Einführung in die Windows Store App Entwicklung mit C# und XAML. Modul 2 Datenbindung und Zugriff auf das lokale Dateisystem

Transcription

1 Einführung in die Windows Store App Entwicklung mit C# und XAML Modul 2 Datenbindung und Zugriff auf das lokale Dateisystem Oktober

2 Referentin Beate Lay C# Programmierung SharePoint Anwendungsentwicklung

3 Mehr erfahren... Microsoft Official Course Essentials of Developing Windows Store Apps Using C# Microsoft Official Course Advanced Windows Store App Development Using C#

4 using System; using System.Linq; using System.Collections.Generic; using System.Collections.ObjectModel; using System.ComponentModel; using System.Runtime.CompilerServices; using Windows.ApplicationModel.Resources.Core; using Windows.Foundation; using Windows.Foundation.Collections; using Windows.UI.Xaml.Data; using Windows.UI.Xaml.Media; using Windows.UI.Xaml.Media.Imaging; using System.Collections.Specialized; using Windows.Storage.FileProperties; using Windows.Storage; using System.Threading.Tasks; using Windows.Storage.Streams; // The data model defined by this file serves as a representative example of a strongly-typed // model that supports notification when members are added, removed, or modified. The property // names chosen coincide with data bindings in the standard item templates. // // Applications may use this model as a starting point and build on it, or discard it entirely and // replace it with something appropriate to their needs. namespace ImageViewer.Data /// <summary> /// Base class for <see cref="sampledataitem"/> and <see cref="sampledatagroup"/> that /// defines properties common to both. /// </summary> [Windows.Foundation.Metadata.WebHostHidden] public abstract class SampleDataCommon : ImageViewer.Common.BindableBase private static Uri _baseuri = new Uri("ms-appx:///"); public SampleDataCommon(String uniqueid, String title, String subtitle, String imagepath, String description)

5 this._uniqueid = uniqueid; this._title = title; this._subtitle = subtitle; this._description = description; this._imagepath = imagepath; private string _uniqueid = string.empty; public string UniqueId get return this._uniqueid; set this.setproperty(ref this._uniqueid, value); private string _title = string.empty; public string Title get return this._title; set this.setproperty(ref this._title, value); private string _subtitle = string.empty; public string Subtitle get return this._subtitle; set this.setproperty(ref this._subtitle, value); private string _description = string.empty; public string Description get return this._description; set this.setproperty(ref this._description, value); private ImageSource _image = null; private String _imagepath = null; public ImageSource Image

6 get set if (this._image == null && this._imagepath!= null) this._image = new BitmapImage(new Uri(SampleDataCommon._baseUri, this._imagepath)); return this._image; this._imagepath = null; this.setproperty(ref this._image, value); public void SetImage(String path) this._image = null; this._imagepath = path; this.onpropertychanged("image"); public override string ToString() return this.title; /// <summary> /// Generic item data model. /// </summary> public class SampleDataItem : SampleDataCommon public SampleDataItem(String uniqueid, String title, String subtitle, String imagepath, String description, BasicProperties content, SampleDataGroup group) : base(uniqueid, title, subtitle, imagepath, description)

7 this._content = content; this._group = group; private BasicProperties _content; public BasicProperties Content get return this._content; set this.setproperty(ref this._content, value); private SampleDataGroup _group; public SampleDataGroup Group get return this._group; set this.setproperty(ref this._group, value); /// <summary> /// Generic group data model. /// </summary> public class SampleDataGroup : SampleDataCommon public SampleDataGroup(String uniqueid, String title, String subtitle, String imagepath, String description) : base(uniqueid, title, subtitle, imagepath, description) Items.CollectionChanged += ItemsCollectionChanged; private void ItemsCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) // Provides a subset of the full items collection to bind to from a GroupedItemsPage // for two reasons: GridView will not virtualize large items collections, and it // improves the user experience when browsing through groups with large numbers of // items. //

