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Add QgsSnapToGridCanvasItem
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‎python/gui/auto_generated/qgssnaptogridcanvasitem.sip.in

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/************************************************************************
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* This file has been generated automatically from *
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* *
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* src/gui/qgssnaptogridcanvasitem.h *
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* *
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* Do not edit manually ! Edit header and run scripts/sipify.pl again *
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************************************************************************/
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class QgsSnapToGridCanvasItem : QObject, QgsMapCanvasItem
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{
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%Docstring
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Shows a grid on the map canvas given a spatial resolution.
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.. versionadded:: 3.4
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%End
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%TypeHeaderCode
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#include "qgssnaptogridcanvasitem.h"
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%End
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public:
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QgsSnapToGridCanvasItem( QgsMapCanvas *mapCanvas );
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%Docstring
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Will automatically be added to the ``mapCanvas``.
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%End
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virtual void paint( QPainter *painter );
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QgsPointXY point() const;
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%Docstring
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A point that will be highlighted on the map canvas.
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The point needs to be in map coordinates. The closest point on the
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grid will be highlighted.
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%End
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void setPoint( const QgsPointXY &point );
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%Docstring
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A point that will be highlighted on the map canvas.
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The point needs to be in map coordinates. The closest point on the
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grid will be highlighted.
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%End
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double precision() const;
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%Docstring
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The resolution of the grid in map units.
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If a crs has been specified it will be in CRS units.
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%End
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void setPrecision( double precision );
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%Docstring
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The resolution of the grid in map units.
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If a crs has been specified it will be in CRS units.
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%End
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QgsCoordinateReferenceSystem crs() const;
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%Docstring
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The CRS in which the grid should be calculated.
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By default will be an invalid QgsCoordinateReferenceSystem and
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as such equal to the CRS of the map canvas.
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%End
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void setCrs( const QgsCoordinateReferenceSystem &crs );
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%Docstring
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The CRS in which the grid should be calculated.
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By default will be an invalid QgsCoordinateReferenceSystem and
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as such equal to the CRS of the map canvas.
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%End
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bool enabled() const;
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%Docstring
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Enable this item. It will be hidden if disabled.
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%End
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void setEnabled( bool enabled );
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%Docstring
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Enable this item. It will be hidden if disabled.
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%End
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};
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/************************************************************************
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* This file has been generated automatically from *
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* *
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* src/gui/qgssnaptogridcanvasitem.h *
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* *
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* Do not edit manually ! Edit header and run scripts/sipify.pl again *
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************************************************************************/

‎python/gui/gui_auto.sip

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%Include auto_generated/qgssearchquerybuilder.sip
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%Include auto_generated/qgsshortcutsmanager.sip
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%Include auto_generated/qgsslider.sip
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%Include auto_generated/qgssnaptogridcanvasitem.sip
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%Include auto_generated/qgsstatusbar.sip
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%Include auto_generated/qgssublayersdialog.sip
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%Include auto_generated/qgssubstitutionlistwidget.sip

‎src/gui/CMakeLists.txt

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qgsshortcutsmanager.cpp
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qgsslider.cpp
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qgssnapindicator.cpp
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qgssnaptogridcanvasitem.cpp
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qgssublayersdialog.cpp
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qgssubstitutionlistwidget.cpp
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qgssqlcomposerdialog.cpp
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qgssearchquerybuilder.h
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qgsshortcutsmanager.h
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qgsslider.h
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qgssnaptogridcanvasitem.h
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qgssqlcomposerdialog.h
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qgsstatusbar.h
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qgssublayersdialog.h

