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TInputLine: add Unicode support
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This is great news!
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@magiblot
magiblot committed Aug 6, 2020
1 parent ca83ead commit cb489d4
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6 changes: 2 additions & 4 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -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).
Expand Down Expand Up @@ -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.
2 changes: 2 additions & 0 deletions include/tvision/dialogs.h
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Expand Up @@ -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();
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59 changes: 59 additions & 0 deletions include/tvision/ttext.h
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Expand Up @@ -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);
Expand All @@ -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,
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72 changes: 43 additions & 29 deletions source/tvision/tinputli.cpp
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Expand Up @@ -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 )
Expand Down Expand Up @@ -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()
Expand All @@ -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)
Expand Down Expand Up @@ -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 )
{
Expand Down Expand Up @@ -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;
Expand All @@ -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);
}
Expand All @@ -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();
Expand All @@ -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();
}

Expand Down

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