Use fuzzy text bounding rect computation to improve performance

Do not use QGraphicsScene as it is not thread-safe

pbfplugin.pro

@@ -1,7 +1,7 @@
 TARGET  = pbf
 TEMPLATE = lib
 CONFIG += plugin
-QT += gui widgets
+QT += gui
 
 PROTOS = protobuf/vector_tile.proto
 include(protobuf/vector_tile.pri)
@@ -17,8 +17,9 @@ HEADERS += src/pbfhandler.h \
     src/tile.h \
     src/function.h \
     src/textpathitem.h \
-    src/textitem.h \
-    src/font.h
+    src/textpointitem.h \
+    src/font.h \
+    src/textitem.h
 SOURCES += src/pbfplugin.cpp \
     src/pbfhandler.cpp \
     src/gzip.cpp \
@@ -28,7 +29,7 @@ SOURCES += src/pbfplugin.cpp \
     src/text.cpp \
     src/function.cpp \
     src/textpathitem.cpp \
-    src/textitem.cpp \
+    src/textpointitem.cpp \
     src/font.cpp
 RESOURCES += pbfplugin.qrc
 

src/text.cpp

@@ -1,8 +1,7 @@
-#include <QGraphicsPixmapItem>
 #include <QFontMetrics>
 #include <QPainter>
 #include "text.h"
-#include "textitem.h"
+#include "textpointitem.h"
 #include "textpathitem.h"
 
 
@@ -134,16 +133,32 @@ static bool reverse(const QPainterPath &path)
 	return (angle > 90 && angle < 270) ? true : false;
 }
 
+
+Text::~Text()
+{
+	for (int i = 0; i < _items.size(); i++)
+		delete _items[i];
+}
+
+void Text::render(QPainter *painter)
+{
+	for (int i = 0; i < _items.size(); i++) {
+		const TextItem *ti = _items.at(i);
+		if (ti->isVisible() && _sceneRect.intersects(ti->boundingRect()))
+			ti->paint(painter);
+	}
+}
+
 void Text::addLabel(const QString &text, const QPointF &pos, const QFont &font,
   const QPen &pen, qreal maxTextWidth)
 {
 	if (text.isEmpty())
 		return;
 
-	TextItem *ti = new TextItem(text, pos, font, maxTextWidth);
+	TextPointItem *ti = new TextPointItem(text, pos, font, maxTextWidth);
 	ti->setPen(pen);
 	addItem(ti);
-	QList<QGraphicsItem*> ci = collidingItems(ti);
+	QList<TextItem*> ci = collidingItems(ti);
 	for (int i = 0; i < ci.size(); i++)
 		ci[i]->setVisible(false);
 }
@@ -163,21 +178,37 @@ void Text::addLabel(const QString &text, const QPainterPath &path,
 		return;
 
 	QPainterPath tp(textPath(path, textWidth, maxAngle, fm.averageCharWidth(),
-	  sceneRect()));
+	  _sceneRect));
 	if (tp.isEmpty())
 		return;
 
 	TextPathItem *pi = new TextPathItem(text, reverse(tp) ? tp.toReversed()
 	  : tp, font);
-	addItem(pi);
-	if (!sceneRect().contains(pi->sceneBoundingRect())) {
+	if (!_sceneRect.contains(pi->boundingRect())) {
 		delete pi;
 		return;
 	}
-
 	pi->setPen(pen);
 
-	QList<QGraphicsItem*> ci = collidingItems(pi);
+	addItem(pi);
+
+	QList<TextItem*> ci = collidingItems(pi);
 	for (int j = 0; j < ci.size(); j++)
 		ci[j]->setVisible(false);
 }
+
+QList<TextItem*> Text::collidingItems(const TextItem *item) const
+{
+	QList<TextItem*> list;
+
+	if (!item->isVisible())
+		return list;
+
+	for (int i = 0; i < _items.size();i ++) {
+		const TextItem *ti = _items.at(i);
+		if (ti != item && ti->isVisible() && ti->collidesWithItem(item))
+			list.append(const_cast<TextItem*>(ti));
+	}
+
+	return list;
+}

src/text.h

@@ -1,18 +1,27 @@
 #ifndef TEXT_H
 #define TEXT_H
 
-#include <QGraphicsScene>
+#include "textitem.h"
 
-class Text : public QGraphicsScene
+class Text
 {
 public:
-	Text(int size, QObject *parent = 0) : QGraphicsScene(parent)
-	  {setSceneRect(0, 0, size, size);}
+	Text(int size) : _sceneRect(QRectF(0, 0, size, size)) {}
+	~Text();
+
+	void render(QPainter *painter);
 
 	void addLabel(const QString &text, const QPointF &pos, const QFont &font,
 	  const QPen &pen, qreal maxTextWidth);
 	void addLabel(const QString &text, const QPainterPath &path,
 	  const QFont &font, const QPen &pen, qreal maxAngle);
+
+private:
+	void addItem(TextItem *item) {_items.append(item);}
+	QList<TextItem *> collidingItems(const TextItem *item) const;
+
+	QRectF _sceneRect;
+	QList<TextItem *> _items;
 };
 
