Port elevation canvas away from QDesktopWidget

python/gui/auto_generated/qgscompoundcolorwidget.sip.in

@@ -9,6 +9,7 @@
 
 
 
+
 class QgsCompoundColorWidget : QgsPanelWidget
 {
 %Docstring(signature="appended")

python/gui/auto_generated/qgsscreenhelper.sip.in

@@ -42,6 +42,13 @@ Returns the window handle for the window the parent widget is associated with, o
 Returns the current screen DPI for the screen that the parent widget appears on.
 
 .. seealso:: :py:func:`screenDpiChanged`
+%End
+
+    double logicalDpi() const;
+%Docstring
+Returns the current logical DPI for the screen that the parent widget appears on.
+
+.. seealso:: :py:func:`logicalDpiChanged`
 %End
 
     QRect availableGeometry() const;
@@ -60,6 +67,13 @@ The available geometry is the geometry excluding window manager reserved areas s
 Emitted whenever the screen ``dpi`` associated with the widget is changed.
 
 .. seealso:: :py:func:`screenDpi`
+%End
+
+    void logicalDpiChanged( double dpi );
+%Docstring
+Emitted whenever the logical ``dpi`` associated with the widget is changed.
+
+.. seealso:: :py:func:`logicalDpi`
 %End
 
     void availableGeometryChanged( const QRect &geometry );

src/gui/elevation/qgselevationprofilecanvas.cpp

@@ -35,10 +35,10 @@
 #include "qgsprofilesnapping.h"
 #include "qgsmaplayerelevationproperties.h"
 #include "qgsapplication.h"
+#include "qgsscreenhelper.h"
 
 #include <QWheelEvent>
 #include <QTimer>
-#include <QDesktopWidget>
 
 ///@cond PRIVATE
 class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
@@ -323,6 +323,8 @@ class QgsElevationProfileCrossHairsItem : public QgsPlotCanvasItem
 QgsElevationProfileCanvas::QgsElevationProfileCanvas( QWidget *parent )
   : QgsPlotCanvas( parent )
 {
+  mScreenHelper = new QgsScreenHelper( this );
+
   mPlotItem = new QgsElevationProfilePlotItem( this );
   mCrossHairsItem = new QgsElevationProfileCrossHairsItem( this, mPlotItem );
   mCrossHairsItem->setZValue( 100 );
@@ -681,7 +683,7 @@ void QgsElevationProfileCanvas::refresh()
   connect( mCurrentJob, &QgsProfilePlotRenderer::generationFinished, this, &QgsElevationProfileCanvas::generationFinished );
 
   QgsProfileGenerationContext generationContext;
-  generationContext.setDpi( QgsApplication::desktop()->logicalDpiX() );
+  generationContext.setDpi( mScreenHelper->logicalDpi() );
   generationContext.setMaximumErrorMapUnits( MAX_ERROR_PIXELS * ( mProfileCurve->length() ) / mPlotItem->plotArea().width() );
   generationContext.setMapUnitsPerDistancePixel( mProfileCurve->length() / mPlotItem->plotArea().width() );
   mCurrentJob->setContext( generationContext );
@@ -824,7 +826,7 @@ void QgsElevationProfileCanvas::refineResults()
   if ( mCurrentJob )
   {
     QgsProfileGenerationContext context;
-    context.setDpi( QgsApplication::desktop()->logicalDpiX() );
+    context.setDpi( mScreenHelper->logicalDpi() );
     const double plotDistanceRange = mPlotItem->xMaximum() - mPlotItem->xMinimum();
     const double plotElevationRange = mPlotItem->yMaximum() - mPlotItem->yMinimum();
     const double plotDistanceUnitsPerPixel = plotDistanceRange / mPlotItem->plotArea().width();

src/gui/elevation/qgselevationprofilecanvas.h

@@ -35,6 +35,7 @@ class Qgs2DPlot;
 class QgsProfileSnapContext;
 class QgsProfileIdentifyContext;
 class QgsProfileIdentifyResults;
+class QgsScreenHelper;
 
 /**
  * \ingroup gui
@@ -273,6 +274,8 @@ class GUI_EXPORT QgsElevationProfileCanvas : public QgsPlotCanvas
 
     void setupLayerConnections( QgsMapLayer *layer, bool isDisconnect );
 
+    QgsScreenHelper *mScreenHelper = nullptr;
+
     QgsCoordinateReferenceSystem mCrs;
     QgsProject *mProject = nullptr;
 

src/gui/qgsscreenhelper.cpp

@@ -55,6 +55,7 @@ bool QgsScreenHelper::eventFilter( QObject *watched, QEvent *event )
     case QEvent::Show:
     {
       updateDevicePixelFromScreen();
+      updateLogicalDpiFromScreen();
       updateAvailableGeometryFromScreen();
 
