I have these controls TDateTimePicker, TComboBox, Tedit and TButton. TButton is disabled by default. What I would like to achieve is to enable TButton when all the other controls are filled or not null.
With the following codes, all the 3 controls starting with TDateTimePicker when filled I don't have any issues it works as expected.
The error comes when I fill TComboxBox followed by TEdit, it enables the TButton even TDateTimePicker is not filled yet. Or vise versa, I will fill TEdit followed by TComboBox, it enables the TButton.
From the codes below, I expect the TButton will not enable unless all the 3 controls are filled.
I've been trying to figure out (all day) how this error come to happen.
I will appreciate anyone there help me figure this out.
procedure TfrmHolidays.EnableSaveButton;
begin
if (edtHolidayName.Text <> NullAsStringValue) and (cmbHolidayType.ItemIndex <> -1)and (dtpHolidayDate.Date <> 0) then
begin
btnHolidaySave.Enabled := True;
end
else
begin
btnHolidaySave.Enabled := False;
end;
end;
procedure TfrmHolidays.dtpHolidayDateChange(Sender: TObject);
begin
EnableSaveButton;
end;
procedure TfrmHolidays.cmbHolidayTypeChange(Sender: TObject);
begin
EnableSaveButton;
end;
procedure TfrmHolidays.edtHolidayNameChange(Sender: TObject);
begin
EnableSaveButton; // triggers enable btnHolidaySave button
end;
By the way, I have more code related to making TDateTimePicker a blank and I supposed there's no issues with that. I also tried nesting within If Statement each condition and I am still getting the error. Further, I tested each condition at a time and It works fine.
Updates:
Here's how I initialized the dtpHolidayDate.Date:
procedure TfrmHolidays.FormCreate(Sender: TObject);
begin
DateTime_SetFormat(dtpHolidayDate.Handle, ' ');
FDTMDateEmpty := True;
end;
procedure TfrmHolidays.dtpHolidayDateCloseUp(Sender: TObject);
begin
DateTime_SetFormat(dtpHolidayDate.Handle, PChar('MMM dd yyyy (ddd)'));
end;
procedure TfrmHolidays.dtpHolidayDateChange(Sender: TObject);
begin
FDTMDateEmpty := False;
EnableSaveButton; // same and updated procedure above
end;
As pointed out in the comments above, you do not have an initialised value for the TDateTimePicker.
What you want is to have it default to a sensible date, rather than set to 0 - that is not at all helpful to users.
I would introduce a Boolean flag that you set yourself once the TDateTimePicker has been set.
You could set this flag in the OnChange event handler.
So something like:
interface
protected
blMyDTFlag: Boolean;
...
implementation
function TfrmHolidays.dtpHolidayDateChange(Sender: TObject);
begin
Self.blMyDTFlag:=True;
end
procedure TfrmHolidays.EnableSaveButton;
begin
if (edtHolidayName.Text <> '') and
(cmbHolidayType.ItemIndex <> -1) and
(Self.dtMyDTFlag) then
btnHolidaySave.Enabled := True
else
btnHolidaySave.Enabled := False;
end;
Although not shown in the question, I can guess that you initialize the date by
dtpHolidayDate.Date := 0;
After this, testing the date against 0 will (most likely) fail because the time portion still contains the time that the control is created.
You can initialize by
dtpHolidayDate.DateTime := 0;
then you can test the date as you do.
Alternatively you can use SameDate to do the comparison.
uses
dateutils;
if (edtHolidayName.Text <> NullAsStringValue) and (cmbHolidayType.ItemIndex <> -1)
and (not SameDate(dtpHolidayDate.Date, 0)) then
Related
I am super newbie and tried to write following code which sets every TEdit.Text to one mentioned in code
procedure TForm2.Button1Click(Sender: TObject);
var
i : integer;
Edit : TEdit;
begin
for i := 0 to Edit.ComponentCount - 1 do
begin
with Edit.Components[i] do
begin
Text := 'Done';
end;
end;
end;
What am I doing wrong ?
Here are the mistakes that I can see:
You never assign a value to Edit.
Typically the form owns all the components, and so a TEdit will have zero owned components.
Edit.Components[i] is of type TComponent which does not have a Text property. If your code compiles, then Text is actually that of the form. The lesson you should learn from this point is never to use with ever again.
You should solve this using code like this:
procedure TForm2.Button1Click(Sender: TObject);
var
i: Integer;
Edit: TEdit;
begin
for i := 0 to ComponentCount-1 do begin
if Components[i] is TEdit then begin
Edit := TEdit(Components[i]);
Edit.Text := 'Done';
end;
end;
end;
Note that here we are using ComponentCount and Components[] from the form itself. We have removed the evil with statement. And we have had to cast the component to a reference of type TEdit, after first using the is operator to check the type of the component.
