[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;

src/gui/qgsmapcanvas.cpp

@@ -189,6 +189,7 @@ void QgsMapCanvasRendererSync::onLayersC2R()
 QgsMapCanvas::QgsMapCanvas( QWidget * parent, const char *name )
     : QGraphicsView( parent )
     , mCanvasProperties( new CanvasProperties )
+    , mMagnificationFactor( 1.0 )
     , mJob( nullptr )
     , mJobCancelled( false )
     , mLabelingResults( nullptr )
@@ -310,6 +311,16 @@ QgsMapCanvas::~QgsMapCanvas()
 
 } // dtor
 
+void QgsMapCanvas::setMagnificationFactor( double level )
+{
+  QgsRectangle ext = extent();
+  ext.scale( mMagnificationFactor / level );
+
+  mMagnificationFactor = level;
+  mSettings.setExtent( ext );
+  refresh();
+}
+
 void QgsMapCanvas::enableAntiAliasing( bool theFlag )
 {
   mSettings.setFlag( QgsMapSettings::Antialiasing, theFlag );
@@ -678,13 +689,17 @@ void QgsMapCanvas::refreshMap()
 
   mSettings.setExpressionContext( expressionContext );
 
+  // magnify level to use in renderers
+  QgsMapSettings settings = mSettings;
+  settings.setOutputDpi( settings.outputDpi() * mMagnificationFactor );
+
   // create the renderer job
   Q_ASSERT( !mJob );
   mJobCancelled = false;
   if ( mUseParallelRendering )
-    mJob = new QgsMapRendererParallelJob( mSettings );
+    mJob = new QgsMapRendererParallelJob( settings );
   else
-    mJob = new QgsMapRendererSequentialJob( mSettings );
+    mJob = new QgsMapRendererSequentialJob( settings );
   connect( mJob, SIGNAL( finished() ), SLOT( rendererJobFinished() ) );
   mJob->setCache( mCache );
 
@@ -757,7 +772,7 @@ void QgsMapCanvas::rendererJobFinished()
 
     p.end();
 
-    mMap->setContent( img, imageRect( img, mJob->mapSettings() ) );
+    mMap->setContent( img, imageRect( img, mSettings ) );
   }
 
   // now we are in a slot called from mJob - do not delete it immediately
@@ -782,7 +797,7 @@ QgsRectangle QgsMapCanvas::imageRect( const QImage& img, const QgsMapSettings& m
 void QgsMapCanvas::mapUpdateTimeout()
 {
   const QImage& img = mJob->renderedImage();
-  mMap->setContent( img, imageRect( img, mJob->mapSettings() ) );
+  mMap->setContent( img, imageRect( img, mSettings ) );
 }
 
 void QgsMapCanvas::stopRendering()

src/gui/qgsmapcanvas.h

@@ -119,6 +119,15 @@ class GUI_EXPORT QgsMapCanvas : public 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 { return mMagnificationFactor; };
+
     void setLayerSet( QList<QgsMapCanvasLayer>& layers );
 
     void setCurrentLayer( QgsMapLayer* layer );
@@ -722,6 +731,9 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
     //! Timer that periodically fires while map rendering is in progress to update the visible map
     QTimer mMapUpdateTimer;
 
+    //! magnification factor
+    double mMagnificationFactor;
+
     //! Job that takes care of map rendering in background
     QgsMapRendererQImageJob* mJob;
 

src/ui/qgsoptionsbase.ui

@@ -2045,6 +2045,39 @@
                     </layout>
                    </widget>
                   </item>
+                  <item>
+                   <layout class="QHBoxLayout" name="horizontalLayout_5">
+                    <property name="topMargin">
+                     <number>0</number>
+                    </property>
+                    <item>
+                     <widget class="QLabel" name="labelMagnifier">
+                      <property name="text">
+                       <string>Magnification level</string>
+                      </property>
+                     </widget>
+                    </item>
+                    <item>
+                     <widget class="QDoubleSpinBox" name="doubleSpinBoxMagnifierDefault"/>
+                    </item>
+                    <item>
+                     <spacer name="horizontalSpacer_4">
+                      <property name="orientation">
+                       <enum>Qt::Horizontal</enum>
+                      </property>
+                      <property name="sizeType">
+                       <enum>QSizePolicy::Expanding</enum>
+                      </property>
+                      <property name="sizeHint" stdset="0">
+                       <size>
+                        <width>40</width>
+                        <height>20</height>
+                       </size>
+                      </property>
+                     </spacer>
+                    </item>
+                   </layout>
+                  </item>
                  </layout>
                 </widget>
                </item>

