网站设计与网页制作培训,小型电商平台有哪些,网站开发合同验收,外部链接链轮的建设对于网站提1.Overview这篇文章主要分享从源代码角度解读wpf中xaml。由于源码查看起来错综复杂“随便找一个对象按下F12就是一个新的世界”#xff0c;看源码的感觉就是在盗梦空间里来回穿梭#xff1b;所以也是耗费很长的时间去阅读源码然后根据自己的理解编写文章和贴出部分关键源码。… 1.Overview这篇文章主要分享从源代码角度解读wpf中xaml。由于源码查看起来错综复杂“随便找一个对象按下F12就是一个新的世界”看源码的感觉就是在盗梦空间里来回穿梭所以也是耗费很长的时间去阅读源码然后根据自己的理解编写文章和贴出部分关键源码。2.Detail大概将从编译、读取、加载这几个维度来解读。以防后面看源码会晕先直接讲结果编写可通过vs完成编译可通过vs完成读取、加载有的帅气的观众就会问了这些研究在实际在项目中应用场景是什么 选择性的加载xamlbaml文件来达到更改UI的操作。动态换肤大家都用过手机app每到过年过节都会看到界面上会出现对应的主题那么我们就可以在程序内设定到了某个节日直接加载对应主题界面的xamlbaml文件来达到这种效果对于动态皮肤场景来说在运行时加载和解析XAML是有意义的。加载不同的.xaml.baml文件以适应不同分辨率的布局简单固定的UI美工人员将设计稿转换为位图可使用blend或者 expression design转成对应的wpf界面还可以适配不同的业务要求。可能这种延伸就是研究的意义吧1编译xamlXAML不仅要能够解决涉及协作问题它还需要快速运行。尽管基于XML格式可以很灵活并且很容易地迁移到其他平台和工具但未必是有效的选择。XML的涉及目标是具有逻辑性、易读而且简单没有被压缩。WPF 使用 BAML(Binaiy Application Markup Language,二进制应用程序标记语言)来克服这 个缺点。BAML 并非新事物它实际上就是 XAML 的二进制表示当在 Visual Studio 中编译 WPF 应用程序时所有 XAML 文件都被转换为 BAML这些 BAML 然后作为资源被嵌入到最 终的 DLL 或 EXE 程序集中。BAML 是标记化的这意味着较长的 XAML 被较短的标记替代。BAML 不仅明显小一些还对其进行了优化从而使它在运行时能够更快地解析。并成为一个内嵌资源BAML由VS编译生成存在obj目录的debug下通过IL反编译项目文件之后可以看到编译完成之后将会被连接到工程的“资源清单”当中。使用Assembly的GetManifestResourceStream方法可以在运行期获取到这个二进制流Assembly asm Assembly.GetExecutingAssembly( );
Stream s asm.GetManifestResourceStream(StreamName);(2)读取、加载xamlbaml使用代码和未经编译的标记(XAML)这种具体方式对于某些特殊情况是很苻意义的* 例如创建高度动态化的用户界面。这种方式在运行时使用 System.Windows.Markup 名 称空间中的 从 XAML 文件中加载部分用户界面。使用代码和编译过的标记(BAML)对于 WPF 而言这是一种更好的方式也是 Visual Studio 支持的一种方式。这种方式为每个窗口创建一个 XAML 橫板这个 XAML 模板 被编译为 BAML并嵌入到最终的程序集中。编译过的 BAML 在运行时被提取出来 用于重新生成用户界面。1.当客户端程序被启动时Runtime接管代码来创建window实例internal object CreateInstanceImpl(BindingFlags bindingAttr,Binder binder,object[] args,CultureInfo culture,object[] activationAttributes,ref StackCrawlMark stackMark){this.CreateInstanceCheckThis();object obj (object) null;try{try{if (activationAttributes ! null)ActivationServices.PushActivationAttributes((Type) this, activationAttributes);if (args null)args EmptyArrayobject.Value;int length args.Length;if (binder null)binder Type.DefaultBinder;if (length 0 (bindingAttr BindingFlags.Public) ! BindingFlags.Default (bindingAttr BindingFlags.Instance) ! BindingFlags.Default (this.IsGenericCOMObjectImpl() || this.IsValueType)){obj this.CreateInstanceDefaultCtor((bindingAttr BindingFlags.NonPublic) BindingFlags.Default, false, true, ref stackMark);}else{ConstructorInfo[] constructors this.GetConstructors(bindingAttr);ListMethodBase methodBaseList new ListMethodBase(constructors.Length);Type[] argumentTypes new Type[length];for (int index 0; index length; index){if (args[index] ! null)argumentTypes[index] args[index].GetType();}for (int index 0; index constructors.Length; index){if (RuntimeType.FilterApplyConstructorInfo((RuntimeConstructorInfo) constructors[index], bindingAttr, CallingConventions.Any, argumentTypes))methodBaseList.Add((MethodBase) constructors[index]);}MethodBase[] methodBaseArray new MethodBase[methodBaseList.Count];methodBaseList.CopyTo(methodBaseArray);if (methodBaseArray ! null methodBaseArray.Length 0)methodBaseArray (MethodBase[]) null;if (methodBaseArray null){if (activationAttributes ! null){ActivationServices.PopActivationAttributes((Type) this);activationAttributes (object[]) null;}throw new MissingMethodException(Environment.GetResourceString(MissingConstructor_Name, (object) this.FullName));}object state (object) null;MethodBase methodBase;try{methodBase