‎src/gui/qgssnaptogridcanvasitem.cpp

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#include "qgssnaptogridcanvasitem.h"
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#include "qgsmapcanvas.h"
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QgsSnapToGridCanvasItem::QgsSnapToGridCanvasItem( QgsMapCanvas *mapCanvas )
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: QgsMapCanvasItem( mapCanvas )
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, mGridPen( QPen( QColor( 127, 127, 127, 150 ), 1 ) )
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, mCurrentPointPen( QPen( QColor( 200, 200, 200, 150 ), 3 ) )
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{
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updateMapCanvasCrs();
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connect( mMapCanvas, &QgsMapCanvas::extentsChanged, this, &QgsSnapToGridCanvasItem::updateZoomFactor );
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connect( mMapCanvas, &QgsMapCanvas::destinationCrsChanged, this, &QgsSnapToGridCanvasItem::updateMapCanvasCrs );
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}
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void QgsSnapToGridCanvasItem::paint( QPainter *painter )
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{
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painter->save();
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QgsRectangle mapRect = mMapCanvas->extent();
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if ( rect() != mapRect )
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setRect( mapRect );
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painter->setRenderHints( QPainter::Antialiasing );
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painter->setCompositionMode( QPainter::CompositionMode_Difference );
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if ( mEnabled && mAvailableByZoomFactor )
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{
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const QgsRectangle layerExtent = mTransform.transformBoundingBox( mapRect, QgsCoordinateTransform::ReverseTransform );
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const QgsPointXY layerPt = mTransform.transform( mPoint, QgsCoordinateTransform::ReverseTransform );
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const double gridXMin = std::ceil( layerExtent.xMinimum() / mPrecision ) * mPrecision;
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const double gridXMax = std::ceil( layerExtent.xMaximum() / mPrecision ) * mPrecision;
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const double gridYMin = std::ceil( layerExtent.yMinimum() / mPrecision ) * mPrecision;
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const double gridYMax = std::ceil( layerExtent.yMaximum() / mPrecision ) * mPrecision;
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for ( int x = gridXMin ; x < gridXMax; x += mPrecision )
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{
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for ( int y = gridYMin ; y < gridYMax; y += mPrecision )
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{
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const QgsPointXY pt = mTransform.transform( x, y );
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const QPointF canvasPt = toCanvasCoordinates( pt );
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if ( qgsDoubleNear( layerPt.x(), x, mPrecision / 3 ) && qgsDoubleNear( layerPt.y(), y, mPrecision / 3 ) )
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{
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painter->setPen( mCurrentPointPen );
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}
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else
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{
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painter->setPen( mGridPen );
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}
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painter->drawLine( canvasPt.x() - 3, canvasPt.y(), canvasPt.x() + 3, canvasPt.y() );
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painter->drawLine( canvasPt.x(), canvasPt.y() - 3, canvasPt.x(), canvasPt.y() + 3 );
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}
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}
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}
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painter->restore();
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}
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QgsPointXY QgsSnapToGridCanvasItem::point() const
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{
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return mPoint;
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}
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void QgsSnapToGridCanvasItem::setPoint( const QgsPointXY &point )
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{
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mPoint = point;
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update();
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}
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double QgsSnapToGridCanvasItem::precision() const
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{
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return mPrecision;
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}
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void QgsSnapToGridCanvasItem::setPrecision( double precision )
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{
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mPrecision = precision;
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updateZoomFactor();
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}
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QgsCoordinateReferenceSystem QgsSnapToGridCanvasItem::crs() const
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{
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return mTransform.sourceCrs();
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}
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void QgsSnapToGridCanvasItem::setCrs( const QgsCoordinateReferenceSystem &crs )
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{
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mTransform.setSourceCrs( crs );
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updateZoomFactor();
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}
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bool QgsSnapToGridCanvasItem::enabled() const
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{
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return mEnabled;
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}
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void QgsSnapToGridCanvasItem::setEnabled( bool enabled )
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{
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mEnabled = enabled;
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update();
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}
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void QgsSnapToGridCanvasItem::updateMapCanvasCrs()
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{
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mTransform.setContext( mMapCanvas->mapSettings().transformContext() );
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mTransform.setDestinationCrs( mMapCanvas->mapSettings().destinationCrs() );
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update();
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}
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void QgsSnapToGridCanvasItem::updateZoomFactor()
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{
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if ( !isVisible() )
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return;
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try
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{
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const int threshold = 5;
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const QgsPointXY centerPoint = mMapCanvas->extent().center();
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const QPointF canvasCenter = toCanvasCoordinates( centerPoint );
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const QgsPointXY pt1 = mMapCanvas->mapSettings().mapToPixel().toMapCoordinates( canvasCenter.x() - threshold, canvasCenter.y() - threshold );
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const QgsPointXY pt2 = mMapCanvas->mapSettings().mapToPixel().toMapCoordinates( canvasCenter.x() + threshold, canvasCenter.y() + threshold );
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const QgsPointXY layerPt1 = mTransform.transform( pt1, QgsCoordinateTransform::ReverseTransform );
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const QgsPointXY layerPt2 = mTransform.transform( pt2, QgsCoordinateTransform::ReverseTransform );
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const double dist = layerPt1.distance( layerPt2 );
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if ( dist < mPrecision )
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mAvailableByZoomFactor = true;
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else
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mAvailableByZoomFactor = false;
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}
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catch ( QgsCsException &e )
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{
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// transform errors?
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// you've probably got worse problems than the grid with your digitizing operations in the current projection.
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mAvailableByZoomFactor = false;
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}
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}

