summaryrefslogtreecommitdiffstats
path: root/src/gui/text/qstatictext.cpp
blob: 95060067f7fd6f4fae7724057b365f8855f1a533 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the test suite of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qstatictext.h"
#include "qstatictext_p.h"
#include <private/qtextengine_p.h>
#include <private/qfontengine_p.h>
#include <qabstracttextdocumentlayout.h>

#include <QtGui/qapplication.h>

QT_BEGIN_NAMESPACE

/*!
    \class QStaticText
    \brief The QStaticText class enables optimized drawing of text when the text and its layout
    is updated rarely.
    \since 4.7

    \ingroup multimedia
    \ingroup text
    \mainclass

    QStaticText provides a way to cache layout data for a block of text so that it can be drawn
    more efficiently than by using QPainter::drawText() in which the layout information is 
    recalculated with every call. 

    The class primarily provides an optimization for cases where the text, its font and the
    transformations on the painter are static over several paint events. If the text or its layout
    is changed for every iteration, QPainter::drawText() is the more efficient alternative, since
    the static text's layout would have to be recalculated to take the new state into consideration.

    Translating the painter will not cause the layout of the text to be recalculated, but will cause
    a very small performance impact on drawStaticText(). Altering any other parts of the painter's
    transformation or the painter's font will cause the layout of the static text to be
    recalculated. This should be avoided as often as possible to maximize the performance
    benefit of using QStaticText.

    In addition, only affine transformations are supported by drawStaticText(). Calling
    drawStaticText() on a projected painter will perform slightly worse than using the regular
    drawText() call, so this should be avoided.

    \code
    class MyWidget: public QWidget
    {
    public:
        MyWidget(QWidget *parent = 0) : QWidget(parent), m_staticText("This is static text")

    protected:
        void paintEvent(QPaintEvent *)
        {
            QPainter painter(this);
            painter.drawStaticText(0, 0, m_staticText);
        }

    private:
        QStaticText m_staticText;
    };
    \endcode

    The QStaticText class can be used to mimic the behavior of QPainter::drawText() to a specific
    point with no boundaries, and also when QPainter::drawText() is called with a bounding 
    rectangle. 

    If a bounding rectangle is not required, create a QStaticText object without setting a preferred
    text width. The text will then occupy a single line.

    If you set a text width on the QStaticText object, this will bound the text. The text will
    be formatted so that no line exceeds the given width. The text width set for QStaticText will
    not automatically be used for clipping. To achieve clipping in addition to line breaks, use
    QPainter::setClipRect(). The position of the text is decided by the argument passed to
    QPainter::drawStaticText() and can change from call to call with a minimal impact on
    performance.

    For extra convenience, it is possible to apply formatting to the text using the HTML subset
    supported by QTextDocument. QStaticText will attempt to guess the format of the input text using
    Qt::mightBeRichText(), and interpret it as rich text if this function returns true. To force
    QStaticText to display its contents as either plain text or rich text, use the function
    QStaticText::setTextFormat() and pass in, respectively, Qt::PlainText and Qt::RichText.

    QStaticText can only represent text, so only HTML tags which alter the layout or appearance of
    the text will be respected. Adding an image to the input HTML, for instance, will cause the
    image to be included as part of the layout, affecting the positions of the text glyphs, but it
    will not be displayed. The result will be an empty area the size of the image in the output.
    Similarly, using tables will cause the text to be laid out in table format, but the borders
    will not be drawn.

    If it's the first time the static text is drawn, or if the static text, or the painter's font
    has been altered since the last time it was drawn, the text's layout has to be
    recalculated. On some paint engines, changing the matrix of the painter will also cause the
    layout to be recalculated. In particular, this will happen for any engine except for the
    OpenGL2 paint engine. Recalculating the layout will impose an overhead on the
    QPainter::drawStaticText() call where it occurs. To avoid this overhead in the paint event, you
    can call prepare() ahead of time to ensure that the layout is calculated.

