/// Compute curve offsets for a curve in a waterfall plot.
/// @param xDataOffset :: Output value of an x-offset that should be applied to
/// the data's bounding rect to fit to a waterfall plot.
/// @param yDataOffset :: Output value of an y-offset that should be applied to
/// the data's bounding rect to fit to a waterfall plot.
void PlotCurve::computeWaterfallOffsets(double &xDataOffset,
double &yDataOffset) {
Plot *plot = static_cast<Plot *>(this->plot());
Graph *g = static_cast<Graph *>(plot->parent());
// Reset the offsets
// These are offsets of the curve in pixels on the screen.
d_x_offset = 0.0;
d_y_offset = 0.0;
if (g->isWaterfallPlot()) {
int index = g->curveIndex(this);
int curves = g->curves();
auto firstCurve = g->curve(0);
// Get the minimum value of the first curve in this plot
double ymin = firstCurve ? firstCurve->minYValue() : 0.0;
PlotCurve *c = dynamic_cast<PlotCurve *>(g->curve(0));
if (index > 0 && c) {
// Compute offsets based on the maximum value for the curve
double xRange = plot->axisScaleDiv(Plot::xBottom)->range();
double yRange = plot->axisScaleDiv(Plot::yLeft)->range();
// First compute offsets in a linear scale
xDataOffset =
index * g->waterfallXOffset() * 0.01 * xRange / (double)(curves - 1);
yDataOffset =
index * g->waterfallYOffset() * 0.01 * yRange / (double)(curves - 1);
// Corresponding offset on the screen in pixels
d_x_offset = plot->canvas()->width() * xDataOffset / xRange;
d_y_offset = plot->canvas()->height() * yDataOffset / yRange;
// Correct the data offsets using actual axis scales. If the scales are
// non-linear the offsets will change.
{ // x-offset
auto trans = plot->axisScaleEngine(Plot::xBottom)->transformation();
auto a =
trans->xForm(g->curve(0)->maxXValue(),
plot->axisScaleDiv(Plot::xBottom)->lowerBound(),
g->curve(0)->maxXValue(), 0, plot->canvas()->width());
auto b = trans->invXForm(a + d_x_offset, 0, plot->canvas()->width(), 1,
g->curve(0)->maxXValue());
xDataOffset = b - g->curve(0)->maxXValue();
}
{ // y-offset
auto trans = plot->axisScaleEngine(Plot::yLeft)->transformation();
auto a =
trans->xForm(g->curve(0)->maxYValue(),
plot->axisScaleDiv(Plot::yLeft)->lowerBound(),
g->curve(0)->maxYValue(), 0, plot->canvas()->height());
auto b = trans->invXForm(a + d_y_offset, 0, plot->canvas()->height(), 1,
g->curve(0)->maxYValue());
yDataOffset = b - g->curve(0)->maxYValue();
}
// Set the z-order of the curves such that the first curve is on top.
setZ(-index);
// Fill down to minimum value of first curve
setBaseline(ymin - yDataOffset);
} else {
// First curve - no offset.
setZ(0);
setBaseline(ymin); // This is for when 'fill under curve' is turn on
xDataOffset = 0.0;
yDataOffset = 0.0;
}
if (g->grid())
g->grid()->setZ(-g->curves() /*Count()*/ - 1);
}
}
