I want to create a procedure to enable or disable button,
can i do it with a single procedure? for example like this:
Procedure MainForm.buttonsEnabled(boolean);
BEGIN
if result=true then
begin
button1.enabled:=True;
button2.enabled:=True;
button3.enabled:=True;
end else
begin
button1.enabled:=false;
button2.enabled:=false;
button3.enabled:=false;
end;
END;
and when I call the procedure to disable or enable the button i can call it like
buttonsEnabled:=True;// to enable button
buttonsEnabled:=False;// to disable button
can I do it like that?
I can't find a way to do that in the simple way
procedure MainForm.buttonsEnabled(AEnabled: Boolean);
begin
button1.Enabled := AEnabled;
button2.Enabled := AEnabled;
button3.Enabled := AEnabled;
end;
buttonsEnabled(True);
//buttonsEnabled(False);
Create a property of the form:
type
TMyForm = class(TForm)
private
procedure SetButtonsEnabled(Value: Boolean);
public // or private perhaps, depending on your usage
property ButtonsEnabled: Boolean write SetButtonsEnabled;
end;
Implement it like this:
procedure TMyForm.SetButtonsEnabled(Value: Boolean);
begin
button1.Enabled := Value;
button2.Enabled := Value;
button3.Enabled := Value;
end;
And then you can use it as you intend:
ButtonsEnabled := SomeBooleanValue;
For multi usage
First Option :
Procedure EnabledDisableControls(Ctrls:Array of TControl; Enabled:Boolean);
var
C:TControl;
begin
for C in Ctrls do
C.Enabled:=Enabled;
end;
//calling example :
procedure TForm1.BtnTestClick(Sender: TObject);
begin
EnabledDisableControls([Button1, Button2, Button3], false {or True});
end;
Second Option :
Recrusivelly (or not) enabling/disabling buttons on a Control :
Procedure EnableDisableButtonsOnControl(C:TControl; Enabled:Boolean; Recrusive:Boolean);
var
i:integer;
begin
if C is TButton {or TBitButton or anything you need} then
C.Enabled:=Enabled
else if C is TWinControl then
for i := 0 to TWinControl(C).ControlCount-1 do
begin
if TWinControl(C).Controls[i] is TButton then
TButton(TWinControl(C).Controls[i]).Enabled:=Enabled
else
if Recrusive then
EnableDisableButtonsOnControl(TWinControl(C).Controls[i],Enabled,true);
end;
end;
//calling example :
procedure TForm1.BtnTestClick(Sender: TObject);
begin
//disable all buttons on Form1:
EnableDisableButtonsOnControl(Self, false, false {or true});
...
//disable all buttons on Panel1:
EnableDisableButtonsOnControl(Panel1, false, false {or true});
...
//disable all buttons on Panel1 recursively:
EnableDisableButtonsOnControl(Panel1, false, true);
end;
Related
I use a custom listview component and I need it to have a popupmenu item "copy data to clipboard". If there is no assigned popup, I create one and add the menuitem, if there is already a menu assigned, add the item to the current popup. Tried to put the code in the constructor, but then I realized, that popupmenu is still not created or associated to my listview. So any idea when to create my default item?
constructor TMyListView.Create(AOwner: TComponent);
var
FpopupMenu: TPopupMenu;
begin
inherited;
.....
FPopUpMenuItem := TMenuItem.Create(self);
FPopUpMenuItem.Caption := 'Copy data to clipboard';
FPopUpMenuItem.OnClick := PopupMenuItemClick;
if assigned(PopupMenu) then begin
popupMenu.Items.Add(FPopUpMenuItem);
end
else begin
FpopupMenu := TPopupMenu.Create(self);
FpopupMenu.Items.Add(FPopUpMenuItem);
PopupMenu := FpopupMenu;
end;
...
end;
Override the virtual TControl.DoContextPopup() method, eg:
type
TMyListView = class(TListView)
protected
...
procedure DoContextPopup(MousePos: TPoint; var Handled: Boolean); override;
...
