Como: Distinguir entre cliques e Double-Clicks

Artigo
08/25/2010

Normalmente, um único clique inicia uma ação da interface do usuário (IU) e um clique duplo estende a ação.Por exemplo, um clique normalmente seleciona um item, e um clique duplo edita o item selecionado.No entanto, os Formulários do Windows não acomodam facilmente um cenário onde um clique e um clique duplo executam ações incompatíveis, porque uma ação ligados evento Click ou MouseClick é executada antes da ação ligada ao evento DoubleClick ou MouseDoubleClick .Este tópico mostra duas soluções para esse problema.Uma solução é para tratar o clique duplo e reverter as ações no tratamento do evento de clique único.Em situações raras talvez você precise simular o comportamento do clique e do clique duplo manipulando o evento MouseDown e usando as propriedades DoubleClickTime e DoubleClickSize da classe SystemInformation.Você medir o tempo entre os cliques e se um segundo clique ocorre antes que o valor de DoubleClickTime for atingido e o clique foi dentro de um retângulo definido por DoubleClickSize, executar a ação de duplo clique; caso contrário, executar a ação de clique único.

Para reverter uma ação de clique

Certifique-se de que o controle com que que você está trabalhando tem o comportamento padrão de clique duplo.Caso contrário, ative o controle com o método SetStyle.Trate o evento de clique duplo e reverta a ação de clique, bem como a ação de clique duplo.O código exemplo a seguir demonstra um como criar um botão personalizado com clique duplo ativado, bem como como reverter a ação de clique no código do manipulador de eventos do clique duplo.

Imports System
Imports System.ComponentModel
Imports System.Drawing
Imports System.Text
Imports System.Windows.Forms



Public Class Form1
    Inherits Form
    Private WithEvents button1 As DoubleClickButton
    Private initialStyle As FormBorderStyle

    Public Sub New() 
        Me.SuspendLayout()
        initialStyle = Me.FormBorderStyle
        Me.ClientSize = New System.Drawing.Size(292, 266)
        button1 = New DoubleClickButton()
        button1.Location = New Point(40, 40)
        button1.AutoSize = True
        button1.Text = "Click or Double Click"
        Me.Controls.Add(button1)
        Me.Name = "Form1"
        Me.ResumeLayout(False)
        Me.PerformLayout()

    End Sub 'New


    ' Handle the double click event.
    Private Sub button1_DoubleClick(ByVal sender As Object, ByVal e As EventArgs) _
        Handles button1.DoubleClick

        ' Change the border style back to the initial style.
        Me.FormBorderStyle = initialStyle
        MessageBox.Show("Rolled back single click change.")

    End Sub


    ' Handle the click event.
    Private Sub button1_Click(ByVal sender As Object, ByVal e As EventArgs) _
         Handles button1.Click

        Me.FormBorderStyle = FormBorderStyle.FixedToolWindow

    End Sub


    <STAThread()> _
    Shared Sub Main()
        Application.EnableVisualStyles()
        Application.Run(New Form1())

    End Sub
End Class

Public Class DoubleClickButton
    Inherits Button

    Public Sub New() 
        ' Set the style so a double click event occurs.
        SetStyle(ControlStyles.StandardClick Or ControlStyles.StandardDoubleClick, True)

    End Sub 'New
End Class 'DoubleClickButton

using System;
using System.ComponentModel;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace MouseRollBackSingleClick
{
    public class Form1 : Form
    {
        private DoubleClickButton button1;
        private FormBorderStyle initialStyle;

        public Form1()
        {
            initialStyle = this.FormBorderStyle;
            this.ClientSize = new System.Drawing.Size(292, 266);
            button1 = new DoubleClickButton();
            button1.Location = new Point (40,40);
            button1.Click += new EventHandler(button1_Click);
            button1.AutoSize = true;
            this.AllowDrop = true;
            button1.Text = "Click or Double Click";
            button1.DoubleClick += new EventHandler(button1_DoubleClick);
            this.Controls.Add(button1);

        }


        // Handle the double click event.
        void button1_DoubleClick(object sender, EventArgs e)
        {
            // Change the border style back to the initial style.
            this.FormBorderStyle = initialStyle;
            MessageBox.Show("Rolled back single click change.");
        }

        // Handle the click event.
        void button1_Click(object sender, EventArgs e)
        {
            this.FormBorderStyle = FormBorderStyle.FixedToolWindow;
        }

        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.Run(new Form1());
        }


    }
    public class DoubleClickButton : Button
    {
        public DoubleClickButton() : base()
        {
            // Set the style so a double click event occurs.
            SetStyle(ControlStyles.StandardClick | 
                ControlStyles.StandardDoubleClick, true);
        }
    }
}

Para fazer a distinção entre os cliques no evento MouseDown

Manipule o evento MouseDown e determine a localização e o espaço de tempo entre os cliques usando as propriedades SystemInformation apropriadas e um componente Timer.Execute a ação apropriada, dependendo se um clique ou clique duplo ocorreu.O exemplo a seguir demonstra como isto pode ser feito.

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Namespace SingleVersusDoubleClick

    Class Form1
        Inherits Form
        Private hitTestRectangle As New Rectangle()
        Private doubleClickRectangle As New Rectangle()
        Private textBox1 As New TextBox()
        Private WithEvents doubleClickTimer As New Timer()
        Private doubleClickBar As New ProgressBar()
        Private label1 As New Label()
        Private label2 As New Label()
        Private isFirstClick As Boolean = True
        Private isDoubleClick As Boolean = False
        Private milliseconds As Integer = 0

        <STAThread()> _
        Public Shared Sub Main()
            Application.EnableVisualStyles()
            Application.Run(New Form1())
        End Sub

        Public Sub New()
            label1.Location = New Point(30, 5)
            label1.Size = New Size(100, 15)
            label1.Text = "Hit test rectangle:"

            label2.Location = New Point(30, 70)
            label2.Size = New Size(100, 15)
            label2.Text = "Double click timer:"

            hitTestRectangle.Location = New Point(30, 20)
            hitTestRectangle.Size = New Size(100, 40)
            doubleClickTimer.Interval = 100

            doubleClickBar.Location = New Point(30, 85)
            doubleClickBar.Minimum = 0
            doubleClickBar.Maximum = SystemInformation.DoubleClickTime

            textBox1.Location = New Point(30, 120)
            textBox1.Size = New Size(200, 100)
            textBox1.AutoSize = False
            textBox1.Multiline = True

            Me.Controls.Add(doubleClickBar)
            Me.Controls.Add(textBox1)
            Me.Controls.Add(label1)
            Me.Controls.Add(label2)
        End Sub

        ' Detect a valid single click or double click.
        Sub Form1_MouseDown(ByVal sender As Object, _
            ByVal e As MouseEventArgs) Handles Me.MouseDown

            ' Verify that the mouse click is in the main hit
            ' test rectangle.
            If Not hitTestRectangle.Contains(e.Location) Then
                Return
            End If

            ' This is the first mouse click.
            If isFirstClick = True Then
                isFirstClick = False

                ' Determine the location and size of the double click 
                ' rectangle to draw around the cursor point.
                doubleClickRectangle = New Rectangle( _
                    e.X - (SystemInformation.DoubleClickSize.Width / 2), _
                    e.Y - (SystemInformation.DoubleClickSize.Height / 2), _
                    SystemInformation.DoubleClickSize.Width, _
                    SystemInformation.DoubleClickSize.Height)
                Invalidate()

                ' Start the double click timer.
                doubleClickTimer.Start()

            ' This is the second mouse click.
            Else
                ' Verify that the mouse click is within the double click
                ' rectangle and is within the system-defined double 
                ' click period.
                If doubleClickRectangle.Contains(e.Location) And _
                    milliseconds < SystemInformation.DoubleClickTime Then
                    isDoubleClick = True
                End If
            End If
        End Sub

        Sub doubleClickTimer_Tick(ByVal sender As Object, _
            ByVal e As EventArgs) Handles doubleClickTimer.Tick

            milliseconds += 100
            doubleClickBar.Increment(100)

            ' The timer has reached the double click time limit.
            If milliseconds >= SystemInformation.DoubleClickTime Then
                doubleClickTimer.Stop()

                If isDoubleClick Then
                    textBox1.AppendText("Perform double click action")
                    textBox1.AppendText(Environment.NewLine)
                Else
                    textBox1.AppendText("Perform single click action")
                    textBox1.AppendText(Environment.NewLine)
                End If

                ' Allow the MouseDown event handler to process clicks again.
                isFirstClick = True
                isDoubleClick = False
                milliseconds = 0
                doubleClickBar.Value = 0
            End If
        End Sub

        ' Paint the hit test and double click rectangles.
        Sub Form1_Paint(ByVal sender As Object, _
            ByVal e As PaintEventArgs) Handles Me.Paint

            ' Draw the border of the main hit test rectangle.
            e.Graphics.DrawRectangle(Pens.Black, hitTestRectangle)

