BufferedGraphics Classe
Definição
Importante
Algumas informações se referem a produtos de pré-lançamento que podem ser substancialmente modificados antes do lançamento. A Microsoft não oferece garantias, expressas ou implícitas, das informações aqui fornecidas.
Fornece um buffer de gráficos para buffer duplo.
public ref class BufferedGraphics sealed : IDisposablepublic sealed class BufferedGraphics : IDisposabletype BufferedGraphics = class
interface IDisposablePublic NotInheritable Class BufferedGraphics
Implements IDisposable- Herança
-
BufferedGraphics
- Implementações
Exemplos
O exemplo de código a seguir demonstra o uso de um BufferedGraphics objeto para desenhar gráficos usando vários tipos de implementações de buffer. Clicar no formulário alternadamente inicia e interrompe um temporizador que causa atualizações de desenho. As atualizações de desenho permitem observar o efeito do buffer duplo. Clicar com o botão direito do mouse nos ciclos de formulário pelos seguintes modos de desenho:
Desenhando substituindo o OnPaint método usando o estilo de OptimizedDoubleBuffer controle.
Desenhando substituindo o OnPaint método para o método de formulário sem usar o estilo de OptimizedDoubleBuffer controle.
Em cada modo, o texto é desenhado que identifica o modo atual e descreve o comportamento que ocorre quando cada botão do mouse é pressionado.
#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.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
Comentários
A BufferedGraphics classe permite implementar buffer duplo personalizado para seus elementos gráficos. Ele fornece um wrapper para um buffer gráfico, juntamente com métodos que você pode usar para gravar no buffer e renderizar seu conteúdo em um dispositivo de saída.
Os gráficos que usam buffer duplo podem reduzir ou eliminar a cintilação causada pela redesenho de uma superfície de exibição. Quando você usa buffer duplo, os elementos gráficos atualizados são desenhados primeiro para um buffer na memória e o conteúdo desse buffer é gravado rapidamente em algumas ou todas as superfícies exibidas. Essa substituição relativamente breve dos gráficos exibidos normalmente reduz ou elimina a cintilação que às vezes ocorre quando os gráficos são atualizados.
Observação
No .NET 6 e em versões posteriores, o pacote System.Drawing.Common, que inclui esse tipo, só tem suporte em sistemas Windows operacionais. O uso desse tipo em aplicativos de plataforma cruzada causa avisos de tempo de compilação e exceções de tempo de run-time. Para obter mais informações, consulte System.Drawing.Common com suporte apenas no Windows.
Observação
A maneira mais simples de usar buffer duplo é definir o sinalizador de estilo de OptimizedDoubleBuffer controle em um controle usando o SetStyle método. Definir o OptimizedDoubleBuffer sinalizador para um controle redireciona toda a pintura para o controle por meio de um buffer gráfico padrão, sem exigir nenhum código adicional. Esse sinalizador é definido como true por padrão.
A BufferedGraphics classe não tem construtor público e deve ser criada por um domínio de BufferedGraphicsContext aplicativo usando seu Allocate método. Você pode recuperar o BufferedGraphicsContext domínio do aplicativo atual da propriedade estática BufferedGraphicsManager.Current .
A Graphics propriedade pode ser usada para desenhar no buffer de gráficos. Essa propriedade fornece acesso ao Graphics objeto que se desenha no buffer de gráficos alocado para esse BufferedGraphics objeto.
O Render método sem argumentos desenha o conteúdo do buffer de gráficos para a superfície especificada quando o buffer foi alocado. Outras sobrecargas do Render método permitem que você especifique um Graphics objeto ou um IntPtr objeto que aponte para um contexto de dispositivo para o qual desenhar o conteúdo do buffer gráfico.
Para obter mais informações sobre como desenhar gráficos com buffer duplo, consulte Gráficos em Buffer Duplo.
Propriedades
| Graphics |
Obtém um objeto Graphics que gera saídas para o buffer de gráficos. |
Métodos
| Dispose() |
Libera todos os recursos usados pelo objeto BufferedGraphics. |
| Equals(Object) |
Determina se o objeto especificado é igual ao objeto atual. (Herdado de Object) |
| Finalize() |
Permite que um objeto tente liberar recursos e executar outras operações de limpeza antes de ser recuperado pela coleta de lixo. |
| GetHashCode() |
Serve como a função de hash padrão. (Herdado de Object) |
| GetType() |
Obtém o Type da instância atual. (Herdado de Object) |
| MemberwiseClone() |
Cria uma cópia superficial do Object atual. (Herdado de Object) |
| Render() |
Grava o conteúdo do buffer de gráficos no dispositivo padrão. |
| Render(Graphics) |
Grava o conteúdo do buffer gráfico no objeto Graphics especificado. |
| Render(IntPtr) |
Grava o conteúdo do buffer de gráficos no contexto de dispositivo associado ao identificador IntPtr especificado. |
| ToString() |
Retorna uma cadeia de caracteres que representa o objeto atual. (Herdado de Object) |
Aplica-se a
Acesso thread-safe
A classe BufferedGraphics não é segura para threads. Ao acessar um buffer de gráficos de threads separados, é importante usar um mecanismo de controle de acesso a threads para evitar conflitos.