As my first instance of the question was too broad, I am going to try and reword this so it is more understandable.
I want to be able to change the visibility of a label based on an item in a check box list being checked. I have a loop that goes through my check box list.
procedure TFrmSettings.CheckBoxSelected;
var
i : Integer;
begin
for i := 0 to CblRequiredFields.Items.Count - 1 do
begin
if CblRequiredFields.Checked[i] then
begin
FrmVReg.ReqFields(CblRequiredFields.Items.Strings[i]);
end;
end;
end;
Here is just a part of the ReqFields procedure as it would be too long to put into this Q.
procedure TFrmVReg.ReqFields(ChkStr : String);
begin
if ChkStr = 'Gender' then
begin
lblGenderReq.Visible := True;
end
else
begin
lblGenderReq.Visible := False;
end;
The problem I keep having is I can either only have one label active at one time or have it where a label will not disappear when it is deselected.
I hope I have reworded this to a point that it isn't as broad as the previous question.
If the FrmVReg form exists before the creation of the FrmSettings you can maintain a lisk of key-value pairs (checbox name and label object) in the CblRequiredFields list directly.
The labels visibility can be synchronized with the CblRequiredFieldschecks using the OnClickCheck event of the TCheckListBox object.
procedure TFrmSettings.CblRequiredFieldsClickCheck(Sender: TObject);
begin
TLabel(CblRequiredFields.Items.Objects[CblRequiredFields.ItemIndex]).Visible := CblRequiredFields.Checked[CblRequiredFields.ItemIndex];
end;
procedure TFrmSettings.FormCreate(Sender: TObject);
begin
CblRequiredFields.AddItem('Gender', FrmVReg.lblGenderReq);
CblRequiredFields.AddItem('Age', FrmVReg.lblAgeReq);
. . .
end;
If the above can't be applied, you can modify the ReqFields method like this:
procedure TFrmVReg.ReqFields(ChkStr: String; Checked: Boolean);
begin
if ChkStr = 'Gender' then
lblGenderReq.Visible := Checked
else if ChkStr = 'Age' then
lblAgeReq.Visible := Checked
//else if . . .
end;
... calling it accordingly with its new signature:
for i := 0 to CblRequiredFields.Items.Count - 1 do
FrmVReg.ReqFields(CblRequiredFields.Items.Strings[i], CblRequiredFields.Checked[i]);
Related
I have a program with n ComboBoxes and n Labels and I want to update the corresponding Label depending on the selection from the adjacent ComboBox i.e ComboBox2 would update Label2.
I am using the same event handler for every ComboBox and currently checking if Combobox1 or Combobox2 has fired the event handler. Is there a way to use the ItemIndex of the ComboBox passed to the procedure, such as Sender.ItemIndex? This is not currently an option and gives the error 'TObject' does not contain a member named 'ItemIndex'.
procedure TForm2.ComboBoxChange(Sender: TObject);
begin
if Sender = ComboBox1 then
Label1.Caption := ComboBox1.Items.Strings[ComboBox1.ItemIndex]
else
Label2.Caption := ComboBox2.Items.Strings[ComboBox2.ItemIndex];
end;
This code has the desired behavior but is obviously not scale-able.
Every component has a Tag property inherited from TComponent, where the Tag is a pointer-sized integer. As such, you can store each TLabel pointer directly in the corresponding TComboBox.Tag, eg:
procedure TForm2.FormCreate(Sender: TObject);
begin
ComboBox1.Tag := NativeInt(Label1);
ComboBox2.Tag := NativeInt(Label2);
end;
This way, ComboBoxChange() can then directly access the TLabel of the changed TComboBox, eg:
procedure TForm2.ComboBoxChange(Sender: TObject);
var
CB: TComboBox;
begin
CB := TComboBox(Sender);
if CB.Tag <> 0 then
TLabel(CB.Tag).Caption := CB.Items.Strings[CB.ItemIndex];
end;
Option 1
This is the most robust one.
Let your form have private members
private
FControlPairs: TArray<TPair<TComboBox, TLabel>>;
procedure InitControlPairs;
and call InitControlPairs when the form is created (either in its constructor, or in its OnCreate handler):
procedure TForm1.InitControlPairs;
begin
FControlPairs :=
[
TPair<TComboBox, TLabel>.Create(ComboBox1, Label1),
TPair<TComboBox, TLabel>.Create(ComboBox2, Label2),
TPair<TComboBox, TLabel>.Create(ComboBox3, Label3)
]
end;
You need to add the controls to this array manually. That's the downside of this approach. But you only need to do this once, right here. Then everything else can be done automagically.
