private static LayoutResult HandleAttemptAsSuccessful(OrphansWidowsLayoutHelper.OrphansWidowsLayoutAttempt
attemptResult, LayoutContext originalContext)
{
originalContext.GetFloatRendererAreas().Clear();
originalContext.GetFloatRendererAreas().AddAll(attemptResult.attemptContext.GetFloatRendererAreas());
if (originalContext.GetMarginsCollapseInfo() != null)
{
MarginsCollapseInfo.UpdateFromCopy(originalContext.GetMarginsCollapseInfo(), attemptResult.attemptContext.
GetMarginsCollapseInfo());
}
return(attemptResult.attemptResult);
}
private static OrphansWidowsLayoutHelper.OrphansWidowsLayoutAttempt AttemptLayout(ParagraphRenderer renderer
, LayoutContext originalContext, LayoutArea attemptArea)
{
OrphansWidowsLayoutHelper.OrphansWidowsLayoutAttempt attemptResult = new OrphansWidowsLayoutHelper.OrphansWidowsLayoutAttempt
();
MarginsCollapseInfo copiedMarginsCollapseInfo = null;
if (originalContext.GetMarginsCollapseInfo() != null)
{
copiedMarginsCollapseInfo = MarginsCollapseInfo.CreateDeepCopy(originalContext.GetMarginsCollapseInfo());
}
List <Rectangle> attemptFloatRectsList = new List <Rectangle>(originalContext.GetFloatRendererAreas());
LayoutContext attemptContext = new LayoutContext(attemptArea, copiedMarginsCollapseInfo, attemptFloatRectsList
, originalContext.IsClippedHeight());
attemptResult.attemptContext = attemptContext;
attemptResult.attemptResult = renderer.DirectLayout(attemptContext);
return(attemptResult);
}
internal static LayoutResult OrphansWidowsAwareLayout(ParagraphRenderer renderer, LayoutContext context, ParagraphOrphansControl
orphansControl, ParagraphWidowsControl widowsControl)
{
OrphansWidowsLayoutHelper.OrphansWidowsLayoutAttempt layoutAttempt = AttemptLayout(renderer, context, context
.GetArea().Clone());
if (context.IsClippedHeight() || renderer.IsPositioned() || layoutAttempt.attemptResult.GetStatus() != LayoutResult
.PARTIAL || layoutAttempt.attemptResult.GetSplitRenderer() == null)
{
return(HandleAttemptAsSuccessful(layoutAttempt, context));
}
ParagraphRenderer splitRenderer = (ParagraphRenderer)layoutAttempt.attemptResult.GetSplitRenderer();
bool orphansViolation = orphansControl != null && splitRenderer != null && splitRenderer.GetLines().Count
< orphansControl.GetMinOrphans() && !renderer.IsFirstOnRootArea();
bool forcedPlacement = true.Equals(renderer.GetPropertyAsBoolean(Property.FORCED_PLACEMENT));
if (orphansViolation && forcedPlacement)
{
orphansControl.HandleViolatedOrphans(splitRenderer, "Ignored orphans constraint due to forced placement.");
}
if (orphansViolation && !forcedPlacement)
{
layoutAttempt = null;
}
else
{
if (widowsControl != null && splitRenderer != null && layoutAttempt.attemptResult.GetOverflowRenderer() !=
null)
{
ParagraphRenderer overflowRenderer = (ParagraphRenderer)layoutAttempt.attemptResult.GetOverflowRenderer();
// Excessively big value to check if widows constraint is violated;
// Make this value less in order to improve performance if you are sure
// that min number of widows will fit in this height. E.g. A4 page height is 842.
int simulationHeight = 3500;
LayoutArea simulationArea = new LayoutArea(context.GetArea().GetPageNumber(), context.GetArea().GetBBox().
Clone().SetHeight(simulationHeight));
// collapsingMarginsInfo might affect available space, which is redundant in case we pass arbitrary space.
// floatedRendererAreas list on new area is considered empty. We don't know if there will be any, however their presence in any case will result in more widows, not less.
// clippedHeight is undefined for the next area, because it is defined by overflow part of the paragraph parent.
// Even if it will be set to true in actual overflow-part layouting, stealing lines approach will result in
// giving bigger part of MAX-HEIGHT to the overflow part and resulting in bigger number of widows, which is better.
// However for possible other approaches which change content "length" (like word/char spacing adjusts),
// if in actual overflow-part layouting clippedHeight will be true, those widows fixing attempts will result in worse results.
LayoutContext simulationContext = new LayoutContext(simulationArea);
LayoutResult simulationResult = overflowRenderer.DirectLayout(simulationContext);
if (simulationResult.GetStatus() == LayoutResult.FULL)
{
// simulationHeight is excessively big in order to allow to layout all of the content remaining in overflowRenderer:
// this way after all of the remaining content is layouted we can check if it has led to widows violation.
// To make this analysis possible, we expect to get result FULL.
// if result is PARTIAL: means that simulationHeight value isn't big enough to layout all of the content remaining in overflowRenderer.
// In this case we assume that widows aren't violated since the amount of the lines to fit the simulatedHeight is expected to be very large.
// if result is NOTHING: unexpected result, limitation of simulation approach. Retry again with forced placement set.
int extraWidows = widowsControl.GetMinWidows() - overflowRenderer.GetLines().Count;
if (extraWidows > 0)
{
int extraLinesToMove = orphansControl != null?Math.Max(orphansControl.GetMinOrphans(), 1) : 1;
if (extraWidows <= widowsControl.GetMaxLinesToMove() && splitRenderer.GetLines().Count - extraWidows >= extraLinesToMove
)
{
LineRenderer lastLine = splitRenderer.GetLines()[splitRenderer.GetLines().Count - 1];
LineRenderer lastLineToLeave = splitRenderer.GetLines()[splitRenderer.GetLines().Count - extraWidows - 1];
float d = lastLineToLeave.GetOccupiedArea().GetBBox().GetY() - lastLine.GetOccupiedArea().GetBBox().GetY()
- AbstractRenderer.EPS;
Rectangle smallerBBox = new Rectangle(context.GetArea().GetBBox());
smallerBBox.DecreaseHeight(d);
smallerBBox.MoveUp(d);
LayoutArea smallerAvailableArea = new LayoutArea(context.GetArea().GetPageNumber(), smallerBBox);
layoutAttempt = AttemptLayout(renderer, context, smallerAvailableArea);
}
else
{
if (forcedPlacement || renderer.IsFirstOnRootArea() || !widowsControl.IsOverflowOnWidowsViolation())
{
if (forcedPlacement)
{
widowsControl.HandleViolatedWidows(overflowRenderer, "forced placement");
}
else
{
widowsControl.HandleViolatedWidows(overflowRenderer, "inability to fix it");
}
}
else
{
layoutAttempt = null;
}
}
}
}
}
}
if (layoutAttempt != null)
{
return(HandleAttemptAsSuccessful(layoutAttempt, context));
}
else
{
return(new LayoutResult(LayoutResult.NOTHING, null, null, renderer));
}
}
