PaintEventArgs.Graphics 属性

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

获取用于进行绘制的图形。

public:
 property System::Drawing::Graphics ^ Graphics { System::Drawing::Graphics ^ get(); };

public System.Drawing.Graphics Graphics { get; }

member this.Graphics : System.Drawing.Graphics

Public ReadOnly Property Graphics As Graphics

属性值

Graphics

用于绘画的 Graphics 对象。 Graphics 对象提供将对象绘制到显示设备上的方法。

示例

下面的示例演示如何处理 Paint 事件并使用 PaintEventArgs 类在窗体上绘制矩形。 处理 MouseDown 和 MouseUp 事件以确定矩形的大小。 该示例还演示 Invalidate 了使矩形区域失效的方法，导致矩形重新绘制。

private:
   Rectangle RcDraw;
   void Form1_MouseDown( Object^ /*sender*/, System::Windows::Forms::MouseEventArgs^ e )
   {
      // Determine the initial rectangle coordinates...
      RcDraw.X = e->X;
      RcDraw.Y = e->Y;
   }

   void Form1_MouseUp( Object^ /*sender*/, System::Windows::Forms::MouseEventArgs^ e )
   {
      // Determine the width and height of the rectangle...
      if ( e->X < RcDraw.X )
      {
         RcDraw.Width = RcDraw.X - e->X;
         RcDraw.X = e->X;
      }
      else
      {
         RcDraw.Width = e->X - RcDraw.X;
      }

      if ( e->Y < RcDraw.Y )
      {
         RcDraw.Height = RcDraw.Y - e->Y;
         RcDraw.Y = e->Y;
      }
      else
      {
         RcDraw.Height = e->Y - RcDraw.Y;
      }

      // Force a repaint of the region occupied by the rectangle...
      this->Invalidate( RcDraw );
   }

   void Form1_Paint( Object^ /*sender*/, System::Windows::Forms::PaintEventArgs^ e )
   {
      // Draw the rectangle...
      float PenWidth = 5;
      e->Graphics->DrawRectangle( gcnew Pen( Color::Blue,PenWidth ), RcDraw );
   }

private Rectangle RcDraw;
private float PenWidth = 5;

private void Form1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{

    // Determine the initial rectangle coordinates...

    RcDraw.X = e.X;
    RcDraw.Y = e.Y;
}

private void Form1_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e)
{

    // Determine the width and height of the rectangle...

    if(e.X < RcDraw.X)
    {
        RcDraw.Width = RcDraw.X - e.X;
        RcDraw.X = e.X;
    }
    else
    {
        RcDraw.Width = e.X - RcDraw.X;
    }

    if(e.Y < RcDraw.Y)
    {
        RcDraw.Height = RcDraw.Y - e.Y;
        RcDraw.Y = e.Y;
    }
    else
    {
        RcDraw.Height = e.Y - RcDraw.Y;
    }

    // Force a repaint of the region occupied by the rectangle...

    this.Invalidate(RcDraw);
}

private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{

    // Draw the rectangle...

    e.Graphics.DrawRectangle(new Pen(Color.Blue, PenWidth), RcDraw);
}

Dim RcDraw As Rectangle
Dim PenWidth As Integer = 5


Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseDown

    ' Determine the initial rectangle coordinates...

    RcDraw.X = e.X
    RcDraw.Y = e.Y

End Sub

Private Sub Form1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseUp

    ' Determine the width and height of the rectangle...

    If e.X < RcDraw.X Then
        RcDraw.Width = RcDraw.X - e.X
        RcDraw.X = e.X
    Else
        RcDraw.Width = e.X - RcDraw.X
    End If

    If e.Y < RcDraw.Y Then
        RcDraw.Height = RcDraw.Y - e.Y
        RcDraw.Y = e.Y
    Else
        RcDraw.Height = e.Y - RcDraw.Y
    End If

    ' Force a repaint of the region occupied by the rectangle...

