Show snap lines in ruler mouse move event

Author: mhugent

src/app/composer/qgscomposer.cpp

@@ -254,6 +254,7 @@ QgsComposer::QgsComposer( QgisApp *qgis, const QString& title )
   mHorizontalRuler = new QgsComposerRuler( QgsComposerRuler::Horizontal );
   mVerticalRuler = new QgsComposerRuler( QgsComposerRuler::Vertical );
   QWidget* fake = new QWidget();
+  fake->setAttribute( Qt::WA_NoMousePropagation );
   fake->setBackgroundRole( QPalette::Window );
   fake->setFixedSize( 20, 20 );
   mViewLayout->addWidget( fake, 0, 0 );

src/gui/qgscomposerruler.cpp

@@ -1,13 +1,16 @@
 #include "qgscomposerruler.h"
 #include "qgscomposition.h"
 #include "qgis.h"
+#include <QDragEnterEvent>
+#include <QGraphicsLineItem>
 #include <QPainter>
 #include <cmath>
 
 const int RULER_MIN_SIZE = 20;
 
-QgsComposerRuler::QgsComposerRuler( QgsComposerRuler::Direction d ): QWidget( 0 ), mDirection( d ), mComposition( 0 )
+QgsComposerRuler::QgsComposerRuler( QgsComposerRuler::Direction d ): QWidget( 0 ), mDirection( d ), mComposition( 0 ), mLineSnapItem( 0 )
 {
+  setMouseTracking( true );
 }
 
 QgsComposerRuler::~QgsComposerRuler()
@@ -111,29 +114,6 @@ void QgsComposerRuler::paintEvent( QPaintEvent* event )
       }
     }
 
-#if 0
-    double markerPos = ( floor( startY / mmDisplay ) + 1 ) * mmDisplay; //marker position in mm
-    while ( markerPos <= endY )
-    {
-      int page = ( int )( markerPos / ( mComposition->paperHeight() + mComposition->spaceBetweenPages() ) );
-      double pageCoord = markerPos - page * ( mComposition->paperHeight() + mComposition->spaceBetweenPages() );
-      if ( page >= mComposition->numPages() )
-      {
-        break;
-      }
-
-      if ( pageCoord < 0 || pageCoord > mComposition->paperHeight() ) //marker is in a page gap
-      {
-        markerPos += mmDisplay;
-        continue;
-      }
-      double pixelCoord = mTransform.map( QPointF( 0, markerPos ) ).y();
-      p.drawLine( 0, pixelCoord, RULER_MIN_SIZE, pixelCoord );
-      p.drawText( QPointF( 0, pixelCoord - 2.0 ), QString::number( pageCoord ) );
-      markerPos += mmDisplay;
-    }
-#endif //0
-
     p.setPen( QColor( Qt::red ) );
     p.drawLine( 0, mMarkerPos.y(), RULER_MIN_SIZE, mMarkerPos.y() );
   }
@@ -146,3 +126,56 @@ void QgsComposerRuler::setSceneTransform( const QTransform& transform )
   mTransform = transform;
   update();
 }
+
+void QgsComposerRuler::mouseMoveEvent( QMouseEvent* event )
+{
+  qWarning( "QgsComposerRuler::mouseMoveEvent" );
+  updateMarker( event->posF() );
+  setSnapLinePosition( event->posF() );
+}
+
+void QgsComposerRuler::mouseReleaseEvent( QMouseEvent* event )
+{
+  Q_UNUSED( event );
+  delete mLineSnapItem;
+  mLineSnapItem = 0;
+}
+
+void QgsComposerRuler::mousePressEvent( QMouseEvent* event )
+{
+  delete mLineSnapItem;
+  mLineSnapItem = 0;
+  mLineSnapItem = createLineSnapItem();
+  mComposition->addItem( mLineSnapItem );
+  setSnapLinePosition( event->posF() );
+  mLineSnapItem->show();
+}
+
+void QgsComposerRuler::setSnapLinePosition( const QPointF& pos )
+{
+  if ( !mLineSnapItem || !mComposition )
+  {
+    return;
+  }
+
+  QPointF transformedPt = mTransform.inverted().map( pos );
+  if ( mDirection == Horizontal )
+  {
+    mLineSnapItem->setLine( QLineF( transformedPt.x(), 0, transformedPt.x(), mComposition->height() ) );
+  }
+  else //vertical
+  {
+    mLineSnapItem->setLine( QLineF( 0, transformedPt.y(), mComposition->width(), transformedPt.y() ) );
+  }
+}
+
+QGraphicsLineItem* QgsComposerRuler::createLineSnapItem()
+{
+  QGraphicsLineItem* item = new QGraphicsLineItem();
+  QPen linePen( Qt::SolidLine );
+  linePen.setColor( Qt::red );
+  linePen.setWidthF( 0.5 );
+  item->setPen( linePen );
+  item->setZValue( 100 );
+  return item;
+}

src/gui/qgscomposerruler.h

@@ -3,6 +3,7 @@
 
 #include <QWidget>
 class QgsComposition;
+class QGraphicsLineItem;
 
 /**A class to show paper scale and the current cursor position*/
 class QgsComposerRuler: public QWidget
@@ -22,17 +23,24 @@ class QgsComposerRuler: public QWidget
     void setSceneTransform( const QTransform& transform );
     void updateMarker( const QPointF& pos ) { mMarkerPos = pos; repaint(); }
 
-    void setComposition( const QgsComposition* c ) { mComposition = c; }
-    const QgsComposition* composition() const { return mComposition; }
+    void setComposition( QgsComposition* c ) { mComposition = c; }
+    QgsComposition* composition() { return mComposition; }
 
   protected:
     void paintEvent( QPaintEvent* event );
+    void mouseMoveEvent( QMouseEvent* event );
+    void mouseReleaseEvent( QMouseEvent* event );
+    void mousePressEvent( QMouseEvent* event );
 
   private:
     Direction mDirection;
     QTransform mTransform;
     QPointF mMarkerPos;
-    const QgsComposition* mComposition; //reference to composition for paper size, nPages
+    QgsComposition* mComposition; //reference to composition for paper size, nPages
+    QGraphicsLineItem* mLineSnapItem;
+
+    void setSnapLinePosition( const QPointF& pos );
+    static QGraphicsLineItem* createLineSnapItem();
 };
 
 #endif // QGSCOMPOSERRULER_H