subsurface/profile-widget/divetextitem.cpp
Berthold Stoeger 15f20961c7 profile: render DiveTextItem onto a pixmap
The DiveTextItems were redrawn on every paint() call. This was
a prohibitively expensive operation (converting the text into
a path, drawing an outline, etc.), which was called numerous
times.

Instead, render the text only when changing into a QPixmap
and blit that pixmap in the paint() call.

This will make it possible to do absolutely positioned
DiveTextItems. So far they were placed relatively in
scene coordinates ranging from 0-100(!).

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
2021-12-17 11:54:23 -08:00

95 lines
2.4 KiB
C++

// SPDX-License-Identifier: GPL-2.0
#include "divetextitem.h"
#include "profilewidget2.h"
#include "core/color.h"
#include "core/errorhelper.h"
#include <QBrush>
#include <QApplication>
static const double outlineSize = 3.0;
DiveTextItem::DiveTextItem(double dpr, double scale, int alignFlags, QGraphicsItem *parent) : QGraphicsPixmapItem(parent),
internalAlignFlags(alignFlags),
dpr(dpr),
scale(scale)
{
setFlag(ItemIgnoresTransformations);
}
void DiveTextItem::set(const QString &t, const QBrush &b)
{
internalText = t;
if (internalText.isEmpty()) {
setPixmap(QPixmap());
return;
}
QFont fnt = getFont(dpr, scale);
QPainterPath textPath;
textPath.addText(0.0, 0.0, fnt, internalText);
QPainterPathStroker stroker;
stroker.setWidth(outlineSize * dpr);
QPainterPath outlinePath = stroker.createStroke(textPath);
QRectF outlineRect = outlinePath.boundingRect();
textPath.translate(-outlineRect.topLeft());
outlinePath.translate(-outlineRect.topLeft());
QPixmap pixmap(outlineRect.size().toSize());
pixmap.fill(Qt::transparent);
{
QPainter painter(&pixmap);
painter.setRenderHints(QPainter::Antialiasing);
painter.setBrush(QBrush(getColor(TEXT_BACKGROUND)));
painter.setPen(Qt::NoPen);
painter.drawPath(outlinePath);
painter.setBrush(b);
painter.setPen(Qt::NoPen);
painter.drawPath(textPath);
}
setPixmap(pixmap);
double yOffset = (internalAlignFlags & Qt::AlignTop) ? 0.0 :
(internalAlignFlags & Qt::AlignBottom) ? -outlineRect.height() :
/*(internalAlignFlags & Qt::AlignVCenter ? */ -outlineRect.height() / 2.0;
double xOffset = (internalAlignFlags & Qt::AlignLeft) ? -outlineRect.width() :
(internalAlignFlags & Qt::AlignHCenter) ? -outlineRect.width() / 2.0 :
/* (internalAlignFlags & Qt::AlignRight) */ 0.0;
setOffset(xOffset, yOffset);
}
const QString &DiveTextItem::text()
{
return internalText;
}
QFont DiveTextItem::getFont(double dpr, double scale)
{
QFont fnt(qApp->font());
double size = fnt.pixelSize();
if (size > 0) {
// set in pixels - so the scale factor may not make a difference if it's too close to 1
size *= scale * dpr;
fnt.setPixelSize(lrint(size));
} else {
size = fnt.pointSizeF();
size *= scale * dpr;
fnt.setPointSizeF(size);
}
return fnt;
}
double DiveTextItem::fontHeight(double dpr, double scale)
{
QFont fnt = getFont(dpr, scale);
QFontMetrics fm(fnt);
return (double)fm.height();
}
double DiveTextItem::height() const
{
return fontHeight(dpr, scale) + outlineSize * dpr;
}