profile: reimplement DivePercentageItem

The tissue percentages were realized as 16 independent polygons.
That didn't work at all with the new absolute scaling.

Reimplement the item and blast it onto a pixmap. Not only is
this artifact-free, it also should (hopefully) be quite a bit
more efficient than painting numerous lines.

In contrast to the old code, this does access the plot_info
structure directly instead of using the model. Not so much
for performance reason, but rather to make things more robust:
We have a strongly typed language. Why would we shoehorn data
through the weakly typed QVariant and mess with wierd
index-arithmetics. Makes no sense to me. Qt-model have to
be used for interfacing with Qt. They are terrible for
intra-application data transfer.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

Subsurface-mobile.pro

@@ -168,6 +168,7 @@ SOURCES += subsurface-mobile-main.cpp \
 	profile-widget/qmlprofile.cpp \
 	profile-widget/divecartesianaxis.cpp \
 	profile-widget/diveeventitem.cpp \
+	profile-widget/divepercentageitem.cpp \
 	profile-widget/diveprofileitem.cpp \
 	profile-widget/profilescene.cpp \
 	profile-widget/animationfunctions.cpp \
@@ -321,6 +322,7 @@ HEADERS += \
 	qt-models/filterconstraintmodel.h \
 	qt-models/filterpresetmodel.h \
 	profile-widget/qmlprofile.h \
+	profile-widget/divepercentageitem.h \
 	profile-widget/diveprofileitem.h \
 	profile-widget/profilescene.h \
 	profile-widget/diveeventitem.h \

profile-widget/CMakeLists.txt

@@ -10,6 +10,8 @@ set(SUBSURFACE_PROFILE_LIB_SRCS
 	divelineitem.h
 	divepixmapitem.cpp
 	divepixmapitem.h
+	divepercentageitem.cpp
+	divepercentageitem.h
 	diveprofileitem.cpp
 	diveprofileitem.h
 	diverectitem.cpp

profile-widget/divecartesianaxis.cpp

@@ -359,6 +359,12 @@ double DiveCartesianAxis::minimum() const
 	return min;
 }
 
+std::pair<double, double> DiveCartesianAxis::screenMinMax() const
+{
+	return position == Position::Bottom ? std::make_pair(rect.left(), rect.right())
+					    : std::make_pair(rect.top(), rect.bottom());
+}
+
 void DiveCartesianAxis::setColor(const QColor &color)
 {
 	QPen defaultPen = gridPen();

profile-widget/divecartesianaxis.h

@@ -41,6 +41,7 @@ public:
 	void setFontLabelScale(qreal scale);
 	double minimum() const;
 	double maximum() const;
+	std::pair<double, double> screenMinMax() const;
 	qreal valueAt(const QPointF &p) const;
 	qreal posAtValue(qreal value) const;
 	void setColor(const QColor &color);
@@ -48,7 +49,7 @@ public:
 	void animateChangeLine(const QRectF &rect, int animSpeed);
 	void setTextVisible(bool arg1);
 	void setLinesVisible(bool arg1);
-	void setLine(const QLineF& line);
+	void setLine(const QLineF &line);
 	virtual void updateTicks(int animSpeed);
 	double width() const; // only for vertical axes
 	double height() const; // only for horizontal axes

