[PATCH] gdiplus: Fix errors in image dimensions.

[Nathan Beckmann]

Use more precise calculations in GdipGetImageDimension.

Add rounding to GdipLoadImageFromStream to account for errors in unit
conversion.

This is in response to a bug found while doing tests for
GdipSaveImageToFile (patch forthcoming). Also fixes Bug 11778.
---
 dlls/gdiplus/image.c |   28 ++++++++++++++++++++++------
 1 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/dlls/gdiplus/image.c b/dlls/gdiplus/image.c
index 330d90f..da1b931 100644
--- a/dlls/gdiplus/image.c
+++ b/dlls/gdiplus/image.c
@@ -45,8 +45,9 @@ static INT ipicture_pixel_height(IPicture *pic)
 
     hdcref = GetDC(0);
 
-    y = (UINT)(((REAL)y) * ((REAL)GetDeviceCaps(hdcref, LOGPIXELSY)) /
-              ((REAL)INCH_HIMETRIC));
+    /* this calculation can lead to truncation error */
+    y = (UINT)((((REAL)y) * ((REAL)GetDeviceCaps(hdcref, LOGPIXELSY)) /
+              ((REAL)INCH_HIMETRIC)) + 0.5);
     ReleaseDC(0, hdcref);
 
     return y;
@@ -61,8 +62,9 @@ static INT ipicture_pixel_width(IPicture *pic)
 
     hdcref = GetDC(0);
 
-    x = (UINT)(((REAL)x) * ((REAL)GetDeviceCaps(hdcref, LOGPIXELSX)) /
-              ((REAL)INCH_HIMETRIC));
+    /* this calculation can lead to truncation error */
+    x = (UINT)((((REAL)x) * ((REAL)GetDeviceCaps(hdcref, LOGPIXELSX)) /
+              ((REAL)INCH_HIMETRIC)) + 0.5);
 
     ReleaseDC(0, hdcref);
 
@@ -485,8 +487,22 @@ GpStatus WINGDIPAPI GdipGetImageDimension(GpImage *image, REAL *width,
         *width = ((GpBitmap*)image)->width;
     }
     else{
-        *height = ipicture_pixel_height(image->picture);
-        *width = ipicture_pixel_width(image->picture);
+        HDC hdc;
+        INT x, y;
+
+        x = y = 0;
+
+        hdc = GetDC(0);
+    
+        IPicture_get_Width(image->picture, &x);
+        IPicture_get_Height(image->picture, &y);
+
+        *width = (((REAL)x) * ((REAL)GetDeviceCaps(hdc, LOGPIXELSX)) /
+                  ((REAL)INCH_HIMETRIC));
+        *height = (((REAL)y) * ((REAL)GetDeviceCaps(hdc, LOGPIXELSY)) /
+                   ((REAL)INCH_HIMETRIC));
+        
+        ReleaseDC(0, hdc);
     }
 
     TRACE("returning (%f, %f)\n", *height, *width);
-- 
1.5.4.2