BufferedGraphics BufferedGraphics BufferedGraphics BufferedGraphics Class

Definición

Proporciona un búfer gráfico para el doble búfer.Provides a graphics buffer for double buffering.

public ref class BufferedGraphics sealed : IDisposable
public sealed class BufferedGraphics : IDisposable
type BufferedGraphics = class
    interface IDisposable
Public NotInheritable Class BufferedGraphics
Implements IDisposable
Herencia
BufferedGraphicsBufferedGraphicsBufferedGraphicsBufferedGraphics
Implementaciones

Ejemplos

En el ejemplo de código siguiente se muestra cómo utilizar un BufferedGraphics objeto que se va a dibujar gráficos con varios tipos de implementaciones de almacenamiento en búfer.The following code example demonstrates using a BufferedGraphics object to draw graphics using several types of buffering implementations. O bien al hacer clic en el formulario se inicia y detiene un temporizador que hace que dibujar las actualizaciones.Clicking the form alternately starts and stops a timer that causes draw updates. Las actualizaciones de dibujo le permiten observar el efecto de almacenamiento en doble búfer.The draw updates allow you to observe the effect of double buffering. Haciendo clic en los ciclos de formulario a través de los siguientes modos de dibujos:Right-clicking the form cycles through the following drawing modes:

En cada modo, se dibuja texto que identifica el modo actual y se describe el comportamiento que tiene lugar cuando se presiona cada botón del mouse.In each mode, text is drawn that identifies the current mode and describes the behavior that occurs when each mouse button is pressed.

#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>
#using <System.dll>

using namespace System;
using namespace System::ComponentModel;
using namespace System::Drawing;
using namespace System::Windows::Forms;

namespace BufferingExample
{
   public ref class BufferingExample: public Form
   {
   private:
      BufferedGraphicsContext^ context;
      BufferedGraphics^ grafx;
      Byte bufferingMode;
      array<String^>^bufferingModeStrings;
      System::Windows::Forms::Timer^ timer1;
      Byte count;

   public:
      BufferingExample()
         : Form()
      {
         array<String^>^tempStrings = {"Draw to Form without OptimizedDoubleBufferring control style","Draw to Form using OptimizedDoubleBuffering control style","Draw to HDC for form"};
         bufferingModeStrings = tempStrings;

         // Configure the Form for this example.
         this->Text = "User double buffering";
         this->MouseDown += gcnew MouseEventHandler( this, &BufferingExample::MouseDownHandler );
         this->Resize += gcnew EventHandler( this, &BufferingExample::OnResize );
         this->SetStyle( static_cast<ControlStyles>(ControlStyles::AllPaintingInWmPaint | ControlStyles::UserPaint), true );

         // Configure a timer to draw graphics updates.
         timer1 = gcnew System::Windows::Forms::Timer;
         timer1->Interval = 200;
         timer1->Tick += gcnew EventHandler( this, &BufferingExample::OnTimer );
         bufferingMode = 2;
         count = 0;

         // Retrieves the BufferedGraphicsContext for the 
         // current application domain.
         context = BufferedGraphicsManager::Current;

         // Sets the maximum size for the primary graphics buffer
         // of the buffered graphics context for the application
         // domain.  Any allocation requests for a buffer larger 
         // than this will create a temporary buffered graphics 
         // context to host the graphics buffer.
         context->MaximumBuffer = System::Drawing::Size( this->Width + 1, this->Height + 1 );

         // Allocates a graphics buffer the size of this form
         // using the pixel format of the Graphics created by 
         // the Form.CreateGraphics() method, which returns a 
         // Graphics object that matches the pixel format of the form.
         grafx = context->Allocate( this->CreateGraphics(), Rectangle(0,0,this->Width,this->Height) );

         // Draw the first frame to the buffer.
         DrawToBuffer( grafx->Graphics );
      }

   private:
      void MouseDownHandler( Object^ /*sender*/, MouseEventArgs^ e )
      {
         if ( e->Button == ::MouseButtons::Right )
         {
            // Cycle the buffering mode.
            if ( ++bufferingMode > 2 )
                        bufferingMode = 0;