This approach will work so long as the form owns all the edits found within it. However, if you create controls dynamically, or if you use frames or parented forms, then this approach, based on ownership via Components[] will not yield all the controls. In such more complex cases you would need to iterate using the parent/child relationship using ControlCount and Controls[].
What am I doing wrong? Just about everything. What I think you are trying to achieve is to put the same text in all TEdits on the form. So you need to go through all the components in TForm (not Edit!) and and check that each is really a Tedit, and if so assign the text. Like this:
procedure TForm2.Button1Click(Sender: TObject);
var
i:integer;
begin
for i := 0 to ComponentCount - 1 do
begin
if Components[ I ] is TEdit then
begin
(Components[ I ] as TEdit).Text := 'Done';
end;
end;
end;
As an aside - avoid using 'with'. It just cases ambiguity and confusion.
You could iterate over all child controls of the form, and if the current control is a TEdit, then you set its text. If the current control is a windowed control, it might have child controls of its own, and you need to redo same thing for this control. Hence, let's use recursion:
procedure SetAllEdits(AParent: TWinControl; const AText: string);
var
i: Integer;
begin
for i := 0 to AParent.ControlCount - 1 do
if AParent.Controls[i] is TCustomEdit then
TCustomEdit(AParent.Controls[i]).Text := AText
else if AParent.Controls[i] is TWinControl then
SetAllEdits(TWinControl(AParent.Controls[i]), AText);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
SetAllEdits(Self, 'test');
end;
There are other ways, like subclassing the edit control and having the new class respond to broadcasted messages.
Answer from D. Heffernan is already good, I'm trying to make it easier to understand for beginner.
In this code, we do "typecast" TEdit to TComponent by command: aEdit := TEdit(aComponent), because TEdit is inherited from TComponent.
What you get from iteration (for ...) is TComponent, not TEdit. You get TEdit by "typecast" it.
procedure TForm2.Button1Click(Sender: TObject);
var
i : Integer;
aComponent : TComponent;
aEdit : TEdit;
begin
for i := 0 to ComponentCount-1 do
begin
aComponent := Components[i];
if aComponent is TEdit then
begin
aEdit := TEdit(aComponent);
aEdit.Text := 'Done';
end;
end;
end;
This is related to another question but doesn't really fit enough to include it with the original. When a Post is called, how can I get the field (or fields) that was modified to a TField?
For logging, I use the OnBeforePost event, which is called (as it says) just before the data is posted. The drawback to this, of course, is that your log table has to have fields wide enough to hold all possible content.
procedure TMyData.SomeTableBeforePost(DataSet: TDataSet);
var
i: Integer;
begin
for i := 0 to DataSet.FieldCount - 1 do
begin
// Skip calculated and lookup fields
if DataSet.Fields[i].FieldType = ftData then
begin
if DataSet.Fields[i].OldValue <> DataSet.Fields[i].NewValue then
begin
LogTable.Insert;
LogTableColumnName.AsString := DataSet.Fields[i].FieldName;
LogTableOldValue.Value := DataSet.Fields[i].OldValue;
LogTableNewValue.Value := DataSet.Fields[i].NewValue;
LogTable.Post;
end;
end;
end;
end;
I'm working with Delphi 7 code to ensure that comments are entered on a tab have been saved before users can switch tabs.
The tabs are located on a TPageControl, and this code is triggered OnExit
procedure TfCallerInfo.tsChaplainExit(Sender: TObject);
begin
{ Compare the saved DB value with the text in the comments field }
if (dmMain.qChaplainCOMMENTS.AsString <> dbmChapComments.Text) then
begin
ShowMessage ('Please save the comments before proceeding.');
pcDetail.ActivePage := tsChaplain; // Remain on the Current Page
tsChaplain.SetFocus;
end;
end;
When users click on another tab tsInfoRequest for instance, the validation does trigger, but the Active Page becomes tsInfoRequest instead of remaining tsChaplain.
Any idea what I'm doing wrong?
There's probably a better way to do what you're trying to do. Use the TPageControl.OnPageChanging event instead.
procedure TfCallerInfo.pcDetailPageChanging(Sender: TObject;
NewPage: TTabSheet; var AllowChange: Boolean);
begin
if pc.ActivePage = tsChaplain then
begin
AllowChange := (dmMain.qChaplainCOMMENTS.AsString = dbmChapComments.Text);
if not AllowChange then
ShowMessage(...);
end;
end;
By the way, a better test might be
AllowChange := not dmMain.gChaplainCOMMENTS.Modified;
TField.Modified is set to True when the content of the field is changed when it's DataSet is in dsEdit or dsInsert mode, and set to False when it's state changes back to dsBrowse.