 #endif // TEXT_H

src/textitem.cpp

@@ -1,39 +0,0 @@
-#include  <QPainter>
-#include "textitem.h"
-
-
-#define FLAGS (Qt::AlignCenter | Qt::TextWordWrap | Qt::TextDontClip)
-
-TextItem::TextItem(const QString &text, const QPointF &pos, const QFont &font,
-  int maxTextWidth, QGraphicsItem *parent) : QGraphicsItem(parent), _text(text),
-  _font(font)
-{
-	QFontMetrics fm(font);
-	int limit = font.pixelSize() * maxTextWidth;
-	// Italic fonts overflow the computed bounding rect, so reduce it
-	// a little bit.
-	if (font.italic())
-		limit -= font.pixelSize() / 2.0;
-
-	QRect br = fm.boundingRect(QRect(0, 0, limit, 0), FLAGS, text);
-	Q_ASSERT(br.isValid());
-	// Expand the bounding rect back to the real content size
-	if (font.italic())
-		br.adjust(-font.pixelSize() / 4.0, 0, font.pixelSize() / 4.0, 0);
-	setPos((pos - QPointF(br.width() / 2.0, br.height() / 2.0)).toPoint());
-	_boundingRect = QRectF(0, 0, br.width(), br.height());
-}
-
-void TextItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
-  QWidget *widget)
-{
-	Q_UNUSED(option);
-	Q_UNUSED(widget);
-
-	painter->setFont(_font);
-	painter->setPen(_pen);
-	painter->drawText(_boundingRect, FLAGS, _text);
-
-	//painter->setPen(Qt::red);
-	//painter->drawRect(_boundingRect);
-}

src/textitem.h

@@ -1,28 +1,36 @@
 #ifndef TEXTITEM_H
 #define TEXTITEM_H
 
-#include <QGraphicsItem>
-#include <QPen>
-#include <QFont>
-#include <QString>
+#include <QPainterPath>
 
-class TextItem : public QGraphicsItem
+#include <QDebug>
+
+class TextItem
 {
 public:
-	TextItem(const QString &text, const QPointF &pos, const QFont &font,
-	  int maxTextWidth, QGraphicsItem *parent = 0);
+	TextItem() : _visible(true) {}
+	virtual ~TextItem() {}
 
-	QRectF boundingRect() const {return _boundingRect;}
-	void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
-	  QWidget *widget);
+	virtual QPainterPath shape() const = 0;
+	virtual QRectF boundingRect() const = 0;
+	virtual void paint(QPainter *painter) const = 0;
 
-	void setPen(const QPen &pen) {_pen = pen;}
+	bool isVisible() const {return _visible;}
+	void setVisible(bool visible) {_visible = visible;}
+
+	bool collidesWithItem(const TextItem *other) const
+	{
+		QRectF r1(boundingRect());
+		QRectF r2(other->boundingRect());
+
+		if (r1.isEmpty() || r2.isEmpty() || !r1.intersects(r2))
+			return false;
+
+		return other->shape().intersects(shape());
+	}
 
 private:
-	QString _text;
-	QRectF _boundingRect;
-	QFont _font;
-	QPen _pen;
+	bool _visible;
 };
 
 #endif // TEXTITEM_H

src/textpathitem.cpp

@@ -4,22 +4,18 @@
 
 
 TextPathItem::TextPathItem(const QString &text, const QPainterPath &path,
-  const QFont &font, QGraphicsItem *parent) : QGraphicsItem(parent),
-  _text(text), _path(path), _font(font)
+  const QFont &font) : _text(text), _path(path), _font(font)
 {
 	QFontMetrics fm(font);
 	QPainterPathStroker s;
 	s.setWidth(fm.height());
 	s.setCapStyle(Qt::FlatCap);
 	_shape = s.createStroke(path).simplified();
+	_boundingRect = _shape.boundingRect();
 }
 
-void TextPathItem::paint(QPainter *painter,
-  const QStyleOptionGraphicsItem *option, QWidget *widget)
+void TextPathItem::paint(QPainter *painter) const
 {
-	Q_UNUSED(option);
-	Q_UNUSED(widget);
-
 	QFontMetrics fm(_font);
 	int textWidth = fm.width(_text);
 

src/textpathitem.h

@@ -1,21 +1,19 @@
 #ifndef TEXTPATHITEM_H
 #define TEXTPATHITEM_H
 
-#include <QGraphicsItem>
-#include <QPainterPath>
 #include <QFont>
 #include <QString>
+#include "textitem.h"
 
