30 if ( !mEnabled || !mAvailableByZoomFactor )
36 painter->setRenderHints( QPainter::Antialiasing );
37 painter->setCompositionMode( QPainter::CompositionMode_Difference );
39 const double scaleFactor = painter->fontMetrics().xHeight() * .2;
41 mGridPen.setWidth( scaleFactor );
42 mCurrentPointPen.setWidth( scaleFactor * 3 );
43 const int gridMarkerLength = scaleFactor * 3;
52 const double gridXMin = std::ceil( layerExtent.
xMinimum() / mPrecision ) * mPrecision;
53 const double gridXMax = std::ceil( layerExtent.
xMaximum() / mPrecision ) * mPrecision;
54 const double gridYMin = std::ceil( layerExtent.
yMinimum() / mPrecision ) * mPrecision;
55 const double gridYMax = std::ceil( layerExtent.
yMaximum() / mPrecision ) * mPrecision;
57 for (
double x = gridXMin ; x < gridXMax; x += mPrecision )
59 for (
double y = gridYMin ; y < gridYMax; y += mPrecision )
66 painter->setPen( mCurrentPointPen );
70 painter->setPen( mGridPen );
72 painter->drawLine( canvasPt.x() - gridMarkerLength, canvasPt.y(), canvasPt.x() + gridMarkerLength, canvasPt.y() );
73 painter->drawLine( canvasPt.x(), canvasPt.y() - gridMarkerLength, canvasPt.x(), canvasPt.y() + gridMarkerLength );
81 mAvailableByZoomFactor =
false;
129void QgsSnapToGridCanvasItem::updateMapCanvasCrs()
138void QgsSnapToGridCanvasItem::updateZoomFactor()
145 const int threshold = 5;
148 if ( extent !=
rect() )
155 static_cast<int>( canvasCenter.y() - threshold ) );
157 static_cast<int>( canvasCenter.y() + threshold ) );
162 const double dist = layerPt1.
distance( layerPt2 );
164 if ( dist < mPrecision )
165 mAvailableByZoomFactor =
true;
167 mAvailableByZoomFactor =
false;
173 mAvailableByZoomFactor =
false;
@ Reverse
Reverse/inverse transform (from destination to source)
This class represents a coordinate reference system (CRS).
Custom exception class for Coordinate Reference System related exceptions.
An abstract class for items that can be placed on the map canvas.
QgsRectangle rect() const
returns canvas item rectangle in map units
QPointF toCanvasCoordinates(const QgsPointXY &point) const
transformation from map coordinates to screen coordinates
QgsMapCanvas * mMapCanvas
pointer to map canvas
void setRect(const QgsRectangle &r, bool resetRotation=true)
sets canvas item rectangle in map units
Map canvas is a class for displaying all GIS data types on a canvas.
void extentsChanged()
Emitted when the extents of the map change.
void destinationCrsChanged()
Emitted when map CRS has changed.
const QgsMapSettings & mapSettings() const
Gets access to properties used for map rendering.
QgsRectangle extent() const
Returns the current zoom extent of the map canvas.
const QgsMapToPixel & mapToPixel() const
QgsCoordinateReferenceSystem destinationCrs() const
Returns the destination coordinate reference system for the map render.
QgsCoordinateTransformContext transformContext() const
Returns the coordinate transform context, which stores various information regarding which datum tran...
QgsPointXY toMapCoordinates(int x, int y) const
Transforms device coordinates to map (world) coordinates.
A class to represent a 2D point.
double distance(double x, double y) const
Returns the distance between this point and a specified x, y coordinate.
A rectangle specified with double values.
double xMinimum() const
Returns the x minimum value (left side of rectangle).
double yMinimum() const
Returns the y minimum value (bottom side of rectangle).
double xMaximum() const
Returns the x maximum value (right side of rectangle).
double yMaximum() const
Returns the y maximum value (top side of rectangle).
QgsPointXY center() const
Returns the center point of the rectangle.
Scoped object for saving and restoring a QPainter object's state.
bool enabled() const
Enable this item.
double precision() const
The resolution of the grid in map units.
void setCrs(const QgsCoordinateReferenceSystem &crs)
The CRS in which the grid should be calculated.
void setPoint(const QgsPointXY &point)
A point that will be highlighted on the map canvas.
void setEnabled(bool enabled)
Enable this item.
QgsSnapToGridCanvasItem(QgsMapCanvas *mapCanvas)
Will automatically be added to the mapCanvas.
void paint(QPainter *painter) override
function to be implemented by derived classes
QgsCoordinateReferenceSystem crs() const
The CRS in which the grid should be calculated.
void setPrecision(double precision)
The resolution of the grid in map units.
QgsPointXY point() const
A point that will be highlighted on the map canvas.
bool qgsDoubleNear(double a, double b, double epsilon=4 *std::numeric_limits< double >::epsilon())
Compare two doubles (but allow some difference)
const QgsCoordinateReferenceSystem & crs