如何限制在面板内拖动图像？

Question

晚上好。我目前正在开发一个交互式地图编辑器。我试图通过使用此代码保持地图图像不被拖出视图

 if (currentPosition.X > 0) 
      currentPosition.X = 0; 
     else if (currentPosition.X < -mapSize.Width + Size.Width) 
      currentPosition.X = -mapSize.Width + Size.Width ; 
     if (currentPosition.Y > 0) 
      currentPosition.Y = 0; 
     else if (currentPosition.Y < -mapSize.Height + Size.Height) 
      currentPosition.Y = -mapSize.Height + Size.Height; 

但是我无法将其拖动到极限Size-mapSize。 currentPosition对应于图像的左上角位置。这里的类

namespace GameMaps 
{ 
public class MapPanel : Panel 
{ 
    private Bitmap shownMap = null; 
    private Point mapLocation; 
    private Size mapSize; 
    private bool dragging; 
    private Point currentPosition; 
    //private Point newPosition; 
    private Point initialPosition; 
    private Point initialMousePosition; 
    private Form1 parentForm; 

    public MapPanel(Form1 parentForm) : base() 
    { 
     this.DoubleBuffered = true; 


     this.parentForm = parentForm; 

    } 
    public MapPanel(Panel targetPanel) : this(new Form1()) 
    { 

    } 

    public void ShowMap(Map map) 
    { 
     if (map == null) return; 
     shownMap = map.MapTexture; 
     mapLocation = new Point(0, 0); 
     mapSize = shownMap.Size; 
     currentPosition = new Point(); 
     initialPosition = new Point(); 
     initialMousePosition = new Point(); //mapLocation; 

    } 
    protected override void OnPaint(PaintEventArgs e) 
    { 
     e.Graphics.PageUnit = GraphicsUnit.Pixel; 
     e.Graphics.PageScale = 1.0F; 
     // base.OnPaint(e); 
     if (shownMap == null) 
     { 
      base.OnPaint(e); 
      return; 
     } 
     e.Graphics.DrawImage(shownMap, currentPosition.X, currentPosition.Y); 

    } 
    protected override void OnMouseDown(MouseEventArgs e) 
    { 
     // base.OnMouseDown(e); 
     if (shownMap == null) 
     { 
      base.OnMouseDown(e); 
      return; 
     } 
     if (dragging) 
     { 
      dragging = false; 
      return; 
     } 
     else dragging = true; 
     initialPosition.X = currentPosition.X; 
     initialPosition.Y = currentPosition.Y; 

     initialMousePosition = e.Location; 
    } 
    protected override void OnMouseMove(MouseEventArgs e) 
    { 
     /*parentForm.label7.Text = currentPosition.X.ToString(); 
     parentForm.label8.Text = currentPosition.Y.ToString(); 
     parentForm.label9.Text = mapSize.Width.ToString(); 
     parentForm.label10.Text = mapSize.Height.ToString(); 
     parentForm.label11.Text = Size.Width.ToString(); 
     parentForm.label12.Text = Size.Width.ToString();*/ 

     //base.OnMouseMove(e); 
     if (!dragging) return; 

     currentPosition.X = e.X - initialMousePosition.X + initialPosition.X; 
     currentPosition.Y = e.Y - initialMousePosition.Y + initialPosition.Y; 

     if (currentPosition.X > 0) 
      currentPosition.X = 0; 
     else if (currentPosition.X < -mapSize.Width + Size.Width) 
      currentPosition.X = -mapSize.Width + Size.Width ; 
     if (currentPosition.Y > 0) 
      currentPosition.Y = 0; 
     else if (currentPosition.Y < -mapSize.Height + Size.Height) 
      currentPosition.Y = -mapSize.Height + Size.Height; 

     //if (currentPosition.X + mapSize.Width < this.Size.Width) 
      // currentPosition.X = this.Size.Width - mapSize.Width; 


     Invalidate(); 

