如何拖放过程中自动滚屏一个DataGridView [英] How To AutoScroll a DataGridView during Drag and Drop
问题描述
一个在我的C＃.NET应用程序的形式有实现拖放来移动行多DataGridViews。拖放大多拖作品的权利，但我一直有一个很难得到DataGridViews到的AutoScroll - 当行拖到靠近箱的顶部或底部，在该方向滚动它
One of the forms in my C# .NET application has multiple DataGridViews that implement drag and drop to move the rows around. The drag and drop mostly works right, but I've been having a hard time getting the DataGridViews to AutoScroll - when a row is dragged near the top or bottom of the box, to scroll it in that direction.
到目前为止，我已经尝试实现一个版本的这个解决方案。我有一个ScrollingGridView类从实现所描述的计时器的DataGridView继承，并根据调试器，定时器被适当地烧制，但是定时器代码：
So far, I've tried implementing a version of this solution. I have a ScrollingGridView class inheriting from DataGridView that implements the described timer, and according to the debugger, the timer is firing appropriately, but the timer code:
const int WM_VSCROLL = 277;
private static extern int SendMessage(IntPtr hWnd, int wMsg, IntPtr wParam, IntPtr lParam);
private void ScrollingGridViewTimerTick(object sender, EventArgs e)
{
SendMessage(Handle, WM_VSCROLL, (IntPtr)scrollDirectionInt, IntPtr.Zero);
}
什么都不做，据我所知，可能是因为我有多DataGridViews形式。我也尝试修改AutoScrollOffset财产，但它还是不执行任何操作。在DataGridView和滚动条类的调查似乎并没有提出任何其他的命令或功能，将实际上使DataGridView的滚动。谁能帮我实际上将滚动DataGridView的一个功能，或者一些其他的方式来解决这个问题？
doesn't do anything as far as I can tell, possibly because I have multiple DataGridViews in the form. I also tried modifying the AutoScrollOffset property, but that didn't do anything either. Investigation of the DataGridView and ScrollBar classes doesn't seem to suggest any other commands or functions that will actually make the DataGridView scroll. Can anyone help me with a function that will actually scroll the DataGridView, or some other way to solve the problem?
推荐答案
我的避风港T看了这段代码在一段时间。不过前阵子我实现了支持只是这一个DataGridView
I haven't looked at this code in a while. But a while back I implemented a DataGridView that supported just this.
class DragOrderedDataGridView : System.Windows.Forms.DataGridView
{
public delegate void RowDroppedEventHangler(object source, DataGridViewRow sourceRow, DataGridViewRow destinationRow);
public event RowDroppedEventHangler RowDropped;
bool bDragging = false;
System.Windows.Forms.DataGridView.HitTestInfo hti = null;
System.Threading.Timer scrollTimer = null;
delegate void SetScrollDelegate(int value);
public bool AllowDragOrdering { get; set; }
protected override void OnMouseDown(System.Windows.Forms.MouseEventArgs e)
{
if (AllowDragOrdering)
{
DataGridView.HitTestInfo hti = this.HitTest(e.X, e.Y);
if (hti.RowIndex != -1
&& hti.RowIndex != this.NewRowIndex
&& e.Button == MouseButtons.Left)
{
bDragging = true;
}
}
base.OnMouseDown(e);
}
protected override void OnMouseMove(System.Windows.Forms.MouseEventArgs e)
{
if (bDragging && e.Button == MouseButtons.Left)
{
DataGridView.HitTestInfo newhti = this.HitTest(e.X, e.Y);
if (hti != null && hti.RowIndex != newhti.RowIndex)
{
System.Diagnostics.Debug.WriteLine("invalidating " + hti.RowIndex.ToString());
Invalidate();
}
hti = newhti;
System.Diagnostics.Debug.WriteLine(string.Format("{0:000} {1} ", hti.RowIndex, e.Location));
Point clientPoint = this.PointToClient(e.Location);
System.Diagnostics.Debug.WriteLine(e.Location + " " + this.Bounds.Size);
if (scrollTimer == null
&& ShouldScrollDown(e.Location))
{
//
// enable the timer to scroll the screen
//
scrollTimer = new System.Threading.Timer(new System.Threading.TimerCallback(TimerScroll), 1, 0, 250);
}
if (scrollTimer == null
&& ShouldScrollUp(e.Location))
{
scrollTimer = new System.Threading.Timer(new System.Threading.TimerCallback(TimerScroll), -1, 0, 250);
}
}
else
{
bDragging = false;
}
if (!(ShouldScrollUp(e.Location) || ShouldScrollDown(e.Location)))
{
StopAutoScrolling();
}
base.OnMouseMove(e);
}
bool ShouldScrollUp(Point location)
{
return location.Y > this.ColumnHeadersHeight
&& location.Y < this.ColumnHeadersHeight + 15
&& location.X >= 0
&& location.X <= this.Bounds.Width;
}
bool ShouldScrollDown(Point location)
{
return location.Y > this.Bounds.Height - 15
&& location.Y < this.Bounds.Height
&& location.X >= 0
&& location.X <= this.Bounds.Width;
}
void StopAutoScrolling()
{
if (scrollTimer != null)
{
//
// disable the timer to scroll the screen
//
scrollTimer.Change(System.Threading.Timeout.Infinite, System.Threading.Timeout.Infinite);
scrollTimer = null;
}
}
void TimerScroll(object state)
{
SetScrollBar((int)state);
}
bool scrolling = false;
void SetScrollBar(int direction)
{
if (scrolling)
{
return;
}
if (this.InvokeRequired)
{
this.Invoke(new Action<int>(SetScrollBar), new object[] {direction});
}
else
{
scrolling = true;
if (0 < direction)
{
if (this.FirstDisplayedScrollingRowIndex < this.Rows.Count - 1)
{
this.FirstDisplayedScrollingRowIndex++;
}
}
else
{
if (this.FirstDisplayedScrollingRowIndex > 0)
{
this.FirstDisplayedScrollingRowIndex--;
}
}
scrolling = false;
}
}
protected override void OnMouseUp(System.Windows.Forms.MouseEventArgs e)
{
bDragging = false;
HitTestInfo livehti = hti;
hti = null;
if (RowDropped != null
&& livehti != null
&& livehti.RowIndex != -1
&& this.CurrentRow.Index != livehti.RowIndex)
{
RowDropped(this, this.CurrentRow, this.Rows[livehti.RowIndex]);
}
StopAutoScrolling();
Invalidate();
base.OnMouseUp(e);
}
protected override void OnCellPainting(System.Windows.Forms.DataGridViewCellPaintingEventArgs e)
{
if (bDragging && hti != null && hti.RowIndex != -1
&& e.RowIndex == hti.RowIndex)
{
//
// draw the indicator
//
Pen p = new Pen(Color.FromArgb(0, 0, 215));
p.Width = 4;
e.Graphics.DrawLine(p, e.CellBounds.Left, e.CellBounds.Top, e.CellBounds.Right, e.CellBounds.Top);
}
base.OnCellPainting(e);
}
}
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