TInputLine: add Unicode support

This is great news!

README.md

@@ -255,8 +255,6 @@ KeyDownEvent {
 ```
 So, in short: views designed without Unicode input in mind will continue to work exactly as they did before, and views which want to be Unicode-aware will have no issues in being so.
 
-For the time being, none of the builtin views have been modified to support Unicode input.
-
 ## Displaying Unicode text
 
 The original design of Turbo Vision uses 16 bits to represent a *screen cell*—8 bit for a character and 8 bit for [BIOS color attributes](https://en.wikipedia.org/wiki/BIOS_color_attributes).
@@ -380,7 +378,7 @@ Here is what it looks like:
 
 Support for creating Unicode-aware views is in place, but most of the views that are part of the original Turbo Vision library have not been adapted to handle Unicode.
 
-* At least `TFrame`, `THistoryViewer`, `TListViewer`, `TInputLine` and `TMenuBox` are able to display Unicode text properly.
+* At least `TFrame`, `THistoryViewer`, `TListViewer` and `TMenuBox` are able to display Unicode text properly.
 * Automatic shortcuts in `TMenuBox` won't work with Unicode text, as shortcuts are still compared against `event.keyDown.charScan.charCode`.
-* `TInputLine` can display but not process Unicode text, as it still believes that every byte is one column wide. This can lead to inconsistencies, because some non-ASCII characters can be represented in the active codepage. For instance, if using CP437, it is possible to type `ç` into a `TInputLine`, but it will be a narrow character instead of a UTF-8 sequence. If you manage to place UTF-8 text in a `TInputLine` (e.g. by selecting a file in a `TFileDialog`), the caret will appear to be out of sync as its position is measured assuming a single-byte encoding.
+* `TInputLine` can display and process Unicode text.
 * `TEditor` assumes a single-byte encoding both when handling input events and when displaying text. So it won't display UTF-8 but at least it has a consistent behaviour.

include/tvision/dialogs.h

@@ -185,7 +185,9 @@ class TInputLine : public TView
  Boolean canScroll( int delta );
  int mouseDelta( TEvent& event );
  int mousePos( TEvent& event );
+ int displayedPos( int pos );
  void deleteSelect();
+ void deleteCurrent();
  void adjustSelectBlock();
  void saveState();
  void restoreState();

include/tvision/ttext.h

@@ -114,6 +114,10 @@ class TText {
 
 public:
 
+ static size_t next(TStringView text);
+ static size_t prev(TStringView text, size_t index);
+ static size_t wseek(TStringView text, int count);
+
 #ifndef __BORLANDC__
  static void eat(TScreenCell *cell, size_t n, size_t &width, std::string_view src, size_t &bytes);
  static void next(std::string_view src, size_t &bytes, size_t &width);
@@ -122,6 +126,61 @@ class TText {
 
 };
 
+#ifdef __BORLANDC__
+
+inline size_t TText::next(TStringView text)
+{
+ return text.size() ? 1 : 0;
+}
+
+inline size_t TText::prev(TStringView text, size_t index)
+{
+ return index ? 1 : 0;
+}
+
+inline size_t TText::wseek(TStringView text, int count)
+{
+ return count > 0 ? count : 0;
+}
+
+#else
+
+inline size_t TText::next(TStringView text)
+{
+ if (text.size()) {
+ std::mbstate_t state {};
+ int64_t len = std::mbrtowc(nullptr, text.data(), text.size(), &state);
+ return len <= 1 ? 1 : len;
+ }
+ return 0;
+}
+
+inline size_t TText::prev(TStringView text, size_t index)
+{
+ if (index) {
+ // Try reading backwards character by character, until a valid
+ // character is found. This tolerates invalid characters.
+ size_t lead = std::min<size_t>(index, 4);
+ for (size_t i = 1; i <= lead; ++i) {
+ std::mbstate_t state {};
+ int64_t size = std::mbrtowc(nullptr, &text[index - i], i, &state);
+ if (size > 0)
+ return size == i ? i : 1;
+ }
+ return 1;
+ }
+ return 0;
+}
+
+inline size_t TText::wseek(TStringView text, int count)
+{
+ size_t index = 0, remainder = 0;
+ wseek(text, index, remainder, count);
+ return index;
+}
+
+#endif
+
 #ifndef __BORLANDC__
 
