I have an Edit Control on a DevExpress Ribbon of type TcxBarEditItem which I am recording the keypresses of to update a "floating" listbox of possible functionality to fire.
For some reason, the TcxBarEditItem and it's parent classes' event handler's do not work at all like Delphi's vanilla equivalents, meaning I have to record these keypresses.
My question however, is how to record/or prohibit, the user doing things like pasting in loads of text, or highlighting and deleting loads of text?
The way in which these controls seem to work means using String(TcxBarEditItem(control).EditValue) (which is how I would access the control as it is a member of a Command class - TS8RibbonCommand) isn't actually indicative of the text in the edit control until the user clicks out of it. I've tried doing loads of things like programmatically setting focus elsewhere and refocusing but nothing else seems to work bar recording the keypresses.
In the code snippet mirroredJumpStart is my copy of what the user is typing. The RefreshJumpStart function takes a string value and iterates over all the different string values in a list and populates a Listbox using AnsiContainsString.
procedure TS8RibbonJumpStartEdit.KeyPress(Sender: TObject; var Key: Char);
begin
if (Key in ['a'..'z']) or (Key in ['A'..'Z']) or (Key in ['0'..'9']) or (Key = ' ') then
manager.mirroredJumpStart := manager.mirroredJumpStart + Key
else if (Key = Chr(VK_BACK)) and (Length(manager.mirroredJumpStart) <> 0) then
Delete(manager.mirroredJumpStart, Length(manager.mirroredJumpStart), 1);
manager.RefreshJumpStart(manager.mirroredJumpStart);
end;
Any help would be great!
Assuming this is a standard TEdit control...
You can limit the amount of text by using MaxLength property
You can catch individual keystrokes by observing Key parameter in the event OnKeyDown
Just a couple little tips, not sure if it will help, because you don't say you're using the TEdit
Related
In a search form I have two components, a TEdit and and TDBGrid. The user enters text into the TEditand in the TEdit.OnChange event I search for matching items in a table using a query. These are displayed in a TDGrid. The event only triggers when the user has entered more than three characters in the TEdit.Textto cut down the overhead.
The problem occurs when the search has returned all possible records and the user wants to select one of the records displayed in the TDBGrid. While I told the users to use the Tab key (or the mouse) to switch from the TEdit to the TDBGrid, they use the return key to do this in another application and are insisting that they should be able to do the same thing in the application I'm altering/adding to. I can understand this, but the problem is that if I use
if (key = VK_RETURN) then key := VK_TAB;
in the TEdit.OnKeyUp event, the original value of the last key pressed in the TEdit is "remembered" as VK_RETURN and is passed to the TDBGrid's OnKeyUp event. Since I have other actions triggered in that event, I get undesired things happening as soon the the TDBGrid gains focus because they also want to select the correct row in the grid by pressing the return key again.
Therefore what I want to do is to "cancel" the key value passed to the TDBGrid from the TEdit. I tried using if (Sender = TEdit) then Key := VK_CANCEL; in the DGBrid's OnKeyUp event but I get a compiler "Incompatible types" error and I can't find anything to tell me how I should use it in this situation.
Is this possible? Or am I going about this the wrong way?
Thanks in advance!
I believe the following approach satisfies your needs and I suspect it to be the shortest such approach:
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if Key = #13 then
Key := #0;
end;
procedure TForm1.Edit1KeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
if Key = VK_RETURN then
begin
PostMessage(Handle, WM_NEXTDLGCTL, 0, 0);
Key := 0;
end;
end;
This will make Enter, in Edit1, move focus to the next control. This is accomplished by posting the form a WM_NEXTDLGCTL message. The OnKeyPress handler is needed to suppress the "invalid input" message beep.
For bonus points, do
PostMessage(Handle, WM_NEXTDLGCTL, Ord(ssShift in Shift), 0);
instead to have Shift+Enter correspond to Shift+Tab.
I'm not quite sure I like this entire idea, though. I think I prefer to have Enter act on key down instead. The target control shoudn't care about this key up message.