    Me.Invalidate(RcDraw)

End Sub

Private Sub Form1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint

    ' Draw the rectangle...

    e.Graphics.DrawRectangle(New Pen(Color.Blue, PenWidth), RcDraw)

End Sub

   // This example creates a PictureBox control on the form and draws to it.
   // This example assumes that the Form_Load event handler method is
   // connected to the Load event of the form.
private:
   PictureBox^ pictureBox1;
   void Form1_Load( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      pictureBox1 = gcnew PictureBox;

      // Dock the PictureBox to the form and set its background to white.
      pictureBox1->Dock = DockStyle::Fill;
      pictureBox1->BackColor = Color::White;

      // Connect the Paint event of the PictureBox to the event handler method.
      pictureBox1->Paint += gcnew System::Windows::Forms::PaintEventHandler( this, &Form1::pictureBox1_Paint );

      // Add the PictureBox control to the Form.
      this->Controls->Add( pictureBox1 );
   }

   void pictureBox1_Paint( Object^ /*sender*/, System::Windows::Forms::PaintEventArgs^ e )
   {
      // Create a local version of the graphics object for the PictureBox.
      Graphics^ g = e->Graphics;

      // Draw a string on the PictureBox.
      g->DrawString( "This is a diagonal line drawn on the control",
         gcnew System::Drawing::Font( "Arial",10 ), System::Drawing::Brushes::Blue, Point(30,30) );

      // Draw a line in the PictureBox.
      g->DrawLine( System::Drawing::Pens::Red, pictureBox1->Left, pictureBox1->Top,
         pictureBox1->Right, pictureBox1->Bottom );
   }

// This example creates a PictureBox control on the form and draws to it.
// This example assumes that the Form_Load event handler method is
// connected to the Load event of the form.

private PictureBox pictureBox1 = new PictureBox();
// Cache font instead of recreating font objects each time we paint.
private Font fnt = new Font("Arial",10);
private void Form1_Load(object sender, System.EventArgs e)
{
    // Dock the PictureBox to the form and set its background to white.
    pictureBox1.Dock = DockStyle.Fill;
    pictureBox1.BackColor = Color.White;
    // Connect the Paint event of the PictureBox to the event handler method.
    pictureBox1.Paint += new System.Windows.Forms.PaintEventHandler(this.pictureBox1_Paint);

    // Add the PictureBox control to the Form.
    this.Controls.Add(pictureBox1);
}

private void pictureBox1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
    // Create a local version of the graphics object for the PictureBox.
    Graphics g = e.Graphics;

    // Draw a string on the PictureBox.
    g.DrawString("This is a diagonal line drawn on the control",
        fnt, System.Drawing.Brushes.Blue, new Point(30,30));
    // Draw a line in the PictureBox.
    g.DrawLine(System.Drawing.Pens.Red, pictureBox1.Left, pictureBox1.Top,
        pictureBox1.Right, pictureBox1.Bottom);
}

' This example creates a PictureBox control on the form and draws to it. 
' This example assumes that the Form_Load event handler method is connected 
' to the Load event of the form.
Private pictureBox1 As New PictureBox()
Private fnt as New Font("Arial", 10)

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
    ' Dock the PictureBox to the form and set its background to white.
    pictureBox1.Dock = DockStyle.Fill
    pictureBox1.BackColor = Color.White
    ' Connect the Paint event of the PictureBox to the event handler method.
    AddHandler pictureBox1.Paint, AddressOf Me.pictureBox1_Paint

    ' Add the PictureBox control to the Form.
    Me.Controls.Add(pictureBox1)
End Sub


Private Sub pictureBox1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs)
    ' Create a local version of the graphics object for the PictureBox.
    Dim g As Graphics = e.Graphics

    ' Draw a string on the PictureBox.
    g.DrawString("This is a diagonal line drawn on the control", _
        fnt, Brushes.Red, New PointF(30.0F, 30.0F))
    ' Draw a line in the PictureBox.
    g.DrawLine(System.Drawing.Pens.Red, pictureBox1.Left, _ 
        pictureBox1.Top, pictureBox1.Right, pictureBox1.Bottom)
End Sub

另请参阅

• Graphics