 inline void TText::eat( TScreenCell *cell, size_t n, size_t &width,

source/tvision/tinputli.cpp

@@ -111,15 +111,15 @@ void TInputLine::draw()
  {
  if( canScroll(-1) )
  b.moveChar( 0, leftArrow, getColor(4), 1 );
- l = selStart - firstPos;
- r = selEnd - firstPos;
+ l = displayedPos(selStart) - firstPos;
+ r = displayedPos(selEnd) - firstPos;
  l = max( 0, l );
  r = min( size.x - 2, r );
  if (l < r)
  b.moveChar( l+1, 0, getColor(3), r - l );
  }
  writeLine( 0, 0, size.x, size.y, b );
- setCursor( curPos-firstPos+1, 0);
+ setCursor( displayedPos(curPos)-firstPos+1, 0);
 }
 
 void TInputLine::getData( void *rec )
@@ -153,8 +153,14 @@ int TInputLine::mousePos( TEvent& event )
  mouse.x = max( mouse.x, 1 );
  int pos = mouse.x + firstPos - 1;
  pos = max( pos, 0 );
- pos = min( pos, strlen(data) );
- return pos;
+ TStringView text = data;
+ pos = min( pos, strwidth(text) );
+ return TText::wseek(text, pos);
+}
+
+int TInputLine::displayedPos( int pos )
+{
+ return strwidth( TStringView(data, pos) );
 }
 
 void TInputLine::deleteSelect()
@@ -166,6 +172,17 @@ void TInputLine::deleteSelect()
  }
 }
 
+void TInputLine::deleteCurrent()
+{
+ TStringView text = data;
+ if( curPos < text.size() )
+ {
+ selStart = curPos;
+ selEnd = curPos + TText::next(text.substr(curPos));
+ deleteSelect();
+ }
+}
+
 void TInputLine::adjustSelectBlock()
 {
  if (curPos < anchor)
@@ -243,7 +260,7 @@ void TInputLine::handleEvent( TEvent& event )
  static char padKeys[] = {0x47,0x4b,0x4d,0x4f,0x73,0x74, 0};
  TView::handleEvent(event);
 
- int delta, i;
+ int delta, i, len, curWidth;
  if( (state & sfSelected) != 0 )
  switch( event.what )
  {
@@ -296,12 +313,10 @@ void TInputLine::handleEvent( TEvent& event )
  switch( event.keyDown.keyCode )
  {
  case kbLeft:
- if( curPos > 0 )
- curPos--;
+ curPos -= TText::prev(TStringView(data), curPos);
  break;
  case kbRight:
- if( curPos < strlen(data) )
- curPos++;
+ curPos += TText::next(TStringView(data+curPos));
  break;
  case kbHome:
  curPos = 0;
@@ -312,41 +327,39 @@ void TInputLine::handleEvent( TEvent& event )
  case kbBack:
  if( curPos > 0 )
  {
- strcpy( data+curPos-1, data+curPos );
- curPos--;
+ TStringView text = data;
+ int len = TText::prev(text, curPos);
+ memmove( data+curPos-len, data+curPos, text.size()-curPos+1 );
+ curPos -= len;
  checkValid(True);
  }
  break;
  case kbDel:
  if( selStart == selEnd )
- if( curPos < strlen(data) )
- {
- selStart = curPos;
- selEnd = curPos + 1;
- }
- deleteSelect();
+ deleteCurrent();
+ else
+ deleteSelect();
  checkValid(True);
  break;
  case kbIns:
  setState(sfCursorIns, Boolean(!(state & sfCursorIns)));
  break;
  default:
- if( event.keyDown.charScan.charCode >= ' ' )
+ if( (len = event.keyDown.textLength) )
  {
  deleteSelect();
  if( (state & sfCursorIns) != 0 )
- /* The following must be a signed comparison! */
- if( curPos < (int) strlen(data) )
- strcpy( data + curPos, data + curPos + 1 );
+ deleteCurrent();
 
  if( checkValid(True) )
  {
- if( strlen(data) < maxLen )
+ if( strlen(data) + len <= maxLen )
  {
  if( firstPos > curPos )
  firstPos = curPos;
- memmove( data+curPos+1, data+curPos, strlen(data+curPos)+1 );
- data[curPos++] = event.keyDown.charScan.charCode;
+ memmove( data+curPos+len, data+curPos, strlen(data+curPos)+1 );
+ memcpy( data+curPos, event.keyDown.text, len );
+ curPos += len;
  }
  checkValid(False);
  }
@@ -366,9 +379,10 @@ void TInputLine::handleEvent( TEvent& event )
  selStart = 0;
  selEnd = 0;
  }
- if( firstPos > curPos )
- firstPos = curPos;
- i = curPos - size.x + 2;
+ curWidth = displayedPos(curPos);
+ if( firstPos > curWidth )
+ firstPos = curWidth;
+ i = curWidth - size.x + 2;
  if( firstPos < i )
  firstPos = i;
  drawView();
@@ -384,7 +398,7 @@ void TInputLine::selectAll( Boolean enable )
  curPos = selEnd = strlen(data);
  else
  curPos = selEnd = 0;
- firstPos = max( 0, curPos-size.x+2 );
+ firstPos = max( 0, displayedPos(curPos)-size.x+2 );
  drawView();
 }