Just to add to Andreas answer, I have used the same approach. There are 3 events you can play around with, onkeydown, onkeypress, onkeyup. At some point you will probably have to assign the key to null to avoid the "beep". The other thing to watch out for are unintended side effects, like moving 2 fields instead of one as has happened to me in the past.
Is there a way to use native tListBox AutoComplete navigation system but based on the items of other ListBox? So when ListBox1 focused when i type some chars items should be selected according to data from ListBox2. Both of them have same amount of items.
Is there a way to use native tListBox AutoComplete navigation system but based on the items of other ListBox?
Yes, but only if the TListBox.Style property is set to either lbVirtual or lbVirtualOwnerDraw. In that case, you must use the TListBox.Count property and TListBox.OnData event to provide strings to the ListBox. The auto-complete functionality will then fire the TListBox.OnDataFind event asking you to locate the typed characters in whatever source you get your strings from. In that event handler, you can search the other TListBox as needed. Just know that the Integer returned by the OnDataFind event handler must be an index relative to the TListBox that the user is typing into, not to the TListBox that you are searching. When the OnDataFind event handler exits, whichever index you return will be selected, unless you return -1 to indicate the characters were not found.
Well i tried to make it native but as far as i get it - it's impossible to combine different item-height functionality (Style=lbOwnerDrawVariable) with DataFind events handling. Ofcourse one can edit TCustomListBox.KeyPress procedure in "VCL\StdCtrls", but i dont like to dig into vcl sources. So i decided to implement AutoComplete feature by myself from a scratch.
First of all i decided to index item-strings for faster search, but there are no need to make full graph (octotree... whatever...) cuz search in my case (and i have about 1k items) anyways performed nearly instantly - so cuz my list is lexicographically sorted i made indexing only for first letters...
//...
const
acceptCharz=[' '..'z'];
//...
type
twoWords=packed record a,b:word; end;
//...
var
alphs:array[' '..'z']of twoWords;// indexes of first letters
fs:tStringList;// list for searching in
fnd:string;// charbuffer for search string
tk:cardinal;// tickCounter for timing
//...
procedure Tform1.button1Click(Sender: TObject);// procedure where list filled with items
var
k,l:integer;
h,q:char;
begin
//... here list-content formed ...
if(fs<>nil)then fs.Free;
fs:=tStringList.Create;
// fltr is tListBox which data should be source of AutoCompletion (ListBox2)
fs.AddStrings(fltr.Items);
for h:=low(alphs)to high(alphs)do alphs[h].a:=$FFFF;// resetting index
h:=#0;
l:=fs.Count-1;
if(l<0)then exit;
for k:=0 to l do begin
s:=AnsiLowerCase(fs.Strings[k]);// for case-insensetivity
fs.Strings[k]:=s;
if(length(s)<0)then continue;
q:=s[1];
if(h<>q)and(q in acceptCharz)then begin
if(k>0)then alphs[h].b:=k-1;
h:=q;
alphs[h].a:=k;// this will work only with sorted data!
end;
end;
if(h<>#0)then alphs[h].b:=l;
end;
//...
// fl is tListBox with custom drawing and OwnerDrawVariable style (ListBox1)
// also fl has same amount of items as fltr
procedure Tform1.flKeyPress(Sender: TObject; var Key: Char);
var
n,i,k,e,l,u,m,a:integer;
s:string;
h:char;
function CharLowerr(h:char):char;// make char LowerCase
begin
Result:=char(LoWord(CharLower(Pointer(h))));
end;
begin
if(getTickCount-tk>=800)then fnd:='';// AutoComplete timeout
tk:=getTickCount;
h:=CharLowerr(key);// for case-insensetivity
if(h in ['a'..'z','0'..'9',' ','-','.'])then fnd:=fnd+h;// u can add all needed chars
if(fnd='')then exit;// if no string to find
h:=fnd[1];// obtain first letter of search-string
a:=alphs[h].a;// get index of first item starting with letter
l:=alphs[h].b;// get index of last item starting with letter
if(a=$FFFF)then exit;// if no such items
e:=length(fnd);// get length of search-string
u:=1;// current length of overlap
m:=1;// max overlap
i:=a;// index to select
if(e>1)then for k:=a to l do begin
s:=fs.Strings[k];
if(length(s)<e)then continue;
for n:=2 to e do begin// compare strings char-by-char
if(s[n]<>fnd[n])then begin// compare failed
u:=n-1;
break;
end else u:=n;
if(u>m)then begin// current overlap is max
m:=u;
i:=k;
end;
end;
if(u=e)or(u<m)then break;// if end of search reached
end;
// select needed index:
fl.ClearSelection;
SendMessage(fl.Handle, LB_SELITEMRANGE, 1, MakeLParam(i, i));
fl.ItemIndex:=i;
inherited;
end;
//...
