Improved text path drawing

src/style.cpp

@@ -271,7 +271,7 @@ bool Style::Layer::Paint::antialias(Layer::Type type) const
 }
 
 Style::Layer::Layout::Layout(const QJsonObject &json)
-  : _textSize(16), _textMaxWidth(10), _lineCap(Qt::FlatCap),
+  : _textSize(16), _textMaxWidth(10), _textMaxAngle(45), _lineCap(Qt::FlatCap),
   _lineJoin(Qt::MiterJoin), _capitalize(false)
 {
 	if (!(json.contains("text-field") && json["text-field"].isString()))
@@ -291,11 +291,14 @@ Style::Layer::Layout::Layout(const QJsonObject &json)
 		_textSize = FunctionF(json["text-size"].toObject());
 	else if (json.contains("text-size") && json["text-size"].isDouble())
 		_textSize = json["text-size"].toDouble();
-
 	if (json.contains("text-max-width") && json["text-max-width"].isObject())
 		_textMaxWidth = FunctionF(json["text-max-width"].toObject());
-	if (json.contains("text-max-width") && json["text-max-width"].isDouble())
+	else if (json.contains("text-max-width") && json["text-max-width"].isDouble())
 		_textMaxWidth = json["text-max-width"].toDouble();
+	if (json.contains("text-max-angle") && json["text-max-angle"].isObject())
+		_textMaxWidth = FunctionF(json["text-max-angle"].toObject());
+	else if (json.contains("text-max-angle") && json["text-max-angle"].isDouble())
+		_textMaxWidth = json["text-max-angle"].toDouble();
 
 	if (json.contains("text-transform") && json["text-transform"].isString())
 		_capitalize = json["text-transform"].toString() == "uppercase";
@@ -411,7 +414,8 @@ void Style::Layer::drawSymbol(int zoom, const QPainterPath &path,
 		tile.text().addLabel(text.trimmed(), path.elementAt(0), font, pen,
 		  _layout.maxTextWidth(zoom));
 	else
-		tile.text().addLabel(text.trimmed(), path, font, pen);
+		tile.text().addLabel(text.trimmed(), path, font, pen,
+		  _layout.maxTextAngle(zoom));
 }
 
 bool Style::load(const QString &fileName)
@@ -454,12 +458,14 @@ void Style::drawFeature(int layer, const QPainterPath &path,
 
 void Style::drawBackground(Tile &tile)
 {
+	QRectF rect(0, 0, tile.size(), tile.size());
 	QPainterPath path;
-	path.addRect(QRectF(0, 0, tile.size(), tile.size()));
+	path.addRect(rect);
 
 	if (_styles.isEmpty()) {
 		tile.painter().setBrush(Qt::lightGray);
-		tile.painter().drawPath(path);
+		tile.painter().setPen(Qt::NoPen);
+		tile.painter().drawRect(rect);
 	} else if (_styles.first().isBackground())
 		_styles.first().drawPath(_zoom, path, tile);
 }

src/style.h

@@ -76,12 +76,14 @@ private:
 
 		class Layout {
 		public:
-			Layout() : _textSize(16), _textMaxWidth(10), _lineCap(Qt::FlatCap),
+			Layout() : _textSize(16), _textMaxWidth(10), _textMaxAngle(45),
-			  _lineJoin(Qt::MiterJoin), _capitalize(false) {}
+			  _lineCap(Qt::FlatCap), _lineJoin(Qt::MiterJoin),
+			  _capitalize(false) {}
 			Layout(const QJsonObject &json);
 
 			bool capitalize() const {return _capitalize;}
 			qreal maxTextWidth(int zoom) const {return _textMaxWidth.value(zoom);}
+			qreal maxTextAngle(int zoom) const {return _textMaxAngle.value(zoom);}
 			const QString &field() const {return _textField;}
 			const QStringList &keys() const {return _keys;}
 			QFont font(int zoom) const;
@@ -93,6 +95,7 @@ private:
 			QString _textField;
 			FunctionF _textSize;
 			FunctionF _textMaxWidth;
+			FunctionF _textMaxAngle;
 			Qt::PenCapStyle _lineCap;
 			Qt::PenJoinStyle _lineJoin;
 			bool _capitalize;

src/text.cpp

@@ -14,23 +14,30 @@ static QPainterPath subpath(const QPainterPath &path, int start, int end)
 	return p;
 }
 
-static QList<QPainterPath> segments(const QPainterPath &path, qreal segmentLimit,
+static QList<QPainterPath> segments(const QPainterPath &path, qreal pathLimit,
-  qreal pathLimit)
+  qreal maxAngle, qreal charWidth, const QRectF &tileRect)
 {
 	QList<QPainterPath> list;
 	int start = 0;
 	qreal length = 0;
+	qreal angle = -1;
 
 	for (int i = 1; i < path.elementCount(); i++) {
 		QLineF l(path.elementAt(i-1), path.elementAt(i));
+		qreal a = l.angle();
 		qreal sl = l.length();
-		if (sl < segmentLimit || length > pathLimit) {
+		if (angle < 0)
+			angle = a;
+		if (!tileRect.contains(path.elementAt(i))
+		  || sl < charWidth || qAbs(angle - a) > maxAngle
+		  || length > pathLimit) {
 			if (length > pathLimit)
 				list.append(subpath(path, start, i - 1));
 			start = i;
 			length = 0;
 		} else
 			length += sl;
+		angle = a;
 	}
 
 	if (length > pathLimit)
@@ -51,6 +58,8 @@ void Text::addLabel(const QString &text, const QPointF &pos, const QFont &font,
 {
 	if (text.isEmpty())
 		return;
+	if (!sceneRect().contains(pos))
+		return;
 
 	TextItem *ti = new TextItem(text, pos, font, maxTextWidth);
 	addItem(ti);
@@ -67,7 +76,7 @@ void Text::addLabel(const QString &text, const QPointF &pos, const QFont &font,
 }
 
 void Text::addLabel(const QString &text, const QPainterPath &path,
-  const QFont &font, const QPen &pen)
+  const QFont &font, const QPen &pen, qreal maxAngle)
 {
 	if (path.elementCount() < 2 || !path.elementAt(0).isMoveTo())
 		return;
@@ -80,7 +89,8 @@ void Text::addLabel(const QString &text, const QPainterPath &path,
 	if (textWidth > path.length())
 		return;
 
-	QList<QPainterPath> list(segments(path, fm.width('M'), textWidth));
+	QList<QPainterPath> list(segments(path, textWidth, maxAngle,
+	  fm.averageCharWidth(), sceneRect()));
 	for (int i = 0; i < list.size(); i++) {
 		const QPainterPath &segment = list.at(i);
 		TextPathItem *pi = new TextPathItem(text, reverse(segment)

src/text.h

@@ -12,7 +12,7 @@ public:
 	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);
+	  const QFont &font, const QPen &pen, qreal maxAngle);
 };
 
 #endif // TEXT_H