New QgsFloatingWidget widget for easy creation of widgets which "float"

above a layout. Supports setting another widget as a anchor point for the widget, eg the floating widget could be set so that it's always placed to the top-right of the anchor widget.
qgis · Dec 5, 2016 · 5da2513 · 5da2513
1 parent f85d24e
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diff --git a/python/gui/gui.sip b/python/gui/gui.sip
@@ -79,6 +79,7 @@
 %Include qgsfilewidget.sip
 %Include qgsfiledownloader.sip
 %Include qgsfilterlineedit.sip
+%Include qgsfloatingwidget.sip
 %Include qgsfocuswatcher.sip
 %Include qgsformannotationitem.sip
 %Include qgsgenericprojectionselector.sip

diff --git a/src/gui/CMakeLists.txt b/src/gui/CMakeLists.txt
@@ -226,6 +226,7 @@ SET(QGIS_GUI_SRCS
   qgsfiledropedit.cpp
   qgsfilewidget.cpp
   qgsfilterlineedit.cpp
+  qgsfloatingwidget.cpp
   qgsfocuswatcher.cpp
   qgsformannotationitem.cpp
   qgsgenericprojectionselector.cpp
@@ -393,6 +394,7 @@ SET(QGIS_GUI_MOC_HDRS
   qgsfiledropedit.h
   qgsfilewidget.h
   qgsfilterlineedit.h
+  qgsfloatingwidget.h
   qgsfocuswatcher.h
   qgsformannotationitem.h
   qgsgenericprojectionselector.h

diff --git a/src/gui/qgsfloatingwidget.cpp b/src/gui/qgsfloatingwidget.cpp
@@ -0,0 +1,179 @@
+/***************************************************************************
+    qgsfloatingwidget.cpp
+    ---------------------
+    begin                : April 2016
+    copyright            : (C) Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgsfloatingwidget.h"
+#include <QEvent>
+
+
+//
+// QgsFloatingWidget
+//
+
+QgsFloatingWidget::QgsFloatingWidget( QWidget *parent )
+    : QWidget( parent )
+    , mAnchorWidget( nullptr )
+    , mParentEventFilter( nullptr )
+    , mAnchorEventFilter( nullptr )
+    , mFloatAnchorPoint( BottomMiddle )
+    , mAnchorWidgetAnchorPoint( TopMiddle )
+{
+  if ( parent )
+  {
+    mParentEventFilter = new QgsFloatingWidgetEventFilter( parent );
+    parent->installEventFilter( mParentEventFilter );
+    connect( mParentEventFilter, SIGNAL( anchorPointChanged() ), this, SLOT( anchorPointChanged() ) );
+  }
+}
+
+void QgsFloatingWidget::setAnchorWidget( QWidget *widget )
+{
+  // remove existing event filter
+  if ( mAnchorWidget )
+  {
+    mAnchorWidget->removeEventFilter( mAnchorEventFilter );
+    delete mAnchorEventFilter;
+    mAnchorEventFilter = nullptr;
+  }
+
+  mAnchorWidget = widget;
+  if ( mAnchorWidget )
+  {
+    mAnchorEventFilter = new QgsFloatingWidgetEventFilter( mAnchorWidget );
+    mAnchorWidget->installEventFilter( mAnchorEventFilter );
+    connect( mAnchorEventFilter, SIGNAL( anchorPointChanged() ), this, SLOT( anchorPointChanged() ) );
+  }
+
+  anchorPointChanged();
+}
+
+QWidget *QgsFloatingWidget::anchorWidget()
+{
+  return mAnchorWidget;
+}
+
+void QgsFloatingWidget::showEvent( QShowEvent *e )
+{
+  anchorPointChanged();
+  QWidget::showEvent( e );
+}
+
+void QgsFloatingWidget::anchorPointChanged()
+{
+  if ( mAnchorWidget )
+  {
+    QPoint anchorWidgetOrigin;
+
+    switch ( mAnchorWidgetAnchorPoint )
+    {
+      case TopLeft:
+        anchorWidgetOrigin = QPoint( 0, 0 );
+        break;
+      case TopMiddle:
+        anchorWidgetOrigin = QPoint( mAnchorWidget->width() / 2, 0 );
+        break;
+      case TopRight:
+        anchorWidgetOrigin = QPoint( mAnchorWidget->width(), 0 );
+        break;
+      case MiddleLeft:
+        anchorWidgetOrigin = QPoint( 0, mAnchorWidget->height() / 2 );
+        break;
+      case Middle:
+        anchorWidgetOrigin = QPoint( mAnchorWidget->width() / 2, mAnchorWidget->height() / 2 );
+        break;
+      case MiddleRight:
+        anchorWidgetOrigin = QPoint( mAnchorWidget->width(), mAnchorWidget->height() / 2 );