‎src/gui/qgssnaptogridcanvasitem.h

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#ifndef QGSSNAPTOGRIDCANVASITEM_H
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#define QGSSNAPTOGRIDCANVASITEM_H
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#include <QObject>
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#include <QPen>
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#include "qgscoordinatereferencesystem.h"
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#include "qgsmapcanvasitem.h"
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#include "qgscoordinatetransform.h"
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/**
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* \ingroup gui
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*
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* Shows a grid on the map canvas given a spatial resolution.
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*
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* \since QGIS 3.4
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*/
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class GUI_EXPORT QgsSnapToGridCanvasItem : public QObject, public QgsMapCanvasItem
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{
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Q_OBJECT
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public:
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/**
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* Will automatically be added to the \a mapCanvas.
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*/
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QgsSnapToGridCanvasItem( QgsMapCanvas *mapCanvas );
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void paint( QPainter *painter ) override;
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/**
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* A point that will be highlighted on the map canvas.
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* The point needs to be in map coordinates. The closest point on the
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* grid will be highlighted.
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*/
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QgsPointXY point() const;
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/**
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* A point that will be highlighted on the map canvas.
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* The point needs to be in map coordinates. The closest point on the
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* grid will be highlighted.
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*/
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void setPoint( const QgsPointXY &point );
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/**
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* The resolution of the grid in map units.
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* If a crs has been specified it will be in CRS units.
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*/
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double precision() const;
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/**
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* The resolution of the grid in map units.
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* If a crs has been specified it will be in CRS units.
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*/
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void setPrecision( double precision );
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/**
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* The CRS in which the grid should be calculated.
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* By default will be an invalid QgsCoordinateReferenceSystem and
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* as such equal to the CRS of the map canvas.
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*/
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QgsCoordinateReferenceSystem crs() const;
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/**
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* The CRS in which the grid should be calculated.
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* By default will be an invalid QgsCoordinateReferenceSystem and
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* as such equal to the CRS of the map canvas.
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*/
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void setCrs( const QgsCoordinateReferenceSystem &crs );
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/**
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* Enable this item. It will be hidden if disabled.
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*/
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bool enabled() const;
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/**
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* Enable this item. It will be hidden if disabled.
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*/
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void setEnabled( bool enabled );
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private slots:
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void updateMapCanvasCrs();
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void updateZoomFactor();
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private:
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QPen mGridPen;
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QPen mCurrentPointPen;
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bool mEnabled = true;
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bool mAvailableByZoomFactor = false;
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double mPrecision = 0.0;
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QgsCoordinateTransform mTransform;
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QgsPointXY mPoint;
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};
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#endif // QGSSNAPTOGRIDCANVASITEM_H

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