewport-height
is greater than the parent’s width
or height
respectively, the element becomes scrollable. Note that the Flickable
doesn’t create a scrollbar. When unset, the viewport-width
and viewport-height
are
calculated automatically based on the Flickable
’s children. This isn’t the
case when using a for
loop to populate the elements. This is a bug tracked in
issue #407 ↗.
The maximum and preferred size of the Flickable
are based on the viewport.
When not part of a layout, its width or height defaults to 100% of the parent element when not specified.
Pointer Event Interaction
If the Flickable
’s area contains elements that use TouchArea
to act on clicking, such as Button
widgets, then the following algorithm is used to distinguish between the user’s intent of scrolling or
interacting with TouchArea
elements:
- If the
Flickable
’sinteractive
property isfalse
, all events are forwarded to elements underneath. - If a press event is received where the event’s coordinates interact with a
TouchArea
, the event is stored and any subsequent move and release events are handled as follows:- If 100ms elapse without any events, the stored press event is delivered to the
TouchArea
. - If a release event is received before 100ms have elapsed, the stored press event as well as the
release event are immediately delivered to the
TouchArea
and the algorithm resets. - Any move events received will start a flicking operation on the
Flickable
if all of the following conditions are met:- The event is received before 500ms have elapsed since receiving the press event.
- The distance to the press event exceeds 8 logical pixels in an orientation in which we are allowed to move.
If
Flickable
decides to flick, any press event sent previously to aTouchArea
, is followed up by an exit event. During the phase of receiving move events, the flickable follows the coordinates.
- If 100ms elapse without any events, the stored press event is delivered to the
- If the interaction of press, move, and release events begins at coordinates that do not intersect with
a
TouchArea
, thenFlickable
will flick immediately on pointer move events when the euclidean distance to the coordinates of the press event exceeds 8 logical pixels.
Properties
interactive
bool default: true
When true, the viewport can be scrolled by clicking on it and dragging it with the cursor.
viewport-width
length default: 0px
The total width of the scrollable element.
viewport-height
length default: 0px
The total height of the scrollable element.
viewport-x
length default: 0px
The position of the scrollable element relative to the Flickable
. This is usually a negative value.
viewport-y
length default: 0px
The position of the scrollable element relative to the Flickable
. This is usually a negative value.
Callbacks
flicked()
Invoked when viewport-x
or viewport-y
is changed by a user action (dragging, scrolling).
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