            // If the previous buffering mode used 
            // the OptimizedDoubleBuffering ControlStyle,
            // disable the control style.
            if ( bufferingMode == 1 )
                        this->SetStyle( ControlStyles::OptimizedDoubleBuffer, true );

            // If the current buffering mode uses
            // the OptimizedDoubleBuffering ControlStyle,
            // enabke the control style.
            if ( bufferingMode == 2 )
                        this->SetStyle( ControlStyles::OptimizedDoubleBuffer, false );

            // Cause the background to be cleared and redraw.
            count = 6;
            DrawToBuffer( grafx->Graphics );
            this->Refresh();
         }
         else
         {
            
            // Toggle whether the redraw timer is active.
            if ( timer1->Enabled )
                        timer1->Stop();
            else
                        timer1->Start();
         }
      }

   private:
      void OnTimer( Object^ /*sender*/, EventArgs^ /*e*/ )
      {
         // Draw randomly positioned ellipses to the buffer.
         DrawToBuffer( grafx->Graphics );

         // If in bufferingMode 2, draw to the form's HDC.
         if ( bufferingMode == 2 )

         // Render the graphics buffer to the form's HDC.
         grafx->Render( Graphics::FromHwnd( this->Handle ) );
         // If in bufferingMode 0 or 1, draw in the paint method.
         else

         // If in bufferingMode 0 or 1, draw in the paint method.
         this->Refresh();
      }

      void OnResize( Object^ /*sender*/, EventArgs^ /*e*/ )
      {
         // Re-create the graphics buffer for a new window size.
         context->MaximumBuffer = System::Drawing::Size( this->Width + 1, this->Height + 1 );
         if ( grafx != nullptr )
         {
            delete grafx;
            grafx = nullptr;
         }

         grafx = context->Allocate( this->CreateGraphics(), Rectangle(0,0,this->Width,this->Height) );

         // Cause the background to be cleared and redraw.
         count = 6;
         DrawToBuffer( grafx->Graphics );
         this->Refresh();
      }

      void DrawToBuffer( Graphics^ g )
      {
         // Clear the graphics buffer every five updates.
         if ( ++count > 5 )
         {
            count = 0;
            grafx->Graphics->FillRectangle( Brushes::Black, 0, 0, this->Width, this->Height );
         }

         // Draw randomly positioned and colored ellipses.
         Random^ rnd = gcnew Random;
         for ( int i = 0; i < 20; i++ )
         {
            int px = rnd->Next( 20, this->Width - 40 );
            int py = rnd->Next( 20, this->Height - 40 );
            g->DrawEllipse( gcnew Pen( Color::FromArgb( rnd->Next( 0, 255 ), rnd->Next( 0, 255 ), rnd->Next( 0, 255 ) ), 1.0f ), px, py, px + rnd->Next( 0, this->Width - px - 20 ), py + rnd->Next( 0, this->Height - py - 20 ) );
         }

         // Draw information strings.
         g->DrawString( String::Format( "Buffering Mode: {0}", bufferingModeStrings[ bufferingMode ] ), gcnew System::Drawing::Font( "Arial",8 ), Brushes::White, 10, 10 );
         g->DrawString( "Right-click to cycle buffering mode", gcnew System::Drawing::Font( "Arial",8 ), Brushes::White, 10, 22 );
         g->DrawString( "Left-click to toggle timed display refresh", gcnew System::Drawing::Font( "Arial",8 ), Brushes::White, 10, 34 );
      }

   protected:
      virtual void OnPaint( PaintEventArgs^ e ) override
      {
         grafx->Render( e->Graphics );
      }
   };
}

[STAThread]
int main()
{
   Application::Run( gcnew BufferingExample::BufferingExample );
}
using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;

namespace BufferingExample 
{
    public class BufferingExample : Form
    {
        private BufferedGraphicsContext context;
        private BufferedGraphics grafx;

	private byte bufferingMode;
	private string[] bufferingModeStrings = 
		{ "Draw to Form without OptimizedDoubleBufferring control style",
		  "Draw to Form using OptimizedDoubleBuffering control style",
		  "Draw to HDC for form" };

	private System.Windows.Forms.Timer timer1;
	private byte count;

        public BufferingExample() : base()
        {
            // Configure the Form for this example.
            this.Text = "User double buffering";
            this.MouseDown += new MouseEventHandler(this.MouseDownHandler);
            this.Resize += new EventHandler(this.OnResize);
            this.SetStyle( ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true );

