showOnScreen method
- RenderObject? descendant,
- Rect? rect,
- Duration duration = Duration.zero,
- Curve curve = Curves.ease,
override
Attempt to make (a portion of) this or a descendant RenderObject visible on screen.
If descendant
is provided, that RenderObject is made visible. If
descendant
is omitted, this RenderObject is made visible.
The optional rect
parameter describes which area of that RenderObject
should be shown on screen. If rect
is null, the entire
RenderObject (as defined by its paintBounds) will be revealed. The
rect
parameter is interpreted relative to the coordinate system of
descendant
if that argument is provided and relative to this
RenderObject otherwise.
The duration
parameter can be set to a non-zero value to bring the
target object on screen in an animation defined by curve
.
See also:
- RenderViewportBase.showInViewport, which RenderViewportBase and SingleChildScrollView delegate this method to.
Implementation
@override
void showOnScreen({
RenderObject? descendant,
Rect? rect,
Duration duration = Duration.zero,
Curve curve = Curves.ease,
}) {
final Rect? localBounds = descendant != null
? MatrixUtils.transformRect(descendant.getTransformTo(this), rect ?? descendant.paintBounds)
: rect;
final Rect? newRect = switch (applyGrowthDirectionToAxisDirection(constraints.axisDirection, constraints.growthDirection)) {
AxisDirection.up => _trim(localBounds, bottom: childExtent),
AxisDirection.left => _trim(localBounds, right: childExtent),
AxisDirection.right => _trim(localBounds, left: 0),
AxisDirection.down => _trim(localBounds, top: 0),
};
super.showOnScreen(
descendant: this,
rect: newRect,
duration: duration,
curve: curve,
);
}