Introduce DPI scale factor for Hi-DPI displays.

This is supposed to stay 1 (no scale) for printers and default virtual
devices, but should be set accordingly (2 or 3) for windows and virtual
devices derived from windows.

Various VCL widgets or paint operations should incrementally become aware of
this, and changed so that they draw nicely on the Hi-DPI displays.  This patch
only introduces the behavior for waved lines.

The default is currently being set depending on the DPI setting only; could be
changed to a more clever way if necessary.

Change-Id: I71118f9ab6b64028d1eeee76e860e999d5cd9d19
Reviewed-on: https://gerrit.libreoffice.org/8516
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
Tested-by: Norbert Thiebaud <nthiebaud@gmail.com>

4 files changed, 12 insertions, 0 deletions

diff --git a/include/vcl/outdev.hxx b/include/vcl/outdev.hxx
index 047a79d46789..1bd07a271e36 100644
--- a/include/vcl/outdev.hxx
+++ b/include/vcl/outdev.hxx
@@ -310,6 +310,7 @@ private:
     long                mnOutHeight;
     sal_Int32           mnDPIX;
     sal_Int32           mnDPIY;
+    sal_Int32           mnDPIScaleFactor; ///< For Hi-DPI displays, we want to draw everything mnDPIScaleFactor-times larger
     /// font specific text alignment offsets in pixel units
     mutable long        mnTextOffX;
     mutable long        mnTextOffY;
diff --git a/vcl/source/gdi/outdev.cxx b/vcl/source/gdi/outdev.cxx
index b777dbe055af..f8ec8723c410 100644
--- a/vcl/source/gdi/outdev.cxx
+++ b/vcl/source/gdi/outdev.cxx
@@ -349,6 +349,7 @@ OutputDevice::OutputDevice() :
     mnOutHeight         = 0;
     mnDPIX              = 0;
     mnDPIY              = 0;
+    mnDPIScaleFactor    = 1;
     mnTextOffX          = 0;
     mnTextOffY          = 0;
     mnOutOffOrigX       = 0;
diff --git a/vcl/source/gdi/virdev.cxx b/vcl/source/gdi/virdev.cxx
index 4ef94b9ce462..0e9d3161e7a5 100644
--- a/vcl/source/gdi/virdev.cxx
+++ b/vcl/source/gdi/virdev.cxx
@@ -97,6 +97,7 @@ void VirtualDevice::ImplInitVirDev( const OutputDevice* pOutDev,
     mpFontCache     = pSVData->maGDIData.mpScreenFontCache;
     mnDPIX          = pOutDev->mnDPIX;
     mnDPIY          = pOutDev->mnDPIY;
+    mnDPIScaleFactor = pOutDev->mnDPIScaleFactor;
     maFont          = pOutDev->maFont;
 
     if( maTextColor != pOutDev->maTextColor )
@@ -406,6 +407,7 @@ void VirtualDevice::ImplSetReferenceDevice( RefDevMode i_eRefDevMode, sal_Int32
 {
     mnDPIX = i_nDPIX;
     mnDPIY = i_nDPIY;
+    mnDPIScaleFactor = 1;
 
     EnableOutput( sal_False );  // prevent output on reference device
     mbScreenComp = sal_False;
diff --git a/vcl/source/window/window.cxx b/vcl/source/window/window.cxx
index 60a14f18a972..f1cab6645536 100644
--- a/vcl/source/window/window.cxx
+++ b/vcl/source/window/window.cxx
@@ -982,6 +982,9 @@ void Window::ImplInit( Window* pParent, WinBits nStyle, SystemParentData* pSyste
 
     }
 
+    // setup the scale factor for Hi-DPI displays
+    mnDPIScaleFactor = std::max((sal_Int32)1, (mpWindowImpl->mpFrameData->mnDPIY + 48) / 96);
+
     const StyleSettings& rStyleSettings = maSettings.GetStyleSettings();
     sal_uInt16 nScreenZoom = rStyleSettings.GetScreenZoom();
     mnDPIX          = (mpWindowImpl->mpFrameData->mnDPIX*nScreenZoom)/100;
@@ -1718,12 +1721,17 @@ void Window::ImplInitResolutionSettings()
         sal_uInt16 nScreenZoom = rStyleSettings.GetScreenZoom();
         mnDPIX = (mpWindowImpl->mpFrameData->mnDPIX*nScreenZoom)/100;
         mnDPIY = (mpWindowImpl->mpFrameData->mnDPIY*nScreenZoom)/100;
+
+        // setup the scale factor for Hi-DPI displays
+        mnDPIScaleFactor = std::max(1, (mpWindowImpl->mpFrameData->mnDPIY + 48) / 96);
+
         SetPointFont( rStyleSettings.GetAppFont() );
     }
     else if ( mpWindowImpl->mpParent )
     {
         mnDPIX  = mpWindowImpl->mpParent->mnDPIX;
         mnDPIY  = mpWindowImpl->mpParent->mnDPIY;
+        mnDPIScaleFactor = mpWindowImpl->mpParent->mnDPIScaleFactor;
     }
 
     // update the recalculated values for logical units