            // Configure a timer to draw graphics updates.
	    timer1 = new System.Windows.Forms.Timer();
	    timer1.Interval = 200;
	    timer1.Tick += new EventHandler(this.OnTimer);

	    bufferingMode = 2;
	    count = 0;

            // Retrieves the BufferedGraphicsContext for the 
            // current application domain.
            context = BufferedGraphicsManager.Current;

            // Sets the maximum size for the primary graphics buffer
            // of the buffered graphics context for the application
            // domain.  Any allocation requests for a buffer larger 
            // than this will create a temporary buffered graphics 
            // context to host the graphics buffer.
            context.MaximumBuffer = new Size(this.Width+1, this.Height+1);

            // Allocates a graphics buffer the size of this form
            // using the pixel format of the Graphics created by 
            // the Form.CreateGraphics() method, which returns a 
            // Graphics object that matches the pixel format of the form.
            grafx = context.Allocate(this.CreateGraphics(), 
                 new Rectangle( 0, 0, this.Width, this.Height ));

	    // Draw the first frame to the buffer.
	    DrawToBuffer(grafx.Graphics);
        }

	private void MouseDownHandler(object sender, MouseEventArgs e)
        {
	    if( e.Button == MouseButtons.Right )
	    {
                 // Cycle the buffering mode.
	         if( ++bufferingMode > 2 )
                     bufferingMode = 0;

                 // If the previous buffering mode used 
                 // the OptimizedDoubleBuffering ControlStyle,
                 // disable the control style.
                 if( bufferingMode == 1 )
                     this.SetStyle( ControlStyles.OptimizedDoubleBuffer, true );

                 // If the current buffering mode uses
                 // the OptimizedDoubleBuffering ControlStyle,
                 // enabke the control style.
                 if( bufferingMode == 2 )
                     this.SetStyle( ControlStyles.OptimizedDoubleBuffer, false );

                 // Cause the background to be cleared and redraw.
                 count = 6;
    	         DrawToBuffer(grafx.Graphics);                 
		 this.Refresh();
	    }
	    else
	    {
                // Toggle whether the redraw timer is active.
		if( timer1.Enabled )
			timer1.Stop();
		else
			timer1.Start(); 
	    }
        }

	private void OnTimer(object sender, EventArgs e)
	{
            // Draw randomly positioned ellipses to the buffer.
	    DrawToBuffer(grafx.Graphics);

            // If in bufferingMode 2, draw to the form's HDC.
	    if( bufferingMode == 2 )            
                    // Render the graphics buffer to the form's HDC.
		    grafx.Render(Graphics.FromHwnd(this.Handle));            
            // If in bufferingMode 0 or 1, draw in the paint method.
	    else
  		    this.Refresh();
	}

        private void OnResize(object sender, EventArgs e)
        {
           // Re-create the graphics buffer for a new window size.
           context.MaximumBuffer = new Size(this.Width+1, this.Height+1);
           if( grafx != null )
           {
	       grafx.Dispose();
               grafx = null;               
           }
           grafx = context.Allocate(this.CreateGraphics(), 
               new Rectangle( 0, 0, this.Width, this.Height ));
           
           // Cause the background to be cleared and redraw.
           count = 6;
    	   DrawToBuffer(grafx.Graphics);                 
	   this.Refresh();
        }	

	private void DrawToBuffer(Graphics g)
	{
            // Clear the graphics buffer every five updates.
	    if( ++count > 5 )
            {
                count = 0;                
                grafx.Graphics.FillRectangle(Brushes.Black, 0, 0, this.Width, this.Height);
            }

            // Draw randomly positioned and colored ellipses.
	    Random rnd = new Random();
	    for( int i=0; i<20; i++ )
	    {
		int px = rnd.Next(20,this.Width-40);
		int py = rnd.Next(20,this.Height-40);
		g.DrawEllipse(new Pen(Color.FromArgb(rnd.Next(0, 255), rnd.Next(0,255), rnd.Next(0,255)), 1), 
			px, py, px+rnd.Next(0, this.Width-px-20), py+rnd.Next(0, this.Height-py-20)); 	    			
	    }

