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Additional fix for STR #2531

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Wiggeling characters in Fl_Text_Display due to advanced kerning.
This commit is contained in:
Matthias Melcher 2019-02-01 18:18:28 +01:00
parent ab90f849ff
commit 389521a885
1 changed files with 48 additions and 21 deletions
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69
src/Fl_Text_Display.cxx
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@ -1967,10 +1967,23 @@ int Fl_Text_Display::handle_vline(
// FIXME: we need to allow two modes for FIND_INDEX: one on the edge of the
// FIXME: character for selection, and one on the character center for cursors.
int i, X, startIndex, style, charStyle;
int startStyle, styleX;
/* STR #2531
The variables startStyle and styleX seem to introduce some additional
complexity. They were required to fix STR #2531 in which a horizontal
character wiggle could be observed when drag-selecting text. This was caused
by native drawing an measuring routines that support kerning (inter-character
spacing, the width of 'T' plus the width of 'e' is greater than the width of
'Te', because advanced typesetting moves the 'e' slightly to the left below
the 'T').
To acommodate this, FLTK uses slightly different routines for a true style
change vs. a change in highlighting only.
*/
int i, X, startIndex, startStyle, style, charStyle;
char *lineStr;
double startX;
double startX, styleX;
if ( lineStartPos == -1 ) {
lineStr = NULL;
@ -1994,8 +2007,8 @@ int Fl_Text_Display::handle_vline(
X = text_area.x - mHorizOffset;
}
startX = styleX = X;
startIndex = startStyle = 0;
startX = X;
startIndex = 0;
if (!lineStr) {
// just clear the background
if (mode==DRAW_LINE) {
@ -2008,8 +2021,8 @@ int Fl_Text_Display::handle_vline(
}
return 0;
}
char currChar = 0, prevChar = 0;
styleX = startX; startStyle = startIndex;
// draw the line
style = position_style(lineStartPos, lineLen, 0);
for (i=0; i<lineLen; ) {
@ -2022,10 +2035,10 @@ int Fl_Text_Display::handle_vline(
double w = 0;
if (prevChar=='\t') {
// draw a single Tab space
styleX = startX; startStyle = startIndex;
double tab = col_to_x(mBuffer->tab_distance());
double xAbs = (mode==GET_WIDTH) ? startX : startX+mHorizOffset-text_area.x;
w = ((int(xAbs/tab)+1)*tab) - xAbs;
styleX = startX+w; startStyle = i;
if (mode==DRAW_LINE)
draw_string( style|BG_ONLY_MASK, startX, Y, startX+w, 0, 0 );
if (mode==FIND_INDEX && startX+w>rightClip) {
@ -2036,19 +2049,15 @@ int Fl_Text_Display::handle_vline(
return lineStartPos + startIndex;
}
} else {
// draw a text segment
// draw the text segment from the previous style change up to this point
if ( (style&0xff)==(charStyle&0xff)) {
w = string_width( lineStr+startStyle, i-startStyle, style ) + styleX - startX;
w = string_width( lineStr+startStyle, i-startStyle, style ) - startX + styleX;
} else {
styleX = startX; startStyle = startIndex;
w = string_width( lineStr+startIndex, i-startIndex, style );
}
if (mode==DRAW_LINE) {
// STR 2531: if only the highlighting changes, but the style is the same,
// we must use some tricky clipping, or kerning between characters will
// make the text wiggle while the user is expanding a selection.
if ( (style&0xff)==(charStyle&0xff)) {
fl_push_clip(startX, Y, w, mMaxsize);
if (startIndex!=startStyle) {
fl_push_clip(startX, Y, w+1, mMaxsize);
draw_string( style, styleX, Y, startX+w, lineStr+startStyle, i-startStyle );
fl_pop_clip();
} else {
@ -2057,10 +2066,21 @@ int Fl_Text_Display::handle_vline(
}
if (mode==FIND_INDEX && startX+w>rightClip) {
// find x pos inside block
int di = find_x(lineStr+startIndex, i-startIndex, style, -(rightClip-startX)); // STR #2788
int di;
if (startIndex!=startStyle) {
di = find_x(lineStr+startStyle, i-startStyle, style, -(rightClip-styleX)); // STR #2788
di = lineStartPos + startStyle + di;
} else {
di = find_x(lineStr+startIndex, i-startIndex, style, -(rightClip-startX)); // STR #2788
di = lineStartPos + startIndex + di;
}
free(lineStr);
IS_UTF8_ALIGNED2(buffer(), (lineStartPos+startIndex+di))
return lineStartPos + startIndex + di;
return di;
}
if ( (style&0xff)!=(charStyle&0xff)) {
startStyle = i;
styleX = startX+w;
}
}
style = charStyle;
@ -2089,8 +2109,8 @@ int Fl_Text_Display::handle_vline(
w = string_width( lineStr+startIndex, i-startIndex, style );
if (mode==DRAW_LINE) {
// STR 2531
if ( (style&0xff)==(charStyle&0xff)) {
fl_push_clip(startX, Y, w, mMaxsize);
if (startIndex!=startStyle) {
fl_push_clip(startX, Y, w+1, mMaxsize);
draw_string( style, styleX, Y, startX+w, lineStr+startStyle, i-startStyle );
fl_pop_clip();
} else {
@ -2099,10 +2119,17 @@ int Fl_Text_Display::handle_vline(
}
if (mode==FIND_INDEX) {
// find x pos inside block
int di = find_x(lineStr+startIndex, i-startIndex, style, -(rightClip-startX)); // STR #2788
int di;
if (startIndex!=startStyle) {
di = find_x(lineStr+startStyle, i-startStyle, style, -(rightClip-styleX)); // STR #2788
di = lineStartPos + startStyle + di;
} else {
di = find_x(lineStr+startIndex, i-startIndex, style, -(rightClip-startX)); // STR #2788
di = lineStartPos + startIndex + di;
}
free(lineStr);
IS_UTF8_ALIGNED2(buffer(), (lineStartPos+startIndex+di))
return lineStartPos + startIndex + di;
return di;
}
}
if (mode==GET_WIDTH) {