binder.BindToMethod(bindingAttr, methodBaseArray, ref args, (ParameterModifier[]) null, culture, (string[]) null, out state);}catch (MissingMethodException ex){methodBase (MethodBase) null;}if (methodBase (MethodBase) null){if (activationAttributes ! null){ActivationServices.PopActivationAttributes((Type) this);activationAttributes (object[]) null;}throw new MissingMethodException(Environment.GetResourceString(MissingConstructor_Name, (object) this.FullName));}if (RuntimeType.DelegateType.IsAssignableFrom(methodBase.DeclaringType))new SecurityPermission(SecurityPermissionFlag.UnmanagedCode).Demand();if (methodBase.GetParametersNoCopy().Length 0){if (args.Length ! 0)throw new NotSupportedException(string.Format((IFormatProvider) CultureInfo.CurrentCulture, Environment.GetResourceString(NotSupported_CallToVarArg)));obj Activator.CreateInstance((Type) this, true);}else{obj ((ConstructorInfo) methodBase).Invoke(bindingAttr, binder, args, culture);if (state ! null)binder.ReorderArgumentArray(ref args, state);}}}finally{if (activationAttributes ! null){ActivationServices.PopActivationAttributes((Type) this);activationAttributes (object[]) null;}}}catch (Exception ex){throw;}return obj;}2.Window构造函数调用Application.LoadComponent读取创建.xaml(baml)IL反编译后的代码/// summary
/// MainWindow
/// /summary
public partial class MainWindow : System.Windows.Window, System.Windows.Markup.IComponentConnector {#line 10 ..\..\..\MainWindow.xaml[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute(Microsoft.Performance, CA1823:AvoidUnusedPrivateFields)]internal System.Windows.Controls.TextBox textBox;#line default#line hiddenprivate bool _contentLoaded;/// summary/// InitializeComponent/// /summary[System.Diagnostics.DebuggerNonUserCodeAttribute()][System.CodeDom.Compiler.GeneratedCodeAttribute(PresentationBuildTasks, 6.0.0.0)]public void InitializeComponent() {if (_contentLoaded) {return;}_contentLoaded true;System.Uri resourceLocater new System.Uri(/WpfApp1;component/mainwindow.xaml, System.UriKind.Relative);#line 1 ..\..\..\MainWindow.xamlSystem.Windows.Application.LoadComponent(this, resourceLocater);#line default#line hidden}[System.Diagnostics.DebuggerNonUserCodeAttribute()][System.CodeDom.Compiler.GeneratedCodeAttribute(PresentationBuildTasks, 6.0.0.0)][System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)][System.Diagnostics.CodeAnalysis.SuppressMessageAttribute(Microsoft.Design, CA1033:InterfaceMethodsShouldBeCallableByChildTypes)][System.Diagnostics.CodeAnalysis.SuppressMessageAttribute(Microsoft.Maintainability, CA1502:AvoidExcessiveComplexity)][System.Diagnostics.CodeAnalysis.SuppressMessageAttribute(Microsoft.Performance, CA1800:DoNotCastUnnecessarily)]void System.Windows.Markup.IComponentConnector.Connect(int connectionId, object target) {switch (connectionId){case 1:this.textBox ((System.Windows.Controls.TextBox)(target));return;}this._contentLoaded true;}
}3.Application.LoadComponent()加载bamlpublic static void LoadComponent(object component, Uri resourceLocator)