    \sa QPainter::drawText(), QPainter::drawStaticText(), QTextLayout, QTextDocument
*/

/*!
    \enum QStaticText::PerformanceHint

    This enum the different performance hints that can be set on the QStaticText. These hints
    can be used to indicate that the QStaticText should use additional caches, if possible,
    to improve performance at the expense of memory. In particular, setting the performance hint
    AggressiveCaching on the QStaticText will improve performance when using the OpenGL graphics
    system or when drawing to a QGLWidget.

    \value ModerateCaching Do basic caching for high performance at a low memory cost.
    \value AggressiveCaching Use additional caching when available. This may improve performance
           at a higher memory cost.
*/

/*!
    Constructs an empty QStaticText
*/
QStaticText::QStaticText()    
    : data(new QStaticTextPrivate)
{
}

/*!
    Constructs a QStaticText object with the given \a text.
*/
QStaticText::QStaticText(const QString &text)
    : data(new QStaticTextPrivate)
{    
    data->text = text;
    data->invalidate();
}

/*!
    Constructs a QStaticText object which is a copy of \a other.
*/
QStaticText::QStaticText(const QStaticText &other)    
{
    data = other.data;
}

/*!
    Destroys the QStaticText.
*/
QStaticText::~QStaticText()
{
    Q_ASSERT(!data || data->ref >= 1);
}

/*!
    \internal
*/
void QStaticText::detach()
{    
    if (data->ref != 1)
        data.detach();
}

/*!
  Prepares the QStaticText object for being painted with the given \a matrix and the given \a font
  to avoid overhead when the actual drawStaticText() call is made.

  When drawStaticText() is called, the layout of the QStaticText will be recalculated if any part
  of the QStaticText object has changed since the last time it was drawn. It will also be
  recalculated if the painter's font is not the same as when the QStaticText was last drawn, or,
  on any other paint engine than the OpenGL2 engine, if the painter's matrix has been altered
  since the static text was last drawn.

  To avoid the overhead of creating the layout the first time you draw the QStaticText after
  making changes, you can use the prepare() function and pass in the \a matrix and \a font you
  expect to use when drawing the text.

  \sa QPainter::setFont(), QPainter::setMatrix()
*/
void QStaticText::prepare(const QTransform &matrix, const QFont &font)
{
    data->matrix = matrix;
    data->font = font;
    data->init();
}


/*!
    Assigns \a other to this QStaticText.
*/
QStaticText &QStaticText::operator=(const QStaticText &other)
{    
    data = other.data;
    return *this;
}

/*!
    Compares \a other to this QStaticText. Returns true if the texts, fonts and text widths
    are equal.
*/
bool QStaticText::operator==(const QStaticText &other) const
{
    return (data == other.data
            || (data->text == other.data->text
                && data->font == other.data->font
                && data->textWidth == other.data->textWidth));
}

/*!
    Compares \a other to this QStaticText. Returns true if the texts, fonts or maximum sizes
    are different.
*/
bool QStaticText::operator!=(const QStaticText &other) const
{
    return !(*this == other);
}

/*!
    Sets the text of the QStaticText to \a text.

    \note This function will cause the layout of the text to require recalculation.

    \sa text()
*/
void QStaticText::setText(const QString &text)
{
    detach();
    data->text = text;
    data->invalidate();
}

/*!
   Sets the text format of the QStaticText to \a textFormat. If \a textFormat is set to
   Qt::AutoText (the default), the format of the text will try to be determined using the
   function Qt::mightBeRichText(). If the text format is Qt::PlainText, then the text will be
   displayed as is, whereas it will be interpreted as HTML if the format is Qt::RichText. HTML tags
   that alter the font of the text, its color, or its layout are supported by QStaticText.

   \note This function will cause the layout of the text to require recalculation.

   \sa textFormat(), setText(), text()
*/
void QStaticText::setTextFormat(Qt::TextFormat textFormat)
{
    detach();
    data->textFormat = textFormat;
    data->invalidate();
}

/*!
  Returns the text format of the QStaticText.

  \sa setTextFormat(), setText(), text()
*/
Qt::TextFormat QStaticText::textFormat() const
{
    return Qt::TextFormat(data->textFormat);
}

/*!
    Returns the text of the QStaticText.