8 // A maximum of 12 items are displayed because it results in filled grid columns // whether there are 1, 2, 3, 4, or 6 rows displayed switch (e.action) case NotifyCollectionChangedAction.Add: if (e.newstartingindex < 12) TopItems.Insert(e.NewStartingIndex,Items[e.NewStartingIndex]); if (TopItems.Count > 12) TopItems.RemoveAt(12); break; case NotifyCollectionChangedAction.Move: if (e.oldstartingindex < 12 && e.newstartingindex < 12) TopItems.Move(e.OldStartingIndex, e.newstartingindex); else if (e.oldstartingindex < 12) TopItems.RemoveAt(e.OldStartingIndex); TopItems.Add(Items[11]); else if (e.newstartingindex < 12) TopItems.Insert(e.NewStartingIndex, Items[e.NewStartingIndex]); TopItems.RemoveAt(12); break; case NotifyCollectionChangedAction.Remove: if (e.oldstartingindex < 12) TopItems.RemoveAt(e.OldStartingIndex); if (Items.Count >= 12) TopItems.Add(Items[11]);

9 break; case NotifyCollectionChangedAction.Replace: if (e.oldstartingindex < 12) TopItems[e.OldStartingIndex] = Items[e.OldStartingIndex]; break; case NotifyCollectionChangedAction.Reset: TopItems.Clear(); while (TopItems.Count < Items.Count && TopItems.Count < 12) TopItems.Add(Items[TopItems.Count]); break; private ObservableCollection<SampleDataItem> _items = new ObservableCollection<SampleDataItem>(); public ObservableCollection<SampleDataItem> Items get return this._items; private ObservableCollection<SampleDataItem> _topitem = new ObservableCollection<SampleDataItem>(); public ObservableCollection<SampleDataItem> TopItems get return this._topitem; /// <summary> /// Creates a collection of groups and items with hard-coded content. /// /// SampleDataSource initializes with placeholder data rather than live production /// data so that sample data is provided at both design-time and run-time. /// </summary>

10 public sealed class SampleDataSource private static SampleDataSource _sampledatasource = new SampleDataSource(); private ObservableCollection<SampleDataGroup> _allgroups = new ObservableCollection<SampleDataGroup>(); public ObservableCollection<SampleDataGroup> AllGroups get return this._allgroups; public static IEnumerable<SampleDataGroup> GetGroups(string uniqueid) if (!uniqueid.equals("allgroups")) throw new ArgumentException("Only 'AllGroups' is supported as a collection of groups"); return _sampledatasource.allgroups; public static SampleDataGroup GetGroup(string uniqueid) // Simple linear search is acceptable for small data sets var matches = _sampledatasource.allgroups.where((group) => group.uniqueid.equals(uniqueid)); if (matches.count() == 1) return matches.first(); return null; public static SampleDataItem GetItem(string uniqueid) // Simple linear search is acceptable for small data sets var matches = _sampledatasource.allgroups.selectmany(group => group.items).where((item) => item.uniqueid.equals(uniqueid)); if (matches.count() == 1) return matches.first(); return null; private ObservableCollection<SampleDataItem> _allitems = new ObservableCollection<SampleDataItem>(); public SampleDataSource(StorageFolder rootfolder = null)

11 ReadAllFiles(rootFolder); private async void ReadAllFiles(StorageFolder rootfolder = null) if (rootfolder == null) rootfolder = KnownFolders.PicturesLibrary; await ReadFolder(rootFolder); SampleDataGroup group = new SampleDataGroup( uniqueid: "1", title: "Gruppe 1", subtitle: string.empty, description: string.empty, imagepath: "Assets/DarkGray.png"); foreach (SampleDataItem item in _allitems) group.items.add(item); item.group = group; this.allgroups.add(group); private async Task ReadFolder(StorageFolder folder) IReadOnlyList<StorageFile> files = await folder.getfilesasync(); SampleDataItem item; foreach (StorageFile file in files) BasicProperties fileproperties = await file.getbasicpropertiesasync(); BitmapImage image;

12 item = new SampleDataItem( uniqueid: file.folderrelativeid, title: file.displayname, subtitle: file.path, imagepath: string.empty, description: string.format("diese Datei wurde am 0:d erstellt.", fileproperties.datemodified), content: fileproperties, group: null); image = new BitmapImage(); IRandomAccessStream stream = await file.openasync(fileaccessmode.read); image.setsource(stream); item.image = image; _allitems.add(item); IReadOnlyList<StorageFolder> subfolders = await folder.getfoldersasync(); foreach (StorageFolder subfolder in subfolders) await ReadFolder(subfolder);