（一）TEdit、TDBEdit、TComboBox、TDBComboBox的输入分三种类型限制：
（1）任意输入
（2）整数输入
（3）浮点数输入
限制的项目如下：
（1）整数输入只能输入数字0-9、+、-
（2）浮点输入只能输入数字0-9、+、-、.
（3）+和-只能有其一，并且只能出现在最前面
（4）.只能有一个
（5）限制小数位数
函数如下：
procedure MxFormatKeyPress(Text:string;SelStart,SelLength:integer; var
Key:Char;EditType:integer;Digits:integer);
begin
if (Key=#27) or (Key=#8) or (EditType=1) then exit;
if EditType=2 then if not (Key in [‘0‘..‘9‘,‘+‘,‘-‘] ) then
Key:=#0;
if EditType=3 then if not (Key in [‘0‘..‘9‘,‘+‘,‘-‘,‘.‘] ) then
Key:=#0;
//控制+-
if (Key =‘-‘) or (Key=‘+‘ ) then begin
if ((Pos(‘-‘,Text) > 0) or (Pos(‘+‘,Text)
> 0 )) and (SelLength=0 ) then Key:=#0;
if SelStart > 0 then Key:=#0;
end;
//控制.
if (Key = ‘.‘) and (EditType=3 ) then begin
if (Pos(‘.‘,Text) > 0) and
(not((SelStart=Pos(‘.‘,Text) ))) then Key:=#0;
if SelStart=0 then Key:=#0;
if (Digits>0) and (SelStart+SelLength0) and
(EditType=3) then
if (pos(‘.‘,Text )>0 ) and
(SelStart>=pos(‘.‘,Text)) then if length(Text)-pos(‘.‘,Text
)>=Digits then Key:=#0;
end;
此函数在所限制组件的OnKeyPress事件中调用。
Key即为OnKeyPress携带的Key:Char参数；
EditType为限制的类型：1-任意输入；2-整数输入；3-浮点输入；
Digits为浮点数输入时小数的位数，如果是零，则可输入任意位数。另外，此函数只适用于有Text、SelStart、SelLength等属性的TWinControl类的派生类。具体限制各组件的二级函数如下：
限制TEdit、TDBEdit：
procedure MxFormatEditKeyPress(Edit:TCustomEdit;var Key:Char;EditType:integer; Digits:integer);
begin
MxFormatKeyPress(Edit.Text,Edit.SelStart,Edit.SelLength,Key,EditType,Digits);
end;
限制TComboBox：
procedure MxFormatComboKeyPress(Combo:TComboBox;var Key:Char;EditType:integer; Digits:integer);
begin
MxFormatKeyPress(Combo.Text,Combo.SelStart,Combo.SelLength,Key,EditType,Digits);
end;
限制TDBComboBox：
procedure MxFormatDBComboKeyPress(Combo:TDBComboBox;var Key:Char; EditType:integer;Digits:integer);
begin
MxFormatKeyPress(Combo.Text,Combo.SelStart,Combo.SelLength,Key,EditType,Digits);
end;
调用示例：
假如Form1上有一ComboBox1，让用户只输入浮点数，并且小数位数为两位。则可以在ComboBox1的OnKeyPress事件中调用上面的函数：
procedure TForm1.ComboBox1KeyPress(Sender: TObject; var Key: Char);
begin
MxFormatComboKeyPress(Combobox1,Key,3,0);
end;
如果你的窗体上有多各TComboBox，并且限制类型一致，则不必每个TComboBox都
书写代码，只需为其中一个编写事件处理代码，其它作连接即可。
procedure TForm1.ComboBox1KeyPress(Sender: TObject; var Key: Char);
begin
MxFormatComboKeyPress(Sender as TComboBox,Key,3,0);
end;
其它组件调用方法同上。
（二）时间的输入
限制类型：
（1）时分
（2）时分秒
组件采用TMaskEdit，数据敏感采用TDBEdit。
限制项目如下：
（1）小时只能输入0-23
（2）分钟不超过59
（3）秒不超过59
（4）用户只能全删，而不能只删某一位数据
（5）箭头键可以更改时间
需要在组件的OnKeyPress和OnKeyDown事件中分别书写代码。
procedure
MxFormatTimeKeyPress(ctl:TCustomMaskEdit;TimeFormat:integer;
var
Key:Char;dts:TDataSource);
var
TextSave:string;
EditingPos:integer;//1-h 2-m 3-s
i:integer;
NumChars:set of Char;
SelStartSave,SelLengthSave:integer;
CharValid:boolean;
begin
NumChars:=[‘0‘..‘9‘];
if Key=^V then Key:=#0;
