From 6f26e88002c5b81ac8d96f62774ec9b176a8c0d0 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Tue, 27 Mar 2012 12:28:04 +0000
Subject: [PATCH] Honour source wxDC coordinate system in wxDC::Blit() in
 wxMSW.

wxGTK and wxOSX already did this so do it in wxMSW as well.

Update the documentation to make this explicit.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71028 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 docs/changes.txt  |  3 +++
 interface/wx/dc.h | 10 +++++++++-
 src/msw/dc.cpp    |  7 +++++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/docs/changes.txt b/docs/changes.txt
index 99810742a2..ddb6934afa 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -207,6 +207,9 @@ Changes in behaviour not resulting in compilation errors, please read this!
   behaved differently in wxMSW and wxGTK/wxOSX before) if more than one item
   is selected in a control with wxDV_MULTIPLE style.
 
+- wxDC::Blit() now honours the source DC coordinate system in wxMSW, as in all
+  the other ports, do not apply scaling to source coordinates manually any more.
+
 
 Changes in behaviour which may result in compilation errors
 -----------------------------------------------------------
diff --git a/interface/wx/dc.h b/interface/wx/dc.h
index 8d8547bb72..fb7590c180 100644
--- a/interface/wx/dc.h
+++ b/interface/wx/dc.h
@@ -1125,6 +1125,11 @@ public:
         target DCs. If you need to apply scaling while copying, use
         StretchBlit().
 
+        Notice that source DC coordinates @a xsrc and @a ysrc are interpreted
+        using the current source DC coordinate system, i.e. the scale, origin
+        position and axis directions are taken into account when transforming
+        them to physical (pixel) coordinates.
+
         @param xdest
             Destination device context x position.
         @param ydest
@@ -1195,7 +1200,10 @@ public:
         source or target DC but calling this method is simpler and can also be
         more efficient if the platform provides a native implementation of it.
 
-        The meaning of its other parameters is the same as with Blit().
+        The meaning of its other parameters is the same as with Blit(), in
+        particular all source coordinates are interpreted using the source DC
+        coordinate system, i.e. are affected by its scale, origin translation
+        and axis direction.
 
         @param xdest
             Destination device context x position.
diff --git a/src/msw/dc.cpp b/src/msw/dc.cpp
index d9f8c91288..7c8b06997b 100644
--- a/src/msw/dc.cpp
+++ b/src/msw/dc.cpp
@@ -2246,6 +2246,13 @@ bool wxMSWDCImpl::DoStretchBlit(wxCoord xdest, wxCoord ydest,
         return false;
     }
 
+    // We need to interpret source-related coordinates in source DC
+    // coordinate system.
+    xsrc = source->LogicalToDeviceX(xsrc);
+    ysrc = source->LogicalToDeviceY(ysrc);
+    srcWidth = source->LogicalToDeviceXRel(srcWidth);
+    srcHeight = source->LogicalToDeviceYRel(srcHeight);
+
     const HDC hdcSrc = GetHdcOf(*implSrc);
 
     // if either the source or destination has alpha channel, we must use
-- 
2.45.2