namespace Unity.UIWidgets.rendering {
public enum CacheExtentStyle {
/// Treat the [Viewport.cacheExtent] as logical pixels.
/// Treat the [Viewport.cacheExtent] as a multiplier of the main axis extent.
viewport ,
}
public interface RenderAbstractViewport {
) {
D . assert ( offset ! = null ) ;
D . assert ( AxisUtils . axisDirectionToAxis ( axisDirection ) ! = AxisUtils . axisDirectionToAxis ( crossAxisDirection ) ) ;
D . assert ( axisDirection ! = null ) ;
D . assert ( crossAxisDirection ! = null ) ;
D . assert ( cacheExtentStyle ! = null ) ;
D . assert ( cacheExtent ! = null | | cacheExtentStyle = = CacheExtentStyle . pixel ) ;
D . assert ( cacheExtentStyle = = CacheExtentStyle . pixel ) ;
_axisDirection = axisDirection ;
_crossAxisDirection = crossAxisDirection ;
_offset = offset ;
return _cacheExtentStyle ;
}
set {
D . assert ( value ! = null ) ;
if ( value = = _cacheExtentStyle ) {
return ;
}
D . assert ( ( ) = > {
if ( ! debugCheckingIntrinsics ) {
D . assert ( ! ( this is RenderShrinkWrappingViewport ) ) ;
throw new UIWidgetsError (
GetType ( ) + " does not support returning intrinsic dimensions.\n" +
"Calculating the intrinsic dimensions would require instantiating every child of " +
"the viewport, which defeats the point of viewports being lazy.\n" +
"If you are merely trying to shrink-wrap the viewport in the main axis direction, " +
"consider a RenderShrinkWrappingViewport render object (ShrinkWrappingViewport widget), " +
"which achieves that effect without implementing the intrinsic dimension API."
) ;
throw new UIWidgetsError ( new List < DiagnosticsNode > {
new ErrorSummary ( $"{GetType()} does not support returning intrinsic dimensions." ) ,
new ErrorDescription (
"Calculating the intrinsic dimensions would require instantiating every child of " +
"the viewport, which defeats the point of viewports being lazy."
) ,
new ErrorHint (
"If you are merely trying to shrink-wrap the viewport in the main axis direction, " +
"consider a RenderShrinkWrappingViewport render object (ShrinkWrappingViewport widget), " +
"which achieves that effect without implementing the intrinsic dimension API."
) ,
} ) ;
}
return true ;
RenderSliver child = ( RenderSliver ) childRaw ;
Rect viewportClip = Offset . zero & size ;
if ( child . constraints . overlap = = 0.0 ) {
if ( child . constraints . overlap = = 0.0 | | ! child . constraints . viewportMainAxisExtent . isFinite ( ) ) {
return viewportClip ;
}
RenderBox pivot = null ;
bool onlySlivers = target is RenderSliver ;
while ( child . parent ! = this ) {
D . assert ( child . parent ! = null , ( ) = > $"target must be a descendant of $ {this}" ) ;
D . assert ( child . parent ! = null , ( ) = > $"{ target} must be a descendant of {this}" ) ;
if ( child is RenderBox ) {
pivot = ( RenderBox ) child ;
}
targetMainAxisExtent = bounds . height ;
break ;
case AxisDirection . right :
leadingScrollOffset + = bounds . left ;
float offset2 = 0.0f ;
switch ( growthDirection ) {
case GrowthDirection . forward :
offset2 = bounds . left ;
break ;
case GrowthDirection . reverse :
offset2 = bounds . right ;
break ;
}
leadingScrollOffset + = offset2 ;
leadingScrollOffset + = bounds . top ;
float offset3 = 0.0f ;
switch ( growthDirection ) {
case GrowthDirection . forward :
offset3 = bounds . top ;
break ;
case GrowthDirection . reverse :
offset3 = bounds . bottom ;
break ;
}
leadingScrollOffset + = offset3 ;
targetMainAxisExtent = bounds . height ;
break ;
case AxisDirection . left :
return MatrixUtils . transformRect ( transform , rect ? ? descendant . paintBounds ) ;
}
D . assert ( targetOffset ! = null ) ;
offset . moveTo ( targetOffset . offset , duration : duration . Value , curve : curve ) ;
return targetOffset . rect ;
}
switch ( axis ) {
case Axis . vertical :
if ( ! constraints . hasBoundedHeight ) {
throw new UIWidgetsError (
"Vertical viewport was given unbounded height.\n" +
"Viewports expand in the scrolling direction to fill their container." +
"In this case, a vertical viewport was given an unlimited amount of " +
"vertical space in which to expand. This situation typically happens " +
"when a scrollable widget is nested inside another scrollable widget.\n" +
"If this widget is always nested in a scrollable widget there " +
"is no need to use a viewport because there will always be enough " +
"vertical space for the children. In this case, consider using a " +
"Column instead. Otherwise, consider using the \"shrinkWrap\" property " +
"(or a ShrinkWrappingViewport) to size the height of the viewport " +
"to the sum of the heights of its children."
