用IronRuby创建WPF应用程序

用IronRuby创建WPF应用程序2010-12-14 infoq 王波译我曾在早期的博文中介绍过IronRuby。在文章中，我扩展了IronRuby的基础知识，来解释需要在Rail应用程序所做的额外工作，好让大家继续深入.NET所实现Ruby语言，但这方面的内容并不够。所以现在我想深入地谈谈IronRuby与项目的兼容性，以便开发全新的应用程序来说明IronRuby和.NET之间的互操作性。实际上，我们会使用WPF（Windows Presentation Foundation），它是.NET Framework的组件，我们可以用它创建富媒体和图形界面。

WPF基础

再次申明，WPF是.NET Framework组件之一，负责呈现富用户界面和其他媒体。它不是.NET Framework中唯一可完成该功能的函数库集，Window Form也可以完成类似工作，在我们需要创建炫目效果的时候，WPF会显得十分有用。无论是演示文档、视频、数据录入表格、某些类型的数据可视化（这是我最希望做的，尤其用IronRuby完成，后面的故事更精彩）抑或用动画把以上的都串联起来，你很可能会发现在给Windows开发这些应用程序的时候 WPF可以满足你的需求。

举例说明。某一天午饭时间，我创建了基于WPF的类似于时钟的应用程序—— 我喜欢参考WPF的“Hello,Wold”应用程序——于是决定使用IronRuby。

注：学习本示例的过程中，需要参考WPF文档。

示例程序

require "WindowsBase"
require "PresentationFramework"
require "PresentationCore"
require "System.Core, Version=3.5.0.0, Culture=neutral,  PublicKeyToken=b77a5c561934e089"

class Clock

   CLOCK_WIDTH   = 150
   CLOCK_HEIGHT  = 150
   LABEL_HEIGHT  = CLOCK_HEIGHT / 7
   LABEL_WIDTH   = CLOCK_WIDTH / 7
   RADIUS     = CLOCK_WIDTH / 2
   RADS      = Math::PI / 180
   MIN_LOCATIONS  = {}
   HOUR_LOCATIONS = {}

   def run！
     plot_locations

     # build our window
     @window = System::Windows::Window.new
     @window.background =  System::Windows::Media::Brushes.LightGray
     @window.width = CLOCK_WIDTH * 2
     @window.height = CLOCK_HEIGHT * 2
     @window.resize_mode =  System::Windows::ResizeMode.NoResize

     @canvas = System::Windows::Controls::Canvas.new
     @canvas.width = CLOCK_WIDTH
     @canvas.height = CLOCK_HEIGHT

     # create shapes to represent clock hands
     @minute_hand = System::Windows::Shapes::Line.new
     @minute_hand.stroke =  System::Windows::Media::Brushes.Black
     @minute_hand.stroke_thickness = 1 
     @minute_hand.x1 = CLOCK_WIDTH / 2
     @minute_hand.y1 = CLOCK_HEIGHT / 2

     @hour_hand = System::Windows::Shapes::Line.new
     @hour_hand.stroke =  System::Windows::Media::Brushes.Black
     @hour_hand.stroke_thickness = 3
     @hour_hand.x1 = CLOCK_WIDTH / 2
     @hour_hand.y1 = CLOCK_HEIGHT / 2

     # .. and stick them to our canvas
     @canvas.children.add（@minute_hand）
     @canvas.children.add（@hour_hand）

     plot_face # draw a clock face
     plot_labels # draw clock numbers
     plot_hands # draw minute / hour hands

     @window.content = @canvas
     app = System::Windows::Application.new
     app.run（@window）
     # the Application object handles the lifecycle of  our app
     # including the execution loop
   end

   # determine 2 sets of equidistant points around the  circumference of a circle
   # of CLOCK_WIDTH and CLOCK_HEIGHT dimensions.
   def plot_locations
     for i in （0..60） # 60 minutes, and 12 hours
       a = i * 6
       x = （RADIUS * Math.sin（a * RADS））.to_i +  （CLOCK_WIDTH / 2）
       y = （CLOCK_HEIGHT / 2） - （RADIUS * Math.cos（a  * RADS））.to_i
       coords = [x, y]
       HOUR_LOCATIONS[i / 5] = coords if i % 5 == 0  # is this also an "hour" location （ie. every 5 minutes）？  
       MIN_LOCATIONS[i] = coords
     end
   end

   # draws a circle to represent the clock"s face
   def plot_face
     extra_x = （CLOCK_WIDTH * 0.15） # pad our circle a  little
     extra_y = （CLOCK_HEIGHT * 0.15）
     face = System::Windows::Shapes::Ellipse.new
     face.fill = System::Windows::Media::Brushes.White
     face.width = CLOCK_WIDTH + extra_x
     face.height = CLOCK_HEIGHT + extra_y
     face.margin = System::Windows::Thickness.new（0 -  （extra_x/2）, 0 - （extra_y/2）, 0, 0）
     face.stroke = System::Windows::Media::Brushes.Gray #  give it a slight border
     face.stroke_thickness = 1
     System::Windows::Controls::Canvas.set_z_index（face, -1） #  send our circle to the back
     @canvas.children.add（face） # add the clock face to  our canvas
   end

   # at each point along the hour locations, put a  number
   def plot_labels
     HOUR_LOCATIONS.each_pair do |p, coords|
       unless p == 0
         lbl = System::Windows::Controls::Label.new
         lbl.horizontal_content_alignment =  System::Windows::HorizontalAlignment.Center
         lbl.width = LABEL_WIDTH
         lbl.height = LABEL_HEIGHT
         lbl.content = p.to_s
         lbl.margin = System::Windows::Thickness.new （coords[0] - （LABEL_WIDTH / 2）, coords[1] - （LABEL_HEIGHT /  2）, 0, 0）
         lbl.padding = System::Windows::Thickness.new（0,  0, 0, 0）
         @canvas.children.add（lbl）
       end
     end
   end

   def plot_hands
     time = Time.now
     hours = time.hour
     minutes = time.min

     if ！@minutes || minutes ！= @minutes
       @hours = hours >= 12 ？ hours - 12 :  hours
       @minutes = minutes == 0 ？ 60 : minutes
       # Dispatcher.BeginInvoke（） is asynchronous, though  it probably doesn"t matter too much here
       @minute_hand.dispatcher.begin_invoke （System::Windows::Threading::DispatcherPriority.Render,  System::Action.new {
         @minute_hand.x2 = MIN_LOCATIONS[@minutes][0]
         @minute_hand.y2 = MIN_LOCATIONS[@minutes][1]
         @hour_hand.x2 = HOUR_LOCATIONS[@hours][0]
         @hour_hand.y2 = HOUR_LOCATIONS[@hours][1]
       }）
     end
   end

end

clock = Clock.new

timer = System::Timers::Timer.new
timer.interval = 1000
timer.elapsed { clock.plot_hands }
timer.enabled = true

clock.run！