{if (component null)throw new ArgumentNullException(nameof (component));if (resourceLocator (Uri) null)throw new ArgumentNullException(nameof (resourceLocator));if (resourceLocator.OriginalString null)throw new ArgumentException(SR.Get(ArgumentPropertyMustNotBeNull, (object) nameof (resourceLocator), (object) OriginalString));Uri curComponentUri !resourceLocator.IsAbsoluteUri ? new Uri(BaseUriHelper.PackAppBaseUri, resourceLocator) : throw new ArgumentException(SR.Get(AbsoluteUriNotAllowed));ParserContext parserContext new ParserContext();parserContext.BaseUri curComponentUri;Stream stream;bool closeStream;if (Application.IsComponentBeingLoadedFromOuterLoadBaml(curComponentUri)){NestedBamlLoadInfo nestedBamlLoadInfo Application.s_NestedBamlLoadInfo.Peek();stream nestedBamlLoadInfo.BamlStream;stream.Seek(0L, SeekOrigin.Begin);parserContext.SkipJournaledProperties nestedBamlLoadInfo.SkipJournaledProperties;nestedBamlLoadInfo.BamlUri (Uri) null;closeStream false;}else{PackagePart resourceOrContentPart Application.GetResourceOrContentPart(resourceLocator);ContentType contentType new ContentType(resourceOrContentPart.ContentType);stream resourceOrContentPart.GetStream();closeStream true;if (!MimeTypeMapper.BamlMime.AreTypeAndSubTypeEqual(contentType))throw new Exception(SR.Get(ContentTypeNotSupported, (object) contentType));}if (!(stream is IStreamInfo streamInfo) || streamInfo.Assembly ! component.GetType().Assembly)throw new Exception(SR.Get(UriNotMatchWithRootType, (object) component.GetType(), (object) resourceLocator));XamlReader.LoadBaml(stream, parserContext, component, closeStream);
} XamlReader.LoadBaml细节代码internal static object LoadBaml(Stream stream,ParserContext parserContext,object parent,bool closeStream)
{object p1 (object) null;EventTrace.EasyTraceEvent(EventTrace.Keyword.KeywordPerf | EventTrace.Keyword.KeywordXamlBaml, EventTrace.Event.WClientParseBamlBegin, (object) parserContext.BaseUri);if (TraceMarkup.IsEnabled)TraceMarkup.Trace(TraceEventType.Start, TraceMarkup.Load);try{if (stream is IStreamInfo streamInfo2)parserContext.StreamCreatedAssembly streamInfo2.Assembly;Baml2006ReaderSettings bamlReaderSettings XamlReader.CreateBamlReaderSettings();bamlReaderSettings.BaseUri parserContext.BaseUri;bamlReaderSettings.LocalAssembly streamInfo2.Assembly;if (bamlReaderSettings.BaseUri (Uri) null || string.IsNullOrEmpty(bamlReaderSettings.BaseUri.ToString()))bamlReaderSettings.BaseUri BaseUriHelper.PackAppBaseUri;Baml2006ReaderInternal baml2006ReaderInternal new Baml2006ReaderInternal(stream, new Baml2006SchemaContext(bamlReaderSettings.LocalAssembly), bamlReaderSettings, parent);Type type (Type) null;if (streamInfo2.Assembly ! (Assembly) null){try{type XamlTypeMapper.GetInternalTypeHelperTypeFromAssembly(parserContext);}catch (Exception ex){if (CriticalExceptions.IsCriticalException(ex))throw;}}if (type ! (Type) null){XamlAccessLevel xamlAccessLevel XamlAccessLevel.AssemblyAccessTo(streamInfo2.Assembly);new XamlLoadPermission(xamlAccessLevel).Assert();try{p1 WpfXamlLoader.LoadBaml((System.Xaml.XamlReader) baml2006ReaderInternal, parserContext.SkipJournaledProperties, parent, xamlAccessLevel, parserContext.BaseUri);}finally{CodeAccessPermission.RevertAssert();}}elsep1 WpfXamlLoader.LoadBaml((System.Xaml.XamlReader) baml2006ReaderInternal, parserContext.SkipJournaledProperties, parent, (XamlAccessLevel) null, parserContext.BaseUri);if (p1 is DependencyObject dependencyObject2)dependencyObject2.SetValue(BaseUriHelper.BaseUriProperty, (object) bamlReaderSettings.BaseUri);if (p1 is Application application2)application2.ApplicationMarkupBaseUri XamlReader.GetBaseUri(bamlReaderSettings.BaseUri);}finally{if (TraceMarkup.IsEnabled)TraceMarkup.Trace(TraceEventType.Stop, TraceMarkup.Load, p1);EventTrace.EasyTraceEvent(EventTrace.Keyword.KeywordPerf | EventTrace.Keyword.KeywordXamlBaml, EventTrace.Event.WClientParseBamlEnd, (object) parserContext.BaseUri);if (closeStream stream ! null)stream.Close();}return p1;
