Created
January 26, 2016 19:48
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Gives the TokenEdit control the ability to be reordered via drag and drop.
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| using System; | |
| using System.Collections; | |
| using System.ComponentModel; | |
| using System.Drawing; | |
| using System.Drawing.Drawing2D; | |
| using System.Linq; | |
| using System.Reflection; | |
| using System.Windows.Forms; | |
| using DevExpress.XtraEditors; | |
| using DevExpress.XtraEditors.ViewInfo; | |
| public sealed class TokenEditDragHelper : IDisposable | |
| { | |
| private readonly TokenEdit edit; | |
| private readonly bool previousAllowDrop; | |
| private TokenEditToken mouseDownToken; | |
| private TokenEditTokenInfo insertBefore; | |
| private bool shouldDrawDropIndicator; | |
| public TokenEditDragHelper(TokenEdit edit) | |
| { | |
| this.edit = edit; | |
| previousAllowDrop = edit.AllowDrop; | |
| edit.AllowDrop = true; | |
| edit.DragEnter += Edit_DragEnter; | |
| edit.DragLeave += Edit_DragLeave; | |
| edit.DragDrop += Edit_DragDrop; | |
| edit.DragOver += Edit_DragOver; | |
| edit.MouseDown += Edit_MouseDown; | |
| edit.MouseMove += Edit_MouseMove; | |
| edit.Paint += Edit_Paint; | |
| } | |
| public void Dispose() | |
| { | |
| edit.DragEnter -= Edit_DragEnter; | |
| edit.DragLeave -= Edit_DragLeave; | |
| edit.DragDrop -= Edit_DragDrop; | |
| edit.DragOver -= Edit_DragOver; | |
| edit.MouseDown -= Edit_MouseDown; | |
| edit.MouseMove -= Edit_MouseMove; | |
| edit.Paint -= Edit_Paint; | |
| edit.AllowDrop = previousAllowDrop; | |
| } | |
| private void Edit_Paint(object sender, PaintEventArgs e) | |
| { | |
| if (!shouldDrawDropIndicator) return; | |
| using (var p = new Pen(Color.Black, 2)) | |
| { | |
| p.CustomEndCap = p.CustomStartCap = GetInsertionLineCap(); | |
| if (insertBefore != null) | |
| e.Graphics.DrawLine(p, insertBefore.Bounds.Left + .5f, insertBefore.Bounds.Top, insertBefore.Bounds.Left + .5f, insertBefore.Bounds.Bottom - .5f); | |
| else | |
| { | |
| var insertAfter = edit.GetViewInfo().GetTokenInfo(edit.SelectedItems.LastToken); | |
| e.Graphics.DrawLine(p, insertAfter.Bounds.Right - .5f, insertAfter.Bounds.Top, insertAfter.Bounds.Right - .5f, insertAfter.Bounds.Bottom - .5f); | |
| } | |
| } | |
| } | |
| private static CustomLineCap insertionLineCap; | |
| private static CustomLineCap GetInsertionLineCap() | |
| { | |
| if (insertionLineCap == null) | |
| using (var customCapPath = new GraphicsPath()) | |
| { | |
| customCapPath.AddPolygon(new[] | |
| { | |
| new PointF(0, 0), | |
| new PointF(-.5f, 0), | |
| new PointF(0, -.5f), | |
| new PointF(.5f, 0) | |
| }); | |
| insertionLineCap = new CustomLineCap(null, customCapPath); | |
| } | |
| return insertionLineCap; | |
| } | |
| private void Edit_MouseDown(object sender, MouseEventArgs e) | |
| { | |
| mouseDownToken = edit.CalcHitInfo(e.Location).Token; | |
| } | |
| private void Edit_MouseMove(object sender, MouseEventArgs e) | |
| { | |
| if (e.Button == MouseButtons.Left && mouseDownToken != null) | |
| edit.DoDragDrop(mouseDownToken, DragDropEffects.Move); | |
| } | |
| private TokenEditToken TryGetValidToken(IDataObject dataObject) | |
