protected override Line CreateLine(GeneratorDirection direction,
int extentOffset,
int breadthOffset,
int availableBreadth,
RecyclerView.Recycler recycler,
RecyclerView.State state,
Uno.UI.IndexPath nextVisibleItem,
bool isNewGroup
)
{
var item = GetFlatItemIndex(nextVisibleItem);
var view = recycler.GetViewForPosition(item, state);
if (!(view is SelectorItem))
{
throw new InvalidOperationException($"Expected {nameof(SelectorItem)} but received {view?.GetType().ToString() ?? "<null>"}");
}
var size = AddViewAtOffset(view, direction, extentOffset, breadthOffset, availableBreadth);
var physicalSize = size.LogicalToPhysicalPixels();
var breadth = (int)(ScrollOrientation == Orientation.Vertical ? physicalSize.Width : physicalSize.Height);
return(new Line
{
NumberOfViews = 1,
Extent = (int)(ScrollOrientation == Orientation.Vertical ? physicalSize.Height : physicalSize.Width),
FirstItem = nextVisibleItem,
LastItem = nextVisibleItem,
Breadth = breadth
});
}
/// <summary>
/// Prefetch a view for given <paramref name="displayPosition"/>.
/// </summary>
private ElementViewRecord PrefetchView(RecyclerView.Recycler recycler, int displayPosition)
{
if (displayPosition < 0)
{
throw new ArgumentException($"{nameof(displayPosition)} must be greater than 0.");
}
var view = GetViewFromIntermediateCache(recycler, displayPosition);
if (view == null)
{
view = recycler.GetViewForPosition(displayPosition);
// Add->Detach allows view to be efficiently re-displayed
Layout.AddView(view);
Layout.TryDetachView(view);
}
var viewHolder = _owner.GetChildViewHolder(view) as UnoViewHolder;
if (!(view is SelectorItem))
{
throw new InvalidOperationException($"{nameof(PrefetchView)} received {view?.GetType()} in place of {nameof(SelectorItem)}.");
}
return(new ElementViewRecord(displayPosition, viewHolder));
}
protected override Line CreateLine(FillDirection direction,
int extentOffset,
int breadthOffset,
int availableBreadth,
RecyclerView.Recycler recycler,
RecyclerView.State state,
IndexPath nextVisibleItem,
bool isNewGroup
)
{
var item = GetFlatItemIndex(nextVisibleItem);
var view = recycler.GetViewForPosition(item, state);
Debug.Assert(view is SelectorItem, "view is SelectorItem (we should never be given a group header)");
var size = AddViewAtOffset(view, direction, extentOffset, breadthOffset, availableBreadth);
var physicalSize = size.LogicalToPhysicalPixels();
var breadth = (int)(ScrollOrientation == Orientation.Vertical ? physicalSize.Width : physicalSize.Height);
return(new Line
{
NumberOfViews = 1,
Extent = (int)(ScrollOrientation == Orientation.Vertical ? physicalSize.Height : physicalSize.Width),
FirstItem = nextVisibleItem,
LastItem = nextVisibleItem,
Breadth = breadth
});
}
/// <summary>
/// Wrapper of <see cref="RecyclerView.Recycler.GetViewForPosition(int)"/> that duplicates bounds checking in managed code, for easier error handling.
