Unity Custom Rect Editor

RectUtils.cs

using UnityEngine;
using UnityEditor;

public class RectUtils 
{
    public static Rect ResizeRect(Rect rect, Handles.DrawCapFunction capFunc, Color capCol, Color fillCol, float capSize, float snap)
    {
        Vector2 halfRectSize = new Vector2(rect.size.x * 0.5f, rect.size.y * 0.5f);

        Vector3[] rectangleCorners =
            { 
                new Vector3(rect.position.x - halfRectSize.x, rect.position.y - halfRectSize.y, 0),   // Bottom Left
                new Vector3(rect.position.x + halfRectSize.x, rect.position.y - halfRectSize.y, 0),   // Bottom Right
                new Vector3(rect.position.x + halfRectSize.x, rect.position.y + halfRectSize.y, 0),   // Top Right
                new Vector3(rect.position.x - halfRectSize.x, rect.position.y + halfRectSize.y, 0)    // Top Left
            }; 

        Handles.color = fillCol;
        Handles.DrawSolidRectangleWithOutline(rectangleCorners, new Color(fillCol.r, fillCol.g, fillCol.b, 0.25f), capCol);

        Vector3[] handlePoints =
            { 
                new Vector3(rect.position.x - halfRectSize.x, rect.position.y, 0),   // Left
                new Vector3(rect.position.x + halfRectSize.x, rect.position.y, 0),   // Right
                new Vector3(rect.position.x, rect.position.y + halfRectSize.y, 0),   // Top
                new Vector3(rect.position.x, rect.position.y - halfRectSize.y, 0)    // Bottom 
            }; 

        Handles.color = capCol;

        var newSize = rect.size;
        var newPosition = rect.position;

        var leftHandle =    Handles.Slider(handlePoints[0], -Vector3.right, capSize, capFunc, snap).x - handlePoints[0].x;
        var rightHandle =   Handles.Slider(handlePoints[1], Vector3.right, capSize, capFunc, snap).x - handlePoints[1].x;
        var topHandle =     Handles.Slider(handlePoints[2], Vector3.up, capSize, capFunc, snap).y - handlePoints[2].y;
        var bottomHandle =  Handles.Slider(handlePoints[3], -Vector3.up, capSize, capFunc, snap).y - handlePoints[3].y;

        newSize = new Vector2(
            Mathf.Max(.1f, newSize.x - leftHandle + rightHandle), 
            Mathf.Max(.1f, newSize.y + topHandle - bottomHandle));

        newPosition = new Vector2(
            newPosition.x + leftHandle * .5f + rightHandle * .5f, 
            newPosition.y + topHandle * .5f + bottomHandle * .5f);

        return new Rect(newPosition.x, newPosition.y, newSize.x, newSize.y);
    }
}

Hello !

Thank you, this has been relly usefull. I however had to modify it a little bit, as it seemed to return a Rect wich had double the actual size on the screen. (I also condensed the code) Here it is :

using UnityEngine;
using UnityEditor;

public class RectUtils {
	public static Rect ResizeRect (Rect rect, Handles.DrawCapFunction capFunc, Color capCol, Color fillCol, float capSize, float snap) {

		Vector3[] rectangleCorners = { 
			new Vector3(rect.min.x, rect.min.y, 0),   // Bottom Left
			new Vector3(rect.max.x, rect.min.y, 0),   // Bottom Right
			new Vector3(rect.max.x, rect.max.y, 0),   // Top Right
			new Vector3(rect.min.x, rect.max.y, 0)    // Top Left
		}; 

		Handles.color = fillCol;
		Handles.DrawSolidRectangleWithOutline(rectangleCorners, new Color(fillCol.r, fillCol.g, fillCol.b, 0.25f), capCol);

		Vector3[] handlePoints = { 
			new Vector3(rect.min.x, rect.center.y, 0),   // Left
			new Vector3(rect.max.x, rect.center.y, 0),   // Right
			new Vector3(rect.center.x, rect.min.y, 0),   // Bottom 
			new Vector3(rect.center.x, rect.max.y, 0)    // Top
		}; 

		Handles.color = capCol;

		Vector3 leftHandle =   Handles.Slider(handlePoints[0], Vector3.right, capSize, capFunc, snap);
		leftHandle.x   = Mathf.Min (leftHandle.x,  handlePoints[1].x-0.1f);
		Vector3 rightHandle =  Handles.Slider(handlePoints[1], Vector3.right, capSize, capFunc, snap);
		rightHandle.x  = Mathf.Max (rightHandle.x, handlePoints[0].x+0.1f);
		Vector3 bottomHandle = Handles.Slider(handlePoints[2], Vector3.up,    capSize, capFunc, snap);
		bottomHandle.y = Mathf.Min (bottomHandle.y, handlePoints[3].y-0.1f);
		Vector3 topHandle =    Handles.Slider(handlePoints[3], Vector3.up,    capSize, capFunc, snap);
		topHandle.y    = Mathf.Max (topHandle.y, handlePoints[2].y+0.1f);

		return Rect.MinMaxRect(leftHandle.x, bottomHandle.y, rightHandle.x, topHandle.y); 
	}
}

Thanks again,

GR