Now, this is where it gets really nice: Let all your comboboxes share this OnChange handler:
procedure TForm1.ComboBoxChanged(Sender: TObject);
var
i: Integer;
begin
for i := 0 to High(FControlPairs) do
if FControlPairs[i].Key = Sender then
FControlPairs[i].Value.Caption := FControlPairs[i].Key.Text;
end;
Option 2
Forget about any private fields. Now instead make sure that each pair has a unique Tag. So the first combo box and label both have Tag = 1, the second pair has Tag = 2, and so on. Then you can do simply
procedure TForm1.ComboBoxChanged(Sender: TObject);
var
TargetTag: Integer;
CB: TComboBox;
i: Integer;
begin
if Sender is TComboBox then
begin
CB := TComboBox(Sender);
TargetTag := CB.Tag;
for i := 0 to ControlCount - 1 do
if (Controls[i].Tag = TargetTag) and (Controls[i] is TLabel) then
begin
TLabel(Controls[i]).Caption := CB.Text;
Break;
end;
end;
end;
as the shared combo-box event handler. The downside here is that you must be sure that you control the Tag properties of all your controls on the form (at least with the same parent as your labels). Also, they must all have the same parent control.
Short Version: Is there any way to control or modify LisBox items individually? for example set their Visible property to False separately.
I found a TListBoxItem class in Fire Monkey when I was searching, but I don't want to use Fire Monkey and want it in VCL.
Detailed Version:
I tried to filter my ListBox using two TStringList and an Edit, one StringList is global to keep the original list (list_files_global) and another StringList to help filtering procedure (list_files_filter) and my primary list of files is my ListBox (list_files).
I created my global StringList on onCreate event while program is starting to store my original list:
procedure Tfrm_main.FormCreate(Sender: TObject);
Begin
list_files_global := TStringList.Create;
list_files_global.Assign(list_files.Items);
End;
and used Edit's onChange event for filtering:
procedure Tfrm_main.edit_files_filterChange(Sender: TObject);
Var
list_files_filter: TStringList;
i: Integer;
Begin
list_files_filter := TStringList.Create;
list_files_filter.Assign(list_files.Items);
list_files.Clear;
for i := 0 to list_files_filter.Count - 1 do
if pos(edit_files_filter.text, list_files_filter[i]) > 0 then
list_files.Items.Add(list_files_filter[i]);
End;
and for switching off the filter, just recover the list from my global list that I created at first:
list_files.Items := list_files_global;
here so far, everything works just fine, but problem is when I'm trying to edit/rename/delete items from filtered list, for example I change an item:
list_files.Items[i] := '-- Changed Item --';
list will be edited, but when I switch off the filter, the original list will be back and all changes are lost.
so I want to know is there any proper way to solve this problem? Something like hiding items individually or change items visibility, etc... so I can change the filtering algorithm and get rid of all this making extra lists.
I searched the internet and looked into Delphi's help file for a whole day and nothing useful came up.
The items of a VCL listbox, List Box in the API, does not have any visibility property. The only option for not showing an item is to delete it.
You can use the control in virtual mode however, where there are no items at all. You decide what data to keep, what to display. That's LBS_NODATA window style in the API. In VCL, set the style property to lbVirtual.
Extremely simplified example follows.
Let's keep an array of records, one record per virtual item.
type
TListItem = record
FileName: string;
Visible: Boolean;
end;
TListItems = array of TListItem;
You can extend the fields as per your requirements. Visibility is one of the main concerns in the question, I added that. You'd probably add something that represents the original name so that you know what name have been changed, etc..
Have one array per listbox. This example contains one listbox.
var
ListItems: TListItems;
Better make it a field though, this is for demonstration only.
Required units.
uses
ioutils, types;
Some initialization at form creation. Empty the filter edit. Set listbox style accordingly. Fill up some file names. All items will be visible at startup.
procedure TForm1.FormCreate(Sender: TObject);
var
ListFiles: TStringDynArray;
i: Integer;
begin
ListFiles := ioutils.TDirectory.GetFiles(TDirectory.GetCurrentDirectory);
SetLength(ListItems, Length(ListFiles));
for i := 0 to High(ListItems) do begin
ListItems[i].FileName := ListFiles[i];
ListItems[i].Visible := True;
end;
ListBox1.Style := lbVirtual;
ListBox1.Count := Length(ListFiles);
Edit1.Text := '';
end;
In virtual mode the listbox is only interested in the Count property. That will arrange how many items will show, accordingly the scrollable area.
