[ease] Use Control+Drag to resize while maintaining the center point of an Actor.

[Nate Stedman <natesm src gnome org>]

commit 0126ff71ea267671b3a18be70ab29e2502f1360a
Author: Nate Stedman <natesm gmail com>
Date:   Thu May 20 00:42:38 2010 -0400

    Use Control+Drag to resize while maintaining the center point of an Actor.

 src/libease/EditorEmbed.vala |   18 ++++++++++++---
 src/libease/Handle.vala      |   47 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 4 deletions(-)
---
diff --git a/src/libease/EditorEmbed.vala b/src/libease/EditorEmbed.vala
index cae6292..2624752 100644
--- a/src/libease/EditorEmbed.vala
+++ b/src/libease/EditorEmbed.vala
@@ -466,11 +466,21 @@ public class Ease.EditorEmbed : ScrollableEmbed
 		float factor = 1 / zoom;
 		var motion = event.motion;
 		var p = (motion.modifier_state & Clutter.ModifierType.SHIFT_MASK) != 0;
+		float change_x = motion.x - mouse_x;
+		float change_y = motion.y - mouse_y;
 		
-		handle.drag(factor * (motion.x - mouse_x),
-		            factor * (motion.y - mouse_y),
-		            selected,
-		            p);
+		// if control is held, resize from the center
+		if ((motion.modifier_state & Clutter.ModifierType.CONTROL_MASK) != 0)
+		{
+			handle.drag_from_center(factor * change_x, factor * change_y,
+			                        selected, p);
+		}
+		
+		// otherwise, drag normally
+		else
+		{
+			handle.drag(factor * change_x, factor * change_y, selected, p);
+		}
 		
 		mouse_x = motion.x;
 		mouse_y = motion.y;
diff --git a/src/libease/Handle.vala b/src/libease/Handle.vala
index cbd21cf..04238d1 100644
--- a/src/libease/Handle.vala
+++ b/src/libease/Handle.vala
@@ -89,6 +89,53 @@ public class Ease.Handle : Clutter.Rectangle
 		}
 	}
 	
+	public void drag_from_center(float change_x, float change_y, Actor target,
+	                             bool prop)
+	{
+		switch (position)
+		{
+			case HandlePosition.TOP_LEFT:
+				target.translate(change_x, change_y);
+				target.resize(-change_x * 2, -change_y * 2, false);
+				break;
+				
+			case HandlePosition.TOP_RIGHT:
+				target.translate(-change_x, change_y);
+				target.resize(change_x * 2, -change_y * 2, prop);
+				break;
+				
+			case HandlePosition.TOP:
+				target.translate(0, change_y);
+				target.resize(0, -change_y * 2, false);
+				break;
+				
+			case HandlePosition.BOTTOM:
+				target.translate(0, -change_y);
+				target.resize(0, change_y * 2, false);
+				break;
+				
+			case HandlePosition.LEFT:
+				target.translate(change_x, 0);
+				target.resize(-change_x * 2, 0, false);
+				break;
+				
+			case HandlePosition.RIGHT:
+				target.translate(-change_x, 0);
+				target.resize(change_x * 2, 0, false);
+				break;
+				
+			case HandlePosition.BOTTOM_LEFT:
+				target.translate(change_x, -change_y);
+				target.resize(-change_x * 2, change_y * 2, prop);
+				break;
+				
+			case HandlePosition.BOTTOM_RIGHT:
+				target.translate(-change_x, -change_y);
+				target.resize(change_x * 2, change_y * 2, prop);
+				break;
+		}
+	}
+	
 	public void reposition(Clutter.Actor selection)
 	{
 		switch (position)