       // keep device pixel ratio up to date on screen or resolution change
@@ -63,6 +64,7 @@ bool QgsScreenHelper::eventFilter( QObject *watched, QEvent *event )
         connect( handle, &QWindow::screenChanged, this, [ = ]( QScreen * )
         {
           disconnect( mScreenDpiChangedConnection );
+          disconnect( mLogicalDpiChangedConnection );
           disconnect( mAvailableGeometryChangedConnection );
 
           if ( QWindow *windowHandleInLambda = windowHandle() )
@@ -70,12 +72,16 @@ bool QgsScreenHelper::eventFilter( QObject *watched, QEvent *event )
             mScreenDpiChangedConnection = connect( windowHandleInLambda->screen(), &QScreen::physicalDotsPerInchChanged, this, &QgsScreenHelper::updateDevicePixelFromScreen );
             updateDevicePixelFromScreen();
 
+            mLogicalDpiChangedConnection = connect( windowHandleInLambda->screen(), &QScreen::logicalDotsPerInchChanged, this, &QgsScreenHelper::updateLogicalDpiFromScreen );
+            updateLogicalDpiFromScreen();
+
             mAvailableGeometryChangedConnection = connect( windowHandleInLambda->screen(), &QScreen::availableGeometryChanged, this, &QgsScreenHelper::updateAvailableGeometryFromScreen );
             updateAvailableGeometryFromScreen();
           }
         } );
 
         mScreenDpiChangedConnection = connect( handle->screen(), &QScreen::physicalDotsPerInchChanged, this, &QgsScreenHelper::updateDevicePixelFromScreen );
+        mLogicalDpiChangedConnection = connect( handle->screen(), &QScreen::logicalDotsPerInchChanged, this, &QgsScreenHelper::updateLogicalDpiFromScreen );
         mAvailableGeometryChangedConnection = connect( handle->screen(), &QScreen::availableGeometryChanged, this, &QgsScreenHelper::updateAvailableGeometryFromScreen );
       }
     }
@@ -100,6 +106,19 @@ void QgsScreenHelper::updateDevicePixelFromScreen()
   }
 }
 
+void QgsScreenHelper::updateLogicalDpiFromScreen()
+{
+  if ( QScreen *screen = QgsScreenHelper::screen() )
+  {
+    const double newDpi = screen->logicalDotsPerInch();
+    if ( !qgsDoubleNear( newDpi, mLogicalDpi ) )
+    {
+      mLogicalDpi = newDpi;
+      emit logicalDpiChanged( mLogicalDpi );
+    }
+  }
+}
+
 void QgsScreenHelper::updateAvailableGeometryFromScreen()
 {
   if ( QScreen *screen = QgsScreenHelper::screen() )

src/gui/qgsscreenhelper.h

@@ -60,6 +60,13 @@ class GUI_EXPORT QgsScreenHelper : public QObject
      */
     double screenDpi() const { return mScreenDpi; }
 
+    /**
+     * Returns the current logical DPI for the screen that the parent widget appears on.
+     *
+     * \see logicalDpiChanged()
+     */
+    double logicalDpi() const { return mLogicalDpi; }
+
     /**
      * Returns the current screen available geometry in pixels.
      *
@@ -78,6 +85,13 @@ class GUI_EXPORT QgsScreenHelper : public QObject
      */
     void screenDpiChanged( double dpi );
 
+    /**
+     * Emitted whenever the logical \a dpi associated with the widget is changed.
+     *
+     * \see logicalDpi()
+     */
+    void logicalDpiChanged( double dpi );
+
     /**
      * Emitted whenever the available geometry of the screen associated with the widget is changed.
      *
@@ -91,6 +105,7 @@ class GUI_EXPORT QgsScreenHelper : public QObject
   private slots:
 
     void updateDevicePixelFromScreen();
+    void updateLogicalDpiFromScreen();
     void updateAvailableGeometryFromScreen();
 
   private:
@@ -100,6 +115,9 @@ class GUI_EXPORT QgsScreenHelper : public QObject
     double mScreenDpi = 96.0;
     QMetaObject::Connection mScreenDpiChangedConnection;
 
+    double mLogicalDpi = 96.0;
+    QMetaObject::Connection mLogicalDpiChangedConnection;
+
     QRect mAvailableGeometry;
     QMetaObject::Connection mAvailableGeometryChangedConnection;