kdeui/util/kwordwrap.cpp

   1 /* This file is part of the KDE libraries
   2    Copyright (C) 2001 David Faure <faure@kde.org>
   3
   4    This library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public
   6    License version 2 as published by the Free Software Foundation.
   7
   8    This library is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11    Library General Public License for more details.
  12
  13    You should have received a copy of the GNU Library General Public License
  14    along with this library; see the file COPYING.LIB.  If not, write to
  15    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  16    Boston, MA 02110-1301, USA.
  17 */
  18
  19 #include "kwordwrap.h"
  20 #include <kdebug.h>
  21
  22 #include <QtGui/QPainter>
  23 #include <QtCore/QMutableVectorIterator>
  24
  25 class KWordWrapPrivate {
  26 public:
  27   QRect m_constrainingRect;
  28   QVector<int> m_breakPositions;
  29   QVector<int> m_lineWidths;
  30   QRect m_boundingRect;
  31   QString m_text;
  32 };
  33
  34 KWordWrap::KWordWrap(const QRect & r)
  35 :       d(new KWordWrapPrivate)
  36 {
  37     d->m_constrainingRect = r;
  38 }
  39
  40 KWordWrap* KWordWrap::formatText( QFontMetrics &fm, const QRect & r, int /*flags*/, const QString & str, int len )
  41 {
  42     KWordWrap* kw = new KWordWrap( r );
  43     // The wordwrap algorithm
  44     // The variable names and the global shape of the algorithm are inspired
  45     // from QTextFormatterBreakWords::format().
  46     //kDebug() << "KWordWrap::formatText " << str << " r=" << r.x() << "," << r.y() << " " << r.width() << "x" << r.height();
  47     int height = fm.height();
  48     if ( len == -1 )
  49         kw->d->m_text = str;
  50     else
  51         kw->d->m_text = str.left( len );
  52     if ( len == -1 )
  53         len = str.length();
  54     int lastBreak = -1;
  55     int lineWidth = 0;
  56     int x = 0;
  57     int y = 0;
  58     int w = r.width();
  59     int textwidth = 0;
  60     bool isBreakable = false;
  61     bool wasBreakable = false; // value of isBreakable for last char (i-1)
  62     bool isParens = false; // true if one of ({[
  63     bool wasParens = false; // value of isParens for last char (i-1)
  64     QString inputString = str;
  65
  66     for ( int i = 0 ; i < len; ++i )
  67     {
  68         const QChar c = inputString.at(i);
  69         const int ww = fm.charWidth(inputString, i);
  70
  71         isParens = ( c == QLatin1Char('(') || c == QLatin1Char('[')
  72                      || c == QLatin1Char('{') );
  73         // isBreakable is true when we can break _after_ this character.
  74         isBreakable = ( c.isSpace() || c.isPunct() || c.isSymbol() ) & !isParens;
  75
  76         // Special case for '(', '[' and '{': we want to break before them
  77         if ( !isBreakable && i < len-1 ) {
  78             const QChar nextc = inputString.at(i + 1); // look at next char
  79             isBreakable = ( nextc == QLatin1Char('(')
  80                             || nextc == QLatin1Char('[')
  81                             || nextc == QLatin1Char('{') );
  82         }
  83         // Special case for '/': after normal chars it's breakable (e.g. inside a path),
  84         // but after another breakable char it's not (e.g. "mounted at /foo")
  85         // Same thing after a parenthesis (e.g. "dfaure [/fool]")
  86         if ( c == QLatin1Char('/') && (wasBreakable || wasParens) )
  87             isBreakable = false;
  88
  89         /*kDebug() << "c='" << QString(c) << "' i=" << i << "/" << len
  90                   << " x=" << x << " ww=" << ww << " w=" << w
  91                   << " lastBreak=" << lastBreak << " isBreakable=" << isBreakable << endl;*/
  92         int breakAt = -1;
  93         if ( x + ww > w && lastBreak != -1 ) // time to break and we know where
  94             breakAt = lastBreak;
  95         if ( x + ww > w - 4 && lastBreak == -1 ) // time to break but found nowhere [-> break here]
