[FEATURE] Draw extent onto canvas in save as image/PDF dialog (#4878)

python/gui/gui_auto.sip

@@ -137,6 +137,7 @@
 %Include qgsmaptoolcapture.sip
 %Include qgsmaptooledit.sip
 %Include qgsmaptoolemitpoint.sip
+%Include qgsmaptoolextent.sip
 %Include qgsmaptoolidentify.sip
 %Include qgsmaptoolidentifyfeature.sip
 %Include qgsmaptoolpan.sip

python/gui/qgsextentgroupbox.sip

@@ -10,6 +10,8 @@
 
 
 
+
+
 class QgsExtentGroupBox : QgsCollapsibleGroupBox
 {
 %Docstring
@@ -34,6 +36,7 @@ class QgsExtentGroupBox : QgsCollapsibleGroupBox
       CurrentExtent,
       UserExtent,
       ProjectLayerExtent,
+      DrawOnCanvas,
     };
 
     explicit QgsExtentGroupBox( QWidget *parent /TransferThis/ = 0 );
@@ -124,6 +127,13 @@ class QgsExtentGroupBox : QgsCollapsibleGroupBox
  :rtype: str
 %End
 
+    void setMapCanvas( QgsMapCanvas *canvas );
+%Docstring
+ Sets the map canvas to enable dragging of extent on a canvas.
+ \param canvas the map canvas
+.. versionadded:: 3.0
+%End
+
   public slots:
 
     void setOutputExtentFromOriginal();
@@ -145,6 +155,12 @@ class QgsExtentGroupBox : QgsCollapsibleGroupBox
 %Docstring
  Sets the output extent to match a ``layer``'s extent (may be transformed to output CRS).
 .. versionadded:: 3.0
+%End
+
+    void setOutputExtentFromDrawOnCanvas();
+%Docstring
+ Sets the output extent by dragging on the canvas.
+.. versionadded:: 3.0
 %End
 
   signals:

python/gui/qgsmaptoolextent.sip

@@ -0,0 +1,75 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/gui/qgsmaptoolextent.h                                           *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+
+
+
+class QgsMapToolExtent : QgsMapTool
+{
+%Docstring
+ A map tool that emits an extent from a rectangle drawn onto the map canvas.
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgsmaptoolextent.h"
+%End
+  public:
+
+    QgsMapToolExtent( QgsMapCanvas *canvas );
+%Docstring
+constructor
+%End
+
+    virtual Flags flags() const;
+    virtual void canvasMoveEvent( QgsMapMouseEvent *e );
+    virtual void canvasPressEvent( QgsMapMouseEvent *e );
+    virtual void canvasReleaseEvent( QgsMapMouseEvent *e );
+    virtual void activate();
+    virtual void deactivate();
+
+    void setRatio( QSize ratio );
+%Docstring
+ Sets a fixed aspect ratio to be used when dragging extent onto the canvas.
+ To unset a fixed aspect ratio, set the width and height to zero.
+ \param ratio aspect ratio's width and height
+ *
+%End
+
+    QSize ratio() const;
+%Docstring
+ Returns the current fixed aspect ratio to be used when dragging extent onto the canvas.
+ If the aspect ratio isn't fixed, the width and height will be set to zero.
+ *
+ :rtype: QSize
+%End
+
+    QgsRectangle extent() const;
+%Docstring
+ Returns the current extent drawn onto the canvas.
+ :rtype: QgsRectangle
+%End
+
+  signals:
+
+    void extentChanged( const QgsRectangle &extent );
+%Docstring
+signal emitted on extent change
+%End
+
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/gui/qgsmaptoolextent.h                                           *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/

src/app/qgsmapsavedialog.cpp

@@ -59,6 +59,7 @@ QgsMapSaveDialog::QgsMapSaveDialog( QWidget *parent, QgsMapCanvas *mapCanvas, QL
   mExtentGroupBox->setOutputCrs( ms.destinationCrs() );
   mExtentGroupBox->setCurrentExtent( mExtent, ms.destinationCrs() );
   mExtentGroupBox->setOutputExtentFromCurrent();
+  mExtentGroupBox->setMapCanvas( mapCanvas );
 
   mScaleWidget->setScale( ms.scale() );
   mScaleWidget->setMapCanvas( mMapCanvas );