Delphi v7
Let me preface my remedial question by saying that I am not a real programer. I am a Deputy Sheriff and I write an occasional project to help us do what we do.
My current project contains several TDBRichEdit controls. I have assigned various formatting processes to toolbar buttons. I would like to be able to change the RichEdit font using a ComboBox. The combobox is populated with the font list, but it does not affect the font of the TDBRichEdit control. I have been trying to figure this out for over a week and I cannot see the problem.
This is what I have done:
Form OnCreate procedure
procedure TForm1.FormCreate(Sender: TObject);
begin
PageControl1.ActivePage:= TabSheet1;
GetFontNames;
SelectionChange(Self);
CurrText.Name := DefFontData.Name;
CurrText.Size := -MulDiv(DefFontData.Height, 72, Screen.PixelsPerInch);
end;
Form Selection Change
procedure TForm1.SelectionChange(Sender: TObject);
begin
if ActiveControl is TDBRichEdit then
with ActiveControl as
TdbRichEdit do begin
try
Ctrlupdating := True;
Size.Text := IntToStr(SelAttributes.Size);
cmbFont.Text := SelAttributes.Name;
finally
Ctrlupdating := False;
end;
end;
end;
Functions (Except for the "ActiveControl part these are not my functions and I don't have enough knowledge to completely understand them.)
Function TForm1.CurrText: TTextAttributes;
begin
if ActiveControl is TDBRichEdit then
with ActiveControl as
TdbRichEdit do begin
if SelLength > 0 then Result := SelAttributes
else Result := DefAttributes;
end;
end;
function EnumFontsProc(var LogFont: TLogFont; var TextMetric: TTextMetric;
FontType: Integer; Data: Pointer): Integer; stdcall;
begin
TStrings(Data).Add(LogFont.lfFaceName);
Result := 1;
end;
OnDraw event of the combobox
procedure TForm1.cmbFontDrawItem(Control: TWinControl; Index: Integer;
Rect: TRect; State: TOwnerDrawState);
begin
with (Control as TComboBox).Canvas do
begin
Font.Name := Screen.Fonts.Strings[Index];
FillRect(Rect) ;
TextOut(Rect.Left, Rect.Top, PChar(Screen.Fonts.Strings[Index]));
end;
end;
OnChange event for the combobox
procedure TForm1.cmbFontChange(Sender: TObject);
begin
if Ctrlupdating then Exit;
CurrText.Name := cmbFont.Items[cmbFont.ItemIndex];
end;
Any Ideas?
In your code you try to modify the text attributes in this code:
procedure TForm1.cmbFontChange(Sender: TObject);
begin
if Ctrlupdating then Exit;
CurrText.Name := cmbFont.Items[cmbFont.ItemIndex];
end;
When this code executes, ActiveControl will be cmbFont. Now look at CurrText.
if ActiveControl is TDBRichEdit then
with ActiveControl as TdbRichEdit do
begin
if SelLength > 0 then
Result := SelAttributes
else
Result := DefAttributes;
end;
So, the first if block will not be entered.
In fact your function appears not to assign anything to Result in this case. You must always assign to Result. The compiler will tell you this when you enable warnings and hints.
Instead of using ActiveControl you should specify the rich edit instance directly. I don't know how your form is arranged, but you'll need to use some other means to work out which rich edit control the change is to be applied to. Perhaps based on the active page of the page control.
I managed to get the combobox working. My code is probably very awkward, but it works. Thank you for your help. I would not have been able to solve this problem without it.
I wrote a separate function for each of the richedit contols. With FormCreate I had to add lines for each of the functions
procedure TForm1.FormCreate(Sender: TObject);
begin
PageControl1.ActivePage:= TabSheet1;
GetFontNames;
SelectionChange(Self);
**CurrText.Name := DefFontData.Name;
CurrText.Size := -MulDiv(DefFontData.Height, 72, Screen.PixelsPerInch);**
end;
In SelectionChange I had to make a call to the PARAGRAPH attributes of the rich edit control. I was not able to do that collectively. I addressed the rich edit control “reProc” only. The others seem to work fine with that one line. I would like to understand that one.