  96             breakAt = i;
  97         if (i == len - 2 && x + ww + fm.charWidth(inputString, i+1) > w) // don't leave the last char alone
  98             breakAt = lastBreak == -1 ? i - 1 : lastBreak;
  99         if ( c == QLatin1Char('\n') ) // Forced break here
 100         {
 101             if ( breakAt == -1 && lastBreak != -1) // only break if not already breaking
 102             {
 103                 breakAt = i - 1;
 104                 lastBreak = -1;
 105             }
 106             // remove the line feed from the string
 107             kw->d->m_text.remove(i, 1);
 108             inputString.remove(i, 1);
 109             len--;
 110         }
 111         if ( breakAt != -1 )
 112         {
 113             //kDebug() << "KWordWrap::formatText breaking after " << breakAt;
 114             kw->d->m_breakPositions.append( breakAt );
 115             int thisLineWidth = lastBreak == -1 ? x + ww : lineWidth;
 116             kw->d->m_lineWidths.append( thisLineWidth );
 117             textwidth = qMax( textwidth, thisLineWidth );
 118             x = 0;
 119             y += height;
 120             wasBreakable = true;
 121             wasParens = false;
 122             if ( lastBreak != -1 )
 123             {
 124                 // Breakable char was found, restart from there
 125                 i = lastBreak;
 126                 lastBreak = -1;
 127                 continue;
 128             }
 129         } else if ( isBreakable )
 130         {
 131             lastBreak = i;
 132             lineWidth = x + ww;
 133         }
 134         x += ww;
 135         wasBreakable = isBreakable;
 136         wasParens = isParens;
 137     }
 138     textwidth = qMax( textwidth, x );
 139     kw->d->m_lineWidths.append( x );
 140     y += height;
 141     //kDebug() << "KWordWrap::formatText boundingRect:" << r.x() << "," << r.y() << " " << textwidth << "x" << y;
 142     if ( r.height() >= 0 && y > r.height() )
 143         textwidth = r.width();
 144     int realY = y;
 145     if ( r.height() >= 0 )
 146     {
 147         while ( realY > r.height() )
 148             realY -= height;
 149         realY = qMax( realY, 0 );
 150     }
 151     kw->d->m_boundingRect.setRect( 0, 0, textwidth, realY );
 152     return kw;
 153 }
 154
 155 KWordWrap::~KWordWrap() {
 156     delete d;
 157 }
 158
 159 QString KWordWrap::wrappedString() const
 160 {
 161     // We use the calculated break positions to insert '\n' into the string
 162     QString ws;
 163     int start = 0;
 164     for (int i = 0; i < d->m_breakPositions.count(); ++i) {
 165         int end = d->m_breakPositions.at(i);
 166         ws += d->m_text.mid( start, end - start + 1 );
 167         ws += QLatin1Char('\n');
 168         start = end + 1;
 169     }
 170     ws += d->m_text.mid( start );
 171     return ws;
 172 }
 173
 174 QString KWordWrap::truncatedString( bool dots ) const
 175 {
 176     if ( d->m_breakPositions.isEmpty() )
 177         return d->m_text;
 178
 179     QString ts = d->m_text.left( d->m_breakPositions.first() + 1 );
 180     if ( dots )
 181         ts += QLatin1String("...");
 182     return ts;
 183 }
 184
 185 static QColor mixColors(double p1, QColor c1, QColor c2) {
 186   return QColor(int(c1.red() * p1 + c2.red() * (1.0-p1)),
 187                 int(c1.green() * p1 + c2.green() * (1.0-p1)),
 188                 int(c1.blue() * p1 + c2.blue() * (1.0-p1)));
 189 }
 190
 191 void KWordWrap::drawFadeoutText(QPainter *p, int x, int y, int maxW,
 192                                    const QString &t) {
 193     QFontMetrics fm = p->fontMetrics();
 194     QColor bgColor = p->background().color();
 195     QColor textColor = p->pen().color();
 196
 197     if ( ( fm.boundingRect( t ).width() > maxW ) && ( t.length() > 1 ) ) {
 198         int tl = 0;
 199         int w = 0;
 200         while ( tl < t.length() ) {
 201             w += fm.charWidth( t, tl );
 202             if ( w >= maxW )
 203                 break;
 204             tl++;
 205         }
 206