src/gui/CMakeLists.txt

@@ -283,6 +283,7 @@ SET(QGIS_GUI_SRCS
   qgsmaptoolcapture.cpp
   qgsmaptooledit.cpp
   qgsmaptoolemitpoint.cpp
+  qgsmaptoolextent.cpp
   qgsmaptoolidentify.cpp
   qgsmaptoolidentifyfeature.cpp
   qgsmaptoolpan.cpp
@@ -437,6 +438,7 @@ SET(QGIS_GUI_MOC_HDRS
   qgsmaptoolcapture.h
   qgsmaptooledit.h
   qgsmaptoolemitpoint.h
+  qgsmaptoolextent.h
   qgsmaptoolidentify.h
   qgsmaptoolidentifyfeature.h
   qgsmaptoolpan.h

src/gui/qgsextentgroupbox.cpp

@@ -12,13 +12,17 @@
  *   (at your option) any later version.                                   *
  *                                                                         *
  ***************************************************************************/
+
 #include "qgsextentgroupbox.h"
 
+#include "qgslogger.h"
 #include "qgscoordinatetransform.h"
 #include "qgsrasterblock.h"
+#include "qgsmapcanvas.h"
 #include "qgsmaplayermodel.h"
 #include "qgsexception.h"
 #include "qgsproject.h"
+
 #include <QMenu>
 #include <QAction>
 
@@ -40,13 +44,15 @@ QgsExtentGroupBox::QgsExtentGroupBox( QWidget *parent )
   mYMaxLineEdit->setValidator( new QDoubleValidator( this ) );
 
   mOriginalExtentButton->setVisible( false );
+  mButtonDrawOnCanvas->setVisible( false );
 
   connect( mCurrentExtentButton, &QAbstractButton::clicked, this, &QgsExtentGroupBox::setOutputExtentFromCurrent );
   connect( mOriginalExtentButton, &QAbstractButton::clicked, this, &QgsExtentGroupBox::setOutputExtentFromOriginal );
+  connect( mButtonDrawOnCanvas, &QAbstractButton::clicked, this, &QgsExtentGroupBox::setOutputExtentFromDrawOnCanvas );
+
   connect( this, &QGroupBox::clicked, this, &QgsExtentGroupBox::groupBoxClicked );
 }
 
-
 void QgsExtentGroupBox::setOriginalExtent( const QgsRectangle &originalExtent, const QgsCoordinateReferenceSystem &originalCrs )
 {
   mOriginalExtent = originalExtent;
@@ -83,6 +89,11 @@ void QgsExtentGroupBox::setOutputCrs( const QgsCoordinateReferenceSystem &output
         setOutputExtentFromLayer( mExtentLayer.data() );
         break;
 
+      case DrawOnCanvas:
+        mOutputCrs = outputCrs;
+        extentDrawn( outputExtent() );
+        break;
+
       case UserExtent:
         try
         {
@@ -167,6 +178,9 @@ void QgsExtentGroupBox::updateTitle()
     case ProjectLayerExtent:
       msg = mExtentLayerName;
       break;
+    case DrawOnCanvas:
+      msg = tr( "drawn on canvas" );
+      break;
   }
   if ( isCheckable() && !isChecked() )
     msg = tr( "none" );
@@ -213,7 +227,17 @@ void QgsExtentGroupBox::setExtentToLayerExtent( const QString &layerId )
 
 void QgsExtentGroupBox::setOutputExtentFromCurrent()
 {
-  setOutputExtent( mCurrentExtent, mCurrentCrs, CurrentExtent );
+  if ( mCanvas )
+  {
+    // Use unrotated visible extent to insure output size and scale matches canvas
+    QgsMapSettings ms = mCanvas->mapSettings();
+    ms.setRotation( 0 );
+    setOutputExtent( ms.visibleExtent(), ms.destinationCrs(), CurrentExtent );
+  }
+  else
+  {
+    setOutputExtent( mCurrentExtent, mCurrentCrs, CurrentExtent );
+  }
 }
 
 
@@ -238,6 +262,34 @@ void QgsExtentGroupBox::setOutputExtentFromLayer( const QgsMapLayer *layer )
   setOutputExtent( layer->extent(), layer->crs(), ProjectLayerExtent );
 }
 
