[f-spot: 30/40] compute the reverse transfomation in order to get the source area

[Stephane Delcroix <sdelcroix src gnome org>]

commit fb56f41d9a42ae42682dd12fe0cac761d85a93e9
Author: Stephane Delcroix <stephane delcroix org>
Date:   Mon Jun 22 15:59:36 2009 +0200

    compute the reverse transfomation in order to get the source area

 src/Utils/PixbufUtils.cs |   20 ++++++++++++++++++++
 src/Widgets/ImageView.cs |   10 +++++-----
 2 files changed, 25 insertions(+), 5 deletions(-)
---
diff --git a/src/Utils/PixbufUtils.cs b/src/Utils/PixbufUtils.cs
index a92dd96..8fef3ed 100644
--- a/src/Utils/PixbufUtils.cs
+++ b/src/Utils/PixbufUtils.cs
@@ -91,6 +91,26 @@ namespace FSpot.Utils
 			return area;
 		}
 
+		public static PixbufOrientation ReverseTransformation (PixbufOrientation orientation)
+		{
+			switch (orientation) {
+			default:
+			case PixbufOrientation.TopLeft:
+			case PixbufOrientation.TopRight:
+			case PixbufOrientation.BottomRight:
+			case PixbufOrientation.BottomLeft:
+				return orientation;
+			case PixbufOrientation.LeftTop:
+				return PixbufOrientation.RightBottom;
+			case PixbufOrientation.RightTop:
+				return PixbufOrientation.LeftBottom;
+			case PixbufOrientation.RightBottom:
+				return PixbufOrientation.LeftTop;
+			case PixbufOrientation.LeftBottom:
+				return PixbufOrientation.RightTop;
+			}
+		}
+
 		public static Pixbuf TransformOrientation (Pixbuf src, PixbufOrientation orientation)
 		{
 			Pixbuf dest;
diff --git a/src/Widgets/ImageView.cs b/src/Widgets/ImageView.cs
index a162b19..87b70ff 100644
--- a/src/Widgets/ImageView.cs
+++ b/src/Widgets/ImageView.cs
@@ -744,11 +744,11 @@ namespace FSpot.Widgets
 
 			Rectangle pixbuf_area = PixbufUtils.TransformOrientation ((int)scaled_width,
 										  (int)scaled_height,
-										  new Rectangle (-(area.X - x_offset),
-										  		 -(area.Y - y_offset),
+										  new Rectangle ((area.X - x_offset),
+												 (area.Y - y_offset),
 												 area.Width,
 												 area.Height),
-										  pixbuf_orientation);
+										  PixbufUtils.ReverseTransformation (pixbuf_orientation));
 			using (Pixbuf temp_pixbuf = new Pixbuf (Colorspace.Rgb, false, 8, pixbuf_area.Width, pixbuf_area.Height)) {
 				if (Pixbuf.HasAlpha)
 					temp_pixbuf.Fill (0x00000000);
@@ -756,10 +756,10 @@ namespace FSpot.Widgets
 				Pixbuf.CompositeColor (temp_pixbuf,
 						       0, 0,
 						       pixbuf_area.Width, pixbuf_area.Height,
-						       pixbuf_area.X, pixbuf_area.Y,
+						       -pixbuf_area.X, -pixbuf_area.Y,
 						       zoom, zoom,
 						       zoom == 1.0 ? InterpType.Nearest : interpolation, 255,
-						       -pixbuf_area.X, -pixbuf_area.Y,
+						       pixbuf_area.X, pixbuf_area.Y,
 						       CheckPattern.CheckSize, CheckPattern.Color1, CheckPattern.Color2);