一款简单的缩放拖拽图片控件

/// <summary>
/// 计算鼠标移动位置是否还在容器内
/// </summary>
/// <returns></returns>
private bool IsMouseInPanel()
{
    if (PanBox.Left < PointToClient(Cursor.Position).X
    && PointToClient(Cursor.Position).X < PanBox.Left + PanBox.Width
    && PanBox.Top < PointToClient(Cursor.Position).Y
    && PointToClient(Cursor.Position).Y < PanBox.Top + PanBox.Height)
    {
        return true;
    }
    else
    {
        return false;
    }
}

/// <summary>
/// 鼠标移动
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void PicBox_MouseMove(object sender, MouseEventArgs e)
{
    //开启移动 左键按下 并且移动位置在框内
    if (_CanMove && isSelected && IsMouseInPanel())
    {
        PicBox.Location = new Point(PicBox.Left + (Cursor.Position.X - mouseDownPoint.X), PicBox.Top + (Cursor.Position.Y - mouseDownPoint.Y));
        mouseDownPoint = Cursor.Position;
    }
}

/// <summary>
/// 控制图片缩放
/// </summary>
/// <param name="change">变化情况，大于 0 放大，小于 0 缩小</param>
public void PicZoomSize(int change)
{
    var t = PicBox.Size;
    t.Width += change;
    t.Height += change;

    //控制最小缩放
    if (t.Width < _ZoomMin) return;
    PicBox.Size = t;

    //图片按中心比例放大缩小
    if (!_ZoomCenter) return;
    PicBox.Location = new Point((this.Width - PicBox.Width) / 2, (this.Height - PicBox.Height) / 2);
}