Scrollbar Annotations

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When grids contain many rows, locating those with validation errors, and those that are focused or selected, can be difficult. To help locate these rows expeditiously, display scrollbar annotations. The latter are colored marks on the vertical scrollbar that reflect the location of corresponding rows in the grid.

Scrollbar_Annotations

How to Enable

The GridView.OptionsScrollAnnotations property provides access to options that allow you to enable/disable specific annotations.

  • ShowErrors — specifies whether to mark rows with validation errors
  • ShowFocusedRow — specifies whether to mark the focused row
  • ShowSelectedRows — specifies whether to mark selected rows
  • ShowCustomAnnotations — specifies whether to mark rows with custom annotations provided using a dedicated event (see below)

Scrollbar annotations are disabled if a property equals to Default. Set the property to True to enable them.


// Enable annotations for the focused row.
gridView.OptionsScrollAnnotations.ShowFocusedRow = DefaultBoolean.True;

The grid control also displays scrollbar annotations for search requests if the Find Panel is in search mode.

Limitations

Scrollbar annotations have the following limitations.

Custom Annotations

The GridView.CustomScrollAnnotation event allows you to provide data about the required custom annotations. Data is represented by the GridScrollAnnotationInfo type, which exposes the following properties.

  • RowHandle — handle of the required row (see Row handles in the Rows topic)
  • Color — color of the mark on the scrollbar

When handling this event, create data objects and add them to the Annotations collection in the event arguments.


void OnCustomScrollAnnotation(object sender, GridCustomScrollAnnotationsEventArgs e) {
    GridScrollAnnotationInfo info = new GridScrollAnnotationInfo() { RowHandle = 74, Color = Color.Red };
    e.Annotations.Add(info);
}

The SetAnnotations method allows you to set annotations for a row array. Note that this method does not add annotations, but resets them.


void OnCustomScrollAnnotation(object sender, GridCustomScrollAnnotationsEventArgs e) {
    int[] rowHandles = new int[] { 5, 17, 74 };
    e.SetAnnotations(Color.Red, rowHandles);
}

How to: Create Row Bookmarks Using Scrollbar Annotations and Row Indicators

NOTE

Run the Scrollbar Annotations & Bookmarks module in the XtraGrid demo to see the functionality in action.

You can provide users with the ability to bookmark specific rows and navigate between them using the keyboard. To implement this functionality, handle the following events.


using DevExpress.XtraEditors.Annotations;
using DevExpress.XtraGrid.Views.Grid;
using DevExpress.XtraGrid.Views.Grid.Drawing;

gridView.CustomScrollAnnotation += OnCustomScrollAnnotation;
gridView.CustomDrawRowIndicator += OnCustomDrawRowIndicator;
gridView.ScrollAnnotationsStyle += OnScrollAnnotationsStyle;
gridView.KeyDown += OnKeyDown;

readonly HashSet<int> bookmarks = new HashSet<int>() { 5, 17, 74 };
// Set custom annotations.
void OnCustomScrollAnnotation(object sender, GridCustomScrollAnnotationsEventArgs e) {
    int[] rowHandles = bookmarks.Select(x => gridView.GetRowHandle(x)).ToArray();
    e.SetAnnotations(DevExpress.LookAndFeel.DXSkinColors.IconColors.Blue, rowHandles);
}
readonly AnnotationsStyle style = new AnnotationsStyle();
void OnScrollAnnotationsStyle(object sender, GridScrollAnnotationsStyleEventArgs e) {
    var styleColor = style.GetColor(e.Kind);
    if(!styleColor.IsEmpty)
        e.Color = styleColor;
}
// Draw a bookmark glyph.
void OnCustomDrawRowIndicator(object sender, RowIndicatorCustomDrawEventArgs e) {
    if(e.RowHandle >= 0) {
        if(e.Info.ImageIndex == GridPainter.IndicatorError ||
            e.Info.ImageIndex == GridPainter.IndicatorFocusedError) {
            e.Info.ImageIndex = (e.RowHandle == gridView.FocusedRowHandle) ? GridPainter.IndicatorFocused : -1;
        }
        if(!bookmarks.Contains(gridView.GetDataSourceRowIndex(e.RowHandle)))
            return;
        e.DefaultDraw();
        var bookmarkImage = svgImageCollection.GetImage("bookmark", GetPalette(), ScaleDPI.ScaleSize(new Size(8, 8)));
        var imageBounds = PlacementHelper.Arrange(bookmarkImage.Size, e.Bounds, ContentAlignment.MiddleLeft);
        e.Cache.DrawImageUnscaled(bookmarkImage, imageBounds);
        e.Handled = true;
    }
}
Utils.Design.ISvgPaletteProvider GetPalette() {
    return Utils.Svg.SvgPaletteHelper.GetSvgPalette(gridControl.LookAndFeel, Utils.Drawing.ObjectState.Normal);
}
// Implement forward and back navigation.
void OnKeyDown(object sender, KeyEventArgs e) {
    if(e.KeyData == (Keys.F2 | Keys.Control) || e.KeyData == (Keys.B | Keys.Control))
        e.Handled = ToggleBookmark(gridView.FocusedRowHandle);
    if(e.KeyData == Keys.F2)
        e.Handled = gridView.MoveToNextScrollAnnotation(ScrollAnnotationKind.Custom);
    if(e.KeyData == (Keys.F2 | Keys.Shift))
        e.Handled = gridView.MoveToPrevScrollAnnotation(ScrollAnnotationKind.Custom);
}
bool ToggleBookmark(int handle) {
    int dataIndex = gridView.GetDataSourceRowIndex(handle);
    if(dataIndex < 0)
        return false;
    if(bookmarks.Contains(dataIndex))
        bookmarks.Remove(dataIndex);
    else
        bookmarks.Add(dataIndex);
    gridView.RefreshScrollAnnotations(ScrollAnnotationKind.Custom);
    gridView.InvalidateRow(handle);
    return true;
}
See Also