C＃visualstudion windows形成图形图表

本文介绍了C＃visualstudion windows形成图形图表的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

您好， 我刚创建了一个图形图表，代码与OlrDb访问基础一起运行并且运行良好。

Chart Graph_121 = new Chart（）; // CréerunChart vide ChartArea ChartArea121 = new ChartArea（）; // ChartArea（zone graphique） Graph_121.ChartAreas.Add（ChartArea121）; // Ajoute le ChartAreaàlaCollection ChartAreas du Chart Series series121 = new Series（）; // Créationserie（qui contiendront les DataPoints）

我的问题如下： 在同一表格中我想添加一个按钮并删除方法清除我的图表，该怎么办？ 什么都行不通：

Graph_121.Clear（） ; ChartArea121.Clear（）; series121.Clear（）;

当前上下文中不存在名称Graph_121！ 我们可以公开声明Graph_121，ChartArea121，series121吗？ br $> b $ b 谢谢 我的尝试：

Control Page_Principale = Graph_121.Page_Principale; Page_Principale.Controls.Remove（Graph_121）; Graph_121.Clear（）; ChartArea121.Clear（）; series121.Clear（）;

解决方案

如果你通过代码创建它，看起来你的图表将超出范围以上。 将您的图表在班级定义为私人或公共成员，以便您的程序的不同部分可以看到图表，而不仅仅是首先创建图表的方法（作为本地变量）。

您好，感谢您的帮助。我刚刚创建了一个这样的方法：

public void MyGraph_121（） { string CentreAnnee = Filtre_Cbo_Annee.Text; Chart Graph_121 = new Chart（）; ChartArea ChartArea121 = new ChartArea（）; Graph_121.ChartAreas.Add（ChartArea121）; 系列series121 = new 系列 { IsValueShownAsLabel = true ， ChartArea = ChartArea1 }; Graph_121.Series.Add（series121）; // 其余代码 }

然后我在页面顶部说：

public int i1，i2，i3，i4，i5，i6，i7 ，i8，i9，i10，i11，i12，i13，i14; public string CentreAnnee; public ChartAreaCollection Graph_121，ChartArea121，series121;

然后一旦显示的图表我用这个按钮测试：

private void button1_Click（ object sender，EventArgs e） { ChartArea121.Clear（ ）; series121.Clear（）; ChartArea121.Clear（）; }

我收到一条错误消息：

System.NullReferenceException： ' 对象引用未设置为对象的实例。' ChartArea121 null 。

如何申报图表项？

public ChartAreaCollection Graph_121，ChartArea121，series121;

它是对象，字符串不会，int也是？ 谢谢

Hello, I just created a Graphics Chart by code that works with an OlrDb access base and works well.

Chart Graph_121 = new Chart(); // Créer un Chart vide ChartArea ChartArea121 = new ChartArea(); // ChartArea (zone graphique) Graph_121.ChartAreas.Add(ChartArea121); // Ajoute le Chart Area à la Collection ChartAreas du Chart Series series121 = new Series(); // Création serie (qui contiendront les DataPoints)

My question is the following : In the same form I want to add a button and delete with the method Clear my Chart, how to do? Nothing works :

Graph_121.Clear(); ChartArea121.Clear(); series121.Clear();

The name Graph_121 does not exist in the current context ! Can we declare Graph_121, ChartArea121, series121 in public? thank you What I have tried:

Control Page_Principale = Graph_121.Page_Principale; Page_Principale.Controls.Remove(Graph_121); Graph_121.Clear(); ChartArea121.Clear(); series121.Clear();

解决方案

Looks like your "chart" is going "out of scope" if you created it "by code" as above. Define your chart "at the class level" as a "private or public" member so that different parts of your program can "see" chart and not just the method that first created chart (as a "local" variable).

Hello, Thanks for your help. I just created a method like this:

public void MyGraph_121() { string CentreAnnee = Filtre_Cbo_Annee.Text; Chart Graph_121 = new Chart(); ChartArea ChartArea121 = new ChartArea(); Graph_121.ChartAreas.Add(ChartArea121); Series series121 = new Series { IsValueShownAsLabel = true, ChartArea = "ChartArea1" }; Graph_121.Series.Add(series121); // rest of the code }

Then I said at the top of my page like this:

public int i1, i2, i3, i4, i5, i6, i7, i8, i9, i10, i11, i12, i13, i14; public string CentreAnnee; public ChartAreaCollection Graph_121, ChartArea121, series121;

Then once the graph displayed I test with this button:

private void button1_Click(object sender, EventArgs e) { ChartArea121.Clear(); series121.Clear(); ChartArea121.Clear(); }

I have as an error message:

System.NullReferenceException : 'Object reference not set to an instance of an object.' ChartArea121 was null.

How to declare Chart items?

public ChartAreaCollection Graph_121, ChartArea121, series121;

Is it objects, string does not go, int either? thank you