GridSnapStrategy Class Reference

snaps to the canvas grid More...

#include <KoSnapStrategy.h>

Inheritance diagram for GridSnapStrategy:

Public Member Functions
QPainterPath	decoration (const KoViewConverter &converter) const override
	returns the current snap strategy decoration
	GridSnapStrategy ()
bool	snap (const QPointF &mousePosition, KoSnapProxy *proxy, qreal maxSnapDistance) override
Public Member Functions inherited from KoSnapStrategy
	KoSnapStrategy (KoSnapGuide::Strategy type)
QPointF	snappedPosition () const
	returns the snapped position form the last call to snapToPoints
SnapType	snappedType () const
KoSnapGuide::Strategy	type () const
	returns the strategies type
virtual	~KoSnapStrategy ()

Additional Inherited Members
Public Types inherited from KoSnapStrategy
enum	SnapType { ToPoint = 0 , ToLine }
Static Public Member Functions inherited from KoSnapStrategy
static qreal	scalarProduct (const QPointF &p1, const QPointF &p2)
static qreal	squareDistance (const QPointF &p1, const QPointF &p2)
Protected Member Functions inherited from KoSnapStrategy
void	setSnappedPosition (const QPointF &position, SnapType snapType)
	sets the current snapped position

Detailed Description

snaps to the canvas grid

Definition at line 110 of file KoSnapStrategy.h.

Constructor & Destructor Documentation

GridSnapStrategy()

GridSnapStrategy::GridSnapStrategy

(

)

Definition at line 421 of file KoSnapStrategy.cpp.

    : KoSnapStrategy(KoSnapGuide::GridSnapping)
{
}

Member Function Documentation

decoration()

QPainterPath GridSnapStrategy::decoration ( const KoViewConverter & converter ) const

overridevirtual

returns the current snap strategy decoration

Implements KoSnapStrategy.

Definition at line 488 of file KoSnapStrategy.cpp.

{
    QSizeF unzoomedSize = converter.viewToDocument(QSizeF(5, 5));
    QPainterPath decoration;
    decoration.moveTo(snappedPosition() - QPointF(unzoomedSize.width(), 0));
    decoration.lineTo(snappedPosition() + QPointF(unzoomedSize.width(), 0));
    decoration.moveTo(snappedPosition() - QPointF(0, unzoomedSize.height()));
    decoration.lineTo(snappedPosition() + QPointF(0, unzoomedSize.height()));
    return decoration;
}

References decoration(), KoSnapStrategy::snappedPosition(), and KoViewConverter::viewToDocument().

snap()

bool GridSnapStrategy::snap ( const QPointF & mousePosition, KoSnapProxy * proxy, qreal maxSnapDistance )

overridevirtual

Implements KoSnapStrategy.

Definition at line 426 of file KoSnapStrategy.cpp.

{
    Q_ASSERT(std::isfinite(maxSnapDistance));
    if (! proxy->canvas()->snapToGrid())
        return false;
 
    // The 1e-10 here is a workaround for some weird division problem.
    // 360.00062366 / 2.83465058 gives 127 'exactly' when shown as a qreal,
    // but when casting into an int, we get 126. In fact it's 127 - 5.64e-15 !
    QPointF offset;
    QSizeF spacing;
    proxy->canvas()->gridSize(&offset, &spacing);
 
    // we want to snap to the nearest grid point, so calculate
    // the grid rows/columns before and after the points position
    int col = static_cast<int>((mousePosition.x() - offset.x()) / spacing.width() + 1e-10);
    int nextCol = col + 1;
    int row = static_cast<int>((mousePosition.y() - offset.y()) / spacing.height() + 1e-10);
    int nextRow = row + 1;
 
    // now check which grid line has less distance to the point
    qreal distToCol = qAbs(offset.x() + col * spacing.width() - mousePosition.x());
    qreal distToNextCol = qAbs(offset.x() + nextCol * spacing.width() - mousePosition.x());
 
    if (distToCol > distToNextCol) {
        col = nextCol;
        distToCol = distToNextCol;
    }
 
    qreal distToRow = qAbs(offset.y() + row * spacing.height() - mousePosition.y());
    qreal distToNextRow = qAbs(offset.y() + nextRow * spacing.height() - mousePosition.y());
    if (distToRow > distToNextRow) {
        row = nextRow;
        distToRow = distToNextRow;
    }
 
    QPointF snappedPoint = mousePosition;
    SnapType snapType = ToPoint;
 
    bool pointIsSnapped = false;
 
    const qreal sqDistance = distToCol * distToCol + distToRow * distToRow;
    const qreal maxSqDistance = maxSnapDistance * maxSnapDistance;
    // now check if we are inside the snap distance
    if (sqDistance < maxSqDistance) {
        snappedPoint = QPointF(offset.x() + col * spacing.width(), offset.y() + row * spacing.height());
        pointIsSnapped = true;
    } else if (distToRow < maxSnapDistance) {
        snappedPoint.ry() = offset.y() + row * spacing.height();
        snapType = ToLine;
        pointIsSnapped = true;
    } else if (distToCol < maxSnapDistance) {
        snappedPoint.rx() = offset.x() + col * spacing.width();
        snapType = ToLine;
        pointIsSnapped = true;
    }
 
    setSnappedPosition(snappedPoint, snapType);
 
    return pointIsSnapped;
}

References KoSnapProxy::canvas(), KoCanvasBase::gridSize(), KoSnapStrategy::setSnappedPosition(), KoCanvasBase::snapToGrid(), KoSnapStrategy::ToLine, and KoSnapStrategy::ToPoint.

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The documentation for this class was generated from the following files:

• libs/flake/KoSnapStrategy.h
• libs/flake/KoSnapStrategy.cpp