[FEATURE] add a map canvas magnifier

python/gui/editorwidgets/qgsdoublespinbox.sip

@@ -14,6 +14,12 @@ class QgsDoubleSpinBox : QDoubleSpinBox
 
     explicit QgsDoubleSpinBox( QWidget *parent /TransferThis/ = 0 );
 
+    /** Sets background color of QLineEdit widget within spin box
+      * @param color the background color
+      * @note added in QGIS 2.16
+      */
+    void setBackgroundColor( const QColor *color = nullptr );
+
     //! determines if the widget will show a clear button
     //! @note the clear button will set the widget to its minimum value
     void setShowClearButton( const bool showClearButton );

python/gui/qgsmapcanvas.sip

@@ -50,6 +50,15 @@ class QgsMapCanvas : QGraphicsView
     //! Destructor
     ~QgsMapCanvas();
 
+    //! Sets the factor of magnification to apply to the map canvas. Indeed, we
+    //! increase/decrease the DPI of the map settings according to this factor
+    //! in order to render marker point, labels, ... bigger.
+    //! @note added in 2.16
+    void setMagnificationFactor( double level );
+
+    //! Returns the magnification factor
+    double magnificationFactor() const;
+
     void setLayerSet( QList<QgsMapCanvasLayer>& layers );
 
     void setCurrentLayer( QgsMapLayer* layer );

src/app/CMakeLists.txt

@@ -51,6 +51,7 @@ SET(QGIS_APP_SRCS
   qgsrulebasedlabelingwidget.cpp
   qgssavestyletodbdialog.cpp
   qgsstatusbarcoordinateswidget.cpp
+  qgsstatusbarmagnifierwidget.cpp
   qgsversioninfo.cpp
   qgswelcomepageitemsmodel.cpp
   qgswelcomepage.cpp
@@ -226,6 +227,7 @@ SET (QGIS_APP_MOC_HDRS
   qgssavestyletodbdialog.h
   qgsshortcutsmanager.h
   qgsstatusbarcoordinateswidget.h
+  qgsstatusbarmagnifierwidget.h
   qgsversioninfo.h
   qgswelcomepageitemsmodel.h
   qgswelcomepage.h

src/app/qgisapp.cpp

@@ -123,6 +123,7 @@
 #include "qgscomposermanager.h"
 #include "qgscomposerview.h"
 #include "qgsstatusbarcoordinateswidget.h"
+#include "qgsstatusbarmagnifierwidget.h"
 #include "qgsconfigureshortcutsdialog.h"
 #include "qgscoordinatetransform.h"
 #include "qgscoordinateutils.h"
@@ -544,6 +545,7 @@ QgisApp::QgisApp( QSplashScreen *splash, bool restorePlugins, bool skipVersionCh
     , mScaleLabel( nullptr )
     , mScaleEdit( nullptr )
     , mScaleEditValidator( nullptr )
+    , mMagnifierWidget( nullptr )
     , mCoordsEdit( nullptr )
     , mRotationLabel( nullptr )
     , mRotationEdit( nullptr )
@@ -997,6 +999,7 @@ QgisApp::QgisApp()
     , mScaleLabel( nullptr )
     , mScaleEdit( nullptr )
     , mScaleEditValidator( nullptr )
+    , mMagnifierWidget( nullptr )
     , mCoordsEdit( nullptr )
     , mRotationLabel( nullptr )
     , mRotationEdit( nullptr )
@@ -2095,6 +2098,13 @@ void QgisApp::createStatusBar()
   statusBar()->addPermanentWidget( mScaleEdit, 0 );
   connect( mScaleEdit, SIGNAL( scaleChanged( double ) ), this, SLOT( userScale() ) );
 