tests/src/gui/testqgsmapcanvas.cpp

@@ -17,7 +17,10 @@
 
 #include <qgsapplication.h>
 #include <qgsmapcanvas.h>
+#include <qgsvectorlayer.h>
 #include <qgsmaprenderer.h>
+#include <qgsmaplayerregistry.h>
+#include <qgsrenderchecker.h>
 
 namespace QTest
 {
@@ -43,6 +46,7 @@ class TestQgsMapCanvas : public QObject
 
     void testMapRendererInteraction();
     void testPanByKeyboard();
+    void testMagnification();
 
   private:
     QgsMapCanvas* mCanvas;
@@ -53,6 +57,7 @@ class TestQgsMapCanvas : public QObject
 void TestQgsMapCanvas::initTestCase()
 {
   QgsApplication::init(); // init paths for CRS lookup
+  QgsApplication::initQgis();
 
   mCanvas = new QgsMapCanvas();
 }
@@ -154,6 +159,79 @@ void TestQgsMapCanvas::testPanByKeyboard()
   }
 }
 
+void TestQgsMapCanvas::testMagnification()
+{
+  // test directory
+  QString testDataDir = QString( TEST_DATA_DIR ) + '/';
+  QString controlImageDir = testDataDir + "control_images/expected_map_magnification/";
+
+  // prepare spy and unit testing stuff
+  QgsRenderChecker checker;
+  checker.setControlPathPrefix( "mapcanvas" );
+  checker.setColorTolerance( 5 );
+
+  QSignalSpy spy( mCanvas, SIGNAL( mapCanvasRefreshed() ) );
+
+  QEventLoop loop;
+  QObject::connect( mCanvas, SIGNAL( mapCanvasRefreshed() ), &loop, SLOT( quit() ) );
+
+  QTimer timer;
+  QObject::connect( &timer, SIGNAL( timeout() ), &loop, SLOT( quit() ) );
+
+  QTemporaryFile tmpFile;
+  tmpFile.setAutoRemove( false );
+  tmpFile.open(); // fileName is not available until open
+  QString tmpName = tmpFile.fileName();
+  tmpFile.close();
+
+  // build vector layer
+  QString myPointsFileName = testDataDir + "points.shp";
+  QFileInfo myPointFileInfo( myPointsFileName );
+  QgsVectorLayer *layer = new QgsVectorLayer( myPointFileInfo.filePath(),
+      myPointFileInfo.completeBaseName(), "ogr" );
+
+  // prepare map canvas
+  QList<QgsMapCanvasLayer> layers;
+  layers.append( layer );
+  mCanvas->setLayerSet( layers );
+  QgsMapLayerRegistry::instance()->addMapLayers( QList<QgsMapLayer *>() << layer );
+
+  mCanvas->setExtent( layer->extent() );
+
+  // refresh and wait for rendering
+  mCanvas->refresh();
+  timer.start( 3000 );
+  loop.exec();
+  QCOMPARE( spy.count(), 1 );
+  spy.clear();
+
+  // control image with magnification factor 1.0
+  mCanvas->saveAsImage( tmpName );
+
+  checker.setControlName( "expected_map_magnification" );
+  checker.setRenderedImage( tmpName );
+  checker.setSizeTolerance( 2, 2 );
+  QCOMPARE( checker.compareImages( "map_magnification", 100 ), true );
+
+  // set magnification factor (auto refresh)
+  mCanvas->setMagnificationFactor( 6.5 );
+  QCOMPARE( mCanvas->magnificationFactor(), 6.5 );
+
+  // wait for rendering
+  timer.start( 3000 );
+  loop.exec();
+  QCOMPARE( spy.count(), 1 );
+  spy.clear();
+
+  // control image with magnification factor 6.5
+  mCanvas->saveAsImage( tmpName );
+
+  checker.setRenderedImage( tmpName );
+  checker.setControlName( "expected_map_magnification_6_5" );
+  controlImageDir = testDataDir + "control_images/";
+  checker.setSizeTolerance( 2, 2 );
+  QCOMPARE( checker.compareImages( "map_magnification_6_5", 100 ), true );
+}
 
 QTEST_MAIN( TestQgsMapCanvas )
 #include "testqgsmapcanvas.moc"