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Clasa CEdit (CE)

CEdit din MFC incapsuleaza functionalitatea unui control de editare folosit pt. a edita text: pe o singura linie sau pe mai multe linii. Zona client din Notepad este un control de editare multilinie. Un control de editare este limitat la 60 KB text. Daca e nevoie de mai mult text vom folosi un control RICH EDIT (imbogatit).

Crearea unui control Edit

Daca m_wndEdit este un obiect CEdit instructiunea

creaza un control single line care face scroll orizontal automat, daca textul nu incape in zona de afisare. Incluzind stilul ES_MULTILINE vom crea un CE multilinie:

WS_HSCROLL si WS_VSCROLL adauga barele de scroll vertical si orizontal. Putem folosi CEdit::SetRect sau CEdit::SetRectNP pt. a defini zona editabila a controlului independent de marginile controlului. O utilizare pt. aceste functii este de a defini marimea paginii care ramine constanta chiar daca controlul este redimensionat. Putem folosi de asemenea CEdit::SetMargins pentru a specifica latimea (in pixeli) marginii stg si dreapta. Implicit latimile marginilor sunt 0.

Cind este prima data creat, un CE va accepta numai 30,000 caractere. Putem modifica acest lucru cu CEdit::LimitText sau CEdit::SetLimitText. Urmatoarea instructiune seteaza nr. max de car. la 32:

Cind folosim un CE multilinie, SetLimitText limiteaza cantitatea totala de text din control, deci nu lungimea fiecarei linii. In acest caz putem controla lungimea liniei numai manual.

O metoda este de a folosi SetFont pt a comuta fontul CE la un font fixed-pitch si CEdit::SetRect pt a specifica dreptunghiul de formatare a carui latime este un pic mai mare decit latimea caracterelor din font inmultita cu nr. de caractere dorit a se afisa pe o linie.

Edit Control Styles

O alta functie folositoare pt a initializa un CE este CEdit::SetTabStops, care seteaza spatiile dintre tab_uri. Implicit tab stopul este de 8 caractere. Ca si CListBox::SetTabStops CEdit::SetTabStops masoara distanta in unitati de dialog.

Inserarea si Regasirea Textului

Textul se insereaza cu SetWindowText si se regaseste cu GetWindowText CEdit mosteneste ambele functii din clasa de baza CWnd. Instructiunea

insereaza textul "Hello, MFC" in controlul m_wndEdit, si

regaseste textul intr-un obiect CString numit string GetWindowText si SetWindowText lucreaza cu ambele tipuri de controale, single line si multiline. Textul inserat cu SetWindowText inlocuieste textul existent, iar GetWindowText returneaza tot textul din control, chiar daca acesta este pe mai multe linii. Pt. a stegte textul apelam SetWindowText cu un sir nul:

Putem insera text fara a stege cel existent cu CEdit::ReplaceSel. Daca unul sau mai multe caractere sunt selectate cind apelam ReplaceSel, textul care se insereaza inlocuieste textul selectat, in caz contrar textul este inserat la pozitia curenta a cursorului (caret-ului).

Un control multiline insereaza line break automat. Daca dorim sa determinam line break-urile dintr-un text folosim CEdit::FmtLines pt a face enable soft line breaks inainte de apelul lui GetWindowText

Cu soft line breaks enabled, fiecare linie este delimitata cu doua CR (0x13) urmat de un LF (0x10). Pt. a invalida soft line break folosim FmtLines( FALSE):

CR introdus in text la apasarea tastei <Enter> sunt semnificate de o pereche CR/LF. FmtLines nu afecteaza modul de afisare al textului intr-un CE multilinie, ci afecteaza numai modul cum este memorat intern textul si formateaza textul regasit cu GetWindowText

Pentru a citi exact o linie de text dintr-un control multilinie folosim CEdit::GetLine GetLine copie continutul unei linii intr-un buffer pe care trebuie sa-l alocam si apoi furnizam functiei adresa acestuia. Linia este identificata de un index 0-based. Instructiunea:

copie prima linie din control in zona data de pBuffer, iar par. 3 indica dimensiunea buff. in bytes. GetLine returneaza numarul de octeti copiati in buffer. Putem determina dinaninte marimea necesara a buff. cu fct. CEdit::LineLength, iar numarul de linii din control il det. cu fct. CEdit::GetLineCount GetLineCount nu returneaza niciodata 0, chiar daca nu exista text valoarea returnata este 1.