+  // zoom widget
+  QSettings mySettings;
+  mMagnifierWidget = new QgsStatusBarMagnifierWidget( statusBar(), mMapCanvas );
+  mMagnifierWidget->setFont( myFont );
+  mMagnifierWidget->setMagnificationLevel( mySettings.value( "/qgis/magnifier_level", 100 ).toInt() );
+  statusBar()->addPermanentWidget( mMagnifierWidget, 0 );
+
   if ( QgsMapCanvas::rotationEnabled() )
   {
     // add a widget to show/set current rotation
@@ -8478,6 +8488,8 @@ void QgisApp::showOptionsDialog( QWidget *parent, const QString& currentPage )
         layer->setLayerName( layer->originalName() );
     }
 
+    mMagnifierWidget->setMagnificationLevel( mySettings.value( "/qgis/magnifier_level" ).toInt() );
+
     //update any open compositions so they reflect new composer settings
     //we have to push the changes to the compositions here, because compositions
     //have no access to qgisapp and accordingly can't listen in to changes

src/app/qgisapp.h

@@ -45,6 +45,7 @@ class QgsComposer;
 class QgsComposerManager;
 class QgsComposerView;
 class QgsStatusBarCoordinatesWidget;
+class QgsStatusBarMagnifierWidget;
 class QgsContrastEnhancement;
 class QgsCustomLayerOrderWidget;
 class QgsDoubleSpinBox;
@@ -1591,6 +1592,9 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
     //! The validator for the mScaleEdit
     QValidator * mScaleEditValidator;
 
+    //! zoom widget
+    QgsStatusBarMagnifierWidget *mMagnifierWidget;
+
     //! Widget that will live in the statusbar to display and edit coords
     QgsStatusBarCoordinatesWidget *mCoordsEdit;
 

src/app/qgsoptions.cpp

@@ -589,6 +589,13 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WindowFlags fl )
   mSimplifyMaximumScaleComboBox->updateScales( myScalesList );
   mSimplifyMaximumScaleComboBox->setScale( 1.0 / mSettings->value( "/qgis/simplifyMaxScale", 1 ).toFloat() );
 
+  // Magnifier
+  doubleSpinBoxMagnifierDefault->setRange( 100, 1000 );
+  doubleSpinBoxMagnifierDefault->setSingleStep( 50 );
+  doubleSpinBoxMagnifierDefault->setDecimals( 0 );
+  doubleSpinBoxMagnifierDefault->setSuffix( "%" );
+  doubleSpinBoxMagnifierDefault->setValue( mSettings->value( "/qgis/magnifier_level", 100 ).toInt() );
+
   // Slightly awkard here at the settings value is true to use QImage,
   // but the checkbox is true to use QPixmap
   chkAddedVisibility->setChecked( mSettings->value( "/qgis/new_layers_visible", true ).toBool() );
@@ -1194,6 +1201,9 @@ void QgsOptions::saveOptions()
   mSettings->setValue( "/qgis/simplifyLocal", !mSimplifyDrawingAtProvider->isChecked() );
   mSettings->setValue( "/qgis/simplifyMaxScale", 1.0 / mSimplifyMaximumScaleComboBox->scale() );
 
+  // magnification
+  mSettings->setValue( "/qgis/magnifier_level", doubleSpinBoxMagnifierDefault->value() );
+
   // project
   mSettings->setValue( "/qgis/projOpenAtLaunch", mProjectOnLaunchCmbBx->currentIndex() );
   mSettings->setValue( "/qgis/projOpenAtLaunchPath", mProjectOnLaunchLineEdit->text() );