}4.加载控件对象提取BAML编译过的XAML解析并创建每个定义的控件对象设置属性、关联事件等内容。internal static object LoadBamlStreamWithSyncInfo(Stream stream, ParserContext pc)
{if (Application.s_NestedBamlLoadInfo null)Application.s_NestedBamlLoadInfo new StackNestedBamlLoadInfo();NestedBamlLoadInfo nestedBamlLoadInfo new NestedBamlLoadInfo(pc.BaseUri, stream, pc.SkipJournaledProperties);Application.s_NestedBamlLoadInfo.Push(nestedBamlLoadInfo);try{return XamlReader.LoadBaml(stream, pc, (object) null, true);}finally{Application.s_NestedBamlLoadInfo.Pop();if (Application.s_NestedBamlLoadInfo.Count 0)Application.s_NestedBamlLoadInfo (StackNestedBamlLoadInfo) null;}
}循环遍历所有xaml里的标签节点生成窗体内的内容。private static object Load(System.Xaml.XamlReader xamlReader,IXamlObjectWriterFactory writerFactory,bool skipJournaledProperties,object rootObject,XamlObjectWriterSettings settings,Uri baseUri)
{XamlContextStackWpfXamlFrame stack new XamlContextStackWpfXamlFrame((FuncWpfXamlFrame) (() new WpfXamlFrame()));int persistId 1;settings.AfterBeginInitHandler (EventHandlerXamlObjectEventArgs) ((sender, args) {if (EventTrace.IsEnabled(EventTrace.Keyword.KeywordPerf | EventTrace.Keyword.KeywordXamlBaml, EventTrace.Level.Verbose)){IXamlLineInfo xamlLineInfo xamlReader as IXamlLineInfo;int num1 -1;int num2 -1;if (xamlLineInfo ! null xamlLineInfo.HasLineInfo){num1 xamlLineInfo.LineNumber;num2 xamlLineInfo.LinePosition;}int num3 (int) EventTrace.EventProvider.TraceEvent(EventTrace.Event.WClientParseXamlBamlInfo, EventTrace.Keyword.KeywordPerf | EventTrace.Keyword.KeywordXamlBaml, EventTrace.Level.Verbose, (object) (args.Instance null ? 0L : PerfService.GetPerfElementID(args.Instance)), (object) num1, (object) num2);}if (args.Instance is UIElement instance3){int num persistId;instance3.SetPersistId(num);}XamlSourceInfoHelper.SetXamlSourceInfo(args.Instance, args, baseUri);if (args.Instance is DependencyObject instance4 stack.CurrentFrame.XmlnsDictionary ! null){XmlnsDictionary xmlnsDictionary stack.CurrentFrame.XmlnsDictionary;xmlnsDictionary.Seal();XmlAttributeProperties.SetXmlnsDictionary(instance4, xmlnsDictionary);}stack.CurrentFrame.Instance args.Instance;});XamlObjectWriter xamlWriter writerFactory null ? new XamlObjectWriter(xamlReader.SchemaContext, settings) : writerFactory.GetXamlObjectWriter(settings);IXamlLineInfo xamlLineInfo1 (IXamlLineInfo) null;try{xamlLineInfo1 xamlReader as IXamlLineInfo;IXamlLineInfoConsumer xamlLineInfoConsumer (IXamlLineInfoConsumer) xamlWriter;bool shouldPassLineNumberInfo false;if (xamlLineInfo1 ! null xamlLineInfo1.HasLineInfo xamlLineInfoConsumer ! null xamlLineInfoConsumer.ShouldProvideLineInfo)shouldPassLineNumberInfo true;IStyleConnector styleConnector rootObject as IStyleConnector;WpfXamlLoader.TransformNodes(xamlReader, xamlWriter, false, skipJournaledProperties, shouldPassLineNumberInfo, xamlLineInfo1, xamlLineInfoConsumer, stack, styleConnector);xamlWriter.Close();return xamlWriter.Result;}catch (Exception ex){if (CriticalExceptions.IsCriticalException(ex) || !XamlReader.ShouldReWrapException(ex, baseUri)){throw;}else{XamlReader.RewrapException(ex, xamlLineInfo1, baseUri);return (object) null;}}
}// Get the XAML content from an external file.