Yeah this code is kinda ugly, but it works fine, as i said - nearly instantly, i just can see how selection jumps thru items while i type, and i type pretty fast...
So it was code which i wrote yesterday and all this could end here, but today i realized that it was absolutely dumb decision at whole: in my case, as i mentioned above, i have listbox with OwnerDrawVariable style, so i have custom MeasureItem and DrawItem procedures and the best decision in this kind of situation will be to turn AutoComplete property true and to fill ListBox1 with items from ListBox2. And strings needed to display could be shown anyways in DrawItem procedure. Also possible to remove ListBox2 and keep strings for displaying inside tStringList variable. So morale is - dont rush into writing boilerplates and try to think more before acting =))
P.S. but one can use this code for some custom AutoComplete handling...
I, have many cxDBButtonEdit in my form, and I want, when the user press ENTER make a click in the first button.
I try to find any methods, procedure, function.. and nothing!
I try to make like this:
if (ActiveControl is TcxDBButtonEdit) then
begin
if ((ActiveControl as TcxDBButtonEdit).Properties.Buttons.Count > 0) and ((ActiveControl as TcxDBButtonEdit).Properties.Buttons.Items[0].Enabled) then
begin
(ActiveControl as TcxDBButtonEdit) <----- HERE
try
GetParentForm(Screen.ActiveForm).Perform(CM_DIALOGKEY, VK_TAB, 0);
Key := #0;
except
end;
end;
end;
Thanks,
You're working much too hard. :-)
Your question asks about clicking the button, but your code indicates sending a tab (VK_TAB). I'm not sure which you're actually wanting to do, so I'll try to address both.
I don't know anything about the TcxDBButtonEdit (or any of the other DevExpress controls), but something like this should work for you (for the tab key):
if (ActiveControl is TcxDBButtonEdit) then
begin
// We know it's a TcxDBButtonEdit, so we can directly cast it
if (TcxDBButtonEdit(ActiveControl).Properties.Buttons.Count > 0) and
(TcxDBButtonEdit(ActiveControl.Properties.Buttons.Items[0].Enabled) then
begin
Key := #0;
Self.SelectNext(ActiveControl, True, True); // See notes below
end;
end;
If you're wanting to actually click the button attached to the edit control, DevExpress support has an article that says that you can do this to invoke the button's click handler (replace the call to SelectNext above):
if (ActiveControl is TcxDBButtonEdit) then
begin
// We know it's a TcxDBButtonEdit, so we can directly cast it
if (TcxDBButtonEdit(ActiveControl).Properties.Buttons.Count > 0) and
(TcxDBButtonEdit(ActiveControl.Properties.Buttons.Items[0].Enabled) then
begin
Key := #0;
TcxCustomEditAccess(ActiveControl).DoButtonClick(0);
end;
end;
(I clearly can't compile the above code, because I don't have the DevEx controls; the line calling DoButtonClick is from their article. If the compiler complains about it, you probably need to add the following to your code (right above the method containing the code that uses it is probably the best place):
type
TcxCustomEditAccess = class(TCxCustomEdit);
From the 'Access' part of the name, it looks like the DoButtonClick might be a protected method of the TcxCustomEdit. Declaring the interposer class allows you access to the protected method.)
Notes about SelectNext:
From the TWinControl.SelectNext documentation
Moves the input focus from the current child control to the next one in the tab order.