/// </summary>
public static View GetViewForPosition(this RecyclerView.Recycler recycler, int position, RecyclerView.State state)
{
if (position < 0 || position >= state.ItemCount)
{
throw new IndexOutOfRangeException($"Invalid item position ({position}). Item count:{state.ItemCount}");
}
return(recycler.GetViewForPosition(position));
}
public View Next(RecyclerView.Recycler recycler)
{
if (ScrapList != null)
{
//todo: check in the scrapList when laying out for predictive animations
}
var view = recycler.GetViewForPosition(CurrentAnchorPosition);
CurrentAnchorPosition += ItemDirection;
return(view);
}
private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
int heightSpec, int[] measuredDimension)
{
View view = recycler.GetViewForPosition(position);
if (view != null)
{
RecyclerView.LayoutParams p = (RecyclerView.LayoutParams)view.LayoutParameters;
int childWidthSpec = ViewGroup.GetChildMeasureSpec(widthSpec,
PaddingLeft + PaddingRight, p.Width);
int childHeightSpec = ViewGroup.GetChildMeasureSpec(heightSpec,
PaddingTop + PaddingBottom, p.Height);
view.Measure(childWidthSpec, childHeightSpec);
measuredDimension[0] = view.MeasuredWidth + p.LeftMargin + p.RightMargin;
measuredDimension[1] = view.MeasuredHeight + p.BottomMargin + p.TopMargin;
recycler.RecycleView(view);
}
}
/**
* 添加或者移除条目
*
* @param recycler RecyclerView
* @param displayRect 显示区域
* @param i 条目下标
*/
private void AddOrRemove(RecyclerView.Recycler recycler, Rect displayRect, int i)
{
View child = recycler.GetViewForPosition(i);
Rect rect = GetItemFrameByPosition(i);
if (!Rect.Intersects(displayRect, rect))
{
RemoveAndRecycleView(child, recycler); // 回收入暂存区
}
else
{
AddView(child);
MeasureChildWithMargins(child, mWidthUsed, mHeightUsed);
RecyclerView.LayoutParams lp = (RecyclerView.LayoutParams)child.LayoutParameters;// getLayoutParams();
LayoutDecorated(child,
rect.Left - mOffsetX + lp.LeftMargin + PaddingLeft,
rect.Top - mOffsetY + lp.TopMargin + PaddingTop,
rect.Right - mOffsetX - lp.RightMargin + PaddingLeft,
rect.Bottom - mOffsetY - lp.BottomMargin + PaddingTop);
}
}
protected override Line CreateLine(GeneratorDirection direction,
int extentOffset,
int breadthOffset,
int availableBreadth,
RecyclerView.Recycler recycler,
RecyclerView.State state,
IndexPath nextVisibleItem,
bool isNewGroup
)
{
var itemsInLine = ResolveMaximumItemsInLine(availableBreadth);
var firstItemInLine = nextVisibleItem;
//Find first item in line, since the item we are passed is the last
if (direction == GeneratorDirection.Backward)
{
// We are recreating the last line of the group - it may be truncated (if the total items are not an even multiple
// of the items-per-line).
if (isNewGroup)
{
itemsInLine = XamlParent.GetItemsOnLastLine(firstItemInLine.Section, itemsInLine);
}
for (int i = 0; i < itemsInLine - 1; i++)
{
firstItemInLine = GetNextUnmaterializedItem(GeneratorDirection.Backward, firstItemInLine).Value;
var isCorrectGroup = firstItemInLine.Section == nextVisibleItem.Section;
if (!isCorrectGroup)
{
//TODO: fix bug that makes this happen (#47229)
}
Debug.Assert(isCorrectGroup, GetAssertMessage("First item should not be from a different group"));
}
}
IndexPath lastItemInLine = firstItemInLine;
IndexPath?currentItem = firstItemInLine;
var availableWidth = ResolveAvailableWidth(availableBreadth);
var availableHeight = ResolveAvailableHeight(availableBreadth);
int usedBreadth = 0;
for (int i = 0; i < itemsInLine; i++)
{
var view = recycler.GetViewForPosition(GetFlatItemIndex(currentItem.Value), state);
if (!(view is SelectorItem))
{
throw new InvalidOperationException($"Expected {nameof(SelectorItem)} but received {view?.GetType().ToString() ?? "<null>"}");
}
//Add view before we measure it, this ensures that DP inheritances are correctly applied
AddView(view, direction);
var slotSize = new Windows.Foundation.Size(availableWidth, availableHeight).PhysicalToLogicalPixels();
var measuredSize = _layouter.MeasureChild(view, slotSize);
var physicalMeasuredSize = measuredSize.LogicalToPhysicalPixels();
