Fmx TMemo unable to show a base64 string appropriately

Question

I need to show a base64 key in a TMemo. Unfortunately, it is impossible to show this base64 string appropriately: it is cut off at every '/' by a Carriage return, or at any '+' where it systematically starts a new line ! I tried everything in my knowledge to make this string in one long phrase (without carriage returns), but unsucessfully. How is it possible to obtain a flat string in base64 (without carriage returns), if possible resizable automatically when the form and TMemo is resized ? Many thanks.

Answer 1

For those who are interested, the code below: a TForm with a TMemo (memo). This solution works for me for a flat Base64 string. At last no longer string cut-off at every / or +. Maybe the solution below needs to be tuned, but it works enough for me. Of course, before to treat the b64 string in an application, it needs to be filtered to eliminate CR-LF but that's OK. I use the events: OnKeyDown, OnResize, OnPainting of the TMemo. I wrote a specific function formatMemo(..) which does the job of aligning the lines appropriately. The code accepts only true B64 characters, and filters faulty characters if any.

#define IS_B64(c) (isalnum(c) || (c == '/') || (c == '+') || (c == '='))

//Adjustments work for Courier New, standard size:
const float FW=7.2;//Font width
const diff=25;//Room for vert. scroll bar

//Gives the number of characters in one line of the TMemo:
//  width : width in pixels where to put the line of chars
//  font_sz : the average width of a character
//  returns the number of characters by line of the TMemo
inline int nchars(int width, float font_sz)
{
    return int(float(width-diff)/font_sz);
}//nchars
//---------------------------------------------------------------------------

//Formats the memo to a certain length of characters:
//  *p : the memo to format
//  nc : the number of characters for each line.
void formatMemo(TMemo *p, int nc)
{
    if(p==0) return;
    AnsiString src, dest;//UnicodeString is less fast...
    //Filter everything as B64 only:
    for(int i=1; i<=p->Text.Length(); ++i) {//Indexing is "1-based" like on Delphi (except on mobiles)
        if(IS_B64(p->Text[i])) dest += p->Text[i];
    }
    p->Lines->Clear();//Erases everyting
    int length=dest.Length(), units=length/nc, remain=length%nc;
    for( int k=0 ; k<units ; ++k) {
        p->Lines->Append( dest.SubString(1+k*nc, nc) );
    }
    if(remain) {
        p->Lines->Append( dest.SubString(1+units*nc, remain) );
    }
}//formatMemo
//---------------------------------------------------------------------------

void __fastcall TForm1::memoKeyDown(TObject *Sender, WORD &Key, System::WideChar  &KeyChar,
          TShiftState Shift)
{
    //This event is triggered before the character is sent in Text.
    //Saves caret position:
    TCaretPosition p={memo->CaretPosition.Line, memo->CaretPosition.Pos};
    memo->Tag=0;//Don't do a format.

    if(Key==0 && !IS_B64(KeyChar))//Printable KeyChar
    {
        //Changes the entry into '0':
        KeyChar='0';
        KeyDown(Key,KeyChar,Shift);

        //Put a backspace to erase:
        Key=vkBack; KeyChar=0;
        KeyDown(Key,KeyChar,Shift);
    }
    else memo->Tag=1;//Programs a format in the OnPainting
    memo->SetFocus();
    memo->CaretPosition=p;//Repositions the caret
}
//---------------------------------------------------------------------------

//In case of resize, reformat the TMemo
void __fastcall TForm1::memoResize(TObject *Sender)
{
    formatMemo(memo, nchars(memo->Width,FW));
}
//---------------------------------------------------------------------------

void __fastcall TForm1::memoPainting(TObject *Sender, TCanvas *Canvas, const TRectF &ARect)
{
    //We will use the Tag of the memo as a parameter, to plan a reformat.
    if(memo->Tag){//A format is asked by OnKeyDown.
        TCaretPosition p={memo->CaretPosition.Line, memo->CaretPosition.Pos};
        formatMemo(memo, nchars(memo->Width,FW));
        memo->SetFocus();
        memo->CaretPosition=p;
        memo->Tag=0;//Done
    }
}
//---------------------------------------------------------------------------