if not (Key in NumChars ) then exit;
TextSave:=ctl.Text;
SelStartSave:=ctl.SelStart;
SelLengthSave:=ctl.SelLength;
case ctl.SelStart of
0,1: EditingPos:=1;
3,4: EditingPos:=2;
6,7: EditingPos:=3;
else EditingPos:=0;
end;
///////////////////////////////////////
CharValid:=true;
case EditingPos of
1: begin
if SelStartSave=0 then begin
if not (Key in
[‘0‘..‘2‘]) then CharValid := False;
if (Key =‘2‘
) and (TextSave[2] in [‘4‘..‘9‘]) then
CharValid:=false;
end;
if (SelStartSave = 1) and
(TextSave[1] = ‘2‘) and
(not (Key in [‘0‘..‘3‘])) then CharValid := False;
end;
2: if (SelStartSave = 3) and not (Key in
[‘0‘..‘5‘]) then CharValid := False;
3: if (SelStartSave = 6) and not (Key in
[‘0‘..‘5‘]) then CharValid := False;
end;
if not CharValid then begin
Key:=#0;exit;
end;
if dts<>nil then dts.DataSet.Edit;
if not (SelStartSave in [2,5]) then
TextSave[SelStartSave+1]:=Key;
if SelLengthSave>1 then begin
for i:=SelStartSave+2 to
SelStartSave+SelLengthSave do
if i in [1,2,4,5,7,8] then
TextSave[i]:=‘0‘;
SelLengthSave:=1;
end;
for i:=1 to length(TextSave) do
if (i in [1,2,4,5,7,8]) and (not (TextSave[i] in
NumChars ) ) then
TextSave[i]:=‘0‘;
////////////////////////////////////
if SelStartSave in [1,4] then
SelStartSave :=SelStartSave+2
else if SelStartSave=length(TextSave)-1 then
SelStartSave :=SelStartSave
else SelStartSave :=SelStartSave+1;
/////////////////////////////////////
ctl.Text :=TextSave;
ctl.SelStart :=SelStartSave;
ctl.SelLength :=SelLengthSave;
Key:=#0;
end;
//此函数分割时间，因为有时候会遇到非法的时间字符串，所以不采用DecodeTime。
function MxSplitStr(SourceStr,SplitStr:string;var ResultArray:array of
string):integer;
var
i:integer;
strTmp:string;
begin
strTmp:=SourceStr;
i:=0;
while pos(SplitStr,strTmp)>0 do begin
ResultArray[i]:=copy(strTmp,1,pos(SplitStr,strTmp)-1);
strTmp:=copy(strTmp,pos(SplitStr,strTmp)+length(SplitStr),length(strTmp)-
pos(SplitStr,strTmp));
i:=i+1;
end;
ResultArray[i]:=strTmp;
result:=i+1;
end;
//此函数检查字符串是否为合法的时间
function TimeValid(TimeStr:string;TimeFormat:integer):boolean;
var
h,m,s:string;
ary:array[0..2] of string;
SplitRet:integer;
i:integer;
begin
result:=true;
SplitRet:=MxSplitStr(TimeStr,‘:‘,ary);
if SplitRet<2 then begin
result:=false; exit;
end;
for i:=0 to 2 do begin
if length(ary[i])>2 then begin
result:=false; exit;
end;
ary[i]:=trim(ary[i]);
end;
h:=ary[0];m:=ary[1];
if TimeFormat=3 then s:=ary[2];
///////////////////////////////
if (h=‘‘) or (strtoint(h)>23 ) then begin
result:=false; exit;
end;
if (m=‘‘ ) or (strtoint(m)>59) then begin
result:=false; exit;
end;
if (TimeFormat=3) then
if (s=‘‘) or (strtoint(s)>59) then begin
result:=false; exit;
end;
end;
//此函数对时分秒进行加减运算
function IncTime(ATime: TDateTime; Hours, Minutes, Seconds,