            // Draw information strings.
	    g.DrawString("Buffering Mode: "+bufferingModeStrings[bufferingMode], new Font("Arial", 8), Brushes.White, 10, 10);
            g.DrawString("Right-click to cycle buffering mode", new Font("Arial", 8), Brushes.White, 10, 22);
            g.DrawString("Left-click to toggle timed display refresh", new Font("Arial", 8), Brushes.White, 10, 34);
	}

	protected override void OnPaint(PaintEventArgs e)
        {            
	    grafx.Render(e.Graphics);
	}

        [STAThread]
        public static void Main(string[] args)
        {
	    Application.Run(new BufferingExample());
        }
    }
}
Imports System
Imports System.ComponentModel
Imports System.Drawing
Imports System.Windows.Forms

Public Class BufferingExample
    Inherits Form
    Private context As BufferedGraphicsContext
    Private grafx As BufferedGraphics
    
    Private bufferingMode As Byte
    Private bufferingModeStrings As String() = _
        {"Draw to Form without OptimizedDoubleBufferring control style", _
         "Draw to Form using OptimizedDoubleBuffering control style", _
         "Draw to HDC for form"}
    
    Private timer1 As System.Windows.Forms.Timer
    Private count As Byte    
    
    Public Sub New()
        ' Configure the Form for this example.
        Me.Text = "User double buffering"
        AddHandler Me.MouseDown, AddressOf Me.MouseDownHandler
        AddHandler Me.Resize, AddressOf Me.ResizeHandler
        Me.SetStyle(ControlStyles.AllPaintingInWmPaint Or ControlStyles.UserPaint, True)
        
        ' Configure a timer to draw graphics updates.
        timer1 = New System.Windows.Forms.Timer()
        timer1.Interval = 200
        AddHandler timer1.Tick, AddressOf Me.OnTimer
        
        bufferingMode = 2
        count = 0
        
        ' Retrieves the BufferedGraphicsContext for the 
        ' current application domain.
        context = BufferedGraphicsManager.Current
        
        ' Sets the maximum size for the primary graphics buffer
        ' of the buffered graphics context for the application
        ' domain.  Any allocation requests for a buffer larger 
        ' than this will create a temporary buffered graphics 
        ' context to host the graphics buffer.
        context.MaximumBuffer = New Size(Me.Width + 1, Me.Height + 1)
        
        ' Allocates a graphics buffer the size of this form
        ' using the pixel format of the Graphics created by 
        ' the Form.CreateGraphics() method, which returns a 
        ' Graphics object that matches the pixel format of the form.
        grafx = context.Allocate(Me.CreateGraphics(), _
            New Rectangle(0, 0, Me.Width, Me.Height))
        
        ' Draw the first frame to the buffer.
        DrawToBuffer(grafx.Graphics)
    End Sub    
    
    Private Sub MouseDownHandler(sender As Object, e As MouseEventArgs)
        If e.Button = MouseButtons.Right Then
            ' Cycle the buffering mode.
            bufferingMode = bufferingMode+1
            If bufferingMode > 2 Then
                bufferingMode = 0
            End If 
            ' If the previous buffering mode used 
            ' the OptimizedDoubleBuffering ControlStyle,
            ' disable the control style.
            If bufferingMode = 1 Then
                Me.SetStyle(ControlStyles.OptimizedDoubleBuffer, True)
            End If 
            ' If the current buffering mode uses
            ' the OptimizedDoubleBuffering ControlStyle,
            ' enabke the control style.
            If bufferingMode = 2 Then
                Me.SetStyle(ControlStyles.OptimizedDoubleBuffer, False)
            End If 
            ' Cause the background to be cleared and redraw.
            count = 6
            DrawToBuffer(grafx.Graphics)
            Me.Refresh()
        Else
            ' Toggle whether the redraw timer is active.
            If timer1.Enabled Then
                timer1.Stop()
            Else
                timer1.Start()
            End If
        End If
    End Sub
     
    Private Sub OnTimer(sender As Object, e As EventArgs)
        ' Draw randomly positioned ellipses to the buffer.
        DrawToBuffer(grafx.Graphics)
        