Clear, Cut, Copy, Paste, and Undo

CEdit furnizeaza functii pentru operatiile enumerate mai sus. Instructiunea:

sterge textul selectat fara a afecta continutul clipboard-ului.Instructiunea:

sterge textul selectat si il copie in clipboard.Instructiunea:

copie textul selectat in clipboard fara a-l sterge.

Putem interoga CE pt. selectia curenta cu un apel al fct. CEdit::GetSel, care returneza o valoare DWORD ce contine doi intregi pe 16 biti ce specifica indexul de inceput si indexul de sfarsit al selectiei. Daca indecsii sunt egali nu exista text selectat. Exista o forma a fct. GetSel care copie indecsii in doi intregi ale caror adrese sunt pasate ca parametrii prin referinta. Putem adauga urmatoare functie IsTextSelected, la clasa controlului de editare derivat din CEdit pentru a determina daca exista sau nu text selectat in control:

CEdit::Cut and CEdit::Copy nu fac nimic daca nu este text selectat. Textul poate fi selectat prin program cu CEdit::SetSel. Instructiunea:

selecteaza 50 de caractere incepind cu al 101-lea caracter si o face vizibila in view daca aceasta nu este vizibila (se face scroll automat). Pt. a preveni defilarea (scrolling), vom folosi si al 3-lea param. al functiei cu valoarea TRUE.

Cind facem selectii prin program intr0un control multilinie, este necesar adesea sa convertim un numar de linie si posibil un offset din interiorul acestei linii intr-un index pe care-l vom folosi in SetSel. Functia CEdit::LineIndex accepta un numar de linie 0-based si returneaza indexul primului caracter din acea linie. In ex. care urmeaza se determina index-ul primului caracter din linia 8 (LineIndex), apoi determinam lungimea liniei si selectam tot textul care se gaseste in acea linie (SetSel):

CEdit furnizeaza fct. LineFromChar pt. a calcula numarul liniei plecind de la index-ul unui caracter.

CEdit::Paste pastes text intr-un CE.

Daca clipboard-ul nu contine text, CEdit::Paste nu are efect. Daca nu exista text selectat cind se apeleaza Paste se insereaza textul din clipboard la pozitia curenta a caret-ului. Daca exista o selectie, atunci textul din clipboard inlocuieste selectia existenta. Putem determina din timp daca exista text in clipboard printr-un apel al fct. ::IsClipboardFormatAvailable. Instructiunea:

seteaza bCanPaste la o val. # 0 daca exista text in clipboard sau 0 in caz contrar. O alta trasatura a unui CE este posibilitatea roll back-ului (undo). to nonzero if text is available from the clipboard, and 0 if it isn't, reface ultima stergere:

Edit controls also feature a built-in undo capability that "rolls back" the previous editing operation. The statement

undoes the last operation, provided that the operation can be undone. Se poate determina din timp daca am putea apela You can determine ahead of time whether calling Undo prinapelul fct. will accomplish anything with CEdit::CanUndo O alta fct.A related function CEdit::EmptyUndoBuffer reseteaza manual flag-ul pentru undo, a.i., urmatoarele apeluri la Undo nu vor face nimic. manually resets the undo flag so that subsequent calls to Undo will do nothing (and calls to CanUndo will return FALSE) until another editing operation is performed.

Notificarile Controlului de EditareEdit Control Notifications

Edit controls send notifications to their parents to report various input events. In app. MFC, notificarile sunt mapate cu macro-uri de forma In MFC applications, these notifications are mapped to handling functions with ON_EN in harta de mesaje a clasei.message map macros. Edit control notifications and the corresponding message map macros are summarized in the table below.

