Fix screen scaling

We don't use wxWidget DPI (which is the screen DPI) for our on-screen
display.  Instead, we use 91 (?!?).  Make this configurable in advanced
config and use the set value in our scaling widget

common/advanced_config.cpp

@@ -131,6 +131,7 @@ static const wxChar ConfigurableToolbars[] = wxT( "ConfigurableToolbars" );
 static const wxChar MaxPastedTextLength[] = wxT( "MaxPastedTextLength" );
 static const wxChar PNSProcessClusterTimeout[] = wxT( "PNSProcessClusterTimeout" );
 static const wxChar ImportSkipComponentBodies[] = wxT( "ImportSkipComponentBodies" );
+static const wxChar ScreenDPI[] = wxT( "ScreenDPI" );
 
 } // namespace KEYS
 
@@ -320,6 +321,8 @@ ADVANCED_CFG::ADVANCED_CFG()
 
     m_ImportSkipComponentBodies = false;
 
+    m_ScreenDPI = 91;
+
     loadFromConfigFile();
 }
 
@@ -634,6 +637,10 @@ void ADVANCED_CFG::loadSettings( wxConfigBase& aCfg )
                                                 &m_ImportSkipComponentBodies,
                                                 m_ImportSkipComponentBodies ) );
 
+    m_entries.push_back( std::make_unique<PARAM_CFG_INT>( true, AC_KEYS::ScreenDPI,
+                                               &m_ScreenDPI, m_ScreenDPI,
+                                               50, 500 ) );
+
     // Special case for trace mask setting...we just grab them and set them immediately
     // Because we even use wxLogTrace inside of advanced config
     m_entries.push_back( std::make_unique<PARAM_CFG_WXSTRING>( true, AC_KEYS::TraceMasks, &m_traceMasks,

common/dialogs/panel_common_settings.cpp

@@ -27,6 +27,8 @@
 #include <bitmaps.h>
 #include <class_draw_panel_gal.h>
 #include <dpi_scaling_common.h>
+#include <eda_draw_frame.h>
+#include <gal/graphics_abstraction_layer.h>
 #include <kiface_base.h>
 #include <kiplatform/ui.h>
 #include <pgm_base.h>

common/gal/graphics_abstraction_layer.cpp

@@ -25,7 +25,7 @@
  */
 
 #include <wx/log.h>
-
+#include <advanced_config.h>
 #include <gal/graphics_abstraction_layer.h>
 #include <gal/definitions.h>
 #include <font/font.h>
@@ -62,7 +62,7 @@ GAL::GAL( GAL_DISPLAY_OPTIONS& aDisplayOptions ) :
 
     // wxDC::GetPPI() reports 96 DPI, but somehow this value
     // is the closest match to the legacy renderer
-    SetScreenDPI( 91 );
+    SetScreenDPI( ADVANCED_CFG::GetCfg().m_ScreenDPI );
     SetDepthRange( VECTOR2D( GAL::MIN_DEPTH, GAL::MAX_DEPTH ) );
     SetLayerDepth( 0.0 );
     SetFlip( false, false );

common/widgets/zoom_correction_ctrl.cpp

@@ -23,6 +23,7 @@
  * Released under GNU GPL v2+
  */
 
+#include <advanced_config.h>
 #include <widgets/zoom_correction_ctrl.h>
 #include <widgets/ui_common.h>
 
@@ -55,7 +56,7 @@ private:
         double value = parent->GetValue();
         ZOOM_CORRECTION_UNITS units = static_cast<ZOOM_CORRECTION_UNITS>( parent->GetUnitsSelection() );
 
-        double dpi = GetDPI().x;
+        double dpi = ADVANCED_CFG::GetCfg().m_ScreenDPI;
         double unitsPerInch = 25.4;
 
         if( units == ZOOM_CORRECTION_UNITS::CM )
@@ -222,6 +223,7 @@ int ZOOM_CORRECTION_CTRL::GetUnitsSelection() const
     return m_unitsChoice->GetSelection();
 }
 
+
 bool ZOOM_CORRECTION_CTRL::TransferDataToWindow()
 {
     m_slider->SetValue( (int)( *m_value * 100 ) );

include/advanced_config.h

@@ -803,6 +803,18 @@ public:
      */
     bool m_ImportSkipComponentBodies;
 
+    /**
+     * Screen DPI setting for display calculations.
+     *
+     * This setting controls the assumed screen DPI for various display calculations.
+     * Can be used to adjust sizing for high-DPI displays or unusual screen configurations.
+     *
+     * Setting name: "ScreenDPI"
+     * Valid values: 50 to 500
+     * Default value: 91
+     */
+    int m_ScreenDPI;
+
     wxString m_traceMasks; ///< Trace masks for wxLogTrace, loaded from the config file.
     ///@}
 

include/gal/graphics_abstraction_layer.h

@@ -644,6 +644,7 @@ public:
      * For instance a typical notebook with HD+ resolution (1600x900) has 106 DPI.
      */
     void SetScreenDPI( double aScreenDPI ) { m_screenDPI = aScreenDPI; }
+    double GetScreenDPI() const            { return m_screenDPI; }
 
     /**
      * Get/set the Point in world space to look at.

include/widgets/zoom_correction_ctrl.h

@@ -49,11 +49,11 @@ class ZOOM_CORRECTION_CTRL : public wxPanel
 public:
     ZOOM_CORRECTION_CTRL( wxWindow* aParent, double& aValue );
 
-    void SetDisplayedValue( double aValue );
+    void   SetDisplayedValue( double aValue );
     double GetValue() const;
-    int GetUnitsSelection() const;
-    bool TransferDataToWindow() override;
-    bool TransferDataFromWindow() override;
+    int    GetUnitsSelection() const;
+    bool   TransferDataToWindow() override;
+    bool   TransferDataFromWindow() override;
 
 private:
     void sliderChanged( wxCommandEvent& aEvent );