var measuredWidth = (int)physicalMeasuredSize.Width;
var measuredHeight = (int)physicalMeasuredSize.Height;
if (_implicitItemWidth == null)
{
//Set these values to dimensions of first materialised item
_implicitItemWidth = measuredWidth;
_implicitItemHeight = measuredHeight;
// When an item dimension is not fixed, we need to arrange based on the measured size,
// otherwise the arrange will be passed a dimension that is too large and the first
// few items will not be visible
if (double.IsNaN(ItemWidth))
{
slotSize.Width = ViewHelper.PhysicalToLogicalPixels(_implicitItemWidth.Value);
}
if (double.IsNaN(ItemHeight))
{
slotSize.Height = ViewHelper.PhysicalToLogicalPixels(_implicitItemHeight.Value);
}
availableWidth = ResolveAvailableWidth(availableBreadth);
availableHeight = ResolveAvailableHeight(availableBreadth);
itemsInLine = ResolveMaximumItemsInLine(availableBreadth);
}
LayoutChild(view,
GeneratorDirection.Forward,
//We always lay out view 'top down' so that it is aligned correctly if its height is less than the line height
direction == GeneratorDirection.Forward ? extentOffset : extentOffset - ResolveItemExtent().Value,
breadthOffset + usedBreadth,
slotSize
);
usedBreadth += ResolveItemBreadth().Value;
lastItemInLine = currentItem.Value;
currentItem = GetNextUnmaterializedItem(GeneratorDirection.Forward, currentItem);
if (currentItem == null || currentItem.Value.Section != firstItemInLine.Section)
{
itemsInLine = i + 1;
break;
}
}
return(new Line
{
NumberOfViews = itemsInLine,
Extent = ResolveItemExtent().Value,
Breadth = usedBreadth,
FirstItem = firstItemInLine,
LastItem = lastItemInLine
});
}
private void layoutChunk(RecyclerView.Recycler recycler, RecyclerView.State state)
{
var view = layoutState.Next(recycler);
if (view == null || !(view.LayoutParameters is RecyclerView.LayoutParams layoutParams))
{
layoutChunkResult.IsFinished = true;
return;
}
if (!(view.Tag is Anchor anchor))
{
return;
}
//todo: check for scrap list if we do predictive animations
if (layoutState.LayoutDirection == TowardsTheEnd)
{
addAnchor(view);
}
else
{
addAnchor(view, 0);
}
MeasureChildWithMargins(view, 0, anchor.Height);
layoutChunkResult.Consumed = anchor.Height;
var anchorLeft = PaddingLeft;
var anchorRight = PaddingLeft;
int anchorTop;
int anchorBottom;
if (layoutState.LayoutDirection == TowardsTheStart)
{
anchorBottom = layoutState.Offset;
anchorTop = layoutState.Offset - layoutChunkResult.Consumed;
}
else
{
anchorTop = layoutState.Offset;
anchorBottom = layoutState.Offset + layoutChunkResult.Consumed;
}
LayoutDecoratedWithMargins(view, anchorLeft, anchorTop, anchorRight, anchorBottom);
if (layoutParams.IsItemRemoved || layoutParams.IsItemChanged)
{
layoutChunkResult.IgnoreConsumed = true;
}
foreach (var anchorData in anchor.AnchoredData)
{
if (anchoredViewsPositions.Get(anchorData.AdapterPosition) != null)
{
continue;
}
var anchoredView = recycler.GetViewForPosition(anchorData.AdapterPosition);
var anchoredViewLeft = anchorLeft + anchorData.LeftOffset;
var anchoredViewTop = anchorTop + anchorData.TopOffset;
if (layoutState.LayoutDirection == TowardsTheEnd)
{
addAnchoredView(anchoredView, anchorData.AdapterPosition);
}
else
{
addAnchoredView(anchoredView, anchorData.AdapterPosition, 0);
}
MeasureChildWithMargins(anchoredView, anchorData.Width, anchorData.Height);
LayoutDecoratedWithMargins(anchoredView,
anchoredViewLeft,
anchoredViewTop,
anchoredViewLeft + anchorData.Width,
anchoredViewTop + anchorData.Height);
}
}
protected override Line CreateLine(FillDirection direction,
int extentOffset,
int breadthOffset,
int availableBreadth,
RecyclerView.Recycler recycler,
RecyclerView.State state,
IndexPath nextVisibleItem,
bool isNewGroup
)
{
var itemsInLine = ResolveMaximumItemsInLine(availableBreadth);
var firstItemInLine = nextVisibleItem;
//Find first item in line, since the item we are passed is the last
if (direction == FillDirection.Back)
{
// We are recreating the last line of the group - it may be truncated (if the total items are not an even multiple
// of the items-per-line).