        ' If in bufferingMode 2, draw to the form's HDC.
        If bufferingMode = 2 Then
            ' Render the graphics buffer to the form's HDC.
            grafx.Render(Graphics.FromHwnd(Me.Handle))
        ' If in bufferingMode 0 or 1, draw in the paint method.
        Else
            Me.Refresh()
        End If
    End Sub
     
    Private Sub ResizeHandler(sender As Object, e As EventArgs)
        ' Re-create the graphics buffer for a new window size.
        context.MaximumBuffer = New Size(Me.Width + 1, Me.Height + 1)
        If (grafx IsNot Nothing) Then
            grafx.Dispose()
            grafx = Nothing
        End If
        grafx = context.Allocate(Me.CreateGraphics(), New Rectangle(0, 0, Me.Width, Me.Height))
        
        ' Cause the background to be cleared and redraw.
        count = 6
        DrawToBuffer(grafx.Graphics)
        Me.Refresh()
    End Sub    
    
    Private Sub DrawToBuffer(g As Graphics)
        ' Clear the graphics buffer every five updates.
        count = count+1
        If count > 5 Then
            count = 0
            grafx.Graphics.FillRectangle(Brushes.Black, 0, 0, Me.Width, Me.Height)
        End If
        
        ' Draw randomly positioned and colored ellipses.
        Dim rnd As New Random()
        Dim i As Integer
        For i = 0 To 21
            Dim px As Integer = rnd.Next(20, Me.Width - 40)
            Dim py As Integer = rnd.Next(20, Me.Height - 40)
            g.DrawEllipse(New Pen(Color.FromArgb(rnd.Next(0, 255), rnd.Next(0, 255), _
                rnd.Next(0, 255)), 1), px, py, px + rnd.Next(0, Me.Width - px - 20), _
                py + rnd.Next(0, Me.Height - py - 20))
        Next i
        
        ' Draw information strings.
        g.DrawString("Buffering Mode: " + bufferingModeStrings(bufferingMode), _
            New Font("Arial", 8), Brushes.White, 10, 10)
        g.DrawString("Right-click to cycle buffering mode", New Font("Arial", 8), _
            Brushes.White, 10, 22)
        g.DrawString("Left-click to toggle timed display refresh", _
            New Font("Arial", 8), Brushes.White, 10, 34)
    End Sub    
    
    Protected Overrides Sub OnPaint(e As PaintEventArgs)
        grafx.Render(e.Graphics)
    End Sub   
    
    <STAThread()>  _
    Public Shared Sub Main(args() As String)
        Application.Run(New BufferingExample())
    End Sub

End Class

Comentarios

La BufferedGraphics clase le permite implementar un doble búfer personalizado para los gráficos.The BufferedGraphics class allows you to implement custom double buffering for your graphics. Proporciona un contenedor para un búfer de gráficos, junto con los métodos que puede usar para escribir en el búfer y representar su contenido en un dispositivo de salida.It provides a wrapper for a graphics buffer, along with methods that you can use to write to the buffer and render its contents to an output device.

Gráficos que usan el almacenamiento en doble búfer pueden reducir o eliminar el parpadeo que se produjo al volver a dibujar una superficie de pantalla.Graphics that use double buffering can reduce or eliminate flicker that is caused by redrawing a display surface. Cuando se usa el almacenamiento en búfer doble, gráficos actualizados se dibujan en primer lugar a un búfer en memoria y el contenido de este búfer, a continuación, se escribe rápidamente en parte o toda la superficie mostrada.When you use double buffering, updated graphics are first drawn to a buffer in memory, and the contents of this buffer are then quickly written to some or all of the displayed surface. Esta sobrescritura relativamente breve de los gráficos mostrados normalmente reduce o elimina el parpadeo que a veces se produce cuando se actualizan los gráficos.This relatively brief overwrite of the displayed graphics typically reduces or eliminates the flicker that sometimes occurs when graphics are updated.

