C#：Windows窗体：可能会导致Invalidate()不重绘？

this.worldBox = new System.Windows.Forms.PictureBox();
this.worldBox.BackColor = System.Drawing.SystemColors.Control;
this.worldBox.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
this.worldBox.Location = new System.Drawing.Point(170,82);
this.worldBox.Name = "worldBox";
this.worldBox.Size = new System.Drawing.Size(261,250);
this.worldBox.TabIndex = 0;
this.worldBox.TabStop = false;
this.worldBox.MouseMove += new 
    System.Windows.Forms.MouseEventHandler(this.worldBox_MouseMove);
this.worldBox.MouseDown += new 
    System.Windows.Forms.MouseEventHandler(this.worldBox_MouseDown);
this.worldBox.MouseUp += new 
    System.Windows.Forms.MouseEventHandler(this.worldBox_MouseUp);

在我的代码中被称为适当地画出世界：

view.DrawWorldBox(worldBox,canvas,gameEngine.GameObjectManager.Controllers,selectedGameObjects,LevelEditorUtils.PREVIEWS);

View.DrawWorldBox：

public void DrawWorldBox(PictureBox worldBox,Panel canvas,ICollection<IGameObjectController> controllers,ICollection<IGameObjectController> selectedGameObjects,IDictionary<string,Image> previews)
{
    int left = Math.Abs(worldBox.Location.X);
    int top = Math.Abs(worldBox.Location.Y);
    Rectangle screenRect = new Rectangle(left,top,canvas.Width,canvas.Height);

    IDictionary<float,ICollection<IGameObjectController>> layers = 
        LevelEditorUtils.LayersOfControllers(controllers);
    IOrderedEnumerable<KeyValuePair<float,ICollection<IGameObjectController>>> sortedLayers 
            = from item in layers
              orderby item.Key descending
              select item;

    using (Graphics g = Graphics.FromImage(worldBox.Image))
    {
        foreach (KeyValuePair<float,ICollection<IGameObjectController>> 
        kv in sortedLayers)
        {
            foreach (IGameObjectController controller in kv.Value)
            {
                // ...

                float scale = controller.View.Scale;
                float width = controller.View.Width;
                float height = controller.View.Height;
                Rectangle controllerRect = new 
                    Rectangle((int)controller.Model.Position.X,(int)controller.Model.Position.Y,(int)(width * scale),(int)(height * scale));

                // cull objects that aren't intersecting with the canvas
                if (controllerRect.IntersectsWith(screenRect))
                {
                    Image img = previews[controller.Model.HumanReadableName];
                    g.DrawImage(img,controllerRect);
                }

                if (selectedGameObjects.Contains(controller))
                {
                    selectionRectangles.Add(controllerRect);
                }
            }
        }
        foreach (Rectangle rect in selectionRectangles)
        {
            g.DrawRectangle(drawingPen,rect);
        }
        selectionRectangles.Clear();
    }
    worldBox.Invalidate();
}

在这里我可以做错什么