+        break;
+      case BottomLeft:
+        anchorWidgetOrigin = QPoint( 0, mAnchorWidget->height() );
+        break;
+      case BottomMiddle:
+        anchorWidgetOrigin = QPoint( mAnchorWidget->width() / 2, mAnchorWidget->height() );
+        break;
+      case BottomRight:
+        anchorWidgetOrigin = QPoint( mAnchorWidget->width(), mAnchorWidget->height() );
+        break;
+    }
+
+    anchorWidgetOrigin = mAnchorWidget->mapTo( parentWidget(), anchorWidgetOrigin );
+    int anchorX = anchorWidgetOrigin.x();
+    int anchorY = anchorWidgetOrigin.y();
+
+    switch ( mFloatAnchorPoint )
+    {
+      case TopLeft:
+        break;
+      case TopMiddle:
+        anchorX = anchorX - width() / 2;
+        break;
+      case TopRight:
+        anchorX = anchorX - width();
+        break;
+      case MiddleLeft:
+        anchorY = anchorY - height() / 2;
+        break;
+      case Middle:
+        anchorY = anchorY - height() / 2;
+        anchorX = anchorX - width() / 2;
+        break;
+      case MiddleRight:
+        anchorX = anchorX - width();
+        anchorY = anchorY - height() / 2;
+        break;
+      case BottomLeft:
+        anchorY = anchorY - height();
+        break;
+      case BottomMiddle:
+        anchorX = anchorX - width() / 2;
+        anchorY = anchorY - height();
+        break;
+      case BottomRight:
+        anchorX = anchorX - width();
+        anchorY = anchorY - height();
+        break;
+    }
+
+    // constrain x so that widget floats within parent widget
+    anchorX = qBound( 0, anchorX, parentWidget()->width() - width() );
+
+    move( anchorX, anchorY );
+  }
+}
+
+//
+// QgsFloatingWidgetEventFilter
+//
+
+/// @cond PRIVATE
+QgsFloatingWidgetEventFilter::QgsFloatingWidgetEventFilter( QWidget *parent )
+    : QObject( parent )
+{
+
+}
+
+bool QgsFloatingWidgetEventFilter::eventFilter( QObject *object, QEvent *event )
+{
+  Q_UNUSED( object );
+  switch ( event->type() )
+  {
+    case QEvent::Move:
+    case QEvent::Resize:
+      emit anchorPointChanged();
+      return true;
+    default:
+      return false;
+  }
+}
+
+///@endcond
diff --git a/src/gui/qgsfloatingwidget.h b/src/gui/qgsfloatingwidget.h
@@ -0,0 +1,130 @@
+/***************************************************************************
+    qgsfloatingwidget.h
+    -------------------
+    begin                : April 2016
+    copyright            : (C) Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+#ifndef QGSFLOATINGWIDGET_H
+#define QGSFLOATINGWIDGET_H
+
+#include <QWidget>
+
+
+/** \ingroup gui
+ * \class QgsFloatingWidget
+ * A QWidget subclass for creating widgets which float outside of the normal Qt layout
+ * system. Floating widgets use an "anchor widget" to determine how they are anchored
+ * within their parent widget.
+ * \note Added in version 2.16
+ */
+
+class GUI_EXPORT QgsFloatingWidget: public QWidget
+{
+    Q_OBJECT
+
+  public:
+
+    //! Reference points for anchoring widget position
+    enum AnchorPoint
+    {
+      TopLeft, //!< Top-left of widget
+      TopMiddle, //!< Top center of widget
+      TopRight, //!< Top-right of widget
+      MiddleLeft, //!< Middle left of widget
+      Middle, //!< Middle of widget
+      MiddleRight, //!< Middle right of widget
+      BottomLeft, //!< Bottom-left of widget
+      BottomMiddle, //!< Bottom center of widget
+      BottomRight, //!< Bottom-right of widget
+    };
+
+    QgsFloatingWidget( QWidget* parent = nullptr );
+
+    /** Sets the widget to "anchor" the floating widget to. The floating widget will be repositioned whenever the
+     * anchor widget moves or is resized so that it maintains the same relative position to the anchor widget.