A common use for EN_CHANGE notifications is to dynamically update other controls as text is entered into an edit control.In ex. urm. se trateaza notificarea (mesaj) EN_CHANGE a unui CE. Un control de tip push buton (m_wndPushButton este facut enable/disable dupa cum exista/nu exista text in CE cu ID=IDC_EDIT si dat de ob. The following code updates a push button m_wndPushButton) as text is entered into an edit control m_wndEdit , ID=IDC_EDIT)

Stilurile se dau in functia This restriction effectively limits the user's selection to items appearing in the list box.

The style flags you pass to Create or CreateEx determine what type of combo box you create. CBS_SIMPLE creates a simple combo box, CBS_DROPDOWN creates a drop-down combo box, and CBS_DROPDOWNLIST creates a drop-down list combo box. Alte stiluri exista pentru cosmetizarea CB. Other styles control additional aspects of the combo box's appearance and behavior, as shown in the table below. Many of these styles will look familiar because they're patterned after list box and edit control styles. CBS_AUTOHSCROLL, for example, does the same thing for the edit control portion of a combo box control that ES_AUTOHSCROLL does for a stand-alone edit control. Cind cream un CB trebuie sa punem stilul When you create a combo box control, don't forget to include the style WS_VSCROLL daca dorim scroll vertical if you want the list box to have a vertical scroll bar and WS_BORDER if you want the control's border to be visible IfDaca m_wndComboBox iseste un a obiect CComboBox object the statementinstructiunea:

ceara un CB drop-down list care contine bara pt. scroll vertical.creates a drop-down list combo box whose list box contains a vertical scroll bar when the number of items in the list box exceeds the number of items that can be displayed and that automatically sorts the items added to it. Dimensiunea controlului (dreptunghiul) trebuie sa fie destul de mare pt. a afisa tot textul. The control rectangle you specify in the call to CComboBox::Create should be large enough to encompass the list box part of the control as well as the edit box.

Combo Box Styles

Exista asemanari intre fct din CE si LB.Not surprisingly, the list of CComboBox member functions reads a lot like the list of member functions for CEdit and CListBox

Adaugare art se face cu Items are added to a combo box, for example, with CComboBox::AddString andsi CComboBox::InsertString

and Nr. max. de car. pt. CE al CB este setat cu the maximum character count for a combo box's edit control is set with CComboBox::LimitText Fct. The GetWindowText andsi SetWindowText functions that lucreaza pt. CE al CB. CComboBox inherits from CWnd get and set the text in the edit control.

Functii specifice:Functions unique to combo boxes include GetLBText care regaseste textul unui art. identificat printr-un index 0-based.

which retrieves the text of an item identified by a 0-based index; GetLBTextLen returneaza lung. unui art., in caractere;

which returns the length of an item, in characters; ShowDropDown afiseaza sau ascunde un CB which hides or displays the drop-down list

box; and GetDroppedState whichreturneaza o valoare ce indica daca CB returns a value indicating whether the drop-down list este afisat. is currently displayed.

Notificari Combo Box Notifications

Combo boxes send notifications to their parents much as edit controls and list boxes do. The following table lists the notifications the parent can expect, the corresponding MFC message-map macros, and the types of combo boxes the notifications apply to.

Combo Box Notifications

Nu toate notificarile se aplica la toate tipurile de CB. Not all notifications apply to all combo box types.

Notificarile CBN_DROPDOWN andsi CBN_CLOSEUP notifications, for example, nu sunt trimise la un CB simpla aren't sent to CBS_SIMPLE) pt. ca un asemenea CB este deschis tot timpul. combo boxes because a simple combo box's list box doesn't open and close. By the same token,

CB cu stilurile CBS_DROPDOWN andsi CBS_DROPDOWNLIST-style combo boxes don't receive nu primesc notificarea CBN_DBLCLK pt. ca pe art. din lista nu se poate face dublu clic. (LB asociat CB se inchide dupa primul clic).notifications because the items in their lists can't be double-clicked. (Why? Because the list box closes after the first click.)

