如何将Form1变量传递给用户控件类？

Question

I have this user control code the User Control is GraphChart:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Web;
using System.Windows.Forms.DataVisualization.Charting;

namespace GatherLinks
{

    public partial class GraphChart : UserControl
    {
        Form1 form1;

        public GraphChart(Form1 f1)
        {
            InitializeComponent();

            form1 = f1;

        }

        private void GraphChart_Load(object sender, EventArgs e)
        {
            chart1.Series.Clear();
            var series1 = new System.Windows.Forms.DataVisualization.Charting.Series
            {
                Name = "Series1",
                Color = System.Drawing.Color.Green,
                IsVisibleInLegend = false,
                IsXValueIndexed = true,
                ChartType = SeriesChartType.Line
            };

            this.chart1.Series.Add(series1);

            //for (int i = 0; i < 100; i++)
            //{
                series1.Points.AddXY(form1.axisX, form1.axisY);
            //}
            chart1.Invalidate();
        }

After adding form1 and f1 variables im getting error:

Error 2 GatherLinks.GraphChart' does not contain a constructor that takes 0 arguments

When I make double click on the error it's moving to Form1 designer cs to the line:

this.graphChart1 = new GatherLinks.GraphChart();

I tried to put Form1 in between the () but it's not working getting an error. How can I solve it ?

EDIT:

I just did in the User Control code:

public partial class GraphChart : UserControl
    {
        Form1 form1;

        public GraphChart() { }
        public GraphChart(Form1 f1)
        {
            InitializeComponent();

            form1 = f1;

        }

But now in Form1 constructor I have this lines:

this.graphChart1.chart1.MouseMove += chart1_MouseMove;
this.graphChart1.chart1.MouseLeave += chart1_MouseLeave;

They worked before fine but as soon as I added the line: public GraphChart() { } Im getting an error when running the application that chart1 is null .

Answer 1

Your first problem is that your UserControl has no idea what the Form1 type is. You need to put a using statement at the top of your file to include your Forms Namespace, In my case I tested with WindowsFormApplication1 though it will be what ever namespace that you used. And in your updated example you are never calling your InitializeComponent Method so you never create your Chart.

You can try something like this if you want to use a parameterless constructor: ( note the addition of the InitializeComponent method to the Default Constructor and the addition of two additional methods SetupGraph and SetForm I also moved the code out of the GraphChart_Load eventhandler to the SetupGraph Method. This works both with passing Form1 in the Constructor and using the Parameterless Constructor as long as you use SetForm before you call SetupGraph )

UserControl

public partial class GraphChart : UserControl
{
    private Chart chart1;
    Form1 form1;
    public GraphChart()
    {
        InitializeComponent();
    }
    public GraphChart(Form1 f1)
    {
        InitializeComponent();
        form1 = f1;
        this.Load+=new EventHandler(GraphChart_Load);
    }
    public void SetForm( Form1 f1)
    {
        form1 = f1;
    }
    public void SetupGraph()
    {
        chart1.Series.Clear();
        var series1 = new System.Windows.Forms.DataVisualization.Charting.Series
        {
            Name = "Series1",
            Color = System.Drawing.Color.Green,
            IsVisibleInLegend = false,
            IsXValueIndexed = true,
            ChartType = SeriesChartType.Line
        };

        this.chart1.Series.Add(series1);

        //for (int i = 0; i < 100; i++)
        //{
        series1.Points.AddXY(form1.axisX, form1.axisY);
        //}
        chart1.Invalidate();
    }
    private void GraphChart_Load(object sender, EventArgs e)
    {
        SetupGraph();
    }

    private void InitializeComponent()
    {
        System.Windows.Forms.DataVisualization.Charting.ChartArea chartArea1 = new System.Windows.Forms.DataVisualization.Charting.ChartArea();
        System.Windows.Forms.DataVisualization.Charting.Legend legend1 = new System.Windows.Forms.DataVisualization.Charting.Legend();
        System.Windows.Forms.DataVisualization.Charting.Series series1 = new System.Windows.Forms.DataVisualization.Charting.Series();
        this.chart1 = new System.Windows.Forms.DataVisualization.Charting.Chart();
        ((System.ComponentModel.ISupportInitialize)(this.chart1)).BeginInit();
        this.SuspendLayout();
        // 
        // chart1
        // 
        chartArea1.Name = "ChartArea1";
        this.chart1.ChartAreas.Add(chartArea1);
        legend1.Name = "Legend1";
        this.chart1.Legends.Add(legend1);
        this.chart1.Location = new System.Drawing.Point(0, 0);
        this.chart1.Name = "chart1";
        series1.ChartArea = "ChartArea1";
        series1.Legend = "Legend1";
        series1.Name = "Series1";
        this.chart1.Series.Add(series1);
        this.chart1.Size = new System.Drawing.Size(519, 473);
        this.chart1.TabIndex = 0;
        this.chart1.Text = "chart1";
        // 
        // GraphChart
        // 
        this.Controls.Add(this.chart1);
        this.Name = "GraphChart";
        ((System.ComponentModel.ISupportInitialize)(this.chart1)).EndInit();
        this.ResumeLayout(false);

    }
}

Form1

public partial class Form1 : Form
{
    public int axisX = 100;
    public int axisY = 100;
    GatherLinks.GraphChart graphChart1;

    public Form1()
    {
        InitializeComponent();

    }

    private void button1_Click(object sender, EventArgs e)
    {
        graphChart1 = new GatherLinks.GraphChart();
        this.Controls.Add(graphChart1);
        graphChart1.SetForm(this);
        graphChart1.SetupGraph();
    }

}

Answer 2

您需要为该类提供一个带有0个参数的构造函数，因此请尝试将以下行添加到GraphChart类中：

public GraphChart(){}