Call SelectNext to move the child control focus. SelectNext selects the first child that follows or precedes CurControl in the tab order and that meets the criteria specified in the other parameters.
The GoForward parameter controls the direction of the search. If GoForward is true, FindNextControl searches forward through the child controls in tab order. If GoForward is false, SelectNext searches backward through the controls. The search wraps past the end of the collection back to CurControl.
The CheckTabStop parameter controls whether the control SelectNext finds must be a tab stop. If CheckTabStop is true, the returned control must have its TabStop property set to true, or the search for the next control continues.
If a child control matches the search criteria, that control obtains the focus. If no such child control is found, the focus remains unchanged.
I have created one form in delphi 7 and added one combobox on it. The combobox contains the list of items. I dont want that user can enter the value to Combobox so i have set
combobox.style := csDropDownList;
But thorugh code i want to use combobox.text := 'New Item'; but its not working. Note that the text I want to show is not in the list of items and I don't want to add it there. Please is any solution to this?
No, this is simply not the way the Windows combobox control works.
However, if you insist, and you don't care that your users will get confused, you can set Style to csDropDown and then do
procedure TForm1.ComboBox1KeyPress(Sender: TObject; var Key: Char);
begin
Key := #0;
end;
as the combobox' OnKeyPress event. Then the user cannot enter text manually, but can only choose from the items in the list. However, you can still set the text to anything you like (even if it isn't in the list) by setting the Text property:
ComboBox1.Text := 'Sample';
Set the ItemIndex property. You can get ComboBox.Items.IndexOf('New Item') to get the index of that text, if you don't already know it.
Combobox.ItemIndex := Combobox.Items.IndexOf('New item');
Below sample code demonstrates how you can draw custom text in response to a WM_DRAWITEM message sent to the ComboBox control's parent window (this should be the form for the sample to work, otherwise subclassing controls or full drawing of items of the control would be necessary).
To receive this message set the Style property of the control to 'csOwnerDrawFixed', but do not put a handler for the OnDrawItem event so that default drawing should be applied in all other cases that we intervene drawing.
The sample sets a text when ItemIndex is -1, but it can be adapted/tweaked otherwise. Note that the drawing code is not complete or accurate, the sample just demonstrates a way how it can be done:
type
TForm1 = class(TForm)
ComboBox1: TComboBox;
[..]
private
procedure WMDrawItem(var Msg: TWMDrawItem); message WM_DRAWITEM;
end;
[...]
procedure TForm1.WMDrawItem(var Msg: TWMDrawItem);
var
Font: HFONT;
begin
inherited;
if (Msg.Ctl = ComboBox1.Handle) and (Msg.DrawItemStruct.itemID = $FFFFFFFF) and
((Msg.DrawItemStruct.itemAction and ODA_DRAWENTIRE) = ODA_DRAWENTIRE) then begin
Font := SelectObject(Msg.DrawItemStruct.hDC, ComboBox1.Canvas.Font.Handle);
SelectObject(Msg.DrawItemStruct.hDC, GetStockObject(DC_BRUSH));
if (Msg.DrawItemStruct.itemState and ODS_SELECTED) = ODS_SELECTED then begin
SetDCBrushColor(Msg.DrawItemStruct.hDC, ColorToRGB(clHighlight));
SetBkColor(Msg.DrawItemStruct.hDC, ColorToRGB(clHighlight));
SetTextColor(Msg.DrawItemStruct.hDC, ColorToRGB(clHighlightText));
end else begin
SetDCBrushColor(Msg.DrawItemStruct.hDC, ColorToRGB(clWindow));
SetBkColor(Msg.DrawItemStruct.hDC, ColorToRGB(clWindow));
SetTextColor(Msg.DrawItemStruct.hDC, ColorToRGB(clWindowText));
end;
FillRect(Msg.DrawItemStruct.hDC, Msg.DrawItemStruct.rcItem, 0);
TextOut(Msg.DrawItemStruct.hDC, 4, 4, '_no_selected_item_', 18);
SelectObject(Msg.DrawItemStruct.hDC, Font);
end;
end;
I think you want the normal thing, to display something in the ComboBox when no selection has yet been made. Instant of a blank rectangle. Imagine a form full of blank comboboxes... ;)
What I've seen most programmers do is have the first item as the title to display in the ComboBox.
