X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/e71508e160653f122f8e5d7f73c2ebf7f928964b..96c9640205933ad0673d5af2c96af0816c50160c:/src/msw/dc.cpp

diff --git a/src/msw/dc.cpp b/src/msw/dc.cpp
index 5079795653..c7f3cfa665 100644
--- a/src/msw/dc.cpp
+++ b/src/msw/dc.cpp
@@ -34,6 +34,7 @@
     #include "wx/bitmap.h"
     #include "wx/dcmemory.h"
     #include "wx/log.h"
+    #include "wx/math.h"
     #include "wx/icon.h"
     #include "wx/dcprint.h"
     #include "wx/module.h"
@@ -82,7 +83,9 @@ IMPLEMENT_ABSTRACT_CLASS(wxMSWDCImpl, wxDCImpl)
 // constants
 // ---------------------------------------------------------------------------
 
-static const int VIEWPORT_EXTENT = 1000;
+// The device space in Win32 GDI measures 2^27*2^27 , so we use 2^27-1 as the
+// maximal possible view port extent.
+static const int VIEWPORT_EXTENT = 134217727;
 
 // ROPs which don't have standard names (see "Ternary Raster Operations" in the
 // MSDN docs for how this and other numbers in wxDC::Blit() are obtained)
@@ -1959,6 +1962,31 @@ bool wxMSWDCImpl::DoGetPartialTextExtents(const wxString& text, wxArrayInt& widt
     return true;
 }
 
+namespace
+{
+
+void ApplyEffectiveScale(double scale, int sign, int *device, int *logical)
+{
+    // To reduce rounding errors as much as possible, we try to use the largest
+    // possible extent (2^27-1) for the device space but we must also avoid
+    // overflowing the int range i.e. ensure that logical extents are less than
+    // 2^31 in magnitude. So the minimal scale we can use is 1/16 as for
+    // anything smaller VIEWPORT_EXTENT/scale would overflow the int range.
+    static const double MIN_LOGICAL_SCALE = 1./16;
+
+    double physExtent = VIEWPORT_EXTENT;
+    if ( scale < MIN_LOGICAL_SCALE )
+    {
+        physExtent *= scale/MIN_LOGICAL_SCALE;
+        scale = MIN_LOGICAL_SCALE;
+    }
+
+    *device = wxRound(physExtent);
+    *logical = sign*wxRound(VIEWPORT_EXTENT/scale);
+}
+
+} // anonymous namespace
+
 void wxMSWDCImpl::RealizeScaleAndOrigin()
 {
     // although it may seem wasteful to always use MM_ANISOTROPIC here instead
@@ -1967,11 +1995,18 @@ void wxMSWDCImpl::RealizeScaleAndOrigin()
 #ifndef __WXWINCE__
     ::SetMapMode(GetHdc(), MM_ANISOTROPIC);
 
-    int width = DeviceToLogicalXRel(VIEWPORT_EXTENT)*m_signX,
-        height = DeviceToLogicalYRel(VIEWPORT_EXTENT)*m_signY;
+    // wxWidgets API assumes that the coordinate space is "infinite" (i.e. only
+    // limited by 2^32 range of the integer coordinates) but in MSW API we must
+    // actually specify the extents that we use so compute them here.
 
-    ::SetViewportExtEx(GetHdc(), VIEWPORT_EXTENT, VIEWPORT_EXTENT, NULL);
-    ::SetWindowExtEx(GetHdc(), width, height, NULL);
+    int devExtX, devExtY,   // Viewport, i.e. device space, extents.
+        logExtX, logExtY;   // Window, i.e. logical coordinate space, extents.
+
+    ApplyEffectiveScale(m_scaleX, m_signX, &devExtX, &logExtX);
+    ApplyEffectiveScale(m_scaleY, m_signY, &devExtY, &logExtY);
+
+    ::SetViewportExtEx(GetHdc(), devExtX, devExtY, NULL);
+    ::SetWindowExtEx(GetHdc(), logExtX, logExtY, NULL);
 
     ::SetViewportOrgEx(GetHdc(), m_deviceOriginX, m_deviceOriginY, NULL);
     ::SetWindowOrgEx(GetHdc(), m_logicalOriginX, m_logicalOriginY, NULL);
@@ -2282,7 +2317,8 @@ bool wxMSWDCImpl::DoStretchBlit(wxCoord xdest, wxCoord ydest,
         // than the wxWidgets fall-back implementation. So we need
         // to be able to switch this on and off at runtime.
 #if wxUSE_SYSTEM_OPTIONS
-        if (wxSystemOptions::GetOptionInt(wxT("no-maskblt")) == 0)
+        static bool s_maskBltAllowed = wxSystemOptions::GetOptionInt("no-maskblt") == 0;
+        if ( s_maskBltAllowed )
 #endif
         {
             if ( dstWidth == srcWidth && dstHeight == srcHeight )
@@ -2406,6 +2442,17 @@ bool wxMSWDCImpl::DoStretchBlit(wxCoord xdest, wxCoord ydest,
             {
                 SET_STRETCH_BLT_MODE(GetHdc());
 
+                // Unlike all the other functions used here (i.e. AlphaBlt(),
+                // MaskBlt(), BitBlt() and StretchBlt()), StretchDIBits() does
+                // not take into account the source DC logical coordinates
+                // automatically as it doesn't even work with the source HDC.
+                // So do this manually to ensure that the coordinates are
+                // interpreted in the same way here as in all the other cases.
+                xsrc = source->LogicalToDeviceX(xsrc);
+                ysrc = source->LogicalToDeviceY(ysrc);
+                srcWidth = source->LogicalToDeviceXRel(srcWidth);
+                srcHeight = source->LogicalToDeviceYRel(srcHeight);
+
                 // Figure out what co-ordinate system we're supposed to specify
                 // ysrc in.
                 const LONG hDIB = ds.dsBmih.biHeight;