从线程启动时模态弹出窗口失败 - CSharp WPF

Question

为了批量上传许多文件，我有一段 CSharp WPF 代码，它会生成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() 打开新的自定义 WPF MessageBox 窗口时，会引发错误，指出无法启动 GUI。仅当生成的线程中的代码尝试打开自定义消息窗口时才会发生这种情况 - 当从主线程打开自定义消息框时，我没有看到问题。

我的临时修复是捕获启动自定义对话框时发生的任何错误，并选择调用标准 MessageBox.Show() 来显示消息。那行得通。

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。有办法解决这个问题吗？

Answer 1

通常（在任何 GUI-API 中）不要从工作线程调用 GUI 函数，也不在 GUI 线程上做繁重的工作。
标准 MessageBox 在工作线程上工作这一事实令人遗憾。

是的，你完全正确。当您的工作线程上发生需要向用户显示的事情时，将通知（信号、事件，无论您的框架如何调用它）发送到 GUI 线程并在那里显示消息。

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);