if (isNewGroup)
{
itemsInLine = XamlParent.GetItemsOnLastLine(firstItemInLine.Section, itemsInLine);
}
for (int i = 0; i < itemsInLine - 1; i++)
{
firstItemInLine = GetNextUnmaterializedItem(FillDirection.Back, firstItemInLine).Value;
var isCorrectGroup = firstItemInLine.Section == nextVisibleItem.Section;
if (!isCorrectGroup)
{
//TODO: fix bug that makes this happen (#47229)
}
Debug.Assert(isCorrectGroup, GetAssertMessage("First item should not be from a different group"));
}
}
IndexPath lastItemInLine = firstItemInLine;
IndexPath?currentItem = firstItemInLine;
var availableWidth = ResolveAvailableWidth(availableBreadth);
var availableHeight = ResolveAvailableHeight(availableBreadth);
int usedBreadth = 0;
for (int i = 0; i < itemsInLine; i++)
{
var view = recycler.GetViewForPosition(GetFlatItemIndex(currentItem.Value), state);
Debug.Assert(view is SelectorItem, "view is SelectorItem (we should never be given a group header)");
//Add view before we measure it, this ensures that DP inheritances are correctly applied
AddView(view, direction);
var slotSize = new Windows.Foundation.Size(availableWidth, availableHeight).PhysicalToLogicalPixels();
var measuredSize = _layouter.MeasureChild(view, slotSize);
var physicalMeasuredSize = measuredSize.LogicalToPhysicalPixels();
var measuredWidth = (int)physicalMeasuredSize.Width;
var measuredHeight = (int)physicalMeasuredSize.Height;
if (_implicitItemWidth == null)
{
//Set these values to dimensions of first materialised item
_implicitItemWidth = measuredWidth;
_implicitItemHeight = measuredHeight;
availableWidth = ResolveAvailableWidth(availableBreadth);
availableHeight = ResolveAvailableHeight(availableBreadth);
itemsInLine = ResolveMaximumItemsInLine(availableBreadth);
}
LayoutChild(view,
FillDirection.Forward,
//We always lay out view 'top down' so that it is aligned correctly if its height is less than the line height
direction == FillDirection.Forward ? extentOffset : extentOffset - ResolveItemExtent().Value,
breadthOffset + usedBreadth,
new Foundation.Size(width: slotSize.Width, height: slotSize.Height)
);
usedBreadth += ResolveItemBreadth().Value;
lastItemInLine = currentItem.Value;
currentItem = GetNextUnmaterializedItem(FillDirection.Forward, currentItem);
if (currentItem == null || currentItem.Value.Section != firstItemInLine.Section)
{
itemsInLine = i + 1;
break;
}
}
return(new Line
{
NumberOfViews = itemsInLine,
Extent = ResolveItemExtent().Value,
Breadth = usedBreadth,
FirstItem = firstItemInLine,
LastItem = lastItemInLine
});
}
//public void Logi(string msg)
//{
// Log.Info(TAG, msg);
//}
//public void Loge(string err)
//{
// Log.Error(TAG, err);
//}
//--- 处理布局 ----------------------------------------------------------------------------------
/**
* 布局子View
*
* @param recycler Recycler
* @param state State
*/
public override void OnLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state)
{
Log.Info(TAG, "Item onLayoutChildren");
Log.Info(TAG, "Item onLayoutChildren isPreLayout = " + state.IsPreLayout);
Log.Info(TAG, "Item onLayoutChildren isMeasuring = " + state.IsMeasuring);
Log.Info(TAG, "Item onLayoutChildren state = " + state);
// 如果是 preLayout 则不重新布局
if (state.IsPreLayout || !state.DidStructureChange())
{
return;
}
if (ItemCount == 0)
{
RemoveAndRecycleAllViews(recycler);
// 页面变化回调
SetPageCount(0);
SetPageIndex(0, false);
return;
}
else
{
SetPageCount(GetTotalPageCount());
SetPageIndex(GetPageIndexByOffset(), false);
}
// 计算页面数量
int mPageCount = ItemCount / mOnePageSize;
if (ItemCount % mOnePageSize != 0)
{
mPageCount++;
}
// 计算可以滚动的最大数值，并对滚动距离进行修正
if (CanScrollHorizontally())
{
mMaxScrollX = (mPageCount - 1) * GetUsableWidth();
mMaxScrollY = 0;
if (mOffsetX > mMaxScrollX)
{
mOffsetX = mMaxScrollX;
}
}
else
{
mMaxScrollX = 0;
mMaxScrollY = (mPageCount - 1) * GetUsableHeight();
if (mOffsetY > mMaxScrollY)
{
mOffsetY = mMaxScrollY;
}
}
// 接口回调
// setPageCount(mPageCount);
// setPageIndex(mCurrentPageIndex, false);
Logi("count = " + ItemCount);
if (mItemWidth <= 0)
{
mItemWidth = GetUsableWidth() / mColumns;
}
if (mItemHeight <= 0)
{
mItemHeight = GetUsableHeight() / mRows;
}
mWidthUsed = GetUsableWidth() - mItemWidth;
mHeightUsed = GetUsableHeight() - mItemHeight;
// 预存储两页的View显示区域
for (int i = 0; i < mOnePageSize * 2; i++)
{
GetItemFrameByPosition(i);
}
if (mOffsetX == 0 && mOffsetY == 0)
{
// 预存储View
for (int i = 0; i < mOnePageSize; i++)
{
if (i >= ItemCount)
{
break; // 防止数据过少时导致数组越界异常
}
View view = recycler.GetViewForPosition(i);
AddView(view);
MeasureChildWithMargins(view, mWidthUsed, mHeightUsed);
}
}
// 回收和填充布局
RecycleAndFillItems(recycler, state, true);
}