src/app/qgsstatusbarmagnifierwidget.cpp

@@ -0,0 +1,114 @@
+/***************************************************************************
+                         qgsstatusbarmagnifierwidget.cpp
+    begin                : April 2016
+    copyright            : (C) 2016 Paul Blottiere, Oslandia
+    email                : paul dot blottiere at oslandia 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 <QFont>
+#include <QHBoxLayout>
+#include <QLabel>
+
+#include <qgsapplication.h>
+#include "qgsstatusbarmagnifierwidget.h"
+#include "qgsmapcanvas.h"
+#include "qgsdoublespinbox.h"
+
+QgsStatusBarMagnifierWidget::QgsStatusBarMagnifierWidget( QWidget* parent,
+    QgsMapCanvas *canvas ) :
+    QWidget( parent ),
+    mCanvas( canvas ),
+    mMagnifier( 100 ),
+    mMagnifierMin( 100 ),
+    mMagnifierMax( 1000 )
+{
+  // label
+  mLabel = new QLabel( this );
+  mLabel->setMinimumWidth( 10 );
+  mLabel->setMargin( 3 );
+  mLabel->setAlignment( Qt::AlignCenter );
+  mLabel->setFrameStyle( QFrame::NoFrame );
+  mLabel->setText( tr( "Magnifier" ) );
+  mLabel->setToolTip( tr( "Magnifier" ) );
+
+  mSpinBox = new QgsDoubleSpinBox( this );
+  mSpinBox->setSuffix( "%" );
+  mSpinBox->setClearValue( mMagnifierMin );
+  mSpinBox->setKeyboardTracking( false );
+  mSpinBox->setMaximumWidth( 120 );
+  mSpinBox->setDecimals( 0 );
+  mSpinBox->setRange( mMagnifierMin, mMagnifierMax );
+  mSpinBox->setWrapping( false );
+  mSpinBox->setSingleStep( 50 );
+  mSpinBox->setToolTip( tr( "Magnifier level" ) );
+
+  connect( mSpinBox, SIGNAL( valueChanged( double ) ), this,
+           SLOT( updateMagnifier() ) );
+
+  // layout
+  mLayout = new QHBoxLayout( this );
+  mLayout->addWidget( mLabel );
+  mLayout->addWidget( mSpinBox );
+  mLayout->setContentsMargins( 0, 0, 0, 0 );
+  mLayout->setAlignment( Qt::AlignRight );
+  mLayout->setSpacing( 0 );
+
+  setLayout( mLayout );
+
+  updateMagnifier();
+}
+
+QgsStatusBarMagnifierWidget::~QgsStatusBarMagnifierWidget()
+{
+}
+
+double QgsStatusBarMagnifierWidget::magnificationLevel()
+{
+  return mMagnifier;
+}
+
+void QgsStatusBarMagnifierWidget::setFont( const QFont& myFont )
+{
+  mLabel->setFont( myFont );
+  mSpinBox->setFont( myFont );
+}
+
+bool QgsStatusBarMagnifierWidget::setMagnificationLevel( int level )
+{
+  bool rc = false;
+
+  if ( level >= mMagnifierMin && level <= mMagnifierMax )
+  {
+    mSpinBox->setValue( level );
+    rc = true;
+  }
+
+  return rc;
+}
+
+void QgsStatusBarMagnifierWidget::updateMagnifier()
+{
+  // get current data
+  mMagnifier = mSpinBox->value();
+
+  // update background color
+  QSettings mySettings;
+  int value = mySettings.value( "/qgis/magnifier_level", 100 ).toInt();
+
+  if ( mMagnifier == value )
+    mSpinBox->setBackgroundColor();
+  else
+    mSpinBox->setBackgroundColor( new QColor( 200, 200, 255 ) );
+
+  // update map canvas
+  mCanvas->setMagnificationFactor( mMagnifier / double( mMagnifierMin ) );
+}