Nota

La manera más sencilla de usar el almacenamiento en doble búfer es establecer el OptimizedDoubleBuffer controlar la marca de estilo de un control mediante la SetStyle método.The simplest way to use double buffering is to set the OptimizedDoubleBuffer control style flag on a control using the SetStyle method. Establecer el OptimizedDoubleBuffer marca para un control de dibujo del control a través de un búfer de gráficos de forma predeterminada, redirige sin necesidad de ningún código adicional.Setting the OptimizedDoubleBuffer flag for a control redirects all painting for the control through a default graphics buffer, without requiring any additional code. Esta marca se establece en true de forma predeterminada.This flag is set to true by default.

El BufferedGraphics clase no tiene ningún constructor público y debe crearse la BufferedGraphicsContext para un dominio de aplicación mediante su Allocate método.The BufferedGraphics class has no public constructor and must be created by the BufferedGraphicsContext for an application domain using its Allocate method. Puede recuperar el BufferedGraphicsContext para el dominio de aplicación actual desde estático BufferedGraphicsManager.Current propiedad.You can retrieve the BufferedGraphicsContext for the current application domain from the static BufferedGraphicsManager.Current property.

El Graphics propiedad puede utilizarse para dibujar en el búfer de gráficos.The Graphics property can be used for drawing to the graphics buffer. Esta propiedad proporciona acceso a la Graphics objeto que se dibuja en el búfer gráfico asignado para este BufferedGraphics objeto.This property provides access to the Graphics object that draws to the graphics buffer allocated for this BufferedGraphics object.

El Render método con ningún dibuja argumentos almacenar en búfer el contenido de los gráficos a la superficie especificada cuando se asignó el búfer.The Render method with no arguments draws the contents of the graphics buffer to the surface specified when the buffer was allocated. Otras sobrecargas de los Render método le permiten especificar un Graphics objeto o un IntPtr objeto que apunta a un contexto de dispositivo que se va a dibujar el contenido del búfer gráfico.Other overloads of the Render method allow you to specify a Graphics object or an IntPtr object that points to a device context to which to draw the contents of the graphics buffer.

Para obtener más información sobre cómo dibujar gráficos de doble búfer, vea Double Buffered Graphics.For more information about drawing double-buffered graphics, see Double Buffered Graphics.

Propiedades

Graphics Graphics Graphics Graphics

Obtiene un objeto Graphics que envía el resultado al búfer gráfico.Gets a Graphics object that outputs to the graphics buffer.

Métodos

Dispose() Dispose() Dispose() Dispose()

Libera todos los recursos utilizados por el objeto BufferedGraphics.Releases all resources used by the BufferedGraphics object.

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Determina si el objeto especificado es igual al objeto actual.Determines whether the specified object is equal to the current object.

(Inherited from Object)
Finalize() Finalize() Finalize() Finalize()

Permite que un objeto intente liberar recursos y realizar otras operaciones de limpieza antes de que sea reclamado por la recolección de elementos no utilizados.Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Sirve como la función hash predeterminada.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Obtiene el Type de la instancia actual.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Crea una copia superficial del objeto Object actual.Creates a shallow copy of the current Object.

(Inherited from Object)
Render() Render() Render() Render()

Escribe el contenido del búfer gráfico en el dispositivo predeterminado.Writes the contents of the graphics buffer to the default device.

Render(Graphics) Render(Graphics) Render(Graphics) Render(Graphics)

Escribe el contenido del búfer gráfico en el objeto Graphics especificado.Writes the contents of the graphics buffer to the specified Graphics object.

Render(IntPtr) Render(IntPtr) Render(IntPtr) Render(IntPtr)

Escribe el contenido del búfer gráfico en el contexto de dispositivo asociado al identificador IntPtr especificado.Writes the contents of the graphics buffer to the device context associated with the specified IntPtr handle.

ToString() ToString() ToString() ToString()

Devuelve una cadena que representa el objeto actual.Returns a string that represents the current object.

(Inherited from Object)

Se aplica a

Seguridad para subprocesos

La clase BufferedGraphics no es segura para la ejecución de subprocesos.The BufferedGraphics class is not thread safe. Al acceder a un búfer de gráficos desde subprocesos independientes, es importante usar un mecanismo de control de acceso de subprocesos para evitar conflictos.When accessing a graphics buffer from separate threads, it is important to use a thread-access control mechanism to prevent conflicts.

Consulte también: