从线程启动时模态弹出窗口失败 - CSharp WPF

Question

要批量上传许多文件，我有一段 CSharp WPF 代码，它产生线程以允许并行上传文件。 如果上传发生错误，将使用 MessageBox 弹出一条消息。这很好用。

但最近我们决定自定义 MessageBox 的外观。我发现当使用 ShowDialog() 打开我们的新自定义 WPF MessageBox 窗口时，会抛出一个错误，提示无法启动 GUI。这只发生在衍生线程中的代码尝试打开自定义消息窗口时——当自定义消息框从主线程打开时，我看不到问题。

我的临时解决方法是捕获自定义对话框启动时发生的任何错误，或者调用标准 MessageBox.Show() 来显示消息。这行得通。

我不确定为什么可以使用标准 MessageBox.Show() 但它不适用于自定义窗口。有没有办法解决这个问题？

Answer 1

通常（在任何 GUI-API 中）不从工作线程调用 GUI 函数，也不在 GUI 线程上做繁重的工作。 标准 MessageBox 在工作线程上工作的事实令人遗憾。

是的，你完全正确。当您的工作线程发生需要向用户显示的事情时，向 GUI 线程发送通知（信号、事件，无论您的框架调用什么）并在那里显示消息。

Answer 2

protected void chkAll_CheckedChanged(object sender, EventArgs e)
    {
        CheckBox chall = (CheckBox)sender;
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            CheckBox chSelect = (CheckBox)GridView1.Rows[i].FindControl("ChkSelect");
            if (chSelect != null)
            {
                chSelect.Checked = chall.Checked;
            }
        }
    }
    protected void chkSelect_CheckedChange(object sender, EventArgs e)
    {
        int i=0;
        CheckBox chkAll = (CheckBox)GridView1.HeaderRow.FindControl("chkAll");
        for ( i = 0; i < GridView1.Rows.Count; i++)
        {
            CheckBox chkSelect = (CheckBox)GridView1.Rows[i].FindControl("ChkSelect");
            if(chkSelect!=null && !chkSelect.Checked  )
                if (chkAll != null)
                {
                    chkAll.Checked = false;
                }
            break;
        }
        if (GridView1.Rows.Count == i && chkAll != null)
        {
            chkAll.Checked = true;
        }

    }
    protected void ddlPaymentMode_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList ddlpaymode = (DropDownList)sender;
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            Label lblpaymode = (Label)GridView1.Rows[i].FindControl("lblPayAmt_Mode");
            CheckBox chpaymode = (CheckBox)GridView1.Rows[i].FindControl("ChkSelect");
            if (chpaymode.Checked)
            {
                lblpaymode.Text = ddlpaymode.SelectedItem.Text;
            }
        }
    }
    protected void ddlBankName_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList ddlBank = (DropDownList)sender;
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            CheckBox cselect = (CheckBox)GridView1.Rows[i].FindControl("ChkSelect");
            Label lblBankName = (Label)GridView1.Rows[i].FindControl("LblBank");
            if (cselect.Checked)
            {
                lblBankName.Text = ddlBank.SelectedItem.Text;
            }

        }
    }
    protected void btnaddbpc_Click(object sender, EventArgs e)
    {
        int temp = Convert.ToInt32(txtChequeNo.Text);
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            CheckBox chkselect = (CheckBox)GridView1.Rows[i].FindControl("ChkSelect");
            Label lblcheckno = (Label)GridView1.Rows[i].FindControl("LblCheque");


            if (chkselect.Checked)
            {

                lblcheckno.Text = Convert.ToString(temp);
                temp++; 
            }

        }
    }
    protected void dtnDelete_Click(object sender, EventArgs e)
    {
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            CheckBox chkselect = (CheckBox)GridView1.Rows[i].FindControl("ChkSelect");
            Label lblcheckno = (Label)GridView1.Rows[i].FindControl("LblCheque");


            if (chkselect.Checked)
            {
                lblcheckno.Text = "";
            }

        }
    }
    protected void btnAddCDate_Click(object sender, EventArgs e)
    {
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            Label lblchqdate = (Label)GridView1.Rows[i].FindControl("LblCheque_Date");
            CheckBox chkselect = (CheckBox)GridView1.Rows[i].FindControl("ChkSelect");
            if (chkselect.Checked)
            {
                lblchqdate.Text = TxtChequeDate.Text;
            }
        }
    }
    protected void btnRemovecDate_Click(object sender, EventArgs e)
    {
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            Label lblchqdate = (Label)GridView1.Rows[i].FindControl("LblCheque_Date");
            CheckBox chkselect = (CheckBox)GridView1.Rows[i].FindControl("ChkSelect");
            if (chkselect.Checked)
            {
                lblchqdate.Text = "";
            }
        }
    }
    protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName == "Modify")
        {
            string ID = e.CommandArgument.ToString();
            //Response.Redirect("Admin_Update_BinryPayment.aspx?id="+ID+"&FromDate='"+ txtfromdate.Text +"'&ToDate='"+txttilldate.Text+"'");
            int Index = ((GridViewRow)((LinkButton)e.CommandSource).Parent.Parent).RowIndex;
            CheckBox chksec = (CheckBox)GridView1.Rows[Index].FindControl("ChkSelect");
            Label lblANo = (Label)GridView1.Rows[Index].FindControl("Label2");
            Label lbAName = (Label)GridView1.Rows[Index].FindControl("Label3");
            Label lbACName = (Label)GridView1.Rows[Index].FindControl("Label3");
            Label lbacNo = (Label)GridView1.Rows[Index].FindControl("lblBankAccountNo");
            Label lbBankName = (Label)GridView1.Rows[Index].FindControl("LblBank");
            Label lbchqNo = (Label)GridView1.Rows[Index].FindControl("LblCheque");
            Label lbchqDate = (Label)GridView1.Rows[Index].FindControl("LblCheque_Date");
            Label lblChqAmt = (Label)GridView1.Rows[Index].FindControl("Label23");
            if (chksec.Checked)
            {
                txtABNo.Text = GridView1.Rows[Index].Cells[3].Text;

Answer 3

        Dispatcher.BeginInvoke(DispatcherPriority.Background, (SendOrPostCallback)delegate {
            // show your MB here
        }, null);