end;
procedure TMyListView.DoContextPopup(MousePos: TPoint; var Handled: Boolean);
var
LPopupMenu: TPopupMenu;
LItem: TMenuItem;
function IsSameEvent(const E1, E2: TNotifyEvent): Boolean;
begin
Result := (TMethod(E1).Code = TMethod(E2).Code) and
(TMethod(E1).Data = TMethod(E2).Data);
end;
begin
inherited DoContextPopup(MousePos, Handled);
if Handled then Exit;
LPopupMenu := PopupMenu;
if not Assigned(LPopupMenu) then
begin
LPopupMenu := TPopupMenu.Create(Self);
PopupMenu := LPopupMenu;
end;
for I := 0 to LPopupMenu.Items.Count-1 do
begin
LItem := LPopupMenu.Items[I];
if IsSameEvent(LItem.OnClick, PopupMenuItemClick) then
Exit;
end;
LItem := TMenuItem.Create(Self);
LItem.Caption := 'Copy data to clipboard';
LItem.OnClick := PopupMenuItemClick;
LPopupMenu.Items.Add(LItem);
end;
The accepted answer indeed works perfectly - unless you add keyboard shortcuts to your menu item. If you do, these won't work before the popup menu has been accessed in some other way, because the items will not have been created.
If you need shortcuts, it may therefore be preferable to move the code from DoContextPopup to Loaded. Most simply,
procedure Loaded; override;
...
procedure Loaded;
var
MI: TMenuItem;
ItemCovered: boolean;
i: integer;
begin
inherited;
if not Assigned(PopupMenu) then
PopupMenu:=TPopupMenu.Create(self);
ItemCovered:=false;
for i := 0 to PopupMenu.Items.Count-1 do
if IsSameEvent(PopupMenu.Items[I].OnClick, CopyDataToClipboardClick) then begin
ItemCovered:=true;
break;
end;
if not ItemCovered then begin
MI:=TMenuItem.Create(PopupMenu);
MI.Caption:='Copy data to clipboard';
MI.OnClick:=CopyDataToClipboardClick;
MI.ShortCut:=ShortCut(Ord('C'),[ssShift,ssCtrl]);
PopupMenu.Items.Add(MI);
end;
end;
This won't check for popup menus added on runtime, but probably serve most cases better.
I have a popup menu associated with my TTabControl. I want to be able select the tab and invoke the drop down in one Right Hand button click. Other controls I seem to remember would have a right button select property.
You can use the OnPopup event handler of your TPopupMenu:
procedure TForm1.PopupMenu1Popup(Sender: TObject);
var
TabIndex : integer;
Pt : TPoint;
begin
Pt := TabControl1.ScreenToClient(TPopupMenu(Sender).PopupPoint);
TabIndex := TabControl1.IndexOfTabAt(Pt.X, Pt.Y);
if(TabIndex <> -1) then
begin
TabControl1.TabIndex := TabIndex;
end;
end;
You can do something like this:
type
TTabControl = class(Vcl.ComCtrls.TTabControl)
private
FRightClickSelect: Boolean;
procedure CNNotify(var Msg: TWMNotify); message CN_NOTIFY;
public
constructor Create(AOwner: TComponent); override;
published
property RightClickSelect: Boolean read FRightClickSelect write FRightClickSelect default False;
end;
implementation
uses
Winapi.CommCtrl;
{ TTabControl }
constructor TTabControl.Create(AOwner: TComponent);
begin
inherited;
FRightClickSelect := False;
end;
procedure TTabControl.CNNotify(var Msg: TWMNotify);
var
Index: Integer;
HitInfo: TTCHitTestInfo;
begin
if FRightClickSelect and (Msg.NMHdr.code = NM_RCLICK) then
begin
HitInfo.pt := ScreenToClient(Mouse.CursorPos);
Index := SendMessage(Handle, TCM_HITTEST, 0, LPARAM(#HitInfo));
if (Index <> -1) and (HitInfo.flags <> TCHT_NOWHERE) then
TabIndex := Index;
end;
inherited;
end;
As the title says, I'd like a component (say, a label) to be notified when it's parent (say, a panel) receives and loses focus. I wandered a bit in Delphi source, in hope of using TControl.Notify, but it's only used to notify child controls of some property changes like font and color. Any suggestions?
Whenever the active control in an application changes, a CM_FOCUSCHANGED message is broadcast to all controls. Simply intercept it, and act accordingly.