    \sa setText()
*/
QString QStaticText::text() const 
{
    return data->text;
}

/*!
  Sets the performance hint of the QStaticText according to the \a
  performanceHint provided. The \a performanceHint is used to
  customize how much caching is done internally to improve
  performance.

  The default is QStaticText::ModerateCaching.

  \note This function will cause the layout of the text to require recalculation.

  \sa performanceHint()
*/
void QStaticText::setPerformanceHint(PerformanceHint performanceHint)
{
    if ((performanceHint == ModerateCaching && !data->useBackendOptimizations)
        || (performanceHint == AggressiveCaching && data->useBackendOptimizations)) {
        return;
    }
    detach();
    data->useBackendOptimizations = (performanceHint == AggressiveCaching);
    data->invalidate();
}

/*!
  Returns which performance hint is set for the QStaticText.

  \sa setPerformanceHint()
*/
QStaticText::PerformanceHint QStaticText::performanceHint() const
{
    return data->useBackendOptimizations ? AggressiveCaching : ModerateCaching;
}

/*!
   Sets the text option structure that controls the layout process to the given \a textOption.

   \sa textOption()
*/
void QStaticText::setTextOption(const QTextOption &textOption)
{
    detach();
    data->textOption = textOption;
    data->invalidate();
}

/*!
    Returns the current text option used to control the layout process.
*/
QTextOption QStaticText::textOption() const
{
    return data->textOption;
}

/*!
    Sets the preferred width for this QStaticText. If the text is wider than the specified width,
    it will be broken into multiple lines and grow vertically. If the text cannot be split into
    multiple lines, it will be larger than the specified \a textWidth.

    Setting the preferred text width to a negative number will cause the text to be unbounded.

    Use size() to get the actual size of the text.

    \note This function will cause the layout of the text to require recalculation.

    \sa textWidth(), size()
*/
void QStaticText::setTextWidth(qreal textWidth)
{
    detach();
    data->textWidth = textWidth;
    data->invalidate();
}

/*!
    Returns the preferred width for this QStaticText.

    \sa setTextWidth()
*/
qreal QStaticText::textWidth() const
{
    return data->textWidth;
}

/*!
  Returns the size of the bounding rect for this QStaticText.

  \sa textWidth()
*/
QSizeF QStaticText::size() const
{
    if (data->needsRelayout)
        data->init();
    return data->actualSize;
}

QStaticTextPrivate::QStaticTextPrivate()
        : textWidth(-1.0), items(0), itemCount(0), glyphPool(0), positionPool(0), charPool(0),
          needsRelayout(true), useBackendOptimizations(false), textFormat(Qt::AutoText),
          untransformedCoordinates(false)
{
}

QStaticTextPrivate::QStaticTextPrivate(const QStaticTextPrivate &other)
    : text(other.text), font(other.font), textWidth(other.textWidth), matrix(other.matrix),
      items(0), itemCount(0), glyphPool(0), positionPool(0), charPool(0), textOption(other.textOption),
      needsRelayout(true), useBackendOptimizations(other.useBackendOptimizations),
      textFormat(other.textFormat), untransformedCoordinates(other.untransformedCoordinates)
{
}

QStaticTextPrivate::~QStaticTextPrivate()
{
    delete[] items;
    delete[] glyphPool;
    delete[] positionPool;
    delete[] charPool;
}

QStaticTextPrivate *QStaticTextPrivate::get(const QStaticText *q)
{
    return q->data.data();
}

Q_GUI_EXPORT extern int qt_defaultDpiX();
Q_GUI_EXPORT extern int qt_defaultDpiY();

namespace {

    class DrawTextItemRecorder: public QPaintEngine
    {
    public:
        DrawTextItemRecorder(bool untransformedCoordinates, bool useBackendOptimizations)
                : m_dirtyPen(false), m_useBackendOptimizations(useBackendOptimizations),
                  m_untransformedCoordinates(untransformedCoordinates)
        {
        }

        virtual void updateState(const QPaintEngineState &newState)
        {
            if (newState.state() & QPaintEngine::DirtyPen)
                m_dirtyPen = true;
        }

        virtual void drawTextItem(const QPointF &position, const QTextItem &textItem)
        {
            const QTextItemInt &ti = static_cast<const QTextItemInt &>(textItem);

