NumberBox
通常你會想要一個只接受數字的輸入框。再次通過從標準控制元件派生，這很容易實現，例如：
using System;
using System.Windows.Forms;
using System.Globalization;
namespace StackOverflowDocumentation
{
public class SONumberBox : SOTextBox
{
private int decPlaces;
private int extraDecPlaces;
private bool perCent;
private bool useThouSep = true;
private string decSep = ".";
private string thouSep = ",";
private double numVal;
public SONumberBox() : base()
{
}
public bool PerCent
{
get
{
return perCent;
}
set
{
perCent = value;
}
}
public double Value
{
get
{
return numVal;
}
set
{
numVal = value;
if (perCent)
{
double test = numVal * 100.0;
this.Text = FormatNumber(test) + "%";
}
else
{
this.Text = FormatNumber(value);
}
}
}
public bool UseThousandSeparator
{
get
{
return useThouSep;
}
set
{
useThouSep = value;
}
}
public int DecimalPlaces
{
get
{
return decPlaces;
}
set
{
decPlaces = value;
}
}
public int ExtraDecimalPlaces
{
get
{
return extraDecPlaces;
}
set
{
extraDecPlaces = value;
}
}
protected override void OnTextChanged(EventArgs e)
{
string newVal = this.Text;
int len = newVal.Length;
if (len == 0)
{
return;
}
bool neg = false;
if (len > 1)
{
if (newVal.Substring(0, 1) == "-")
{
newVal = newVal.Substring(1, len - 1);
len = newVal.Length;
neg = true;
}
}
double val = 1.0;
string endChar = newVal.Substring(newVal.Length - 1);
switch (endChar)
{
case "M":
case "m":
if (len > 1)
{
val = double.Parse(newVal.Substring(0, len - 1)) * 1000000.0;
}
else
{
val *= 1000000.0;
}
if (neg)
{
val = -val;
}
this.Text = FormatNumber(val);
break;
case "T":
case "t":
if (len > 1)
{
val = double.Parse(newVal.Substring(0, len - 1)) * 1000.0;
}
else
{
val *= 1000.0;
}
if (neg)
{
val = -val;
}
this.Text = FormatNumber(val);
break;
}
base.OnTextChanged(e);
}
protected override void OnKeyPress(KeyPressEventArgs e)
{
bool handled = false;
switch (e.KeyChar)
{
case '-':
if (this.Text.Length == 0)
{
break;
}
else if (this.SelectionStart == 0)
{
//negative being inserted first
break;
}
else
{
handled = true;
break;
}
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
case '0':
case (char)Keys.Back:
break;
case 'M':
case 'm':
case 'T':
case 't':
case '%':
//check last pos
int l = this.Text.Length;
int sT = this.SelectionStart;
int sL = this.SelectionLength;
if ((sT + sL) != l)
{
handled = true;
}
break;
default:
string thisChar = e.KeyChar.ToString();
if (thisChar == decSep)
{
char[] txt = this.Text.ToCharArray();
for (int i = 0; i < txt.Length; i++)
{
if (txt[i].ToString() == decSep)
{
handled = true;
break;
}
}
break;
}
else if (thisChar != thouSep)
{
handled = true;
}
break;
}
if (!handled)
{
base.OnKeyPress(e);
}
else
{
e.Handled = true;
}
}
protected override void OnLeave(EventArgs e)
{
string tmp = this.Text;
if (tmp == "")
{
tmp = "0";
numVal = NumberLostFocus(ref tmp);
this.Text = tmp;
}
if (tmp.Substring(tmp.Length - 1) == "%")
{
tmp = tmp.Substring(0, tmp.Length - 1);
numVal = 0.0;
numVal = NumberLostFocus(ref tmp) / 100.0;
double test = numVal * 100.0;
this.Text = FormatNumber(test) + "%";
}
else if (perCent)
{
numVal = NumberLostFocus(ref tmp);
double test = numVal * 100.0;
this.Text = FormatNumber(test) + "%";
}
else
{
numVal = NumberLostFocus(ref tmp);
this.Text = tmp;
}
base.OnLeave(e);
}
private string FormatNumber(double amount)
{
NumberFormatInfo nF = new NumberFormatInfo();
nF.NumberDecimalSeparator = decSep;
nF.NumberGroupSeparator = thouSep;
string decFormat;
if (useThouSep)
{
decFormat = "#,##0";
}
else
{
decFormat = "#0";
}
if (decPlaces > 0)
{
decFormat += ".";
for (int i = 0; i < decPlaces; i++)
{
decFormat += "0";
}
if (extraDecPlaces > 0)
{
for (int i = 0; i < extraDecPlaces; i++)
{
decFormat += "#";
}
}
}
else if (extraDecPlaces > 0)
{
decFormat += ".";
for (int i = 0; i < extraDecPlaces; i++)
{
decFormat += "#";
}
}
return (amount.ToString(decFormat, nF));
}
private double NumberLostFocus(ref string amountBox)
{
if (amountBox.Substring(0, 1) == decSep)
amountBox = "0" + amountBox;
NumberFormatInfo nF = new NumberFormatInfo();
nF.NumberDecimalSeparator = decSep;
nF.NumberGroupSeparator = thouSep;
try
{
double d = 0.0;
int l = amountBox.Length;
if (l > 0)
{
char[] c = amountBox.ToCharArray();
char endChar = c[l - 1];
switch (endChar)
{
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
{
stripNonNumerics(ref amountBox);
d = Double.Parse(amountBox, nF);
break;
}
case 'm':
case 'M':
{
if (amountBox.Length == 1)
d = 1000000.0;
else
{
string s = amountBox.Substring(0, l - 1);
stripNonNumerics(ref s);
d = Double.Parse(s, nF) * 1000000.0;
}
break;
}
case 't':
case 'T':
{
if (amountBox.Length == 1)
d = 1000.0;
else
{
string s = amountBox.Substring(0, l - 1);
stripNonNumerics(ref s);
d = Double.Parse(s, nF) * 1000.0;
}
break;
}
default:
{
//remove offending char
string s = amountBox.Substring(0, l - 1);
if (s.Length > 0)
{
stripNonNumerics(ref s);
d = Double.Parse(s, nF);
}
else
d = 0.0;
break;
}
}
}
amountBox = FormatNumber(d);
return (d);
}
catch (Exception e)
{
//handle exception here;
return 0.0;
}
}
private void stripNonNumerics(ref string amountBox)
{
bool dSFound = false;
char[] tmp = decSep.ToCharArray();
char dS = tmp[0];
string cleanNum = "";
int l = amountBox.Length;
if (l > 0)
{
char[] c = amountBox.ToCharArray();
for (int i = 0; i < l; i++)
{
char b = c[i];
switch (b)
{
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
cleanNum += b;
break;
case '-':
if (i == 0)
cleanNum += b;
break;
default:
if ((b == dS) && (!dSFound))
{
dSFound = true;
cleanNum += b;
}
break;
}
}
}
amountBox = cleanNum;
}
}
除了限制數字輸入外，此類還有一些特殊功能。它公開了一個屬性 Value 來表示數字的 double 值，它格式化文字，可選地有千位分隔符，它提供大數字的簡寫輸入：10M 擴充套件到 10,000,000.00（小數位數是屬性） ）。為簡潔起見，十進位制和千位分隔符已經過硬編碼。在生產系統中，這些也是使用者偏好。