profile-widget/divepercentageitem.cpp

@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "divepercentageitem.h"
+#include "divecartesianaxis.h"
+#include "core/dive.h"
+#include "core/profile.h"
+
+#include <array>
+
+DivePercentageItem::DivePercentageItem(const DiveCartesianAxis &hAxis, const DiveCartesianAxis &vAxis, double dpr) :
+	hAxis(hAxis), vAxis(vAxis), dpr(dpr)
+{
+}
+
+static constexpr int num_tissues = 16;
+
+// Calculate the number of scanlines for every drawn tissue.
+static std::array<int, num_tissues> calcLinesPerTissue(int size)
+{
+	std::array<int, num_tissues> res;
+
+	// A Bresenham-inspired algorithm without the weird half steps at the beginning and the end.
+	if (size <= 0) {
+		std::fill(res.begin(), res.end(), 0);
+	} else if (size >= num_tissues) {
+		int step = size / num_tissues;
+		int err_inc = size % num_tissues;
+		int err = 0;
+		for (int i = 0; i < num_tissues; ++i) {
+			res[i] = step;
+			err += err_inc;
+			if (err >= num_tissues) {
+				err -= num_tissues;
+				++res[i];
+			}
+		}
+	} else { // size < num_tissues
+		int step = num_tissues / size;
+		int err_inc = num_tissues % size;
+		int err = 0;
+		int act = 0;
+		std::fill(res.begin(), res.end(), 0);
+		for (int i = 0; i < size; ++i) {
+			res[act] = 1;
+			act += step;
+			err += err_inc;
+			if (err >= size) {
+				err -= size;
+				++act;
+			}
+		}
+	}
+	return res;
+}
+
+static QRgb colorScale(double value, int inert)
+{
+	QColor color;
+	double scaledValue = value / (AMB_PERCENTAGE * inert) * 1000.0;
+	if (scaledValue < 0.8)	// grade from cyan to blue to purple
+		color.setHsvF(0.5 + 0.25 * scaledValue / 0.8, 1.0, 1.0);
+	else if (scaledValue < 1.0)	// grade from magenta to black
+		color.setHsvF(0.75, 1.0, (1.0 - scaledValue) / 0.2);
+	else if (value < AMB_PERCENTAGE)	// grade from black to bright green
+		color.setHsvF(0.333, 1.0, (value - AMB_PERCENTAGE * inert / 1000.0) / (AMB_PERCENTAGE - AMB_PERCENTAGE * inert / 1000.0));
+	else if (value < 65)		// grade from bright green (0% M) to yellow-green (30% M)
+		color.setHsvF(0.333 - 0.133 * (value - AMB_PERCENTAGE) / (65.0 - AMB_PERCENTAGE), 1.0, 1.0);
+	else if (value < 85)		// grade from yellow-green (30% M) to orange (70% M)
+		color.setHsvF(0.2 - 0.1 * (value - 65.0) / 20.0, 1.0, 1.0);
+	else if (value < 100)		// grade from orange (70% M) to red (100% M)
+		color.setHsvF(0.1 * (100.0 - value) / 15.0, 1.0, 1.0);
+	else if (value < 120)		// M value exceeded - grade from red to white
+		color.setHsvF(0.0, 1 - (value - 100.0) / 20.0, 1.0);
+	else	// white
+		color.setHsvF(0.0, 0.0, 1.0);
+	return color.rgba();
+}
+
+void DivePercentageItem::replot(const dive *d, const struct divecomputer *dc, const plot_info &pi)
+{
+	auto [minX, maxX] = hAxis.screenMinMax();
+	auto [minY, maxY] = vAxis.screenMinMax();
+	int width = lrint(maxX) - lrint(minX);
+	int height = lrint(maxY) - lrint(minY);
+	if (width <= 0 || height <= 0) {
+		setPixmap(QPixmap());
+		return;
+	}
+
+	std::array<int, num_tissues> linesPerTissue = calcLinesPerTissue(height);
+
+	QImage img(width, height, QImage::QImage::Format_ARGB32);
+
+	int line = 0;
+	for (int tissue = 0; tissue < num_tissues; ++tissue) {
+		if (linesPerTissue[tissue] <= 0)
+			continue;
+		int x = 0;
+		QRgb *scanline = (QRgb *)img.scanLine(line);
+		QRgb color = 0;
+		const struct event *ev = NULL;
+		for (int i = 0; i < pi.nr; i++) {
+			const plot_data &item = pi.entry[i];
+			int sec = item.sec;
+			int nextX = lrint(hAxis.posAtValue(sec)) - lrint(minX);
+			if (nextX == x)
+				continue;
+
+			double value = item.percentages[tissue];
+			struct gasmix gasmix = get_gasmix(d, dc, sec, &ev, gasmix);
+			int inert = get_n2(gasmix) + get_he(gasmix);
+			color = colorScale(value, inert);
+			if (nextX >= width)
+				nextX = width - 1;
+			for (; x <= nextX; ++x)
+				scanline[x] = color;
+			if (nextX >= width - 1)
+				break;
+		}
+		for (; x < width; ++x)
+			scanline[x] = color;
+		++line;
+
+		// Clone line if needed
+		for (int i = 0; i < linesPerTissue[tissue] - 1; ++i) {
+			QRgb *scanline2 = (QRgb *)img.scanLine(line);
+			std::copy(scanline, scanline + width, scanline2);
+			++line;
+		}
+	}
+	setPixmap(QPixmap::fromImage(img));
+	setPos(minX, minY);
+}

profile-widget/divepercentageitem.h

@@ -0,0 +1,23 @@
+#ifndef DIVEPERCENTAGEITEM_H
+#define DIVEPERCENTAGEITEM_H
+
+#include <QGraphicsPixmapItem>
+
+struct dive;
+struct divecomputer;
+struct plot_info;
+class DivePlotDataModel;
+class DiveCartesianAxis;
+
+class DivePercentageItem : public QGraphicsPixmapItem {
+public:
+	DivePercentageItem(const DiveCartesianAxis &hAxis, const DiveCartesianAxis &vAxis, double dpr);
+	void replot(const dive *d, const divecomputer *dc, const plot_info &pi);
+private:
+	const DiveCartesianAxis &hAxis;
+	const DiveCartesianAxis &vAxis;
+	int hDataColumn;
+	double dpr;
+};
+
+#endif

profile-widget/diveprofileitem.cpp

@@ -233,74 +233,6 @@ void DiveHeartrateItem::paint(QPainter *painter, const QStyleOptionGraphicsItem*
 	painter->restore();
 }
 
