public partial class Form1 : Form
{
Point downPoint , upPoint;
List<Shapes> shapes = new List<Shapes>();
public ShapesEnum shapeType;
public Form1()
{
InitializeComponent();
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
foreach (var s in shapes)
s.Draw(e.Graphics);
}
protected override void OnMouseDown(MouseEventArgs e)
{
downPoint = e.Location;
}
protected override void OnMouseUp(MouseEventArgs e)
{
base.OnMouseUp(e);
upPoint = e.Location;
CreateShape();
this.Invalidate();
}
private void CreateShape()
{
if (shapeType == ShapesEnum.Circle)
{
Rectangle rect = new Rectangle(downPoint.X, downPoint.Y, upPoint.X - downPoint.X, upPoint.Y - downPoint.Y);
Ellipse ellipse = new Ellipse() { rect = rect };
shapes.Add(ellipse);
}
else if (shapeType == ShapesEnum.Rectangle)
{
Rectangle rect = new Rectangle(downPoint.X, downPoint.Y, upPoint.X - downPoint.X, upPoint.Y - downPoint.Y);
Rect rectangle = new Rect() { rect = rect };
shapes.Add(rectangle);
}
else if (shapeType == ShapesEnum.Line)
{
Point pt1 = new Point (upPoint.X, upPoint.Y);
Point pt2 = new Point (downPoint.X, downPoint.Y);
Ln rectangle = new Ln() { PointUp = pt1, PointDown = pt2 };
shapes.Add(rectangle);
}
lblStatus.Text = string.Format("dn:{0} up:{1} ct:{2}", downPoint, upPoint, shapes.Count());
}
private void btnCircle_Click(object sender, EventArgs e)
{
shapeType = ShapesEnum.Circle;
}
private void btnRectangle_Click(object sender, EventArgs e)
{
shapeType = ShapesEnum.Rectangle;
}
private void btnLine_Click(object sender, EventArgs e)
{
shapeType = ShapesEnum.Line;
}
}
这是目前我的绘画程序的主要部分。
public enum ShapesEnum { Circle, Rectangle, Line }
abstract class Shapes
{
public Rectangle rect { get; set; }
public Color color { get; set; }
public bool isFilled { get; set; }
public abstract void Draw(Graphics g);
}
class Ellipse : Shapes
{
public override void Draw(Graphics g)
{
g.DrawEllipse(Pens.Black, rect);
}
}
class Rect : Shapes
{
public override void Draw(Graphics g)
{
g.DrawRectangle(Pens.Black, rect);
}
}
class Ln : Shapes
{
public Point PointUp { get; set; }
public Point PointDown { get; set; }
public override void Draw(Graphics g)
{
g.DrawLine(Pens.Black, PointUp, PointDown);
}
}
这是我的类,用于继承形状。根据形状,将调用其中一个类。
绘制椭圆效果很好。画线也是一样。但是,在绘制矩形时存在一个错误。如果我把鼠标从左上拖到右下放开,这将起作用。但是,如果我转到另一个方向,它在表单上是不可见的,但shapes.Count()
仍然会添加到shapes
.
是什么导致了这个错误?