移动另一个控制的可视区域

Question

内的控制我有一个PictureBox这是一个TabPage里面，当然这TabPage是TabView的一部分，这TabView是Form内。我希望用户能够在标签页内移动此图片框。为此，我现在用的图片框的MouseDown，MouseMove和MouseUp事件：

private void pictureBoxPackageView_MouseDown(object sender, MouseEventArgs e) 
{ 
    if (!_mapPackageIsMoving) 
    { 
     _mapPackageIsMoving = true; 
    } 
} 

private void pictureBoxPackageView_MouseMove(object sender, MouseEventArgs e) 
{ 
    if(_mapPackageIsMoving) 
    { 
     pictureBoxPackageView.Location = MousePosition; //This is not exact at all! 
     return; 
    } 

    //Some other code for some other stuff when picturebox is not moving... 
} 

private void pictureBoxPackageView_MouseUp(object sender, MouseEventArgs e) 
{ 
    if (_mapPackageIsMoving) 
    { 
     _mapPackageIsMoving = false; //Mouse button is up, end moving! 
     return; 
    } 
} 

但我的问题出在MouseMove事件。只要按下按钮后移动鼠标，图片框就会跳出标签页的可见区域。

我需要知道如何处理移动只在标签页的矩形内，如果图片框被拖出标签视图的可见区域，它不应该再移动，除非用户将鼠标放在标签内视图的可见矩形。

任何帮助/提示将appriciated！

Answer 1

你需要一个变量来保存图片框的原始位置：

从HansPassant answer修改：

private Point start = Point.Empty; 

void pictureBoxPackageView_MouseUp(object sender, MouseEventArgs e) { 
    _mapPackageIsMoving = false; 
} 

void pictureBoxPackageView_MouseMove(object sender, MouseEventArgs e) { 
    if (_mapPackageIsMoving) { 
    pictureBoxPackageView.Location = new Point(
          pictureBoxPackageView.Left + (e.X - start.X), 
          pictureBoxPackageView.Top + (e.Y - start.Y)); 
    } 
} 

void pictureBoxPackageView_MouseDown(object sender, MouseEventArgs e) { 
    start = e.Location; 
    _mapPackageIsMoving = true; 
}