Here's the filter part, this is case sensitive.
procedure TForm1.Edit1Change(Sender: TObject);
var
Text: string;
Cnt: Integer;
i: Integer;
begin
Text := Edit1.Text;
if Text = '' then begin
for i := 0 to High(ListItems) do
ListItems[i].Visible := True;
Cnt := Length(ListItems);
end else begin
Cnt := 0;
for i := 0 to High(ListItems) do begin
ListItems[i].Visible := Pos(Text, ListItems[i].FileName) > 0;
if ListItems[i].Visible then
Inc(Cnt);
end;
end;
ListBox1.Count := Cnt;
end;
The special case in the edit's OnChange is that when the text is empty. Then all items will show. Otherwise code is from the question. Here we also keep the total number of visible items, so that we can update the listbox accordingly.
Now the only interesting part, listbox demands data.
procedure TForm1.ListBox1Data(Control: TWinControl; Index: Integer;
var Data: string);
var
VisibleIndex: Integer;
i: Integer;
begin
VisibleIndex := -1;
for i := 0 to High(ListItems) do begin
if ListItems[i].Visible then
Inc(VisibleIndex);
if VisibleIndex = Index then begin
Data := ListItems[i].FileName;
Break;
end;
end;
end;
What happens here is that the listbox requires an item to show providing its index. We loop through the master list counting visible items to find out which one matches that index, and supply its text.
This is something I often do, but with list views instead of list boxes. The basic principles are the same, though.
I tend to store the individual items as objects, which are reference types in Delphi. And I keep them all in one main unfiltered list, which owns the objects, while I maintain a filtered list (which does not own the objects) for display purposes. Like #Sertac, I combine this with a virtual list view.
To see how this works in practice, create a new VCL application and drop a list view (lvDisplay) and an edit control (eFilter) on the main form:
Notice I have added three columns to the list view control: "Name", "Age", and "Colour". I also make it virtual (OwnerData = True).
Now define the class for the individual data items:
type
TDogInfo = class
Name: string;
Age: Integer;
Color: string;
constructor Create(const AName: string; AAge: Integer; const AColor: string);
function Matches(const AText: string): Boolean;
end;
where
{ TDogInfo }
constructor TDogInfo.Create(const AName: string; AAge: Integer;
const AColor: string);
begin
Name := AName;
Age := AAge;
Color := AColor;
end;
function TDogInfo.Matches(const AText: string): Boolean;
begin
Result := ContainsText(Name, AText) or ContainsText(Age.ToString, AText) or
ContainsText(Color, AText);
end;
And let us create the unfiltered list of dogs:
TForm1 = class(TForm)
eFilter: TEdit;
lvDisplay: TListView;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
FList, FFilteredList: TObjectList<TDogInfo>;
public
end;
where
function GetRandomDogName: string;
const
DogNames: array[0..5] of string = ('Buster', 'Fido', 'Pluto', 'Spot', 'Bill', 'Rover');
begin
Result := DogNames[Random(Length(DogNames))];
end;
function GetRandomDogColor: string;
const
DogColors: array[0..2] of string = ('Brown', 'Grey', 'Black');
begin
Result := DogColors[Random(Length(DogColors))];
end;
procedure TForm1.FormCreate(Sender: TObject);
var
i: Integer;
begin
FList := TObjectList<TDogInfo>.Create(True); // Owns the objects
// Populate with sample data
for i := 1 to 1000 do
FList.Add(
TDogInfo.Create(GetRandomDogName, Random(15), GetRandomDogColor)
);
FFilteredList := FList;
lvDisplay.Items.Count := FFilteredList.Count;
lvDisplay.Invalidate;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
if FFilteredList <> FList then
FreeAndNil(FFilteredList);
FreeAndNil(FList);
end;
The idea is that the list view control always displays the FFilteredList, which either points to the same object instance as FList, or points to a filtered (or sorted) version of it:
// The list view's OnData event handler
procedure TForm1.lvDisplayData(Sender: TObject; Item: TListItem);
