Merge branch 'shiyun/skia' of https://github.com/Unity-Technologies/com.unity.uiwidgets into shiyun/skia

com.unity.uiwidgets/Runtime/rendering/list_body.cs

         }
 
         protected override void performLayout() {
+            BoxConstraints constraints = this.constraints;
             D.assert(() => {
                 switch (mainAxis) {
                     case Axis.horizontal:
                         break;
                 }
 
-                throw new UIWidgetsError(
-                    "RenderListBody must have unlimited space along its main axis.\n" +
-                    "RenderListBody does not clip or resize its children, so it must be " +
-                    "placed in a parent that does not constrain the main " +
-                    "axis. You probably want to put the RenderListBody inside a " +
-                    "RenderViewport with a matching main axis.");
+                throw new UIWidgetsError(new List<DiagnosticsNode>{
+                    new ErrorSummary("RenderListBody must have unlimited space along its main axis."),
+                    new ErrorDescription(
+                        "RenderListBody does not clip or resize its children, so it must be " +
+                        "placed in a parent that does not constrain the main axis."
+                    ),
+                    new ErrorHint(
+                    "You probably want to put the RenderListBody inside a " +
+                        "RenderViewport with a matching main axis."
+                    )
+                });
             });
 
             D.assert(() => {
                         break;
                 }
 
-                throw new UIWidgetsError(
-                    "RenderListBody must have a bounded constraint for its cross axis.\n" +
-                    "RenderListBody forces its children to expand to fit the RenderListBody\"s container, " +
-                    "so it must be placed in a parent that constrains the cross " +
-                    "axis to a finite dimension. If you are attempting to nest a RenderListBody with " +
-                    "one direction inside one of another direction, you will want to " +
-                    "wrap the inner one inside a box that fixes the dimension in that direction, " +
-                    "for example, a RenderIntrinsicWidth or RenderIntrinsicHeight object. " +
-                    "This is relatively expensive, however."
-                );
+                throw new UIWidgetsError(new List<DiagnosticsNode>{
+                    new ErrorSummary("RenderListBody must have a bounded constraint for its cross axis."),
+                    new ErrorDescription(
+                        "RenderListBody forces its children to expand to fit the RenderListBody's container, " +
+                        "so it must be placed in a parent that constrains the cross " +
+                        "axis to a finite dimension."
+                    ),
+                    // TODO(jacobr): this hint is a great candidate to promote to being an
+                    // automated quick fix in the future.
+                    new ErrorHint(
+                        "If you are attempting to nest a RenderListBody with " +
+                        "one direction inside one of another direction, you will want to " +
+                        "wrap the inner one inside a box that fixes the dimension in that direction, " +
+                        "for example, a RenderIntrinsicWidth or RenderIntrinsicHeight object. " +
+                        "This is relatively expensive, however." // (that's why we don't do it automatically)
+                    )
+                });
             });
 
             float mainAxisExtent = 0.0f;

com.unity.uiwidgets/Runtime/rendering/list_wheel_viewport.cs

                 minWidth: 0.0f
             );
 
-            float visibleHeight = size.height;
+            float visibleHeight = size.height * _squeeze;
             if (renderChildrenOutsideViewport) {
                 visibleHeight *= 2;
             }
 
             float fractionalY = (untransformedPaintingCoordinates.dy + _itemExtent / 2.0f) / size.height;
 
-            float angle = -(fractionalY - 0.5f) * 2.0f * _maxVisibleRadian;
+            float angle = -(fractionalY - 0.5f) * 2.0f * _maxVisibleRadian / squeeze;
             if (angle > Mathf.PI / 2.0f || angle < -Mathf.PI / 2.0f) {
                 return;
             }
             Offset offsetToCenter =
                 new Offset(untransformedPaintingCoordinates.dx, -deltaY - _topScrollMarginExtent);
 
-            if (!useMagnifier) {
+            bool shouldApplyOffCenterDim = overAndUnderCenterOpacity < 1;
+            if (useMagnifier || shouldApplyOffCenterDim) {
+                _paintChildWithMagnifier(context, offset, child, transform, offsetToCenter, untransformedPaintingCoordinates);
+            } else {
-            else {
-                _paintChildWithMagnifier(
-                    context,
-                    offset,
-                    child,
-                    transform,
-                    offsetToCenter,
-                    untransformedPaintingCoordinates
-                );
-            }
         }
 
         void _paintChildWithMagnifier(
                     magnifierTopLinePosition);
 
                 context.pushClipRect(
-                    false,
+                    needsCompositing,
-                            false,
+                            needsCompositing,
-                                context2.paintChild(
-                                    child,
-                                    offset2 + untransformedPaintingCoordinates);
+                                context2.paintChild(child, offset2 + untransformedPaintingCoordinates);
-                    false,
+                    needsCompositing,
                     offset,
                     untransformedPaintingCoordinates.dy <= magnifierTopLinePosition
                         ? topHalfRect
             Matrix4 cylindricalTransform,
             Offset offsetToCenter
         ) {
-            context.pushTransform(
-                false,
-                offset,
-                cylindricalTransform,
-                // this._centerOriginTransform(cylindricalTransform),
-                (PaintingContext _context, Offset _offset) => { _context.paintChild(child, _offset + offsetToCenter); }
-            );
+            PaintingContextCallback painter = (PaintingContext _context, Offset _offset) => {
+                _context.paintChild(
+                    child,
+                    _offset + offsetToCenter
+                );
+            };
         }
 
         public override Rect describeApproximatePaintClip(RenderObject child) {
 
             ListWheelParentData parentData = (ListWheelParentData) child.parentData;
             float targetOffset = parentData.offset.dy;
-            Matrix4 transform = target.getTransformTo(this);
+            Matrix4 transform = target.getTransformTo(child);
             Rect bounds = MatrixUtils.transformRect(transform, rect);
             Rect targetRect = bounds.translate(0.0f, (size.height - itemExtent) / 2);