    // (e.X - initialPosition.X + xinit, e.Y - init_loc.Y + yinit); 
    } 
    protected override void OnMouseLeave(EventArgs e) 
    { 
     // base.OnMouseLeave(e); 
     dragging = false; 
     // F*! if I hold the mouse down this does not work 
    } 

    protected override void OnMouseUp(MouseEventArgs e) 
    { 
     //base.OnMouseUp(e); 
     dragging = false; 
    } 
} 

}

Answer 1

井的全部代码，似乎什么都有，除了一个事实，即我所用，而不是其DisplayRectangle（Size.Width == DisplayRectangle小组的大小没有不好的逻辑.WIDTH-2）。整个问题是我使用的图像已经从Photoshop中导出，并且分辨率为72dpi而不是96dpi：相同尺寸，但使用DrawImage时，它们被放大。这是我的解决方案。这仍然有待纠正，但这是解决我原来的问题。还有一些变量名称被改变了。

namespace GameMaps 
{ 
public class MapPanel : Panel 
{ 
    private Map sourceMap; 

    private Bitmap mapTexture; 
    private Size mapSize; 
    private Point mapPosition; 
    private float dpiX, dpiY; 

    private Point initialPosition; 
    private Point initialMousePosition; 

    private bool dragging; 

    /* Constructors */ 
    public MapPanel() : base() 
    { 
     this.DoubleBuffered = true; 

     this.sourceMap = null; 
     this.dpiX = 96.0F; this.dpiY = 96.0F; // For now, this Application won't be DPI aware 
    } 

    public MapPanel(Panel targetPanel) : this() 
    { 
     // TO DO 
    } 

    /* Show a Map */ 
    public void ShowMap(Map map) 
    { 
     if (map == null) 
      return; 
     sourceMap = map; 

     mapTexture = new Bitmap(map.MapTexture); 
     mapTexture.SetResolution(dpiX, dpiY); 
     mapSize = mapTexture.Size; // ? 
     mapPosition = new Point(0, 0); 
    } 

    protected override void OnPaint(PaintEventArgs e) 
    { 
     // base.OnPaint(e); 

     e.Graphics.PageUnit = GraphicsUnit.Pixel; // ? 
     e.Graphics.PageScale = 1.0F; // ? 

     if (sourceMap == null) 
     { 
      base.OnPaint(e); 
      return; 
     } 
     e.Graphics.DrawImage(mapTexture, mapPosition.X, mapPosition.Y); 
    } 

    protected override void OnMouseDown(MouseEventArgs e) 
    { 
     // base.OnMouseDown(e); 

     if (sourceMap == null) 
     { 
      base.OnMouseDown(e); 
      return; 
     } 

     if (dragging) 
     { 
      dragging = false; 
      return; 
     } 
     else dragging = true; 

     initialPosition.X = mapPosition.X; 
     initialPosition.Y = mapPosition.Y; 

     initialMousePosition.X = e.Location.X; 
     initialMousePosition.Y = e.Location.Y; 
    } 

    protected override void OnMouseMove(MouseEventArgs e) 
    { 
     //base.OnMouseMove(e); 

     if (!dragging) return; 

     mapPosition.X = e.X - initialMousePosition.X + initialPosition.X; 
     mapPosition.Y = e.Y - initialMousePosition.Y + initialPosition.Y; 

     if (mapPosition.X > 0) 
      mapPosition.X = 0; 
     else if (mapPosition.X < DisplayRectangle.Width - mapSize.Width) 
      mapPosition.X = DisplayRectangle.Width - mapSize.Width; 

     if (mapPosition.Y > 0) 
      mapPosition.Y = 0; 
     else if (mapPosition.Y < DisplayRectangle.Height - mapSize.Height) 
      mapPosition.Y = DisplayRectangle.Height - mapSize.Height; 

     Invalidate(); // Force Repaint 
    } 

    protected override void OnMouseLeave(EventArgs e) 
    { 
     // base.OnMouseLeave(e); 

     dragging = false; 
     // TO DO: Correct this 
    } 

    protected override void OnMouseUp(MouseEventArgs e) 
    { 
     //base.OnMouseUp(e); 

     dragging = false; 
    } 
} 
}