            ' Fill in the double click rectangle.
            e.Graphics.FillRectangle(Brushes.Blue, doubleClickRectangle)
        End Sub
    End Class
End Namespace

using System;
using System.Drawing;
using System.Windows.Forms;

namespace SingleVersusDoubleClick
{
    class Form1 : Form
    {
        private Rectangle hitTestRectangle = new Rectangle();
        private Rectangle doubleClickRectangle = new Rectangle();
        private TextBox textBox1 = new TextBox();
        private Timer doubleClickTimer = new Timer();
        private ProgressBar doubleClickBar = new ProgressBar();
        private Label label1 = new Label();
        private Label label2 = new Label();
        private bool isFirstClick = true;
        private bool isDoubleClick = false;
        private int milliseconds = 0;

        [STAThread]
        public static void Main()
        {
            Application.EnableVisualStyles();
            Application.Run(new Form1());
        }

        public Form1()
        {
            label1.Location = new Point(30, 5);
            label1.Size = new Size(100, 15);
            label1.Text = "Hit test rectangle:";

            label2.Location = new Point(30, 70);
            label2.Size = new Size(100, 15);
            label2.Text = "Double click timer:";

            hitTestRectangle.Location = new Point(30, 20);
            hitTestRectangle.Size = new Size(100, 40);

            doubleClickTimer.Interval = 100;
            doubleClickTimer.Tick +=
                new EventHandler(doubleClickTimer_Tick);

            doubleClickBar.Location = new Point(30, 85);
            doubleClickBar.Minimum = 0;
            doubleClickBar.Maximum = SystemInformation.DoubleClickTime;

            textBox1.Location = new Point(30, 120);
            textBox1.Size = new Size(200, 100);
            textBox1.AutoSize = false;
            textBox1.Multiline = true;

            this.Paint += new PaintEventHandler(Form1_Paint);
            this.MouseDown += new MouseEventHandler(Form1_MouseDown);
            this.Controls.AddRange(new Control[] { doubleClickBar, textBox1, 
                label1, label2 });
        }

        // Detect a valid single click or double click.
        void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            // Verify that the mouse click is in the main hit
            // test rectangle.
            if (!hitTestRectangle.Contains(e.Location))
            {
                return;
            }

            // This is the first mouse click.
            if (isFirstClick)
            {
                isFirstClick = false;

                // Determine the location and size of the double click 
                // rectangle area to draw around the cursor point.
                doubleClickRectangle = new Rectangle(
                    e.X - (SystemInformation.DoubleClickSize.Width / 2),
                    e.Y - (SystemInformation.DoubleClickSize.Height / 2),
                    SystemInformation.DoubleClickSize.Width,
                    SystemInformation.DoubleClickSize.Height);
                Invalidate();

                // Start the double click timer.
                doubleClickTimer.Start();
            }

            // This is the second mouse click.
            else
            {
                // Verify that the mouse click is within the double click
                // rectangle and is within the system-defined double 
                // click period.
                if (doubleClickRectangle.Contains(e.Location) &&
                    milliseconds < SystemInformation.DoubleClickTime)
                {
                    isDoubleClick = true;
                }
            }
        }

        void doubleClickTimer_Tick(object sender, EventArgs e)
        {
            milliseconds += 100;
            doubleClickBar.Increment(100);

            // The timer has reached the double click time limit.
            if (milliseconds >= SystemInformation.DoubleClickTime)
            {
                doubleClickTimer.Stop();

                if (isDoubleClick)
                {
                    textBox1.AppendText("Perform double click action");
                    textBox1.AppendText(Environment.NewLine);
                }
                else
                {
                    textBox1.AppendText("Perform single click action");
                    textBox1.AppendText(Environment.NewLine);
                }

                // Allow the MouseDown event handler to process clicks again.
                isFirstClick = true;
                isDoubleClick = false;
                milliseconds = 0;
                doubleClickBar.Value = 0;
            }
        }

        // Paint the hit test and double click rectangles.
        void Form1_Paint(object sender, PaintEventArgs e)
        {
            // Draw the border of the main hit test rectangle.
            e.Graphics.DrawRectangle(Pens.Black, hitTestRectangle);

            // Fill in the double click rectangle.
            e.Graphics.FillRectangle(Brushes.Blue, doubleClickRectangle);
        }
    }
}