-DivePercentageItem::DivePercentageItem(const DivePlotDataModel &model, const DiveCartesianAxis &hAxis, int hColumn,
-				       const DiveCartesianAxis &vAxis, int vColumn, int i, double dpr) :
-	AbstractProfilePolygonItem(model, hAxis, hColumn, vAxis, vColumn, dpr),
-	tissueIndex(i)
-{
-}
-
-void DivePercentageItem::replot(const dive *d, bool)
-{
-	// Ignore empty values. a heart rate of 0 would be a bad sign.
-	QPolygonF poly;
-	colors.clear();
-	for (int i = 0, modelDataCount = dataModel.rowCount(); i < modelDataCount; i++) {
-		int sec = dataModel.index(i, hDataColumn).data().toInt();
-		QPointF point(hAxis.posAtValue(sec), vAxis.posAtValue(64 - 4 * tissueIndex));
-		poly.append(point);
-
-		double value = dataModel.index(i, vDataColumn).data().toDouble();
-		struct gasmix gasmix = gasmix_air;
-		const struct event *ev = NULL;
-		gasmix = get_gasmix(d, get_dive_dc_const(d, dc_number), sec, &ev, gasmix);
-		int inert = get_n2(gasmix) + get_he(gasmix);
-		colors.push_back(ColorScale(value, inert));
-	}
-	setPolygon(poly);
-}
-
-QColor DivePercentageItem::ColorScale(double value, int inert)
-{
-	QColor color;
-	double scaledValue = value / (AMB_PERCENTAGE * inert) * 1000.0;
-	if (scaledValue < 0.8)	// grade from cyan to blue to purple
-		color.setHsvF(0.5 + 0.25 * scaledValue / 0.8, 1.0, 1.0);
-	else if (scaledValue < 1.0)	// grade from magenta to black
-		color.setHsvF(0.75, 1.0, (1.0 - scaledValue) / 0.2);
-	else if (value < AMB_PERCENTAGE)	// grade from black to bright green
-		color.setHsvF(0.333, 1.0, (value - AMB_PERCENTAGE * inert / 1000.0) / (AMB_PERCENTAGE - AMB_PERCENTAGE * inert / 1000.0));
-	else if (value < 65)		// grade from bright green (0% M) to yellow-green (30% M)
-		color.setHsvF(0.333 - 0.133 * (value - AMB_PERCENTAGE) / (65.0 - AMB_PERCENTAGE), 1.0, 1.0);
-	else if (value < 85)		// grade from yellow-green (30% M) to orange (70% M)
-		color.setHsvF(0.2 - 0.1 * (value - 65.0) / 20.0, 1.0, 1.0);
-	else if (value < 100)		// grade from orange (70% M) to red (100% M)
-		color.setHsvF(0.1 * (100.0 - value) / 15.0, 1.0, 1.0);
-	else if (value < 120)		// M value exceeded - grade from red to white
-		color.setHsvF(0.0, 1 - (value - 100.0) / 20.0, 1.0);
-	else	// white
-		color.setHsvF(0.0, 0.0, 1.0);
-	return color;
-
-}
-
-void DivePercentageItem::paint(QPainter *painter, const QStyleOptionGraphicsItem*, QWidget*)
-{
-	if (polygon().isEmpty())
-		return;
-	painter->save();
-	QPen mypen;
-	mypen.setCapStyle(Qt::FlatCap);
-	mypen.setCosmetic(false);
-	QPolygonF poly = polygon();
-	for (int i = 1; i < poly.count(); i++) {
-		mypen.setBrush(QBrush(colors[i]));
-		painter->setPen(mypen);
-		painter->drawLine(poly[i - 1], poly[i]);
-	}
-	painter->restore();
-}
-
 DiveTemperatureItem::DiveTemperatureItem(const DivePlotDataModel &model, const DiveCartesianAxis &hAxis, int hColumn,
 					 const DiveCartesianAxis &vAxis, int vColumn, double dpr) :
 	AbstractProfilePolygonItem(model, hAxis, hColumn, vAxis, vColumn, dpr)

profile-widget/diveprofileitem.h

@@ -97,21 +97,6 @@ private:
 	QString visibilityKey;
 };
 