DependencyObject rootElement;
using (FileStream fs new FileStrearn(xamlFile, FileMode Open)){
rootElement (DependencyObject)XamlReader.Load(fs)
}// Insert the markup into this window.
this.Content rootElement;
// Find the control with the appropriate
buttonl (Button)LogicalTreeHelper.FindLogicalNode(rootElement, ibuttonl);
name.
// Wire up the event handler.
buttonl.Click buttonl Click【截选内容1这一段引用lindexi文章内的内容原文地址在文章末尾】在 WPF 中在 XAML 里面定义的对象的创建实际上不是完全通过反射来进行创建的在WPF框架里面有进行了一系列的优化。将会通过 XamlTypeInvoker 的 CreateInstance 方法来进行对象的创建而默认的 XamlTypeInvoker 的 CreateInstance 定义如下。还有其他精彩内容在原文里可以查看public virtual object CreateInstance(object[] arguments){ThrowIfUnknown();if (!_xamlType.UnderlyingType.IsValueType (arguments null || arguments.Length 0)){object result DefaultCtorXamlActivator.CreateInstance(this);if (result ! null){return result;}}return CreateInstanceWithActivator(_xamlType.UnderlyingType, arguments);}private object CreateInstanceWithActivator(Type type, object[] arguments){return SafeReflectionInvoker.CreateInstance(type, arguments);}【截选内容2这一段引用lindexi文章内的内容原文地址在文章末尾】在 EnsureConstructorDelegate 方法里面将会判断如果对象是公开的那么尝试获取默认构造函数将默认构造函数做成委托。此时的性能将会是类型第一次进入的时候的速度比较慢但是后续进入的时候就能使用委托创建此时性能将会比较好。通过反射创建委托提升性能的方法详细请看 .NET Core/Framework 创建委托以大幅度提高反射调用的性能 - walterlvprivate static bool EnsureConstructorDelegate(XamlTypeInvoker type)
{// 如果类型初始化过构造函数创建那么返回这是缓存的方法if (type._constructorDelegate ! null){return true;}// 如果不是公开的方法那么将无法使用反射创建委托的科技if (!type.IsPublic){return false;}// 反射获取对象的构造函数Type underlyingType type._xamlType.UnderlyingType.UnderlyingSystemType;// Look up public ctors only, for equivalence with Activator.CreateInstanceConstructorInfo tConstInfo underlyingType.GetConstructor(Type.EmptyTypes);IntPtr constPtr tConstInfo.MethodHandle.GetFunctionPointer();// 反射创建委托这样下次访问就不需要使用反射可以提升性能// This requires Reflection PermissionActionobject ctorDelegate ctorDelegate (Actionobject)s_actionCtor.Invoke(new object[] { null, constPtr });type._constructorDelegate ctorDelegate;return true;
}也就是说只有第一次的类型进入才会调用反射创建委托用来提升性能之后的进入将会使用第一次创建出来的委托来创建对象这样能提升性能。4.Referencedotnet/wpf: WPF is a .NET Core UI framework for building Windows desktop applications. (github.com)dotnet 读 WPF 源代码笔记 XAML 创建对象的方法 (lindexi.com)