+void QgsExtentGroupBox::setOutputExtentFromDrawOnCanvas()
+{
+  if ( mCanvas )
+  {
+    mMapToolPrevious = mCanvas->mapTool();
+    if ( !mMapToolExtent )
+    {
+      mMapToolExtent.reset( new QgsMapToolExtent( mCanvas ) );
+      connect( mMapToolExtent.get(), &QgsMapToolExtent::extentChanged, this, &QgsExtentGroupBox::extentDrawn );
+      connect( mMapToolExtent.get(), &QgsMapTool::deactivated, this, [ = ]
+      {
+        window()->setVisible( true );
+        mMapToolPrevious = nullptr;
+      } );
+    }
+    mCanvas->setMapTool( mMapToolExtent.get() );
+    window()->setVisible( false );
+  }
+}
+
+void QgsExtentGroupBox::extentDrawn( const QgsRectangle &extent )
+{
+  setOutputExtent( extent, mCanvas->mapSettings().destinationCrs(), DrawOnCanvas );
+  mCanvas->setMapTool( mMapToolPrevious );
+  window()->setVisible( true );
+  mMapToolPrevious = nullptr;
+}
+
 void QgsExtentGroupBox::groupBoxClicked()
 {
   if ( !isCheckable() )
@@ -269,3 +321,16 @@ QString QgsExtentGroupBox::titleBase() const
 {
   return mTitleBase;
 }
+
+void QgsExtentGroupBox::setMapCanvas( QgsMapCanvas *canvas )
+{
+  if ( canvas )
+  {
+    mCanvas = canvas;
+    mButtonDrawOnCanvas->setVisible( true );
+  }
+  else
+  {
+    mButtonDrawOnCanvas->setVisible( false );
+  }
+}

src/gui/qgsextentgroupbox.h

@@ -12,10 +12,13 @@
  *   (at your option) any later version.                                   *
  *                                                                         *
  ***************************************************************************/
+
 #ifndef QGSEXTENTGROUPBOX_H
 #define QGSEXTENTGROUPBOX_H
 
 #include "qgscollapsiblegroupbox.h"
+#include "qgsmaptool.h"
+#include "qgsmaptoolextent.h"
 #include "qgis.h"
 
 #include "ui_qgsextentgroupboxwidget.h"
@@ -24,6 +27,8 @@
 #include "qgsrectangle.h"
 #include "qgis_gui.h"
 
+#include <memory>
+
 class QgsCoordinateReferenceSystem;
 class QgsMapLayerModel;
 class QgsMapLayer;
@@ -52,6 +57,7 @@ class GUI_EXPORT QgsExtentGroupBox : public QgsCollapsibleGroupBox, private Ui::
       CurrentExtent,   //!< Map canvas extent
       UserExtent,      //!< Extent manually entered/modified by the user
       ProjectLayerExtent, //!< Extent taken from a layer within the project
+      DrawOnCanvas, //!< Extent taken from a rectangled drawn onto the map canvas
     };
 
     /**
@@ -135,6 +141,13 @@ class GUI_EXPORT QgsExtentGroupBox : public QgsCollapsibleGroupBox, private Ui::
      */
     QString titleBase() const;
 
+    /**
+     * Sets the map canvas to enable dragging of extent on a canvas.
+     * \param canvas the map canvas
+     * \since QGIS 3.0
+     */
+    void setMapCanvas( QgsMapCanvas *canvas );
+
   public slots:
 
     /**
@@ -158,6 +171,12 @@ class GUI_EXPORT QgsExtentGroupBox : public QgsCollapsibleGroupBox, private Ui::
      */
     void setOutputExtentFromLayer( const QgsMapLayer *layer );
 
+    /**
+     * Sets the output extent by dragging on the canvas.
+     * \since QGIS 3.0
+     */
+    void setOutputExtentFromDrawOnCanvas();
+
   signals:
 
     /**
@@ -175,6 +194,8 @@ class GUI_EXPORT QgsExtentGroupBox : public QgsCollapsibleGroupBox, private Ui::
     void groupBoxClicked();
     void layerMenuAboutToShow();
 
+    void extentDrawn( const QgsRectangle &extent );
+
   private:
     void setOutputExtent( const QgsRectangle &r, const QgsCoordinateReferenceSystem &srcCrs, QgsExtentGroupBox::ExtentState state );
     void setOutputExtentFromLineEdit();
@@ -199,6 +220,10 @@ class GUI_EXPORT QgsExtentGroupBox : public QgsCollapsibleGroupBox, private Ui::
     QPointer< const QgsMapLayer > mExtentLayer;
     QString mExtentLayerName;
 
+    std::unique_ptr< QgsMapToolExtent > mMapToolExtent;
+    QPointer< QgsMapTool > mMapToolPrevious = nullptr;
+    QgsMapCanvas *mCanvas = nullptr;
+
     void setExtentToLayerExtent( const QString &layerId );
 
 };