            QStaticTextItem currentItem;
            currentItem.fontEngine = ti.fontEngine;
            currentItem.font = ti.font();
            currentItem.charOffset = m_chars.size();
            currentItem.numChars = ti.num_chars;
            currentItem.glyphOffset = m_glyphs.size(); // Store offset into glyph pool
            currentItem.positionOffset = m_glyphs.size(); // Offset into position pool
            currentItem.useBackendOptimizations = m_useBackendOptimizations;
            if (m_dirtyPen)
                currentItem.color = state->pen().color();

            QTransform matrix = m_untransformedCoordinates ? QTransform() : state->transform();
            matrix.translate(position.x(), position.y());

            QVarLengthArray<glyph_t> glyphs;
            QVarLengthArray<QFixedPoint> positions;
            ti.fontEngine->getGlyphPositions(ti.glyphs, matrix, ti.flags, glyphs, positions);

            int size = glyphs.size();
            Q_ASSERT(size == positions.size());
            currentItem.numGlyphs = size;

            m_glyphs.resize(m_glyphs.size() + size);
            m_positions.resize(m_glyphs.size());
            m_chars.resize(m_chars.size() + ti.num_chars);

            glyph_t *glyphsDestination = m_glyphs.data() + currentItem.glyphOffset;
            memcpy(glyphsDestination, glyphs.constData(), sizeof(glyph_t) * currentItem.numGlyphs);

            QFixedPoint *positionsDestination = m_positions.data() + currentItem.positionOffset;
            memcpy(positionsDestination, positions.constData(), sizeof(QFixedPoint) * currentItem.numGlyphs);

            QChar *charsDestination = m_chars.data() + currentItem.charOffset;
            memcpy(charsDestination, ti.chars, sizeof(QChar) * currentItem.numChars);

            m_items.append(currentItem);
        }

        virtual void drawPolygon(const QPointF *, int , PolygonDrawMode )
        {
            /* intentionally empty */
        }

        virtual bool begin(QPaintDevice *)  { return true; }
        virtual bool end() { return true; }
        virtual void drawPixmap(const QRectF &, const QPixmap &, const QRectF &) {}
        virtual Type type() const
        {
            return User;
        }

        QVector<QStaticTextItem> items() const
        {
            return m_items;
        }

        QVector<QFixedPoint> positions() const
        {
            return m_positions;
        }

        QVector<glyph_t> glyphs() const
        {
            return m_glyphs;
        }

        QVector<QChar> chars() const
        {
            return m_chars;
        }

    private:
        QVector<QStaticTextItem> m_items;
        QVector<QFixedPoint> m_positions;
        QVector<glyph_t> m_glyphs;
        QVector<QChar> m_chars;

        bool m_dirtyPen;
        bool m_useBackendOptimizations;
        bool m_untransformedCoordinates;
    };

    class DrawTextItemDevice: public QPaintDevice
    {
    public:
        DrawTextItemDevice(bool untransformedCoordinates, bool useBackendOptimizations)
        {
            m_paintEngine = new DrawTextItemRecorder(untransformedCoordinates,
                                                     useBackendOptimizations);
        }

        ~DrawTextItemDevice()
        {
            delete m_paintEngine;
        }

        int metric(PaintDeviceMetric m) const
        {
            int val;
            switch (m) {
            case PdmWidth:
            case PdmHeight:
            case PdmWidthMM:
            case PdmHeightMM:
                val = 0;
                break;
            case PdmDpiX:
            case PdmPhysicalDpiX:
                val = qt_defaultDpiX();
                break;
            case PdmDpiY:
            case PdmPhysicalDpiY:
                val = qt_defaultDpiY();
                break;
            case PdmNumColors:
                val = 16777216;
                break;
            case PdmDepth:
                val = 24;
                break;
            default:
                val = 0;
                qWarning("DrawTextItemDevice::metric: Invalid metric command");
            }
            return val;
        }

        virtual QPaintEngine *paintEngine() const
        {
            return m_paintEngine;
        }

