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ccdf826466
- slightly improved assert message when row cell counts don't match column count. - more breadcrumbs in API documentation. more documentation in general. - added more documentation for the direction of the "ascending" arrow. - two samples for PaginatedDataTable. - make PaginatedDataTable support hot reloading across changes to the number of columns. - introduce matrix3MoreOrLessEquals. An earlier version of this PR used it in tests, but eventually it was not needed. The function seems useful to keep though.
76 lines
3.5 KiB
Dart
76 lines
3.5 KiB
Dart
// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:flutter/foundation.dart';
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import 'data_table.dart';
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/// A data source for obtaining row data for [PaginatedDataTable] objects.
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///
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/// A data table source provides two main pieces of information:
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///
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/// * The number of rows in the data table ([rowCount]).
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/// * The data for each row (indexed from `0` to `rowCount - 1`).
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///
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/// It also provides a listener API ([addListener]/[removeListener]) so that
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/// consumers of the data can be notified when it changes. When the data
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/// changes, call [notifyListeners] to send the notifications.
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///
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/// DataTableSource objects are expected to be long-lived, not recreated with
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/// each build.
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///
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/// If a [DataTableSource] is used with a [PaginatedDataTable] that supports
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/// sortable columns (see [DataColumn.onSort] and
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/// [PaginatedDataTable.sortColumnIndex]), the rows reported by the data source
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/// must be reported in the sorted order.
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abstract class DataTableSource extends ChangeNotifier {
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/// Called to obtain the data about a particular row.
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///
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/// Rows should be keyed so that state can be maintained when the data source
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/// is sorted (e.g. in response to [DataColumn.onSort]). Keys should be
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/// consistent for a given [DataRow] regardless of the sort order (i.e. the
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/// key represents the data's identity, not the row position).
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///
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/// The [DataRow.byIndex] constructor provides a convenient way to construct
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/// [DataRow] objects for this method's purposes without having to worry about
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/// independently keying each row. The index passed to that constructor is the
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/// index of the underlying data, which is different than the `index`
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/// parameter for [getRow], which represents the _sorted_ position.
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///
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/// If the given index does not correspond to a row, or if no data is yet
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/// available for a row, then return null. The row will be left blank and a
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/// loading indicator will be displayed over the table. Once data is available
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/// or once it is firmly established that the row index in question is beyond
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/// the end of the table, call [notifyListeners]. (See [rowCount].)
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///
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/// If the underlying data changes, call [notifyListeners].
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DataRow? getRow(int index);
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/// Called to obtain the number of rows to tell the user are available.
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///
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/// If [isRowCountApproximate] is false, then this must be an accurate number,
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/// and [getRow] must return a non-null value for all indices in the range 0
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/// to one less than the row count.
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///
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/// If [isRowCountApproximate] is true, then the user will be allowed to
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/// attempt to display rows up to this [rowCount], and the display will
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/// indicate that the count is approximate. The row count should therefore be
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/// greater than the actual number of rows if at all possible.
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///
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/// If the row count changes, call [notifyListeners].
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int get rowCount;
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/// Called to establish if [rowCount] is a precise number or might be an
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/// over-estimate. If this returns true (i.e. the count is approximate), and
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/// then later the exact number becomes available, then call
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/// [notifyListeners].
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bool get isRowCountApproximate;
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/// Called to obtain the number of rows that are currently selected.
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///
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/// If the selected row count changes, call [notifyListeners].
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///
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/// Selected rows are those whose [DataRow.selected] property is set to true.
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int get selectedRowCount;
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}
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