c# - 旋转形状时，它与旋转的形状保持在一起

Question

我是一名学生，我是新来的。我有一个类(class)项目来制作类似 Paint 的程序。我有一个基类Shape，带有 DrawSelf、Contains 等。矩形、椭圆和三角形的方法和类。我还有另外两个类 DisplayProccesor，它是绘图类，以及 DialogProcessor，它控制与用户的对话。这些是项目的要求。

public class DisplayProcessor
{

    public DisplayProcessor()
    {
    }

    /// <summary>
    /// List of shapes
    /// </summary>
    private List<Shape> shapeList = new List<Shape>();
    public List<Shape> ShapeList
    {
        get { return shapeList; }
        set { shapeList = value; }
    }

    /// <summary>
    /// Redraws all shapes in shapeList
    /// </summary>
    public void ReDraw(object sender, PaintEventArgs e)
    {
        e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
        Draw(e.Graphics);
    }

    public virtual void Draw(Graphics grfx)
    {
        int n = shapeList.Count;
        Shape shape;

        for (int i = 0; i <= n - 1; i++)
        {
            shape = shapeList[i];
            DrawShape(grfx, shape);
        }
    }

    public virtual void DrawShape(Graphics grfx, Shape item)
    {
        item.DrawSelf(grfx);
    }
}

这是另一个:

public class DialogProcessor : DisplayProcessor
{
    public DialogProcessor()
    {
    }

    private Shape selection;
    public Shape Selection
    {
        get { return selection; }
        set { selection = value; }
    }

    private bool isDragging;
    public bool IsDragging
    {
        get { return isDragging; }
        set { isDragging = value; }
    }

    private PointF lastLocation;
    public PointF LastLocation
    {
        get { return lastLocation; }
        set { lastLocation = value; }
    }

   public void AddRandomRectangle()
    {
        Random rnd = new Random();
        int x = rnd.Next(100, 1000);
        int y = rnd.Next(100, 600);

        RectangleShape rect = new RectangleShape(new Rectangle(x, y, 100, 200));
        rect.FillColor = Color.White;

        ShapeList.Add(rect);
    }
}

所以，我想旋转一个由用户选择的形状。 我这样试试它旋转它，但我得到这个:http://www.freeimagehosting.net/qj3zp

public class RectangleShape : Shape
{

    public override void DrawSelf(Graphics grfx)
    {
        grfx.TranslateTransform(Rectangle.X + Rectangle.Width / 2, Rectangle.Y + Rectangle.Height / 2);
        grfx.RotateTransform(base.RotationAngle);
        grfx.TranslateTransform( - (Rectangle.X + Rectangle.Width / 2), -( Rectangle.Y + Rectangle.Height / 2));
        grfx.FillRectangle(new SolidBrush(FillColor), Rectangle.X, Rectangle.Y, Rectangle.Width, Rectangle.Height);
        grfx.DrawRectangle(Pens.Black, Rectangle.X, Rectangle.Y, Rectangle.Width, Rectangle.Height);
        grfx.ResetTransform();
    }
}

Answer 1

我很难理解你的问题。我的猜测是当你旋转第一个形状并绘制它时。然后画另一个形状，第二个形状也旋转。

这是因为，所有 DrawSelf 方法都使用相同的图形引用，因此对一个方法使用的任何转换都会影响同一上下文中的所有后续调用。

您只需调用 Graphics.ResetTransform 即可解决此问题每个 DrawSelf 方法末尾的方法。

public override void DrawSelf(Graphics grfx)
    {
        base.DrawSelf(grfx);

        //grfx.FillRectangle(new SolidBrush(FillColor), Rectangle.X, Rectangle.Y, Rectangle.Width, Rectangle.Height);
        //grfx.DrawRectangle(Pens.Black, Rectangle.X, Rectangle.Y, Rectangle.Width, Rectangle.Height);

        grfx.TranslateTransform(Rectangle.X + Rectangle.Width / 2, Rectangle.Y + Rectangle.Height/2);
        grfx.RotateTransform(base.RotationAngle);
        grfx.TranslateTransform(-(Rectangle.X + Rectangle.Width / 2), -(Rectangle.Y + Rectangle.Height/2));
        grfx.FillRectangle(new SolidBrush(FillColor), Rectangle.X, Rectangle.Y, Rectangle.Width, Rectangle.Height);
        grfx.DrawRectangle(Pens.Black, Rectangle.X,Rectangle.Y, Rectangle.Width, Rectangle.Height);
        grfx.ResetTransform();
    }