src/app/qgsstatusbarmagnifierwidget.h

@@ -0,0 +1,78 @@
+/***************************************************************************
+                         qgsstatusbarmagnifierwidget.h
+    begin                : April 2016
+    copyright            : (C) 2016 Paul Blottiere, Oslandia
+    email                : paul dot blottiere at oslandia 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 QGSSTATUSBARMAGNIFIERWIDGET_H
+#define QGSSTATUSBARMAGNIFIERWIDGET_H
+
+class QLabel;
+class QFont;
+class QHBoxLayout;
+class QgsMapCanvas;
+class QgsDoubleSpinBox;
+
+#include <QWidget>
+
+/**
+  * A widget which lets the user select the current level of magnification to
+  * apply to the canvas.
+  * @note added in 2.16
+  */
+class APP_EXPORT QgsStatusBarMagnifierWidget : public QWidget
+{
+    Q_OBJECT
+
+  public:
+
+    /** Constructor
+      * @param parent is the parent widget
+      * @param canvas the map canvas
+      */
+    QgsStatusBarMagnifierWidget( QWidget* parent, QgsMapCanvas *canvas );
+
+    /** Destructor */
+    virtual ~QgsStatusBarMagnifierWidget();
+
+    /** Set the font of the text
+      * @param font the font to use
+      */
+    void setFont( const QFont& font );
+
+    /** Returns the current magnification level
+      * @return magnification level
+      */
+    double magnificationLevel();
+
+    /** Set the magnification level
+      * @param level the magnification level
+      * @return true if the level is valid, false otherwise
+      */
+    bool setMagnificationLevel( int level );
+
+  private slots:
+
+    void updateMagnifier();
+
+  private:
+    QgsMapCanvas *mCanvas;
+    QHBoxLayout *mLayout;
+    QLabel *mLabel;
+    QgsDoubleSpinBox *mSpinBox;
+    int mMagnifier;
+    int mMagnifierMin;
+    int mMagnifierMax;
+};
+
+#endif

src/core/qgsmapsettings.h

@@ -283,7 +283,6 @@ class CORE_EXPORT QgsMapSettings
     double mMapUnitsPerPixel;
     double mScale;
 
-
     // utiity stuff
     QgsScaleCalculator mScaleCalculator;
     QgsMapToPixel mMapToPixel;

src/gui/editorwidgets/qgsdoublespinbox.cpp

@@ -46,6 +46,19 @@ QgsDoubleSpinBox::QgsDoubleSpinBox( QWidget *parent )
   connect( this, SIGNAL( valueChanged( double ) ), this, SLOT( changed( double ) ) );
 }
 
+void QgsDoubleSpinBox::setBackgroundColor( const QColor *c )
+{
+  if ( c )
+  {
+    QString rgb = QString( "rgb(%1, %2, %3)" ).arg( c->red() ).arg( c->green() ).arg( c->blue() );
+    this->lineEdit()->setStyleSheet( QString( "background-color: %1" ).arg( rgb ) );
+  }
+  else
+    this->lineEdit()->setStyleSheet( "" );
+
+  this->setStyleSheet( "" );
+}
+
 void QgsDoubleSpinBox::setShowClearButton( const bool showClearButton )
 {
   mShowClearButton = showClearButton;

src/gui/editorwidgets/qgsdoublespinbox.h

@@ -40,6 +40,12 @@ class GUI_EXPORT QgsDoubleSpinBox : public QDoubleSpinBox
 
     explicit QgsDoubleSpinBox( QWidget *parent = nullptr );
 
+    /** Sets background color of QLineEdit widget within spin box
+      * @param color the background color
+      * @note added in QGIS 2.16
+      */
+    void setBackgroundColor( const QColor *color = nullptr );
+
     //! determines if the widget will show a clear button
     //! @note the clear button will set the widget to its minimum value
     void setShowClearButton( const bool showClearButton );
@@ -80,10 +86,11 @@ class GUI_EXPORT QgsDoubleSpinBox : public QDoubleSpinBox
     virtual double valueFromText( const QString & text ) const override;
     virtual QValidator::State validate( QString & input, int & pos ) const override;
 
+    void paintEvent( QPaintEvent* e ) override;
+
   protected:
     virtual void resizeEvent( QResizeEvent* event ) override;
     virtual void changeEvent( QEvent* event ) override;
-    virtual void paintEvent( QPaintEvent* event ) override;
 
   private slots:
     void changed( double value );
@@ -92,6 +99,8 @@ class GUI_EXPORT QgsDoubleSpinBox : public QDoubleSpinBox
     int frameWidth() const;
     bool shouldShowClearForValue( const double value ) const;
 
+    void updateStyleSheet( const QColor& backgroundColor = QColor() );
+
     bool mShowClearButton;
     ClearValueMode mClearValueMode;
     double mCustomClearValue;