Jain's 學習之路

I've been working with MVVM and WPF for a couple of weeks now. I decided to log what I've learned here. Here goes a getting started tutorial with MVVM. Download the source code . The Model-View-ViewModel pattern was introduced by John Gossman to effectively utilize the functionality of WPF. Since then, MVVM has been used in a number of WPF applications with very impressive results. MVVM has three components: Model: It is your data or classes that represent entities in your application. It normally contains no WPF-specific code. View: This is the User Interface element visible to the user. Its DataContext is its ViewModel. ViewModel: It contains all the data that needs to be displayed and procedures to modify the model at will. The magic about MVVM is that the ViewModel knows nothing about the View. You see that this is very loosely coupled. The View knows the ViewModel but the ViewModel does not know the View. You can very easily replace the View without affecting t...

Style 用來在類型的不同實例之間共享屬性、資源和事件處理程序，您可以將 Style 看作是將一組屬性值應用到多個元素的捷徑。 　　這是MSDN上對Style的描述，翻譯的還算中規中矩。Style（樣式），簡單來說，就是一種對屬性值的批處理，類似于Html的CSS，可以快速的設置一系列屬性值到UI元素。   示例 　　一個最簡單的Style的例子： <Window> <Grid> <Grid.Resources> <Style TargetType="{x:Type Button}" x:Key="ButtonStyle"> <Setter Property="Height" Value="22"/> <Setter Property="Width" Value="60"/> </Style> </Grid.Resources> <Button Content="Button" Style="{StaticResource ButtonStyle}"/> <Button Content="Button" Style="{StaticResource ButtonStyle}" Margin="156,144,286,145" /> </Grid> </Window> 　　關于Resources的知識，請參見 MSDN ，這里創建了一個目標類型為Button的ButtonStyle，兩個Button使用靜態資源（ StaticResource ）的查找方式來找到這個Style。Style中定義了Button的高度（Height）和寬度（Width），當使用了這個Style后，兩個Button無需手動設置，即可自動設置...

在 WPF 中有很多種方式來描繪圖形, 其 DrawingVisual 是一個輕量級的 Class, 它需一個 container 來承接, 並不提供 Layout, Hit-Testing 及 Event-Handling. 那來實作一下如何使用 DrawingVisual 來描繪圖形. 建立一個 class, 它繼承 FrameworkElement Class, 並描繪一個 Rectangle . public class MyVisualHost : FrameworkElement { private VisualCollection childern; public MyVisualHost() { childern = new VisualCollection(this); childern.Add(CreateDrawingVisualRectangle()); } protected override int VisualChildrenCount { get { return childern.Count; } } protected override Visual GetVisualChild(int index) { return childern[index]; } private DrawingVisual CreateDrawingVisualRectangle() { DrawingVisual drawing = new DrawingVisual(); using (DrawingContext content = drawing.RenderOpen()) { content.DrawRectangle(Brushes.Red, new Pen(Brushes....

  WPF性能優化一 - Rendering Tier  根据硬件配置的不同，WPF采用不同的Rendering Tier做渲染。下列情況請特別注意，因為在這些情況下，即使是處于Rendering Tier 2的情況下也不會硬件加速。(不全，其余請查閱SDK)  WPF性能優化二 - 布局和設計  盡量多使用Canvas等簡單的布局元素，少使用Grid或者StackPanel等復雜的，越復雜性能開銷越大。  建立邏輯樹或者視覺樹的時候，遵循Top-Down的原則。  WPF性能優化三 - 圖像  對Image做動畫處理的時候（如調整大小等），可以使用這條語句RenderOptions.SetBitmapScalingMode(MyImage,BitmapScalingMode.LowQuality)，以改善性能。 用TileBrush的時候，可以CachingHint。  WPF性能優化四 - 對象行為  訪問CLR對象和CLR屬性的效率會比訪問DependencyObject/DependencyProperty高。注意這里指的是訪問，不要和前面的綁定混淆了。但是，把屬性注冊為DependencyProperty會有很多的優點：比如繼承、數据綁定和Style。 WPF性能優化五 - 應用程序資源  在自定義控件，盡量不要在控件的ResourceDictionary定義資源，而應該放在Window或者Application級。因為放在控件中會使每個實例都保留一份資源的拷貝。 盡量使用Static Resources,但不能盲目使用。  WPF性能優化六 - 文本  文字少的時候用TextBlock或者label,長的時候用FlowDocument.  使用元素TextFlow和TextBlock時，如果不需要TextFlow的某些特性，就應該考慮使用TextBlock，因為它的效率更高。  在TextFlow中使用UIElement（比如TextBlock）所需的代价要比使用TextElement（比如Run）的代价高.在FlowDocument中盡量避免使用Te...

Today was the first day of my NHibernate course, and I think that it might be good to point out a few of the samples that we worked with. Those are pretty basic NHibernate queries, but they are probably going to be useful for beginners. Let us take my usual Blog model, and see what kind of queries (and results) we can come up with: Let us find a blog by its identifier: var blog = s.Get<Blog>(1); Which results in: We can also try: var blog = s.Load<Blog>(1); Which would result in… absolutely no SQL queries. You can look at a more deep discussion of that here . Now, let us try to search by a property: var blogs = s.CreateCriteria<Blog>() .Add(Restrictions.Eq("Title", "Ayende @ Rahien")) .List<Blog>(); Which results in: If we try to make the same with HQL, it would look: var blogs = s.CreateQuery("from Blog b where b.Title = :title") .SetParameter("title","Ayende @ Rahien") .List<Blog>(); Whic...

最近在看 Flex 的 Framework, 以 Adobe 官方建議的 Cairngorm 做為開始. 1. ModelLocator : 此部份提供了 Model 的功能, 使用Signleton design pattern 的設計把所有的資料都收集到這邊. 2. Command, Event, FrontController: 在 Front Controller 註冊 Command  與對應的 Event, Event Dispatcher 監聽 Event, 爾後操作過程中 dispatch event 觸發 Command 執行動作, 最後 Update Model 更新 View 顯示. 3. Interact with a server : ServiceLocator : 此 Class 提供了 application 將使用的所有 services, 它包含了 HTTPService, WebService, RemoteObject 呼叫. Business Delegate : 此 Class 有三個 Function     to locate the service that is needed     to call a method on the service     to route the result to the specified responder Value Object : 此 Class 一般定義 property 並不需要任何的 methods, 使用來跟 Server 做 transfer strongly-typed complex data object. 4. Responders, Commands, Delegates : Responders : Responders should deal only in strongly-typed application objects. Responders may set values on the model. Commands : Commands never deal directly with ser...

當程式要得知 Server 上的 Protocol 是否已開啟, 可以試著去連接來查看, 下面的程式碼即可得知 Server 上其 Protocol 是否已開啟.下面提供一個簡單的範例. TcpClient client = new TcpClient(); bool isPortExist = false; Random rnd = new Random(); int portId = rnd.Next(10000, 60000); try { client.Connect("localhost", portId); isPortExist = true; } catch (Exception ex) { isPortExist = false; } finally { Console.WriteLine(string.Format("Port Id : {0},protocol {1}", portId, isPortExist ? "opened." : "closed.")); } Console.Read();