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

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

namespace SingleVersusDoubleClick
{
    public ref class Form1 : public Form
    {
    private:
        Rectangle hitTestRectangle;
    private:
        Rectangle doubleClickRectangle;
    private:
        TextBox^ outputBox;
    private:
        Timer^ doubleClickTimer;
    private:
        ProgressBar^ doubleClickBar;
    private:
        Label^ hitTestLabel;
    private:
        Label^ timerLabel;
    private:
        bool isFirstClick;
    private:
        bool isDoubleClick;
    private:
        int milliseconds;

    public:
        Form1()
        {
            hitTestRectangle = Rectangle();
            hitTestRectangle.Location = Point(30, 20);
            hitTestRectangle.Size = System::Drawing::Size(100, 40);

            doubleClickRectangle = Rectangle();

            outputBox = gcnew TextBox();
            outputBox->Location = Point(30, 120);
            outputBox->Size = System::Drawing::Size(200, 100);
            outputBox->AutoSize = false;
            outputBox->Multiline = true;

            doubleClickTimer = gcnew Timer();
            doubleClickTimer->Interval = 100;
            doubleClickTimer->Tick +=
                gcnew EventHandler(this, &Form1::doubleClickTimer_Tick);

            doubleClickBar = gcnew ProgressBar();
            doubleClickBar->Location = Point(30, 85);
            doubleClickBar->Minimum = 0;
            doubleClickBar->Maximum = SystemInformation::DoubleClickTime;

            hitTestLabel = gcnew Label();
            hitTestLabel->Location = Point(30, 5);
            hitTestLabel->Size = System::Drawing::Size(100, 15);
            hitTestLabel->Text = "Hit test rectangle:";

            timerLabel = gcnew Label();
            timerLabel->Location = Point(30, 70);
            timerLabel->Size = System::Drawing::Size(100, 15);
            timerLabel->Text = "Double click timer:";

            isFirstClick = true;

            this->Paint += gcnew PaintEventHandler(this, &Form1::Form1_Paint);
            this->MouseDown += 
                gcnew MouseEventHandler(this, &Form1::Form1_MouseDown);
            this->Controls->
                AddRange(gcnew array<Control^> { doubleClickBar, outputBox,
                hitTestLabel, timerLabel });
        }

        // Detect a valid single click or double click.
    private:
        void Form1_MouseDown(Object^ sender, MouseEventArgs^ e)
        {
            // Verify that the mouse click is in the main hit
            // test rectangle.
            if (!hitTestRectangle.Contains(e->Location))
            {
                return;
            }

            // This is the first mouse click.
            if (isFirstClick)
            {
                isFirstClick = false;

                // Determine the location and size of the double click
                // rectangle area to draw around the cursor point.
                doubleClickRectangle = Rectangle(
                    e->X - (SystemInformation::DoubleClickSize.Width / 2),                    
                    e->Y - (SystemInformation::DoubleClickSize.Height / 2),                    
                    SystemInformation::DoubleClickSize.Width,                    
                    SystemInformation::DoubleClickSize.Height);
                Invalidate();

                // Start the double click timer.
                doubleClickTimer->Start();
            }

            // This is the second mouse click.
            else
            {
                // Verify that the mouse click is within the double click
                // rectangle and is within the system-defined double
                // click period.
                if (doubleClickRectangle.Contains(e->Location) &&
                    milliseconds < SystemInformation::DoubleClickTime)
                {
                    isDoubleClick = true;
                }
            }
        }

    private:
        void doubleClickTimer_Tick(Object^ sender, EventArgs^ e)
        {
            milliseconds += 100;
            doubleClickBar->Increment(100);

            // The timer has reached the double click time limit.
            if (milliseconds >= SystemInformation::DoubleClickTime)
            {
                doubleClickTimer->Stop();

                if (isDoubleClick)
                {
                    outputBox->AppendText("Perform double click action");
                    outputBox->AppendText(Environment::NewLine);
                }
                else
                {
                    outputBox->AppendText("Perform single click action");
                    outputBox->AppendText(Environment::NewLine);
                }

                // Allow the MouseDown event handler to process clicks again.
                isFirstClick = true;
                isDoubleClick = false;
                milliseconds = 0;
                doubleClickBar->Value = 0;
            }
        }

        // Paint the hit test and double click rectangles.
    private:
        void Form1_Paint(Object^ sender, PaintEventArgs^ e)
        {
            // Draw the border of the main hit test rectangle.
            e->Graphics->DrawRectangle(Pens::Black, hitTestRectangle);

            // Fill in the double click rectangle.
            e->Graphics->FillRectangle(Brushes::Blue, doubleClickRectangle);
        }
    };
}


[STAThread]
int main()
{
    Application::EnableVisualStyles();
    Application::Run(gcnew SingleVersusDoubleClick::Form1);
}

Compilando o código

Esses exemplos requerem:

Referências para as montagens (assemblys) do System, System.Drawing e System.Windows.Forms.

Para obter informações sobre como criar este exemplo da linha de comando para Visual Basic ou Visual C#, consulte Criando a partir da linha de comando (Visual Basic) ou Linha de comando criando com csc.exe.Você também pode criar esses exemplos em Visual Studio colando o código em novos projetos.

Consulte também

Outros recursos

Entrada do Mouse em um Aplicativo de Formulários do Windows

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