        QVector<glyph_t> glyphs() const
        {
            return m_paintEngine->glyphs();
        }

        QVector<QFixedPoint> positions() const
        {
            return m_paintEngine->positions();
        }

        QVector<QStaticTextItem> items() const
        {
            return m_paintEngine->items();
        }

        QVector<QChar> chars() const
        {
            return m_paintEngine->chars();
        }

    private:
        DrawTextItemRecorder *m_paintEngine;
    };
}

void QStaticTextPrivate::paintText(const QPointF &topLeftPosition, QPainter *p)
{
    bool preferRichText = textFormat == Qt::RichText
                          || (textFormat == Qt::AutoText && Qt::mightBeRichText(text));

    if (!preferRichText) {
        QTextLayout textLayout;
        textLayout.setText(text);
        textLayout.setFont(font);
        textLayout.setTextOption(textOption);

        qreal leading = QFontMetricsF(font).leading();
        qreal height = -leading;

        textLayout.beginLayout();
        while (1) {
            QTextLine line = textLayout.createLine();
            if (!line.isValid())
                break;

            if (textWidth >= 0.0)
                line.setLineWidth(textWidth);
            height += leading;
            line.setPosition(QPointF(0.0, height));
            height += line.height();
        }
        textLayout.endLayout();

        actualSize = textLayout.boundingRect().size();
        textLayout.draw(p, topLeftPosition);
    } else {
        QTextDocument document;
#ifndef QT_NO_CSSPARSER
        QColor color = p->pen().color();
        document.setDefaultStyleSheet(QString::fromLatin1("body { color: #%1%2%3 }")
                                      .arg(QString::number(color.red(), 16), 2, QLatin1Char('0'))
                                      .arg(QString::number(color.green(), 16), 2, QLatin1Char('0'))
                                      .arg(QString::number(color.blue(), 16), 2, QLatin1Char('0')));
#endif
        document.setDefaultFont(font);
        document.setDocumentMargin(0.0);        
#ifndef QT_NO_TEXTHTMLPARSER
        document.setHtml(text);
#else
        document.setPlainText(text);
#endif
        if (textWidth >= 0.0)
            document.setTextWidth(textWidth);
        else
            document.adjustSize();
        document.setDefaultTextOption(textOption);

        p->save();
        p->translate(topLeftPosition);
        QAbstractTextDocumentLayout::PaintContext ctx;
        ctx.palette.setColor(QPalette::Text, p->pen().color());
        document.documentLayout()->draw(p, ctx);
        p->restore();

        if (textWidth >= 0.0)
            document.adjustSize(); // Find optimal size

        actualSize = document.size();
    }
}

void QStaticTextPrivate::init()
{
    delete[] items;
    delete[] glyphPool;
    delete[] positionPool;
    delete[] charPool;

    position = QPointF(0, 0);

    DrawTextItemDevice device(untransformedCoordinates, useBackendOptimizations);
    {
        QPainter painter(&device);
        painter.setFont(font);
        painter.setTransform(matrix);

        paintText(QPointF(0, 0), &painter);
    }

    QVector<QStaticTextItem> deviceItems = device.items();
    QVector<QFixedPoint> positions = device.positions();
    QVector<glyph_t> glyphs = device.glyphs();
    QVector<QChar> chars = device.chars();

    itemCount = deviceItems.size();
    items = new QStaticTextItem[itemCount];

    glyphPool = new glyph_t[glyphs.size()];
    memcpy(glyphPool, glyphs.constData(), glyphs.size() * sizeof(glyph_t));

    positionPool = new QFixedPoint[positions.size()];
    memcpy(positionPool, positions.constData(), positions.size() * sizeof(QFixedPoint));

    charPool = new QChar[chars.size()];
    memcpy(charPool, chars.constData(), chars.size() * sizeof(QChar));

    for (int i=0; i<itemCount; ++i) {
        items[i] = deviceItems.at(i);

        items[i].glyphs = glyphPool + items[i].glyphOffset;
        items[i].glyphPositions = positionPool + items[i].positionOffset;
        items[i].chars = charPool + items[i].charOffset;
    }

    needsRelayout = false;
}

QT_END_NAMESPACE