DrawTools的理解.

Question

最近下载了一个C# DrawTools,运行时有几个地方不明白,为什么在画图的过程中鼠标可以选中图形,而且还可以拖动,请问各位大虾这个功能是怎么实现的...

Answer 1

把代码贴出来啊，是不是用ArcEngine做的？

Answer 2

对于每个画出来的对象，它都有一个Handle的概念，事实上就是控制点，比如DrawRectangle，它就有
/// <summary>
        /// Move handle to new point (resizing)
        /// </summary>
        /// <param name="point"></param>
        /// <param name="handleNumber"></param>
        public override void MoveHandleTo(Point point, int handleNumber)
        {
            int left = Rectangle.Left;
            int top = Rectangle.Top;
            int right = Rectangle.Right;
            int bottom = Rectangle.Bottom;            switch ( handleNumber )
            {
                case 1:
                    left = point.X;
                    top = point.Y;
                    break;
                case 2:
                    top = point.Y;
                    break;
                case 3:
                    right = point.X;
                    top = point.Y;
                    break;
                case 4:
                    right = point.X;
                    break;
                case 5:
                    right = point.X;
                    bottom = point.Y;
                    break;
                case 6:
                    bottom = point.Y;
                    break;
                case 7:
                    left = point.X;
                    bottom = point.Y;
                    break;
                case 8:
                    left = point.X;
                    break;
            }            SetRectangle(left, top, right - left, bottom - top);
        }将其中一个控制点移动到新的位置并重设Rectangle的范围对于Move，它用
/// <summary>
        /// Move object
        /// </summary>
        /// <param name="deltaX"></param>
        /// <param name="deltaY"></param>
        public override void Move(int deltaX, int deltaY)
        {
            rectangle.X += deltaX;
            rectangle.Y += deltaY;
        }
来将rectangle的坐标进行平移

Answer 3

那也是画上去的，你看GraphicsList类中有public void Draw(Graphics g)
        {
            int n = graphicsList.Count;
            DrawObject o;            // Enumerate list in reverse order to get first
            // object on the top of Z-order.
            for (int i = n - 1; i >= 0; i--)
            {
                o = graphicsList[i];                o.Draw(g);                if (o.Selected == true)
                {
                    o.DrawTracker(g);
                }
            }
        }
就是一个对象是selected状态时，就画Tracker，然后你再看DrawObject类中有/// <summary>
        /// Draw tracker for selected object
        /// </summary>
        /// <param name="g"></param>
        public virtual void DrawTracker(Graphics g)
        {
            if ( ! Selected )
                return;            SolidBrush brush = new SolidBrush(Color.Black);            for ( int i = 1; i <= HandleCount; i++ )
            {
                g.FillRectangle(brush, GetHandleRectangle(i));
            }            brush.Dispose();
        }
都是画上去的

Answer 4

额。。多写写多看看就能明白了。。你说的选择框是在ToolPointer里实现的，在MouseMove的时候有这么一段if (selectMode == SelectionMode.NetSelection)
            {
                // Remove old selection rectangle
                ControlPaint.DrawReversibleFrame(
                    drawArea.RectangleToScreen(DrawRectangle.GetNormalizedRectangle(startPoint, oldPoint)),
                    Color.Black,
                    FrameStyle.Dashed);                // Draw new selection rectangle
                ControlPaint.DrawReversibleFrame(
                    drawArea.RectangleToScreen(DrawRectangle.GetNormalizedRectangle(startPoint, point)),
                    Color.Black,
                    FrameStyle.Dashed);                return;
            }
就是用来画选择框的