begin
if FFilteredList = nil then
Exit;
if not InRange(Item.Index, 0, FFilteredList.Count - 1) then
Exit;
Item.Caption := FFilteredList[Item.Index].Name;
Item.SubItems.Add(FFilteredList[Item.Index].Age.ToString);
Item.SubItems.Add(FFilteredList[Item.Index].Color);
end;
// The edit control's OnChange handler
procedure TForm1.eFilterChange(Sender: TObject);
var
i: Integer;
begin
if string(eFilter.Text).IsEmpty then // no filter, display all items
begin
if FFilteredList <> FList then
begin
FreeAndNil(FFilteredList);
FFilteredList := FList;
end;
end
else
begin
if (FFilteredList = nil) or (FFilteredList = FList) then
FFilteredList := TObjectList<TDogInfo>.Create(False); // doesn't own the objects
FFilteredList.Clear;
for i := 0 to FList.Count - 1 do
if FList[i].Matches(eFilter.Text) then
FFilteredList.Add(FList[i]);
end;
lvDisplay.Items.Count := FFilteredList.Count;
lvDisplay.Invalidate;
end;
The result:
Notice that there always is only one in-memory object for each dog, so if you rename a dog, the changes will reflect in the list view, filtered or not. (But don't forget to invalidate it!)
I wonder how caught a row of a listview and transform object.
I carry an .xml file and play in a listview , after loading this file you need to double-click in a row, take all of the data line and throw in a LabelEdit , as shown in the code below .
procedure TForm1.LstbxDadosDblClick(Sender: TObject);
begin
if Assigned(TMensagem(LstbxDados.Items.Objects[LstbxDados.ItemIndex])) then
begin
with TMensagem(LstbxDados.Items.Objects[LstbxDados.ItemIndex]) do
begin
EdtPara.Text := Para;
EdtDe.Text := De;
EdtCabecalho.Text := Cabecalho;
EdtCorpo.Text := Corpo;
end;
end;
end;
TMensagem = class
private
FCorpo: String;
FCabecalho: String;
FPara: String;
FDe: String;
public
property Para : String read FPara write FPara;
property De : String read FDe write FDe;
property Cabecalho: String read FCabecalho write FCabecalho;
property Corpo : String read FCorpo write FCorpo;
end;
Many ways to edit an object where the current object can change at any time (like with a double click). Here is one of the easiest: save when the current object changes and save at the very end. Here is a quick and dirty solution.
Add a member to the form or global in the implementation section
FLastMensagem: TMensagem;
May want to initialize to nil on create or initialization (left to you). Now in the event save data when the TMensagem object changes
procedure TForm1.LstbxDadosDblClick(Sender: TObject);
var
LNewMensagem: TMensagem;
begin
LNewMensagem := TMensagem(LstbxDados.Items.Objects[LstbxDados.ItemIndex]));
if Assigned(LNewMensagem) then
begin
// When we switch, capture the dialog before updating it
if Assigned(FMensagem) and (LNewMensagem <> FLastMensagem) then
begin
FLastMensagem.Para := EdtPara.Text;
FLastMensagem.De := EdtDe.Text;
FLastMensagem.Cabecalho := EdtCabecalho.Text;
FLastMensagem.Corpo := EdtCorpo.Text;
end;
EdtPara.Text := LNewMensagem.Para;
EdtDe.Text := LNewMensagem.De;
EdtCabecalho.Text := LNewMensagem.Cabecalho;
EdtCorpo.Text := LNewMensagem.Corpo;
//Set the last dblclicked
FLastMensagem := LNewMensagem
end;
end;
Of course the very last edit needs to be saved, that you can do in say a form close (not sure what your full design is). For example
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
if Assigned(FLastMensagem) then
begin
FLastMensagem.Para := EdtPara.Text;
FLastMensagem.De := EdtDe.Text;
FLastMensagem.Cabecalho := EdtCabecalho.Text;
FLastMensagem.Corpo := EdtCorpo.Text;
end;
end;
I have two TEdit boxes that I am using to specify file paths, one is for UNC paths, the other is for a local path. However, I would like it so if the user can only enter text in one box. If they enter text in one box, it should clear the other one. How should I go about doing this? Also, not sure if I should use an OnEnter, OnChange, or some other method.
