RAD Studio VCL Reference
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Specifies the length, in characters, of the selected text in the edit portion of the combo box.
property SelLength: Integer;
__property int SelLength;
The selected portion of the text in the edit region of the combo box is the string of SelLength characters that starts at the character specified by the SelStart property. The selected text appears highlighted in the edit region of the combo box.
To select a section of text in the edit region, first set the SelStart property to position the cursor, and then set SelLength to the number of characters that should be selected. The SelText property is the substring that is selected.
C++ Examples:
/* The following example shows how to complete partial strings typed into a combo box. The code represents the OnKeyPress event handler of the combo box, which performs most of the default keystroke handling before finding a matching list item and updating the text. Note: This OnKeyPress event handler does not deal with the case when the user types the Delete key. That case must be caught in the OnKeyDown event handler instead. */ void __fastcall TForm1::ComboBox1KeyPress(TObject *Sender, char &Key) { // first, process the keystroke to obtain the current string // This code requires all items in list to be uppercase if (Key >= 'a' && Key <= 'z') Key -= 32; // Force Uppercase only! TComboBox *pCB = (TComboBox *)Sender; AnsiString TmpStr; bool BackSpace = (Key == (char)VK_BACK); if (BackSpace && pCB->SelLength) TmpStr = pCB->Text.SubString(1,pCB->SelStart)+ pCB->Text.SubString(pCB->SelLength+pCB->SelStart+1,255); else if (BackSpace) // SelLength == 0 TmpStr = pCB->Text.SubString(1,pCB->SelStart-1)+ pCB->Text.SubString(pCB->SelStart+1,255); else //Key is a visible character TmpStr = pCB->Text.SubString(1,pCB->SelStart)+ Key + pCB->Text.SubString(pCB->SelLength+pCB->SelStart+1,255); if (TmpStr.IsEmpty()) return; // set SelSt to the current insertion point int SelSt = pCB->SelStart; if (BackSpace && SelSt > 0) SelSt--; else if (!BackSpace) SelSt++; Key = 0; // indicate that key was handled if (SelSt == 0) { pCB->Text = ""; return; } // Now that TmpStr is the currently typed string, see if we can locate a match bool Found = false; for (int i = 1; i < pCB->Items->Count; i++) if (TmpStr == pCB->Items->Strings[i-1].SubString(1,TmpStr.Length())) { pCB->Text = pCB->Items->Strings[i-1]; // update to the match that was found pCB->ItemIndex = i-1; Found = true; break; } if (Found) // select the untyped end of the string { pCB->SelStart = SelSt; pCB->SelLength = pCB->Text.Length() - SelSt; } else Beep(); } //--------------------------------------------------------------------------- TStringList *CharSetList; void __fastcall TForm1::AddCharacterSet(AnsiString S) { CharSetList->Add(S); } void __fastcall TForm1::FormCreate(TObject *Sender) { CharSetList = new TStringList(); GetCharsetValues(AddCharacterSet); CharSetList->Sort(); ComboBox1->Items = CharSetList; }
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