| { | |
| var token = (TokenEditToken)dataObject.GetData(typeof(TokenEditToken)); | |
| return token != null && edit.Properties.Tokens.Contains(token) ? token : null; | |
| } | |
| private void Edit_DragEnter(object sender, DragEventArgs e) | |
| { | |
| e.Effect = TryGetValidToken(e.Data) != null ? DragDropEffects.Move : DragDropEffects.None; | |
| shouldDrawDropIndicator = true; | |
| } | |
| private void Edit_DragOver(object sender, DragEventArgs e) | |
| { | |
| insertBefore = GetTokenInsertBefore(edit, edit.PointToClient(new Point(e.X, e.Y))); | |
| edit.Invalidate(); | |
| } | |
| private void Edit_DragLeave(object sender, EventArgs e) | |
| { | |
| shouldDrawDropIndicator = false; | |
| edit.Invalidate(); | |
| } | |
| private void Edit_DragDrop(object sender, DragEventArgs e) | |
| { | |
| shouldDrawDropIndicator = false; | |
| edit.Invalidate(); | |
| var validToken = TryGetValidToken(e.Data); | |
| if (validToken == null) return; | |
| var tokenInsertBefore = GetTokenInsertBefore(edit, edit.PointToClient(new Point(e.X, e.Y))); | |
| var removeIndex = edit.SelectedItems.IndexOf(validToken); | |
| var insertIndex = tokenInsertBefore == null ? edit.SelectedItems.Count : edit.SelectedItems.IndexOf(tokenInsertBefore.Token); | |
| if (insertIndex > removeIndex) insertIndex--; | |
| if (insertIndex == removeIndex) return; | |
| // There is no other way to do a generic insert that works for any binding mode | |
| var innerList = (IList)typeof(ReadOnlyCollectionBase).GetProperty("InnerList", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(edit.SelectedItems); | |
| innerList.RemoveAt(removeIndex); | |
| innerList.Insert(insertIndex, validToken); | |
| typeof(TokenEditTokenReadOnlyCollectionBase).GetMethod("RaiseListChanged", BindingFlags.Instance | BindingFlags.NonPublic) | |
| .Invoke(edit.SelectedItems, new object[] { new ListChangedEventArgs(ListChangedType.Reset, -1) }); | |
| } | |
| private static TokenEditTokenInfo GetTokenInsertBefore(TokenEdit edit, Point location) | |
| { | |
| // We can't rely on CalcHitInfo because it does not give nearest row/nearest token information for points between tokens. | |
| var rows = edit.GetViewInfo().VisibleItems.Cast<TokenEditTokenInfo>().GroupBy(_ => _.RowIndex).OrderBy(_ => _.Key).ToList(); | |
| int rowIndex; | |
| for (rowIndex = 0; rowIndex < rows.Count - 1; rowIndex++) | |
| { | |
| var rowBottom = rows[rowIndex].First().Bounds.Bottom - 1; | |
| if (location.Y <= rowBottom) break; | |
| var nextRowTop = rows[rowIndex + 1].First().Bounds.Top; | |
| if (location.Y < nextRowTop) | |
| { | |
| if (nextRowTop - location.Y < location.Y - rowBottom) rowIndex++; | |
| break; | |
| } | |
| } | |
| var tokensInRow = rows[rowIndex].OrderBy(_ => _.Bounds.Left).ToList(); | |
| int tokenIndex; | |
| for (tokenIndex = 0; tokenIndex < tokensInRow.Count; tokenIndex++) | |
| if (location.X <= tokensInRow[tokenIndex].Bounds.Left + (tokensInRow[tokenIndex].Bounds.Width + 1) / 2) | |
| return tokensInRow[tokenIndex]; | |
| rowIndex++; | |
| return rowIndex == rows.Count ? null : rows[rowIndex].OrderBy(_ => _.Bounds.Left).First(); | |
| } | |
| } |
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