You can do it pretty simply. Create one OnChange handler, and assign it to both TEdits using the Object Inspector's Events tab. Then you can use something like the following:
procedure TForm1.EditChanged(Sender: TObject); //Sender is the edit being changed
begin
if Sender = UNCEdit then // If it's is the UNCEdit being changed
begin
LocalPathEdit.OnChange := nil; // Prevent recursive calling!
LocalPathEdit.Text := ''; // Clear the text
LocalPathEdit.OnChange := EditChanged; // Restore the event handler
end;
else
begin
UNCEdit.OnChange := nil;
UNCEdit.Text := '';
UNCEdit.OnChange := EditChanged;
end;
end;
This can be streamlined slightly, but it's not quite as readable to others. It can also be protected with a try..finally, although for simply clearing an edit's text content it's not really needed.
procedure TForm1.EditChanged(Sender: TObject);
var
TmpEdit: TEdit;
begin
if Sender = UNCEdit then
TmpEdit := LocalPathEdit
else
TmpEdit := UNCEdit;
TmpEdit.OnChange := nil;
try
TmpEdit.Text := '';
finally
TmpEdit.OnChange := EditChanged;
end;
end;
If you want to keep the two edit boxes, this is how I would do it.
procedure TForm1.Edit1Exit(Sender: TObject);
begin
if (Edit1.text <> '') then
Edit2.text:= '';
end;
procedure TForm1.Edit2Exit(Sender: TObject);
begin
if (Edit2.text <> '') then
Edit1.text:= '';
end;
You want the value check so that you don't accidentally wipe the value when your users tab through the fields.
You could hook both edit boxes to the following KeyPress event
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
If Sender = Edit1 then
Edit2.clear
else
if Sender = Edit2 then
Edit1.clear;
end;
i have a problem on how to retrieve the items in memo from table into tchecklistbox...before this i do the procedure to insert the items that have been checked into memo in tbl POS_CatBreakDownValue..but now i want to know how to retrieve items from table and automatic check in tchecklistbox...thanks..here my procedure to insert the checklist into memo in table..i hope anyone can help me..thanks
procedure TfrmSysConfig.saveCatBreakDownValue;
var
lstCat:TStringList;
i :integer;
begin
lstcat := TStringList.Create;
try
for i:=0 to clCat.Items.Count-1 do begin
if clCat.Checked[i] then begin
lstcat.Add(clcat.Items.Strings[i]);
end;
end;
tblMainPOS_CatBreakDownValue.Value := lstCat.Text;
finally
lstcat.Free;
end;
end;
procedure TfrmSysConfig.saveCatBreakDownValue;
var
lstCat: TStringList;
i:integer;
begin
lstcat := TStringList.Create;
try
for i:=0 to clCat.Items.Count-1 do begin
if clCat.Checked[i] then begin
lstcat.Add(clcat.Items.Strings[i]);
end;
end;
tblMainPOS_CatBreakDownValue.Value := lstCat.Text;
finally
lstcat.Free;
end;
end;
Reading your code I'm guessing you've got a MemoField in a database that you are reading and writing the checked values from/to. You also have a predefined list of checkable items.
So you'll need to create a new string list and read the field back into it (Revesing the writing code). for each item in the list get the Index and check it.
Something like..
procedure TfrmSysConfig.saveCatBreakDownValue;
var
lstCat: TStringList;
i, Index:integer;
begin
lstcat := TStringList.Create;
try
lstcat.Text = tblMainPOS_CatBreakDownValue.Value;
for i:=0 to lstcat.Count-1 do
begin
Index := clCat.Items.IndexOf(lstcat.Items[i])
if Index > -1 then
begin
clCat.Checked[Index] := True;
end;
end;
finally
lstcat.Free;
end;
end;
Not sure I understand your question 100%
TCheckListBox can check or uncheck items using the Checked Property.
CheckListBox.Checked[Index] := True/False;
Since you sound like your comparing strings you may need to determine the index in the TCheckListBox based on the string this can be done like this:
CheckListBox1.Items.IndexOf('StringToFind')
If the string is not found then the result is -1;
If you want to check lines in a TMemo Control and see if they exists as rows in a table you can do the following.
While not Table.EOF do
begin
if Memo1.lines.IndexOf(Table.FieldByName('MyField').AsString) = -1 then
begin
// What you want to do if not found
end
else
begin
// what you want to do if it is found.
end;
Table.Next;
end;