 207         int n = qMin( tl, 3);
 208         if ( t.isRightToLeft() ) {
 209             x += maxW; // start from the right side for RTL string
 210             if (tl > 3) {
 211                 x -= fm.width( t.left( tl - 3 ) );
 212                 p->drawText( x, y, t.left( tl - 3 ) );
 213             }
 214             for (int i = 0; i < n; i++) {
 215                 p->setPen( mixColors( 0.70 - i * 0.25, textColor, bgColor ) );
 216                 QString s( t.at( tl - n + i ) );
 217                 x -= fm.width( s );
 218                 p->drawText( x, y, s );
 219             }
 220         }
 221         else {
 222             if (tl > 3) {
 223                 p->drawText( x, y, t.left( tl - 3 ) );
 224                 x += fm.width( t.left( tl - 3 ) );
 225             }
 226             for (int i = 0; i < n; i++) {
 227                 p->setPen( mixColors( 0.70 - i * 0.25, textColor, bgColor ) );
 228                 QString s( t.at( tl - n + i ) );
 229                 p->drawText( x, y, s );
 230                 x += fm.width( s );
 231             }
 232         }
 233     }
 234     else
 235         p->drawText( x, y, t );
 236 }
 237
 238 void KWordWrap::drawTruncateText(QPainter *p, int x, int y, int maxW,
 239                                  const QString &t) {
 240     QString tmpText = p->fontMetrics().elidedText(t, Qt::ElideRight, maxW);
 241     p->drawText( x, y, tmpText );
 242 }
 243
 244 void KWordWrap::drawText( QPainter *painter, int textX, int textY, int flags ) const
 245 {
 246     //kDebug() << "KWordWrap::drawText text=" << wrappedString() << " x=" << textX << " y=" << textY;
 247     // We use the calculated break positions to draw the text line by line using QPainter
 248     int start = 0;
 249     int y = 0;
 250     QFontMetrics fm = painter->fontMetrics();
 251     int height = fm.height(); // line height
 252     int ascent = fm.ascent();
 253     int maxwidth = d->m_boundingRect.width();
 254     int i;
 255     int lwidth = 0;
 256     int end = 0;
 257     for (i = 0; i < d->m_breakPositions.count() ; ++i )
 258     {
 259         // if this is the last line, leave the loop
 260         if ( (d->m_constrainingRect.height() >= 0) &&
 261              ((y + 2 * height) > d->m_constrainingRect.height()) )
 262             break;
 263         end = d->m_breakPositions.at(i);
 264         lwidth = d->m_lineWidths.at(i);
 265         int x = textX;
 266         if ( flags & Qt::AlignHCenter )
 267             x += ( maxwidth - lwidth ) / 2;
 268         else if ( flags & Qt::AlignRight )
 269             x += maxwidth - lwidth;
 270         painter->drawText( x, textY + y + ascent, d->m_text.mid( start, end - start + 1 ) );
 271         y += height;
 272         start = end + 1;
 273     }
 274
 275     // Draw the last line
 276     lwidth = d->m_lineWidths.last();
 277     int x = textX;
 278     if ( flags & Qt::AlignHCenter )
 279         x += ( maxwidth - lwidth ) / 2;
 280     else if ( flags & Qt::AlignRight )
 281         x += maxwidth - lwidth;
 282     if ( (d->m_constrainingRect.height() < 0) ||
 283          ((y + height) <= d->m_constrainingRect.height()) ) {
 284         if ( i == d->m_breakPositions.count() )
 285             painter->drawText( x, textY + y + ascent, d->m_text.mid( start ) );
 286         else if (flags & FadeOut)
 287             drawFadeoutText( painter, textX, textY + y + ascent,
 288                              d->m_constrainingRect.width(),
 289                              d->m_text.mid( start ) );
 290         else if (flags & Truncate)
 291             drawTruncateText( painter, textX, textY + y + ascent,
 292                               d->m_constrainingRect.width(),
 293                               d->m_text.mid( start ) );
 294         else
 295             painter->drawText( x, textY + y + ascent,
 296                                d->m_text.mid( start ) );
 297     }
 298 }
 299
 300 QRect KWordWrap::boundingRect() const
 301 {
 302     return d->m_boundingRect;
 303 }
 304