- const double MinSpacing = 80;
-
- const double min_period = _view.scale() * MinSpacing;
-
- const int order = (int)floorf(log10f(min_period));
- const double order_decimal = pow(10, order);
-
- int unit = 0;
- double tick_period = 0.0f;
-
- do
- {
- tick_period = order_decimal * ScaleUnits[unit++];
- } while(tick_period < min_period && unit < countof(ScaleUnits));
-
- const int prefix = (order - FirstSIPrefixPower) / 3;
- assert(prefix >= 0);
- assert(prefix < countof(SIPrefixes));
-
- const int text_height = p.boundingRect(0, 0, INT_MAX, INT_MAX,
- Qt::AlignLeft | Qt::AlignTop, "8").height();
-
- // Draw the tick marks
- p.setPen(Qt::black);
-
- const double minor_tick_period = tick_period / MinorTickSubdivision;
- const double first_major_division =
- floor(_view.offset() / tick_period);
- const double first_minor_division =
- ceil(_view.offset() / minor_tick_period);
- const double t0 = first_major_division * tick_period;
-
- int division = (int)round(first_minor_division -
- first_major_division * MinorTickSubdivision);
- while(1)
- {
- const double t = t0 + division * minor_tick_period;
- const double x = (t - _view.offset()) / _view.scale();
-
- if(x >= width())
- break;
-
- if(division % MinorTickSubdivision == 0)
- {
- // Draw a major tick
- QString s;
- QTextStream ts(&s);
- ts << (t / order_decimal) << SIPrefixes[prefix] << "s";
- p.drawText(x, 0, 0, text_height, Qt::AlignCenter | Qt::AlignTop |
- Qt::TextDontClip, s);
- p.drawLine(x, text_height, x, View::RulerHeight);
- }
- else
- {
- // Draw a minor tick
- p.drawLine(x,
- (text_height + View::RulerHeight) / 2, x,
- View::RulerHeight);
- }