So, in FormCreate (after you've populated the ComboBox), you set its ItemIndex to 0, and this displays the title.
In its OnChange event you can choose to take no action if item 0 is selected ("real" items then have base 1 for index), or get ItemIndex-1 and skip action if < 0.
Must be a super common complaint from everyone who has used Comboboxes the first time. I can't understand how none of the coders recognize it.
All Borland et al would have had to do was to initialize a new ComboBox with ItemIndex=0 and the confusion would have been gone. It's certainly not obvious that you have to set index 0 - since you see the blank line when clicked, the logical conclusion is that it has index 0. Probably they wanted to give designers the option to add a label outside the combobox instead.
In code I have developed some years ago I have been using this a lot to close the current form on pressing the Escape key at any moment:
procedure TSomeForm.FormKeyPress(Sender: TObject; var Key: Char);
begin
if key = #27 then close;
end;
This behaviour is defined for the TForm. The form's KeyPreview property is be set to True to let the form react to key presses before any other components. It all works perfectly well for the best part of the program, however, when the Escape key is pressed while a TEdit component is focused a sound (a ding sound used by Windows to signify invalid operation) is issued. It still works fine but I have never quite managed to get rid of the sound.
What's the problem with this?
Steps to recreate:
new VCL Forms application, set the form's KeyPreview to true
on the Events tab double-click the onKeyPress event and enter dummy code:
if key=#27 then ;
add a TListBox, TCheckBox, TEdit to the form and run the application
in the application try pressing Esc and NOTHING happens, as specified by the dummy code
focus the TEdit and press Esc. Nothing happens but the sound is played.
You get the ding because you left the ESC in the input. See how Key is a var? Set it to #0 and you eliminate the ding. That removes it from further processing.
procedure TSomeForm.FormKeyPress(Sender: TObject; var Key: Char);
begin
if key = #27 then
begin
key := #0;
close;
end;
end;
KeyPreview is just that, a preview of what will be passed to the controls unless you stop it.
Starting from Jim's answer (thanks Jim) I had to make it work for me. What I needed was to make a dropped down combobox close keeping the selected item and move to the next/previous control when TAB/shift+TAB was pressed. Everytime I did press TAB the annoying sound filled the room. My work arroud was using onKeyDown event to catch the shiftstate, declaring var aShift: boolean; in form's interface and use the following code:
procedure TForm2.StComboKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
if ssShift in Shift then aShift := true else aShift := false;
end;
procedure TForm2.StComboKeyPress(Sender: TObject; var Key: Char);
begin
if Key=char(VK_TAB) then
begin
Key := #0;
StCombo.DroppedDown := false;
if aShift
then previousControl.SetFocus
else nextControl.SetFocus;
end;
end;
Using the menu items and setting them to invisible, and using the shortcut, is a quick workaround that I've just stumbled across, but won't work if you need a shortcut that uses a character that is used in the first letter of an existing shortcut: For example for Alt+ENTER, you need to add something like this to the form create procedure:
MainMenu1.Items[0].ShortCut:=TextToShortCut('Alt+e');
However it's probably easier to use TActionList instead, and even though something like Alt+E is not listed you can add it.
It's an old thread... but anyway, here's a far better one: catching Alt-C!
Unlike ESC, Alt-C isn't serviced by KeyPress, so setting Key to #0 in KeyPress doesn't work, and the horrendous "ding!" is issued every time.
After hours of trying, here's the workaround I found:
- create a main menu option to service the request
- set its ShortCut to Alt+C - yes indeed, that is NOT one of the available ShortCut choices(!!)... but it does work anyway!
- do the processing in that menu option's OnClick
- you may even make in "in the background": you may set the menu option's Visible to false - as long as its Enabled stays true, it will be activated by Alt-C even though it will not be visible in the menu.
Hope that may help! And if you have something more elegant, please advise.