) ;
throw new UIWidgetsError ( new List < DiagnosticsNode > {
new ErrorSummary ( "Vertical viewport was given unbounded height." ) ,
new ErrorDescription (
"Vertical viewport was given unbounded height.\n" +
"Viewports expand in the scrolling direction to fill their container." +
"In this case, a vertical viewport was given an unlimited amount of " +
"vertical space in which to expand. This situation typically happens " +
"when a scrollable widget is nested inside another scrollable widget.\n"
) ,
new ErrorHint ( "If this widget is always nested in a scrollable widget there " +
"is no need to use a viewport because there will always be enough " +
"vertical space for the children. In this case, consider using a " +
"Column instead. Otherwise, consider using the \"shrinkWrap\" property " +
"(or a ShrinkWrappingViewport) to size the height of the viewport " +
"to the sum of the heights of its children."
)
} ) ;
}
if ( ! constraints . hasBoundedWidth ) {
break ;
case Axis . horizontal :
if ( ! constraints . hasBoundedWidth ) {
throw new UIWidgetsError (
"Horizontal viewport was given unbounded width.\n" +
"Viewports expand in the scrolling direction to fill their container." +
"In this case, a horizontal viewport was given an unlimited amount of " +
"horizontal space in which to expand. This situation typically happens " +
"when a scrollable widget is nested inside another scrollable widget.\n" +
"If this widget is always nested in a scrollable widget there " +
"is no need to use a viewport because there will always be enough " +
"horizontal space for the children. In this case, consider using a " +
"Row instead. Otherwise, consider using the \"shrinkWrap\" property " +
"(or a ShrinkWrappingViewport) to size the width of the viewport " +
"to the sum of the widths of its children."
) ;
throw new UIWidgetsError ( new List < DiagnosticsNode > {
new ErrorSummary ( "Horizontal viewport was given unbounded width." ) ,
new ErrorDescription (
"Viewports expand in the scrolling direction to fill their container. " +
"In this case, a horizontal viewport was given an unlimited amount of " +
"horizontal space in which to expand. This situation typically happens " +
"when a scrollable widget is nested inside another scrollable widget."
) ,
new ErrorHint (
"If this widget is always nested in a scrollable widget there " +
"is no need to use a viewport because there will always be enough " +
"horizontal space for the children. In this case, consider using a " +
"Row instead. Otherwise, consider using the \"shrinkWrap\" property " +
"(or a ShrinkWrappingViewport) to size the width of the viewport " +
"to the sum of the widths of its children."
)
} ) ;
}
if ( ! constraints . hasBoundedHeight ) {
offset . applyContentDimensions ( 0.0f , 0.0f ) ;
return ;
}
D . assert ( center . parent = = this ) ;
float mainAxisExtent = 0.0f ;
float crossAxisExtent = 0.0f ;
switch ( axis ) {
}
float centerOffsetAdjustment = center . centerOffsetAdjustment ;
int count = 0 ;
do {
var correction = _attemptLayout ( mainAxisExtent , crossAxisExtent ,
"RenderViewport render objects, during layout, can retry if either their " +
"slivers or their ViewportOffset decide that the offset should be corrected " +
"to take into account information collected during that layout.\n" +
"In the case of this RenderViewport object, however, this happened $count " +
$ "In the case of this RenderViewport object, however, this happened {count} "+
"times and still there was no consensus on the scroll offset. This usually " +
"indicates a bug. Specifically, it means that one of the following three " +
"problems is being experienced by the RenderViewport object:\n" +
protected override bool debugThrowIfNotCheckingIntrinsics ( ) {
D . assert ( ( ) = > {
if ( ! debugCheckingIntrinsics ) {
throw new UIWidgetsError (
GetType ( ) + " does not support returning intrinsic dimensions.\n" +
"Calculating the intrinsic dimensions would require instantiating every child of " +
"the viewport, which defeats the point of viewports being lazy.\n" +
"If you are merely trying to shrink-wrap the viewport in the main axis direction, " +
"you should be able to achieve that effect by just giving the viewport loose " +
"constraints, without needing to measure its intrinsic dimensions."
) ;
throw new UIWidgetsError ( new List < DiagnosticsNode > {
new ErrorSummary ( $"{GetType()} does not support returning intrinsic dimensions." ) ,
new ErrorDescription (
"Calculating the intrinsic dimensions would require instantiating every child of " +
"the viewport, which defeats the point of viewports being lazy."
) ,
new ErrorHint (
"If you are merely trying to shrink-wrap the viewport in the main axis direction, " +
"you should be able to achieve that effect by just giving the viewport loose " +
"constraints, without needing to measure its intrinsic dimensions."
)
} ) ;
}
return true ;
bool _hasVisualOverflow = false ;
protected override void performLayout ( ) {
BoxConstraints constraints = this . constraints ;
if ( firstChild = = null ) {
switch ( axis ) {
case Axis . vertical :
guanghuispark
4 年前