-class DivePercentageItem : public AbstractProfilePolygonItem {
-	Q_OBJECT
-public:
-	DivePercentageItem(const DivePlotDataModel &model, const DiveCartesianAxis &hAxis, int hColumn, const DiveCartesianAxis &vAxis, int vColumn, int i, double dpr);
-	void replot(const dive *d, bool in_planner) override;
-	void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override;
-
-private:
-	std::vector<QColor> colors;	// Must have same number of elements as the polygon
-	QString visibilityKey;
-	int tissueIndex;
-	QColor ColorScale(double value, int inert);
-
-};
-
 class DiveGasPressureItem : public AbstractProfilePolygonItem {
 	Q_OBJECT
 

profile-widget/profilescene.cpp

@@ -2,6 +2,7 @@
 #include "profilescene.h"
 #include "diveeventitem.h"
 #include "divecartesianaxis.h"
+#include "divepercentageitem.h"
 #include "diveprofileitem.h"
 #include "divetextitem.h"
 #include "tankitem.h"
@@ -69,6 +70,7 @@ ProfileScene::ProfileScene(double dpr, bool printMode, bool isGrayscale) :
 	diveCeiling(createItem<DiveCalculatedCeiling>(*profileYAxis, DivePlotDataModel::CEILING, 1, dpr)),
 	decoModelParameters(new DiveTextItem(dpr, 1.0, Qt::AlignHCenter | Qt::AlignTop, nullptr)),
 	heartBeatItem(createItem<DiveHeartrateItem>(*heartBeatAxis, DivePlotDataModel::HEARTBEAT, 1, dpr)),
+	percentageItem(new DivePercentageItem(*timeAxis, *percentageAxis, dpr)),
 	tankItem(new TankItem(*timeAxis, dpr))
 {
 	init_plot_info(&plotInfo);
@@ -119,10 +121,10 @@ ProfileScene::ProfileScene(double dpr, bool printMode, bool isGrayscale) :
 	for (int i = 0; i < 16; i++) {
 		DiveCalculatedTissue *tissueItem = createItem<DiveCalculatedTissue>(*profileYAxis, DivePlotDataModel::TISSUE_1 + i, i + 1, dpr);
 		allTissues.append(tissueItem);
-		DivePercentageItem *percentageItem = createItem<DivePercentageItem>(*percentageAxis, DivePlotDataModel::PERCENTAGE_1 + i, i + 1, i, dpr);
-		allPercentages.append(percentageItem);
 	}
 
+	percentageItem->setZValue(1.0);
+
 	// Add items to scene
 	addItem(diveComputerText);
 	addItem(tankItem);
@@ -134,6 +136,7 @@ ProfileScene::ProfileScene(double dpr, bool printMode, bool isGrayscale) :
 	addItem(cylinderPressureAxis);
 	addItem(percentageAxis);
 	addItem(heartBeatAxis);
+	addItem(percentageItem);
 
 	for (AbstractProfilePolygonItem *item: profileItems)
 		addItem(item);
@@ -189,8 +192,7 @@ void ProfileScene::updateVisibility()
 #ifndef SUBSURFACE_MOBILE
 	for (DiveCalculatedTissue *tissue: allTissues)
 		tissue->setVisible(prefs.calcalltissues && prefs.calcceiling);
-	for (DivePercentageItem *percentage: allPercentages)
+	percentageItem->setVisible(prefs.percentagegraph);
-		percentage->setVisible(prefs.percentagegraph);
 #endif
 	meanDepthItem->setVisible(prefs.show_average_depth);
 	reportedCeiling->setVisible(prefs.dcceiling);
@@ -468,6 +470,9 @@ void ProfileScene::plotDive(const struct dive *dIn, int dcIn, DivePlannerPointsM
 	for (AbstractProfilePolygonItem *item: profileItems)
 		item->replot(d, inPlanner);
 
+	if (prefs.percentagegraph)
+		percentageItem->replot(d, currentdc, dataModel->data());
+
 	// The event items are a bit special since we don't know how many events are going to
 	// exist on a dive, so I cant create cache items for that. that's why they are here
 	// while all other items are up there on the constructor.

profile-widget/profilescene.h

@@ -96,7 +96,7 @@ private:
 	DiveTextItem *decoModelParameters;
 	QList<DiveCalculatedTissue *> allTissues;
 	DiveHeartrateItem *heartBeatItem;
-	QList<DivePercentageItem *> allPercentages;
+	DivePercentageItem *percentageItem;
 	TankItem *tankItem;
 };