MSecs: Integer): TDateTime;
begin
Result := ATime + (Hours div 24) + (((Hours mod 24) *
3600000 +
Minutes * 60000 + Seconds * 1000 + MSecs) /
MSecsPerDay);
if Result < 0 then Result := Result + 1;
end;
//时分秒加减运算的二级函数
function TimeAdd(TimeStr:string;TimeFormat:integer;
HStep,MStep,SStep:integer):string;
var
dt:Tdatetime;
begin
if not TimeValid(TimeStr,TimeFormat) then
if TimeFormat=2 then begin result:=‘00:00‘;
exit; end
else begin result:=‘00:00:00‘;exit; end;
dt:=strtotime(TimeStr);
if TimeFormat=2 then
result:=FormatDateTime(‘hh:mm‘,IncTime(dt,HStep,MStep,SStep,0))
else
result:=FormatDateTime(‘hh:mm:ss‘,IncTime(dt,HStep,MStep,SStep,0))
end;
//限制组件的OnKeyDown
procedure MxFormatTimeKeyDown(ctl:TCustomMaskEdit;TimeFormat:integer;
var Key:word;Shift:
TShiftState;dts:TDataSource);
var
TextSave:string;
SelStartSave,SelLengthSave:integer;
EditingPos:integer;//1-h 2-m 3-s
i:integer;
begin
if (ssShift in Shift) and (Key<>vk_delete ) then exit;
if not (Key in [vk_delete,vk_back,vk_up,vk_down] ) then
exit;
if (dts<>nil ) and (not
dts.DataSet.Active ) then exit;
if (dts<>nil) and (not dts.DataSet.Modified ) then
dts.DataSet.Edit;
//////////////////////////////////////
TextSave:=ctl.Text;
SelStartSave:=ctl.SelStart;
SelLengthSave:=ctl.SelLength;
case SelStartSave of
0,1: EditingPos:=1;
3,4: EditingPos:=2;
6,7: EditingPos:=3;
else EditingPos:=0;
end;
if SelStartSave=length(TextSave) then
EditingPos:=TimeFormat;
if Key=vk_delete then begin
if SelLengthSave=length(TextSave) then
TextSave:=‘‘
else begin
if not (SelStartSave in [2,5]) then
TextSave[SelStartSave+1]:=‘0‘;
if SelLengthSave>1 then begin
for i:=SelStartSave+2 to
SelStartSave+SelLengthSave do
if i in
[1,2,4,5,7,8] then TextSave[i]:=‘0‘;
SelLengthSave:=1;
end;
end;
Key:=0;
end;
if Key=vk_back then begin
if SelLengthSave=length(TextSave) then
TextSave:=‘‘
else if SelLengthSave<=1 then begin
if not (SelStartSave in [3,6]) then
begin
TextSave[SelStartSave]:=‘0‘;
SelStartSave:=SelStartSave-1;
end else begin
TextSave[SelStartSave-1]:=‘0‘;
SelStartSave:=SelStartSave-2;
end;
SelLengthSave:=1;
end else begin
for i:=SelStartSave+1 to
SelStartSave+SelLengthSave do
if i in [1,2,4,5,7,8]
then TextSave[i]:=‘0‘;
SelLengthSave:=1;
end;
Key:=0;
end;
///////////////////////////////////////
if (Key=vk_up) or (Key=vk_down ) then begin
if trim(TextSave)=‘:‘ then begin
if TimeFormat=2 then
TextSave:=‘00:00‘
else TextSave:=‘00:00:00‘
end else begin
if Key=vk_up then
case EditingPos of
1:
TextSave:=TimeAdd(TextSave,TimeFormat,1,0,0);
2:
TextSave:=TimeAdd(TextSave,TimeFormat,0,1,0);
3:
TextSave:=TimeAdd(TextSave,TimeFormat,0,0,1);
end;
if Key=vk_down then
case EditingPos of
1:
TextSave:=TimeAdd(TextSave,TimeFormat,-1,0,0);
2:
TextSave:=TimeAdd(TextSave,TimeFormat,0,-1,0);
3:
TextSave:=TimeAdd(TextSave,TimeFormat,0,0,-1);
end;
end;
end;
///////////////////////////////////////
ctl.Text :=TextSave;
ctl.SelStart :=SelStartSave;
ctl.SelLength :=SelLengthSave;
end;
以上函数的TimeFormat参数代表时间的类型：1-时:分；2-时:分:秒
要完成对时间的输入限制，只需调用上面的MxFormatTimeKeyPress，
MxFormatTimeKeyDown两个函数。
调用示例：
（1）TMaskEdit
procedure TForm1.MaskEdit1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
MxFormatTimeKeyDown(Sender as
TCustomMaskEdit,2,Key,Shift,nil);
end;
procedure TForm1.MaskEdit1KeyPress(Sender: TObject; var
Key: Char);
begin
MxFormatTimeKeyPress(Sender as TCustomMaskEdit,2,Key,nil);
end;
并且，TMaskEdit的EditMask属性设为‘99:99‘
（2）TDBEdit
procedure TForm1.DBEdit1KeyPress(Sender: TObject; var Key:
Char);
begin
MxFormatTimeKeyPress(Sender as TCustomMaskEdit,2,Key,(Sender
as TDBEdit).DataSource);
end;
procedure TForm1.DBEdit1KeyDown(Sender: TObject; var Key:
Word;
Shift: TShiftState);
begin
MxFormatTimeKeyDown(Sender as
TCustomMaskEdit,2,Key,Shift,(Sender as TDBEdit).DataSource);
end;
在TDBEdit所连接的数据源打开后，设定所连字段的EditMask属性为99:99：
DBEdit1.Field.EditMask :=‘99:99‘;
（三）日期的输入
采用Rx的日期组件TDateEdit、TDBDateEdit。如果你还没安装，请在本站下载。
无需对日期的输入作限制，只需方便用户的输入。即：箭头键可以改变相应的
日期元素，因为Rx五次功能。函数如下：
procedure MxSpinRxDateEdit(Edit:TCustomDateEdit;Key:word;Shift:TShiftState;
dts:TDataSource);
var
DateStr,Mark,str:string;
MarkPos1,MarkPos2:integer;
DateOrd:TDateOrder;
DateFlag,step:integer;
OldSelStart:integer;
begin
if Shift<>[] then exit;
if not (Key in [vk_up,vk_down] ) then exit;
if (dts<>nil ) and (not
dts.DataSet.Active ) then exit;
if (dts<>nil ) and (not dts.DataSet.Modified) then
dts.DataSet.Edit;
OldSelStart:=Edit.SelStart;
DateStr:=Edit.EditText;
Mark:=GetDateMark(DateStr);
MarkPos1:=pos(Mark,DateStr);
str:=copy(DateStr,MarkPos1+1,length(DateStr)-MarkPos1);
MarkPos2:=MarkPos1+pos(Mark,str);
DateOrd:=GetDateOrder(ShortDateFormat);
DateFlag:=GetDateFlag(MarkPos1,MarkPos2,Edit.SelStart,DateOrd);
if Key=vk_up then step:=1
else if Key=vk_down then step:=-1
else step:=0;
case DateFlag of
1: Edit.Date := IncYear(Edit.Date ,step);
2: Edit.Date := IncMonth(Edit.Date ,step);
3: Edit.Date := IncDay(Edit.Date ,step);
end;
Edit.SelStart :=OldSelStart;
end;
此函数在组件的OnKeyDown事件中调用，对于TDateEdit，DataSoure参数为nil。
记着引用Rx的单元ToolEdit和DateUtil。
调用示例：
procedure TForm1.DateEdit1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
MxSpinRxDateEdit(Sender as TCustomDateEdit,Key,Shift,nil);
end;
procedure TForm1.DBDateEdit1KeyDown(Sender: TObject; var
Key: Word;
Shift: TShiftState);
begin
MxSpinRxDateEdit(Sender as TCustomDateEdit,Key,Shift,(Sender
as TDBDateEdit).DataSource);
end;