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// SPDX-License-Identifier: GPL-2.0
#include "legend.h"
#include "statscolors.h"
#include "zvalues.h"
#include <cmath>
#include <QFontMetrics>
#include <QPen>
static const double legendBorderSize = 2.0;
static const double legendBoxBorderSize = 1.0;
static const double legendBoxBorderRadius = 4.0; // radius of rounded corners
static const double legendBoxScale = 0.8; // 1.0: text-height of the used font
static const double legendInternalBorderSize = 2.0;
static const QColor legendColor(0x00, 0x8e, 0xcc, 192); // Note: fourth argument is opacity
static const QColor legendBorderColor(Qt::black);
Legend::Legend(StatsView &view, const std::vector<QString> &names) :
ChartRectItem(view, ChartZValue::Legend,
QPen(legendBorderColor, legendBorderSize), QBrush(legendColor), legendBoxBorderRadius),
displayedItems(0), width(0.0), height(0.0),
font(QFont()), // Make configurable
posInitialized(false)
{
entries.reserve(names.size());
QFontMetrics fm(font);
fontHeight = fm.height();
int idx = 0;
for (const QString &name: names)
entries.emplace_back(name, idx++, (int)names.size(), fm);
}
Legend::Entry::Entry(const QString &name, int idx, int numBins, const QFontMetrics &fm) :
name(name),
rectBrush(QBrush(binColor(idx, numBins)))
{
width = fm.height() + 2.0 * legendBoxBorderSize + fm.size(Qt::TextSingleLine, name).width();
}
void Legend::hide()
{
ChartRectItem::resize(QSizeF(1,1));
img->fill(Qt::transparent);
}
void Legend::resize()
{
if (entries.empty())
return hide();
QSizeF size = sceneSize();
// Silly heuristics: make the legend at most half as high and half as wide as the chart.
// Not sure if that makes sense - this might need some optimization.
int maxRows = static_cast<int>(size.height() / 2.0 - 2.0 * legendInternalBorderSize) / fontHeight;
if (maxRows <= 0)
return hide();
int numColumns = ((int)entries.size() - 1) / maxRows + 1;
int numRows = ((int)entries.size() - 1) / numColumns + 1;
double x = legendInternalBorderSize;
displayedItems = 0;
for (int col = 0; col < numColumns; ++col) {
double y = legendInternalBorderSize;
double nextX = x;
for (int row = 0; row < numRows; ++row) {
int idx = col * numRows + row;
if (idx >= (int)entries.size())
break;
entries[idx].pos = QPointF(x, y);
nextX = std::max(nextX, x + entries[idx].width);
y += fontHeight;
++displayedItems;
}
x = nextX;
width = nextX;
if (width >= size.width() / 2.0) // More than half the chart-width -> give up
break;
}
width += legendInternalBorderSize;
height = 2 * legendInternalBorderSize + numRows * fontHeight;
ChartRectItem::resize(QSizeF(width, height));
// Paint rectangles
painter->setPen(QPen(legendBorderColor, legendBoxBorderSize));
for (int i = 0; i < displayedItems; ++i) {
QPointF itemPos = entries[i].pos;
painter->setBrush(entries[i].rectBrush);
QRectF rect(itemPos, QSizeF(fontHeight, fontHeight));
// Decrease box size by legendBoxScale factor
double delta = fontHeight * (1.0 - legendBoxScale) / 2.0;
rect = rect.adjusted(delta, delta, -delta, -delta);
painter->drawRect(rect);
}
// Paint labels
painter->setPen(darkLabelColor); // QPainter uses pen not brush for text!
painter->setFont(font);
for (int i = 0; i < displayedItems; ++i) {
QPointF itemPos = entries[i].pos;
itemPos.rx() += fontHeight + 2.0 * legendBoxBorderSize;
QRectF rect(itemPos, QSizeF(entries[i].width, fontHeight));
painter->drawText(rect, entries[i].name);
}
if (!posInitialized) {
// At first, place in top right corner
setPos(QPointF(size.width() - width - 10.0, 10.0));
posInitialized = true;
} else {
// Try to keep relative position with what it was before
setPos(QPointF(size.width() * centerPos.x() - width / 2.0,
size.height() * centerPos.y() - height / 2.0));
}
}
void Legend::setPos(QPointF newPos)
{
// Round the position to integers or horrible artifacts appear (at least on desktop)
QPointF posInt(round(newPos.x()), round(newPos.y()));
// Make sure that the center is inside the drawing area,
// so that the user can't lose the legend.
QSizeF size = sceneSize();
if (size.width() < 1.0 || size.height() < 1.0)
return;
double widthHalf = floor(width / 2.0);
double heightHalf = floor(height / 2.0);
QPointF sanitizedPos(std::clamp(posInt.x(), -widthHalf, size.width() - widthHalf - 1.0),
std::clamp(posInt.y(), -heightHalf, size.height() - heightHalf - 1.0));
// Set position
ChartRectItem::setPos(sanitizedPos);
// Remember relative position of center for next time
QPointF centerPosAbsolute(sanitizedPos.x() + width / 2.0,
sanitizedPos.y() + height / 2.0);
centerPos = QPointF(centerPosAbsolute.x() / size.width(),
centerPosAbsolute.y() / size.height());
}
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