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WPF:位图不显示

drawing image wpf .net c#

codymanix · 技术社区 · 14 年前

我想做一些模拟。会有无数的精灵漂浮在周围。因为我认为每帧渲染1000次组成精灵的相同基本体会很慢,所以我希望将它们渲染一次为位图,然后每帧显示一个精灵。

我的WPF来源很简单:

<Window x:Class="WPFGraphicsTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="800" Width="1000">
    <Canvas>

    </Canvas>
</Window>

这是我的代码:

    public partial class MainWindow : Window
    {
        Ellipse e;
        RenderTargetBitmap bmp2;

        public MainWindow()
        {
            InitializeComponent();

            e = new Ellipse();
            e.Width = 40;
            e.Height = 40;
            e.Fill = new SolidColorBrush(Color.FromRgb(0, 0, 200));

            ((Canvas)this.Content).Children.Add(e);
            ((Canvas)this.Content).Measure(new Size(1000, 800));
            ((Canvas)this.Content).Arrange(new Rect(new Size(1000, 800)));

            RenderTargetBitmap bmp2 = new RenderTargetBitmap(40, 40, 96, 96, PixelFormats.Pbgra32);

            bmp2.Render(e);
            ((Canvas)this.Content).Children.Remove(e);
}


        protected override void OnRender(DrawingContext drawingContext)
        {
            base.OnRender(drawingContext);

            drawingContext.DrawImage(bmp2, new Rect(100,100, 40, 40));

        }
}

为什么这不管用?

1 回复 | 直到 14 年前

Chris Taylor 14 年前

可以将图像对象放在画布上,然后使用RenderTargetBitmap更新图像。例如

<Window x:Class="WPFGraphicsTest.MainWindow" 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        Title="MainWindow" Height="800" Width="1000"> 
    <Canvas> 
      <Image Name="frameImage" />
    </Canvas> 
</Window>

public partial class MainWindow : Window
  {
    DispatcherTimer _timer = new DispatcherTimer();

    RenderTargetBitmap _renderSurface = 
      new RenderTargetBitmap(100, 100, 96, 96, PixelFormats.Pbgra32);

    Random _rnd = new Random();

    public MainWindow()
    {
      InitializeComponent();

      _timer = new DispatcherTimer();
      _timer.Interval = TimeSpan.FromMilliseconds(100);
      _timer.Tick += new EventHandler(_timer_Tick);
      _timer.Start();      
    }

    void _timer_Tick(object sender, EventArgs e)
    {
      DrawingVisual visual = new DrawingVisual();
      DrawingContext context = visual.RenderOpen();
      int value = _rnd.Next(40);
      context.DrawEllipse(
        new SolidColorBrush(Colors.Red), 
        new Pen(new SolidColorBrush(Colors.Black), 1), 
        new Point(value, value), value, value);
      context.Close();

      _renderSurface.Render(visual);
      frameImage.Source = _renderSurface;
    }    
  }