-std::pair<double, unsigned int> Ruler::calculate_tick_spacing(
- QPainter& p, double scale, double offset)
-{
- const double SpacingIncrement = 32.0f;
- const double MinValueSpacing = 32.0f;
-
- double min_width = SpacingIncrement, typical_width;
-
- double tick_period;
- unsigned int prefix;
-
- do {
- const double min_period = scale * min_width;
-
- const int order = (int)floorf(log10f(min_period));
- const double order_decimal = pow(10.0, order);
-
- unsigned int unit = 0;
-
- do {
- tick_period = order_decimal * ScaleUnits[unit++];
- } while (tick_period < min_period && unit < countof(ScaleUnits));
-
- prefix = (order - pv::util::FirstSIPrefixPower) / 3;
-
- typical_width = p.boundingRect(0, 0, INT_MAX, INT_MAX,
- AlignLeft | AlignTop, pv::util::format_time(offset,
- prefix)).width() + MinValueSpacing;
-
- min_width += SpacingIncrement;
-
- } while(typical_width > tick_period / scale);
-
- return std::make_pair(tick_period, prefix);
-}
-