Also, I assumed that by when it's parent (say, a panel) receives and loses focus you mean whenever a (nested) child control on that parent/panel receives or loses focus.
type
TLabel = class(StdCtrls.TLabel)
private
function HasCommonParent(AControl: TWinControl): Boolean;
procedure CMFocusChanged(var Message: TCMFocusChanged);
message CM_FOCUSCHANGED;
end;
procedure TLabel.CMFocusChanged(var Message: TCMFocusChanged);
const
FontStyles: array[Boolean] of TFontStyles = ([], [fsBold]);
begin
inherited;
Font.Style := FontStyles[HasCommonParent(Message.Sender)];
end;
function TLabel.HasCommonParent(AControl: TWinControl): Boolean;
begin
Result := False;
while AControl <> nil do
begin
if AControl = Parent then
begin
Result := True;
Break;
end;
AControl := AControl.Parent;
end;
end;
If you don't like to subclass TJvGradientHeader, then it is possible to design this generically by the use of Screen.OnActiveControlChange:
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
FHeaders: TList;
procedure ActiveControlChanged(Sender: TObject);
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
FHeaders := TList.Create;
FHeaders.Add(Label1);
FHeaders.Add(Label2);
Screen.OnActiveControlChange := ActiveControlChanged;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
FHeaders.Free;
end;
function HasCommonParent(AControl: TWinControl; AMatch: TControl): Boolean;
begin
Result := False;
while AControl <> nil do
begin
if AControl = AMatch.Parent then
begin
Result := True;
Break;
end;
AControl := AControl.Parent;
end;
end;
procedure TForm1.ActiveControlChanged(Sender: TObject);
const
FontStyles: array[Boolean] of TFontStyles = ([], [fsBold]);
var
I: Integer;
begin
for I := 0 to FHeaders.Count - 1 do
TLabel(FHeaders[I]).Font.Style :=
FontStyles[HasCommonParent(Screen.ActiveControl, TLabel(FHeaders[I]))];
end;
Note that I chose TLabel to demonstrate this works also for TControl derivatives.
We have a combo box with more than 100 items.
We want to filter out the items as we enter characters in combo box. For example if we entered 'ac' and click on the drop down option then we want it to display items starting with 'ac' only.
How can I do this?
Maybe you'd be happier using the autocompletion features built in to the OS. I gave an outline of how to do that here previously. Create an IAutoComplete object, hook it up to your combo box's list and edit control, and the OS will display a drop-down list of potential matches automatically as the user types. You won't need to adjust the combo box's list yourself.
To expand on Rob's answer about using the OnChange event, here is an example of how to do what he suggests.
procedure TForm1.FormCreate(Sender: TObject);
begin
FComboStrings := TStringList.Create;
FComboStrings.Add('Altair');
FComboStrings.Add('Alhambra');
FComboStrings.Add('Sinclair');
FComboStrings.Add('Sirius');
FComboStrings.Add('Bernard');
FComboStrings.Sorted := True;
ComboBox1.AutoComplete := False;
ComboBox1.Items.Text := FComboStrings.Text;
ComboBox1.Sorted := True;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
FreeAndNil(FComboStrings);
end;
procedure TForm1.ComboBox1Change(Sender: TObject);
var
Filter: string;
i: Integer;
idx: Integer;
begin
// Dropping down the list puts the text of the first item in the edit, this restores it
Filter := ComboBox1.Text;
ComboBox1.DroppedDown := True;
ComboBox1.Text := Filter;
ComboBox1.SelStart := Length(Filter);
for i := 0 to FComboStrings.Count - 1 do
if SameText(LeftStr(FComboStrings[i], Length(ComboBox1.Text)), ComboBox1.Text) then
begin
if ComboBox1.Items.IndexOf(FComboStrings[i]) < 0 then
ComboBox1.Items.Add(FComboStrings[i]);
end
else
begin
idx := ComboBox1.Items.IndexOf(FComboStrings[i]);
if idx >= 0 then
ComboBox1.Items.Delete(idx);
end;
end;
My brief contribution working with objects in the combobox:
procedure FilterComboBox(Combo: TComboBox; DefaultItems: TStrings);
function Origin: TStrings;
begin
if Combo.Tag = 0 then
begin
Combo.Sorted := True;
Result := TStrings.Create;
Result := Combo.Items;
Combo.Tag := Integer(Result);
end
else
Result := TStrings(Combo.Tag);
end;
var
Filter: TStrings;
I: Integer;
iSelIni: Integer;
begin
if(Combo.Text <> EmptyStr) then
begin
iSelIni:= Length(Combo.Text);
Filter := TStringList.Create;
try
for I := 0 to Origin.Count - 1 do
if AnsiContainsText(Origin[I], Combo.Text) then
Filter.AddObject(Origin[I], TObject(Origin.Objects[I]));
Combo.Items.Assign(Filter);
Combo.DroppedDown:= True;
Combo.SelStart := iSelIni;
Combo.SelLength := Length(Combo.Text);
finally
Filter.Free;
end;
end
else
Combo.Items.Assign(DefaultItems);
end;
You can handle the combo box's OnChange event. Keep a master list of all items separate from the UI control, and whenever the combo box's edit control changes, adjust the combo box's list accordingly. Remove items that don't match the current text, or re-add items from the master list that you removed previously.
