From 8ee95e63a92b07ba89003243b0e93718762a7d88 Mon Sep 17 00:00:00 2001 From: "Eduardo M. Fleury" Date: Wed, 4 Nov 2009 10:49:05 -0300 Subject: QGAL: Support for out-of-order parallel anchors Now parallel anchors account for the fact they may be composed of anchors with different directions. We arbitrarily set the direction of the parallel anchor to be the same direction as the first child. The methods refreshSizeHints and updateChildren were updated to support this situation. Signed-off-by: Eduardo M. Fleury Reviewed-by: Caio Marcelo de Oliveira Filho --- src/gui/graphicsview/qgraphicsanchorlayout_p.cpp | 46 ++++++++++++++++++++---- src/gui/graphicsview/qgraphicsanchorlayout_p.h | 9 ++--- 2 files changed, 45 insertions(+), 10 deletions(-) diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp index 7ad994c..95922ca 100644 --- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp +++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp @@ -218,9 +218,20 @@ bool AnchorData::refreshSizeHints(const QLayoutStyleInfo *styleInfo) void ParallelAnchorData::updateChildrenSizes() { - firstEdge->sizeAtMinimum = secondEdge->sizeAtMinimum = sizeAtMinimum; - firstEdge->sizeAtPreferred = secondEdge->sizeAtPreferred = sizeAtPreferred; - firstEdge->sizeAtMaximum = secondEdge->sizeAtMaximum = sizeAtMaximum; + firstEdge->sizeAtMinimum = sizeAtMinimum; + firstEdge->sizeAtPreferred = sizeAtPreferred; + firstEdge->sizeAtMaximum = sizeAtMaximum; + + const bool secondFwd = (secondEdge->from == from); + if (secondFwd) { + secondEdge->sizeAtMinimum = sizeAtMinimum; + secondEdge->sizeAtPreferred = sizeAtPreferred; + secondEdge->sizeAtMaximum = sizeAtMaximum; + } else { + secondEdge->sizeAtMinimum = -sizeAtMinimum; + secondEdge->sizeAtPreferred = -sizeAtPreferred; + secondEdge->sizeAtMaximum = -sizeAtMaximum; + } firstEdge->updateChildrenSizes(); secondEdge->updateChildrenSizes(); @@ -239,8 +250,16 @@ bool ParallelAnchorData::refreshSizeHints_helper(const QLayoutStyleInfo *styleIn return false; } - minSize = qMax(firstEdge->minSize, secondEdge->minSize); - maxSize = qMin(firstEdge->maxSize, secondEdge->maxSize); + // Account for parallel anchors where the second edge is backwards. + // We rely on the fact that a forward anchor of sizes min, pref, max is equivalent + // to a backwards anchor of size (-max, -pref, -min) + const bool secondFwd = (secondEdge->from == from); + const qreal secondMin = secondFwd ? secondEdge->minSize : -secondEdge->maxSize; + const qreal secondPref = secondFwd ? secondEdge->prefSize : -secondEdge->prefSize; + const qreal secondMax = secondFwd ? secondEdge->maxSize : -secondEdge->minSize; + + minSize = qMax(firstEdge->minSize, secondMin); + maxSize = qMin(firstEdge->maxSize, secondMax); // This condition means that the maximum size of one anchor being simplified is smaller than // the minimum size of the other anchor. The consequence is that there won't be a valid size @@ -249,7 +268,22 @@ bool ParallelAnchorData::refreshSizeHints_helper(const QLayoutStyleInfo *styleIn return false; } - prefSize = qMax(firstEdge->prefSize, secondEdge->prefSize); + // The equivalent preferred Size of a parallel anchor is calculated as to + // reduce the deviation from the original preferred sizes _and_ to avoid shrinking + // items below their preferred sizes, unless strictly needed. + + // ### This logic only holds if all anchors in the layout are "well-behaved" in the + // following terms: + // + // - There are no negative-sized anchors + // - All sequential anchors are composed of children in the same direction as the + // sequential anchor itself + // + // With these assumptions we can grow a child knowing that no hidden items will + // have to shrink as the result of that. + // If any of these does not hold, we have a situation where the ParallelAnchor + // does not have enough information to calculate its equivalent prefSize. + prefSize = qMax(firstEdge->prefSize, secondPref); prefSize = qMin(prefSize, maxSize); // See comment in AnchorData::refreshSizeHints() about sizeAt* values diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.h b/src/gui/graphicsview/qgraphicsanchorlayout_p.h index 1e11ee2..8d77b1a 100644 --- a/src/gui/graphicsview/qgraphicsanchorlayout_p.h +++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.h @@ -256,10 +256,11 @@ struct ParallelAnchorData : public AnchorData type = AnchorData::Parallel; orientation = first->orientation; - // ### Those asserts force that both child anchors have the same direction, - // but can't we simplify a pair of anchors in opposite directions? - Q_ASSERT(first->from == second->from); - Q_ASSERT(first->to == second->to); + // This assert whether the child anchors share their vertices + Q_ASSERT(((first->from == second->from) && (first->to == second->to)) || + ((first->from == second->to) && (first->to == second->from))); + + // We arbitrarily choose the direction of the first child as "our" direction from = first->from; to = first->to; #ifdef QT_DEBUG -- cgit v0.12