dpi_scaling.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2019 KiCad Developers, see AUTHORS.TXT for contributors.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include <gal/dpi_scaling.h>

#include <core/optional.h>

#include <env_vars.h>
#include <settings/common_settings.h>
#include <kiplatform/ui.h>

#include <wx/log.h>


const wxChar* const traceHiDpi = wxT( "KICAD_TRACE_HIGH_DPI" );


static OPT<double> getKiCadConfiguredScale( const COMMON_SETTINGS& aConfig )
{
 OPT<double> scale;
 double canvas_scale = aConfig.m_Appearance.canvas_scale;

 if( canvas_scale > 0.0 )
 {
 scale = canvas_scale;
 }

 if( scale )
 {
 wxLogTrace( traceHiDpi, wxT( "Scale factor (configured): %f" ), *scale );
 }

 return scale;
}


static OPT<double> getEnvironmentScale()
{
 const wxPortId port_id = wxPlatformInfo::Get().GetPortId();
 OPT<double> scale;

 if( port_id == wxPORT_GTK )
 {
 // Under GTK, the user can use GDK_SCALE to force the scaling
 scale = ENV_VAR::GetEnvVar<double>( "GDK_SCALE" );
 }

 if( scale )
 {
 wxLogTrace( traceHiDpi, wxT( "Scale factor (environment): %f" ), *scale );
 }

 return scale;
}


DPI_SCALING::DPI_SCALING( COMMON_SETTINGS* aConfig, const wxWindow* aWindow )
 : m_config( aConfig ), m_window( aWindow )
{
}


double DPI_SCALING::GetScaleFactor() const
{
 OPT<double> val;

 if( m_config )
 {
 val = getKiCadConfiguredScale( *m_config );
 }

 if( !val )
 {
 val = getEnvironmentScale();
 }

 if( !val && m_window )
 {
 // Use the native WX reporting.
 // On Linux, this will not work until WX 3.2 and GTK >= 3.10
 // Otherwise it returns 1.0
 val = KIPLATFORM::UI::GetSystemScaleFactor( m_window );
 wxLogTrace( traceHiDpi, wxT( "Scale factor (WX): %f" ), *val );
 }

 if( !val )
 {
 // Nothing else we can do, give it a default value
 val = GetDefaultScaleFactor();
 wxLogTrace( traceHiDpi, wxT( "Scale factor (default): %f" ), *val );
 }

 return *val;
}


bool DPI_SCALING::GetCanvasIsAutoScaled() const
{
 if( m_config == nullptr )
 {
 // No configuration given, so has to be automatic scaling
 return true;
 }

 const bool automatic = getKiCadConfiguredScale( *m_config ) == boost::none;
 wxLogTrace( traceHiDpi, wxT( "Scale is automatic: %d" ), automatic );
 return automatic;
}


void DPI_SCALING::SetDpiConfig( bool aAuto, double aValue )
{
 wxCHECK_RET( m_config != nullptr, wxT( "Setting DPI config without a config store." ) );

 const double value = aAuto ? 0.0 : aValue;

 m_config->m_Appearance.canvas_scale = value;
}


double DPI_SCALING::GetMaxScaleFactor()
{
 // displays with higher than 4.0 DPI are not really going to be useful
 // for KiCad (even an 8k display would be effectively only ~1080p at 4x)
 return 6.0;
}


double DPI_SCALING::GetMinScaleFactor()
{
 // scales under 1.0 don't make sense from a HiDPI perspective
 return 1.0;
}

double DPI_SCALING::GetDefaultScaleFactor()
{
 // no scaling => 1.0
 return 1.0;
}