As Rob already answered, you could filter on the OnChange event, see the following code example. It works for multiple ComboBoxes.
{uses}
Contnrs, StrUtils;
type
TForm1 = class(TForm)
ComboBox1: TComboBox;
ComboBox2: TComboBox;
procedure FormCreate(Sender: TObject);
procedure ComboBoxChange(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
FComboLists: TList;
procedure FilterComboBox(Combo: TComboBox);
end;
implementation
{$R *.dfm}
procedure TForm1.ComboBoxChange(Sender: TObject);
begin
if Sender is TComboBox then
FilterComboBox(TComboBox(Sender));
end;
procedure TForm1.FilterComboBox(Combo: TComboBox);
function Origin: TStrings;
begin
if Combo.Tag = 0 then
begin
Combo.Sorted := True;
Result := TStringList.Create;
Result.Assign(Combo.Items);
FComboLists.Add(Result);
Combo.Tag := Integer(Result);
end
else
Result := TStrings(Combo.Tag);
end;
var
Filter: TStrings;
I: Integer;
begin
Filter := TStringList.Create;
try
for I := 0 to Origin.Count - 1 do
if AnsiStartsText(Combo.Text, Origin[I]) then
Filter.Add(Origin[I]);
Combo.Items.Assign(Filter);
Combo.SelStart := Length(Combo.Text);
finally
Filter.Free;
end;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
FComboLists := TObjectList.Create(True);
// For Each ComboBox, set AutoComplete at design time to false:
ComboBox1.AutoComplete := False;
ComboBox2.AutoComplete := False;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
FComboLists.Free;
end;
In Delphi I show/hide controls during runtime and it does not look good as controls suddenly appear or disappear , so any one know a component that can do the show/hide (using visible property) but with some sort of animation ?
thanks
Give it a go with AnimateWindow. Only for WinControls, well, it doesn't look stunning anyway:
procedure TForm1.Button1Click(Sender: TObject);
begin
if Button2.Visible then
AnimateWindow(Button2.Handle, 250, AW_HIDE or AW_VER_NEGATIVE or AW_SLIDE)
else
AnimateWindow(Button2.Handle, 250, AW_VER_POSITIVE or AW_SLIDE);
Button2.Visible := not Button2.Visible; // synch with VCL
end;
edit: A threaded version to hide show multiple controls simultaneously:
type
TForm1 = class(TForm)
..
private
procedure AnimateControls(Show: Boolean; Controls: array of TWinControl);
procedure OnAnimateEnd(Sender: TObject);
public
end;
implementation
..
type
TAnimateThr = class(TThread)
protected
procedure Execute; override;
public
FHWnd: HWND;
FShow: Boolean;
constructor Create(Handle: HWND; Show: Boolean);
end;
{ TAnimateThr }
constructor TAnimateThr.Create(Handle: HWND; Show: Boolean);
begin
FHWnd := Handle;
FShow := Show;
FreeOnTerminate := True;
inherited Create(True);
end;
procedure TAnimateThr.Execute;
begin
if FShow then
AnimateWindow(FHWnd, 250, AW_VER_POSITIVE or AW_SLIDE)
else
AnimateWindow(FHWnd, 250, AW_HIDE or AW_VER_NEGATIVE or AW_SLIDE);
end;
{ Form1 }
procedure TForm1.OnAnimateEnd(Sender: TObject);
begin
FindControl(TAnimateThr(Sender).FHWnd).Visible := TAnimateThr(Sender).FShow;
end;
procedure TForm1.AnimateControls(Show: Boolean; Controls: array of TWinControl);
var
i: Integer;
begin
for i := Low(Controls) to High(Controls) do
with TAnimateThr.Create(Controls[i].Handle, Show) do begin
OnTerminate := OnAnimateEnd;
Resume;
end;
end;
procedure TForm1.Button5Click(Sender: TObject);
begin
AnimateControls(not Button1.Visible,
[Button1, Button2, Button3, Edit1, CheckBox1]);
end;