Notificarile CBN_EDITUPDATE andsi CBN_EDITCHANGE notifications are sunt echivalente cu equivalent to EN_UPDATE andsi EN_CHANGE trime de CE, si notifications sent by edit controls, and CBN_SELCHANGE este la fel cu is to combo boxes as LBN_SELCHANGE pt. LB.

is to list boxes.

One nuance you should be aware of Cind procesam when processing notificarea CBN_SELCHANGE notifications is that when a notification arrives CE asociat poate sa nu fie actualizat cu selectia din LB asociat. the edit control might not have been updated to match the list box selection. Therefore, you should use Va trebui sa folosim GetLBText pentru a regasi noul text selectat in loc de to retrieve the newly selected text instead of GetWindowText

Indexul art. selectat il gasim cu You can get the index of the selected item with CComboBox::GetCurSel

Clasa The CScrollBar Class

MFC's Clasa CScrollBar incapsuleaza controlul scroll bar creat din class encapsulates scroll bar controls created from the "SCROLLBAR" WNDCLASS. Controalele scroll bar sunt identice in cea mai mare parte cu "ferestrele" scroll bar. In timp ce ferestrele Scroll bar controls are identical in most respects to the "window" scroll bars used in Chapter 2's Accel application. But whereas window scroll bars sunt create cu stilurile are created by adding WS_VSCROLL andsi WS_HSCROLL flags to the window style controalele scroll bar controls sunt create explicit cu are created explicitly with CScrollBar::Create Barele scroll window sint lipite de fereastra principala, controalele scroll bar pot fi plasate oriunde in fereastra si pot fi setate la orice latime si inaltime. And though a window scroll bar runs the full length of the window's client area and is inherently glued to the window border, scroll bar controls can be placed anywhere in the window and can be set to any height and width.

You create vertical scroll bars by specifying the styleStil SBS_VERT pentru CSB vertical si and horizontal scroll bars by specifying SBS_HORZ pentru orizontal IfDaca m_wndVScrollBar andsi m_wndHScrollBar sunt obiecte are CScrollBar objects, the statements instructiunile:

creaza doua controale CSB, unul vertical si unul orizontal. create two scroll bar controls, one vertical and the other horizontal.

Obtinerea dim. standard folosite de W se obtin printr-un apel al fct.You can query Windows for the standard width of a vertical scroll bar or the standard height of a horizontal scroll bar with the API ::GetSystemMetrics API function The following code fragment sets nWidth and nHeight to the system's standard scroll bar width and height:

Ca alternativa la crearea CSB standard se poate specifica An alternative method for creating a scroll bar with a standard height or width is to specify the style SBS_TOPALIGN, SBS_BOTTOMALIGN, SBS_LEFTALIGN, or SBS_RIGHTALIGN when creating it. SBS_LEFTALIGN and SBS_RIGHTALIGN align a vertical scroll bar control along the left or right border of the rectangle specified in the call to Create and assign it a standard width. SBS_TOPALIGN and SBS_BOTTOMALIGN align a horizontal scroll bar control along the top or bottom border of the rectangle and assign it a standard height.

Unlike the other classic controls, scroll bar controls don't send WM_COMMAND messages; they send WM_VSCROLL and WM_HSCROLL messages instead. MFC applications process these messages with OnVScroll and OnHScroll handlers, as described in Chapter 2. I didn't mention two scroll bar notification codes in Chapter 2 because they apply only to scroll bar controls. SB_TOP means that the user pressed the Home key while the scroll bar had the input focus, and SB_BOTTOM means the user pressed End.

MFC's CScrollBar class includes a handful of functions for manipulating scroll bars, most of which should seem familiar to you because they work just like the similarly named CWnd functions. CScrollBar::GetScrollPos and CScrollBar::SetScrollPos get and set the scroll bar's thumb position. CScrollBar::GetScrollRange and CScrollBar::SetScrollRange get and set the scroll bar range. You use CScrollBar::SetScrollInfo to set the range, position, and thumb size in one step. For details, refer to the discussion of CWnd::SetScrollInfo in Chapter 2.