Fix display of sliced images on MS-Windows

* src/w32term.c (x_draw_image_foreground): Fix detection of
scaled images for sliced images.  Scale the original width of
a slice and its coordinates of origin as well.

src/w32term.c

@@ -1896,6 +1896,24 @@ x_draw_image_foreground (struct glyph_string *s)
 	  orig_height = s->slice.height;
 	}
 
+      double w_factor = 1.0, h_factor = 1.0;
+      bool scaled = false;
+      int orig_slice_width  = s->slice.width,
+	  orig_slice_height = s->slice.height;
+      int orig_slice_x = s->slice.x, orig_slice_y = s->slice.y;
+      /* For scaled images we need to restore the original slice's
+	 dimensions and origin coordinates, from before the scaling.  */
+      if (s->img->width != orig_width || s->img->height != orig_height)
+	{
+	  scaled = true;
+	  w_factor = (double) orig_width  / (double) s->img->width;
+	  h_factor = (double) orig_height / (double) s->img->height;
+	  orig_slice_width = s->slice.width * w_factor + 0.5;
+	  orig_slice_height = s->slice.height * h_factor + 0.5;
+	  orig_slice_x = s->slice.x * w_factor + 0.5;
+	  orig_slice_y = s->slice.y * h_factor + 0.5;
+	}
+
       if (s->img->mask)
 	{
 	  HDC mask_dc = CreateCompatibleDC (s->hdc);
@@ -1903,7 +1921,7 @@ x_draw_image_foreground (struct glyph_string *s)
 
 	  SetTextColor (s->hdc, RGB (255, 255, 255));
 	  SetBkColor (s->hdc, RGB (0, 0, 0));
-	  if (s->slice.width == orig_width && s->slice.height == orig_height)
+	  if (!scaled)
 	    {
 	      BitBlt (s->hdc, x, y, s->slice.width, s->slice.height,
 		      compat_hdc, s->slice.x, s->slice.y, SRCINVERT);
@@ -1922,14 +1940,14 @@ x_draw_image_foreground (struct glyph_string *s)
 		  && (pmode = SetStretchBltMode (s->hdc, HALFTONE)) != 0)
 		SetBrushOrgEx (s->hdc, 0, 0, NULL);
 	      StretchBlt (s->hdc, x, y, s->slice.width, s->slice.height,
-			  compat_hdc, s->slice.x, s->slice.y,
-			  orig_width, orig_height, SRCINVERT);
+			  compat_hdc, orig_slice_x, orig_slice_y,
+			  orig_slice_width, orig_slice_height, SRCINVERT);
 	      StretchBlt (s->hdc, x, y, s->slice.width, s->slice.height,
-			  mask_dc, s->slice.x, s->slice.y,
-			  orig_width, orig_height, SRCAND);
+			  mask_dc, orig_slice_x, orig_slice_y,
+			  orig_slice_width, orig_slice_height, SRCAND);
 	      StretchBlt (s->hdc, x, y, s->slice.width, s->slice.height,
-			  compat_hdc, s->slice.x, s->slice.y,
-			  orig_width, orig_height, SRCINVERT);
+			  compat_hdc, orig_slice_x, orig_slice_y,
+			  orig_slice_width, orig_slice_height, SRCINVERT);
 	      if (pmode)
 		SetStretchBltMode (s->hdc, pmode);
 	    }
@@ -1940,7 +1958,7 @@ x_draw_image_foreground (struct glyph_string *s)
 	{
 	  SetTextColor (s->hdc, s->gc->foreground);
 	  SetBkColor (s->hdc, s->gc->background);
-	  if (s->slice.width == orig_width && s->slice.height == orig_height)
+	  if (!scaled)
 	    BitBlt (s->hdc, x, y, s->slice.width, s->slice.height,
 		    compat_hdc, s->slice.x, s->slice.y, SRCCOPY);
 	  else
@@ -1951,8 +1969,8 @@ x_draw_image_foreground (struct glyph_string *s)
 		  && (pmode = SetStretchBltMode (s->hdc, HALFTONE)) != 0)
 		SetBrushOrgEx (s->hdc, 0, 0, NULL);
 	      StretchBlt (s->hdc, x, y, s->slice.width, s->slice.height,
-			  compat_hdc, s->slice.x, s->slice.y,
-			  orig_width, orig_height, SRCCOPY);
+			  compat_hdc, orig_slice_x, orig_slice_y,
+			  orig_slice_width, orig_slice_height, SRCCOPY);
 	      if (pmode)
 		SetStretchBltMode (s->hdc, pmode);
 	    }