-class TextPathItem : public QGraphicsItem
+class TextPathItem : public TextItem
 {
 public:
 	TextPathItem(const QString &text, const QPainterPath &path,
-	  const QFont &font, QGraphicsItem *parent = 0);
+	  const QFont &font);
 
 	QPainterPath shape() const {return _shape;}
-	QRectF boundingRect() const {return _shape.boundingRect();}
-	void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
-	  QWidget *widget);
+	QRectF boundingRect() const {return _boundingRect;}
+	void paint(QPainter *painter) const;
 
 	void setPen(const QPen &pen) {_pen = pen;}
 
@@ -23,6 +21,7 @@ private:
 	QString _text;
 	QPainterPath _path;
 	QPainterPath _shape;
+	QRectF _boundingRect;
 	QFont _font;
 	QPen _pen;
 };

src/textpointitem.cpp

@@ -0,0 +1,88 @@
+#include <QPainter>
+#include <QtMath>
+#include "textpointitem.h"
+
+
+#define FLAGS (Qt::AlignCenter | Qt::TextWordWrap | Qt::TextDontClip)
+
+static QRectF fuzzyBoundingRect(const QString &str, const QFont &font,
+  int maxTextWidth)
+{
+	int limit = font.pixelSize() * maxTextWidth;
+	qreal cw = font.pixelSize() * 0.6;
+	qreal lh = font.pixelSize() * 1.25;
+	int width = 0, lines = 0;
+
+	QStringList l(str.split('\n'));
+	for (int i = 0; i < l.size(); i++) {
+		int lw = (int)(l.at(i).length() * cw);
+		if (lw > limit) {
+			l[i].replace('-', ' ');
+			l[i].replace('/', ' ');
+			QStringList words(l.at(i).split(' '));
+			int pl = 0;
+			for (int j = 0; j < words.size(); j++) {
+				int wl = (int)(words.at(j).length() * cw);
+				if (wl + pl < limit) {
+					pl += wl + cw;
+				} else {
+					if (wl > limit) {
+						if (pl > 0)
+							lines++;
+					} else
+						lines++;
+					width = qMax(width, qMax(pl, wl));
+					pl = wl;
+				}
+			}
+			width = qMax(width, pl);
+			lines++;
+		} else {
+			width = qMax(width, lw);
+			lines++;
+		}
+	}
+
+	return QRectF(0, 0, width, lines * lh);
+}
+
+/*
+static QRectF exactBoundingRect(const QString &str, const QFont &font,
+  int maxTextWidth)
+{
+	QFontMetrics fm(font);
+	int limit = font.pixelSize() * maxTextWidth;
+	// Italic fonts overflow the computed bounding rect, so reduce it
+	// a little bit.
+	if (font.italic())
+		limit -= font.pixelSize() / 2.0;
+
+	QRect br = fm.boundingRect(QRect(0, 0, limit, 0), FLAGS, str);
+	Q_ASSERT(br.isValid());
+	// Expand the bounding rect back to the real content size
+	if (font.italic())
+		br.adjust(-font.pixelSize() / 4.0, 0, font.pixelSize() / 4.0, 0);
+
+	return br;
+}
+*/
+
+TextPointItem::TextPointItem(const QString &text, const QPointF &pos,
+  const QFont &font, int maxTextWidth) :_text(text), _font(font)
+{
+	_boundingRect = fuzzyBoundingRect(text, font, maxTextWidth);
+	//_boundingRect = exactBoundingRect(text, font, maxTextWidth);
+
+	_boundingRect.moveCenter(pos);
+	_shape.addRect(_boundingRect);
+}
+
+void TextPointItem::paint(QPainter *painter) const
+{
+	painter->setFont(_font);
+	painter->setPen(_pen);
+	painter->drawText(_boundingRect, FLAGS, _text);
+
+	//painter->setPen(Qt::red);
+	//painter->drawRect(_boundingRect);
+}

src/textpointitem.h

@@ -0,0 +1,29 @@
+#ifndef TEXTPOINTITEM_H
+#define TEXTPOINTITEM_H
+
+#include <QPen>
+#include <QFont>
+#include <QString>
+#include "textitem.h"
+
+class TextPointItem : public TextItem
+{
+public:
+	TextPointItem(const QString &text, const QPointF &pos, const QFont &font,
+	  int maxTextWidth);
+
+	QRectF boundingRect() const {return _boundingRect;}
+	QPainterPath shape() const {return _shape;}
+	void paint(QPainter *painter) const;
+
+	void setPen(const QPen &pen) {_pen = pen;}
+
+private:
+	QString _text;
+	QPainterPath _shape;
+	QRectF _boundingRect;
+	QFont _font;
+	QPen _pen;
+};
+
+#endif // TEXTPOINTITEM_H