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profile: render DiveTextItem onto a pixmap

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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>
This commit is contained in:
Berthold Stoeger 2021-08-22 19:48:49 +02:00 • committed by Dirk Hohndel
parent 04e0d96bae
commit 15f20961c7
2 changed files with 48 additions and 49 deletions
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86
profile-widget/divetextitem.cpp
View file

@ -5,33 +5,60 @@
#include "core/errorhelper.h"
#include <QBrush>
#include <QDebug>
#include <QApplication>
DiveTextItem::DiveTextItem(double dpr, double scale, int alignFlags, QGraphicsItem *parent) : QGraphicsItemGroup(parent),
static const double outlineSize = 3.0;
DiveTextItem::DiveTextItem(double dpr, double scale, int alignFlags, QGraphicsItem *parent) : QGraphicsPixmapItem(parent),
internalAlignFlags(alignFlags),
textBackgroundItem(new QGraphicsPathItem(this)),
textItem(new QGraphicsPathItem(this)),
dpr(dpr),
scale(scale)
{
setFlag(ItemIgnoresTransformations);
textBackgroundItem->setBrush(QBrush(getColor(TEXT_BACKGROUND)));
textBackgroundItem->setPen(Qt::NoPen);
textItem->setPen(Qt::NoPen);
}
void DiveTextItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
updateText();
QGraphicsItemGroup::paint(painter, option, widget);
}
void DiveTextItem::set(const QString &t, const QBrush &b)
{
textItem->setBrush(b);
internalText = t;
updateText();
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()
@ -64,32 +91,5 @@ double DiveTextItem::fontHeight(double dpr, double scale)
double DiveTextItem::height() const
{
return fontHeight(dpr, scale);
}
void DiveTextItem::updateText()
{
if (internalText.isEmpty())
return;
QFont fnt = getFont(dpr, scale);
QFontMetrics fm(fnt);
QPainterPath textPath;
qreal xPos = 0, yPos = 0;
QRectF rect = fm.boundingRect(internalText);
yPos = (internalAlignFlags & Qt::AlignTop) ? 0 :
(internalAlignFlags & Qt::AlignBottom) ? +rect.height() :
/*(internalAlignFlags & Qt::AlignVCenter ? */ +rect.height() / 4;
xPos = (internalAlignFlags & Qt::AlignLeft) ? -rect.width() :
(internalAlignFlags & Qt::AlignHCenter) ? -rect.width() / 2 :
/* (internalAlignFlags & Qt::AlignRight) */ 0;
textPath.addText(xPos, yPos, fnt, internalText);
QPainterPathStroker stroker;
stroker.setWidth(3);
textBackgroundItem->setPath(stroker.createStroke(textPath));
textItem->setPath(textPath);
return fontHeight(dpr, scale) + outlineSize * dpr;
}

11
profile-widget/divetextitem.h
View file

@ -4,29 +4,28 @@
#include <QObject>
#include <QFont>
#include <QGraphicsItemGroup>
#include <QGraphicsPixmapItem>
class QBrush;
/* A Line Item that has animated-properties. */
class DiveTextItem : public QObject, public QGraphicsItemGroup {
class DiveTextItem : public QObject, public QGraphicsPixmapItem {
Q_OBJECT
Q_PROPERTY(QPointF pos READ pos WRITE setPos)
Q_PROPERTY(qreal opacity READ opacity WRITE setOpacity)
public:
// Note: vertical centring is based on the actual rendered text, not on the font metrics.
// This is fine for placing text in the "tankbar", but it will look disastrous when
// placing text items next to each other. This may have to be fixed.
DiveTextItem(double dpr, double scale, int alignFlags, QGraphicsItem *parent);
void set(const QString &text, const QBrush &brush);
const QString &text();
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
static QFont getFont(double dpr, double scale);
static double fontHeight(double dpr, double scale);
double height() const;
private:
void updateText();
int internalAlignFlags;
QGraphicsPathItem *textBackgroundItem;
QGraphicsPathItem *textItem;
QString internalText;
double dpr;
double scale;