+     * @param widget anchor widget. Both the floating widget and the anchor widget must share some common parent.
+     * @see anchorWidget()
+     */
+    void setAnchorWidget( QWidget* widget );
+
+    /** Returns the widget that the floating widget is "anchored" tto. The floating widget will be repositioned whenever the
+     * anchor widget moves or is resized so that it maintains the same relative position to the anchor widget.
+     * @see setAnchorWidget()
+     */
+    QWidget* anchorWidget();
+
+    /** Returns the floating widget's anchor point, which corresponds to the point on the widget which should remain
+     * fixed in the same relative position whenever the widget's parent is resized or moved.
+     * @see setAnchorPoint()
+     */
+    AnchorPoint anchorPoint() const { return mFloatAnchorPoint; }
+
+    /** Sets the floating widget's anchor point, which corresponds to the point on the widget which should remain
+     * fixed in the same relative position whenever the widget's parent is resized or moved.
+     * @param point anchor point
+     * @see anchorPoint()
+     */
+    void setAnchorPoint( AnchorPoint point ) { mFloatAnchorPoint = point; anchorPointChanged(); }
+
+    /** Returns the anchor widget's anchor point, which corresponds to the point on the anchor widget which
+     * the floating widget should "attach" to. The floating widget should remain fixed in the same relative position
+     * to this anchor widget whenever the widget's parent is resized or moved.
+     * @see setAnchorWidgetPoint()
+     */
+    AnchorPoint anchorWidgetPoint() const { return mAnchorWidgetAnchorPoint; }
+
+    /** Returns the anchor widget's anchor point, which corresponds to the point on the anchor widget which
+     * the floating widget should "attach" to. The floating widget should remain fixed in the same relative position
+     * to this anchor widget whenever the widget's parent is resized or moved.
+     * @see setAnchorWidgetPoint()
+     */
+    void setAnchorWidgetPoint( AnchorPoint point ) { mAnchorWidgetAnchorPoint = point; anchorPointChanged(); }
+
+  protected:
+    void showEvent( QShowEvent* e ) override;
+
+  private slots:
+
+    //! Repositions the floating widget to a changed anchor point
+    void anchorPointChanged();
+
+  private:
+
+    QWidget* mAnchorWidget;
+    QObject* mParentEventFilter;
+    QObject* mAnchorEventFilter;
+    AnchorPoint mFloatAnchorPoint;
+    AnchorPoint mAnchorWidgetAnchorPoint;
+
+};
+
+/// @cond PRIVATE
+
+class QgsFloatingWidgetEventFilter: public QObject
+{
+    Q_OBJECT
+
+  public:
+
+    QgsFloatingWidgetEventFilter( QWidget* parent = nullptr );
+
+    virtual bool eventFilter( QObject* object, QEvent* event ) override;
+
+  signals:
+
+    //! Emitted when the filter's parent is moved or resized
+    void anchorPointChanged();
+
+};
+
+/// @endcond
+
+#endif // QGSFLOATINGWIDGET_H
diff --git a/tests/src/python/CMakeLists.txt b/tests/src/python/CMakeLists.txt
@@ -49,6 +49,7 @@ ADD_PYTHON_TEST(PyQgsFeatureIterator test_qgsfeatureiterator.py)
 ADD_PYTHON_TEST(PyQgsField test_qgsfield.py)
 ADD_PYTHON_TEST(PyQgsFieldModel test_qgsfieldmodel.py)
 ADD_PYTHON_TEST(PyQgsFilterLineEdit test_qgsfilterlineedit.py)
+ADD_PYTHON_TEST(PyQgsFloatingWidget test_qgsfloatingwidget.py)
 ADD_PYTHON_TEST(PyQgsFontUtils test_qgsfontutils.py)
 ADD_PYTHON_TEST(PyQgsGeometryAvoidIntersections test_qgsgeometry_avoid_intersections.py)
 ADD_PYTHON_TEST(PyQgsGeometryGeneratorSymbolLayer test_qgsgeometrygeneratorsymbollayer.py)