Form Selection Change
procedure TForm1.SelectionChange(Sender: TObject);
begin
if ActiveControl is TDBRichEdit then
with reProc.Paragraph do begin
try do begin
You gave me the idea. I was not able to address all the richedit controls collectively, so I wrote a function for each of the richedit controls separately.
function TForm1.CurrText: TTextAttributes;
begin
if reProc.SelLength > 0 then Result := reProc.SelAttributes
else Result := **reProc.DefAttributes;**
For the OnChange event for the combobox I had to add lines for each of the functions
procedure TForm1.cmbFontChange(Sender: TObject);
begin
if Ctrlupdating then Exit;
**CurrText.Name := cmbFont.Items[cmbFont.ItemIndex];**
end;
I have a form one which I want to show a file open dialog box before the full form opens.
I already found that I can't do UI related stuff in FormShow, but it seems that I can in FormActivate (which I protect from being called a second time...)
However, if the user cancels out of the file open dialog, I want to close the form without proceeding.
But, a form close in the activate event handler generates an error that I can't change the visibility of the form.
So how does one do some UI related operation during form start up and then perhaps abort the form (or am I trying to stuff a function into the form that should be in another form?)
TIA
It would be best (i think) to show the file open dialog BEFORE you create and show the form. If you want to keep all code together you might add a public class procedure OpenForm() or something:
class procedure TForm1.OpenForm( ... );
var
O: TOpenDialog;
F: TForm1;
begin
O := TOpenDialog.Create();
try
// set O properties.
if not O.Execute then Exit
F := TForm1.Create( nil );
try
F.Filename := O.FIlename;
F.ShowModal();
finally
F.Free();
end;
finally
O.Free();
end;
end;
Set a variable as a condition of the opendialog and close the form on the formshow event if the flag is not set correctly.
procedure TForm1.FormCreate(Sender: TObject);
begin
ToClose := not OpenDialog1.Execute;
end;
procedure TForm1.FormShow(Sender: TObject);
begin
if ToClose then Close();
end;
or even more simply
procedure TForm1.FormShow(Sender: TObject);
begin
if not OpenDialog1.Execute then Close();
end;
If you want to keep the logic conditioning the opening self-contained in the Form, you can put a TOpenDialog in your Form and use a code like this in your OnShow event:
procedure TForm2.FormShow(Sender: TObject);
begin
if OpenDialog1.Execute(Handle) then
Color := clBlue
else
PostMessage(Handle, WM_CLOSE, 0, 0); // NB: to avoid any visual glitch use AlpaBlend
end;
If you don't need this encapsulation, a better alternative can be to check the condition before trying to show the form, for instance by embedding the Form2.Show call in a function that tests all the required conditions first.
Two Ways....
1. using oncreate and onactivate
create a global flag or even 2
var
aInitialized:boolean;
Set the flag to false in the oncreate handler.
aInitialized := false; //we have not performed our special code yet.
Inside onActivate have something like this
if not aInitialized then
begin
//our one time init code. special stuff or whatever
If successful
then set aInitialized := true
else aInitialized := false
end;
And how to close it without showing anything just add your terminate to the formshow. of course you need to test for some reason to close.. :)
Procedure Tmaindlg.FormShow(Sender: TObject);
Begin
If (shareware1.Sharestatus = ssExpired) or (shareware1.Sharestatus = ssTampered) Then
application.Terminate;
End;
In your DPR you will need to add a splash screen type effect. In my case I am showing progress as the application starts. You could also just show the form and get some data.
Code from the splash.pas
Procedure tsplashform.bumpit(str: string);
Begin
label2.Caption := str;
gauge1.progress := gauge1.progress + trunc(100 / items);
update;
If gauge1.progress >= items * (trunc(100 / items)) Then Close;
End;
Program Billing;
uses
Forms,
main in 'main.pas' {maindlg},
Splash in 'splash.pas' {splashform};
{$R *.RES}
Begin
Application.Initialize;
Application.Title := 'Billing Manager';
SplashForm := TSplashForm.Create(Application);
SplashForm.Show;
SplashForm.Update;
splash.items := 5;
SplashForm.bumpit('Loading Main...');
Application.CreateForm(Tmaindlg, maindlg);
SplashForm.bumpit('Loading Datamodule...');
Application.CreateForm(TfrmSingleWorkorder, frmSingleWorkorder);
SplashForm.bumpit('Loading SQL Builder...');
Application.CreateForm(TDm, Dm);
SplashForm.bumpit('Loading Security...');
Application.CreateForm(TSQLForm, SQLForm);
SplashForm.bumpit('Loading Reports...');
Application.CreateForm(Tpickrptdlg, pickrptdlg);
Application.Run;
End.