kolourpaint/patches/checkerboard-faster-render.diff

   1 At 100% zoom: kpMainWindow::drawTransparentBackground() accounts for
   2 about 75% of kpView::paintEvent()'s time.  Bottleneck is
   3 QPainter::fillRect().  QPainter::drawPixmap() seems much faster.  For
   4 800x600, renderer goes from 10ms to 1ms.
   5
   6 2007-10-12:
   7 Have not reprofiled KolourPaint under Qt4 to determine whether this patch
   8 is still worthwhile (I suspect it still is since QPainter/X11 could not
   9 magically have gotten faster).  In any case, the patch needs to be updated
  10 before being applied.
  11
  12 --- kpmainwindow.cpp    2004-08-05 02:10:38.000000000 +1000
  13 +++ kpmainwindow.cpp    2004-09-29 11:24:45.000000000 +1000
  14 @@ -838,12 +838,116 @@
  15  }
  16
  17
  18 +#if 1
  19 +// (indexed by [isPreview][parity])
  20 +static QPixmap *checkerBoardCache [2][2] = {{0, 0}, {0, 0}};
  21 +
  22 +
  23 +static int checkerBoardCellSize (bool isPreview)
  24 +{
  25 +    return !isPreview ? 16 : 10;
  26 +}
  27 +
  28 +
  29 +// public
  30 +static QPixmap *createCheckerBoardCache (bool isPreview, bool parity)
  31 +{
  32 +    int cellSize = checkerBoardCellSize (isPreview);
  33 +    const int rep = 2;  // must be multiple of 2
  34 +
  35 +    QPixmap *newPixmap = new QPixmap (cellSize * rep, cellSize * rep);
  36 +    QPainter painter (newPixmap);
  37 +
  38 +    int parityAsInt = parity ? 1 : 0;
  39 +    for (int y = 0; y < rep; y++)
  40 +    {
  41 +        for (int x = 0; x < rep; x++)
  42 +        {
  43 +            QColor col;
  44 +
  45 +            if ((parityAsInt + x + y) % 2)
  46 +            {
  47 +                if (!isPreview)
  48 +                    col = QColor (213, 213, 213);
  49 +                else
  50 +                    col = QColor (224, 224, 224);
  51 +            }
  52 +            else
  53 +                col = Qt::white;
  54 +
  55 +            painter.fillRect (x * cellSize, y * cellSize,
  56 +                              cellSize, cellSize,
  57 +                              col);
  58 +        }
  59 +    }
  60 +
  61 +    painter.end ();
  62 +    return newPixmap;
  63 +}
  64 +
  65 +void kpMainWindow::drawTransparentBackground (QPainter *painter,
  66 +                                              int /*viewWidth*/, int /*viewHeight*/,
  67 +                                              const QRect &rect,
  68 +                                              bool isPreview)
  69 +{
  70 +#if DEBUG_KP_MAIN_WINDOW && 1 || 1
  71 +    kDebug () << "\tkpMainWindow::drawTransparentBackground(rect="
  72 +               << rect << ")" << endl;
  73 +    QTime totalTimer; totalTimer.start ();
  74 +#endif
  75 +
  76 +    int cellSize = checkerBoardCellSize (isPreview);
  77 +
  78 +
  79 +    int starty = rect.y ();
  80 +    if (starty % cellSize)
  81 +        starty -= (starty % cellSize);
  82 +
  83 +    int startx = rect.x ();
  84 +    if (startx % cellSize)
  85 +        startx -= (startx % cellSize);
  86 +
  87 +
  88 +    int parity = ((startx / cellSize + starty / cellSize) % 2) ? 1 : 0;
  89 +
  90 +    if (!checkerBoardCache [isPreview][parity])
  91 +    {
  92 +        checkerBoardCache [isPreview][parity] = createCheckerBoardCache (isPreview, parity);
  93 +    }
  94 +
  95 +    QPixmap *tilePixmap = checkerBoardCache [isPreview][parity];
  96 +    for (int y = starty; y <= rect.bottom (); y += tilePixmap->height ())
  97 +    {
  98 +        for (int x = startx; x <= rect.right (); x += tilePixmap->width ())
  99 +        {
 100 +            painter->drawPixmap (x - rect.x (), y - rect.y (), *tilePixmap);
 101 +        }
 102 +    }
 103 +
 104 +#if DEBUG_KP_MAIN_WINDOW && 1 || 1
 105 +{
 106 +    const int totalTimerElapsed = totalTimer.elapsed ();
 107 +    kDebug () << "\t\ttotal=" << totalTimerElapsed << endl;
 108 +}
 109 +#endif
 110 +}
 111 +
 112 +
 113 +#else
 114 +
 115  // public
 116  void kpMainWindow::drawTransparentBackground (QPainter *painter,
 117                                                int /*viewWidth*/, int /*viewHeight*/,
 118                                                const QRect &rect,
 119                                                bool isPreview)
 120  {
 121 +#if DEBUG_KP_MAIN_WINDOW && 1
 122 +    kDebug () << "\tkpMainWindow::drawTransparentBackground(rect="
 123 +               << rect << ")" << endl;
 124 +    QTime totalTimer; totalTimer.start ();
 125 +#endif
 126 +
 127 +
 128      const int cellSize = !isPreview ? 16 : 10;
 129
 130      int starty = rect.y ();
 131 @@ -877,8 +982,15 @@
 132          }
 133      }
 134      painter->restore ();
 135 -}
 136
 137 +#if DEBUG_KP_MAIN_WINDOW && 1 || 1
 138 +{
 139 +    const int totalTimerElapsed = totalTimer.elapsed ();
 140 +    kDebug () << "\t\ttotal=" << totalTimerElapsed << endl;
 141 +}
 142 +#endif
 143 +}
 144 +#endif
 145
 146  // private slot
 147  void kpMainWindow::slotUpdateCaption ()