Avoid overprinting of cylinder presssure labels for CCR dives

This patch takes the cylinder pressures of CCR dives and prints them
in a non-overlapping way.

Remaining issue: When the dive profile is made taller by dragging the
window or the appropriate slider far down the screen, the labels move
further apart; similarly, when the profle is made flat/shallow by dragging
the window edge or appropriate slider up, the labels get close to each
other and start to overlap.

There are quite a few lines of additional code going into the patch. This
is primarily because separate provisions for when po2 > p(diluent) or vice
versa. In addition, I could not determine the size of the text characters
which would allow much more precise placement of text. This is because the
.scale member of the text is private and not available in the methods
involved in printing the labels. However, the height of the vertical scale
of the cylinder pressure graph can be determined [e.g. vAxis->maximum()].
This helped a lot to get the positioning of the text more or less correct.

While the results of the patch is not perfect, It contributes
significantly to make the profiles of Poseidon dives more readable.

Signed-off-by: willem ferguson <willemferguson@zoology.up.ac.za>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

2 files changed, 68 insertions, 20 deletions

diff --git a/qt-ui/profile/diveprofileitem.cpp b/qt-ui/profile/diveprofileitem.cpp
index 66faf982d..47d7e4b5e 100644
--- a/qt-ui/profile/diveprofileitem.cpp
+++ b/qt-ui/profile/diveprofileitem.cpp
@@ -627,7 +627,7 @@ void DiveGasPressureItem::modelDataChanged(const QModelIndex &topLeft, const QMo
 			o2mbar = GET_O2CYLINDER_PRESSURE(entry);
 
 		if (entry->cylinderindex != last_index) {
-			polygons.append(QPolygonF()); // this is the polygon that will be actually drawned on screen.
+			polygons.append(QPolygonF()); // this is the polygon that will be actually drawn on screen.
 			last_index = entry->cylinderindex;
 		}
 		if (!mbar) {
@@ -654,6 +654,18 @@ void DiveGasPressureItem::modelDataChanged(const QModelIndex &topLeft, const QMo
 
 	cyl = -1;
 	o2mbar = 0;
+
+	double print_y_offset[8][2] = { { 0, -0.5 }, { 0, -0.5 }, { 0, -0.5 }, { 0, -0.5 }, { 0, -0.5 } ,{ 0, -0.5 }, { 0, -0.5 }, { 0, -0.5 } };
+	// CCR dives: These are offset values used to print the gas lables and pressures on a CCR dive profile at
+	// appropriate Y-coordinates: One doublet of values for each of 8 cylinders.
+	// Order of offsets within a doublet: gas lable offset; gas pressure offset.
+	// The array is initialised with default values that apply to non-CCR dives.
+
+	bool offsets_initialised = false;
+	int o2cyl = -1, dilcyl = -1;
+	QFlags<Qt::AlignmentFlag> alignVar, align_dil = Qt::AlignBottom, align_o2 = Qt::AlignBottom;
+	double axisRange = (vAxis->maximum() - vAxis->minimum())/1000;
+	double axisLog = log10(log10(axisRange));
 	for (int i = 0, count = dataModel->rowCount(); i < count; i++) {
 		entry = dataModel->data().entry + i;
 		mbar = GET_PRESSURE(entry);
@@ -661,57 +673,93 @@ void DiveGasPressureItem::modelDataChanged(const QModelIndex &topLeft, const QMo
 			o2mbar = GET_O2CYLINDER_PRESSURE(entry);
 
 		if (o2mbar) {
-			if (!seen_cyl[displayed_dive.oxygen_cylinder_index]) {
-				plotPressureValue(o2mbar, entry->sec, Qt::AlignRight | Qt::AlignBottom);
-				plotGasValue(o2mbar, entry->sec, Qt::AlignRight | Qt::AlignBottom, displayed_dive.cylinder[displayed_dive.oxygen_cylinder_index].gasmix);
+			// The first time an o2 value is detected, see if the oxygen cyl pressure graph starts above or below the dil graph
+			if (!offsets_initialised) {	// Initialise the parameters for placing the text correctly near the graph line:
+				o2cyl = displayed_dive.oxygen_cylinder_index;
+				dilcyl = displayed_dive.diluent_cylinder_index;
+				if ((o2mbar > mbar)) {	// If above, write o2 start cyl pressure above graph and diluent pressure below graph:
+					print_y_offset[o2cyl][0] = -7 * axisLog; // y offset for oxygen gas lable (above)
+					print_y_offset[o2cyl][1] = -0.5;	 // y offset for oxygen start pressure value (above)
+					print_y_offset[dilcyl][0] = 5 * axisLog; // y offset for diluent gas lable (below)
+					print_y_offset[dilcyl][1] = 0;		 // y offset for diluent start pressure value (below)
+					align_dil = Qt::AlignBottom;
+					align_o2  = Qt::AlignTop;
+				} else {					// ... else write o2 start cyl pressure below graph:
+					print_y_offset[o2cyl][0]  = 5 * axisLog; // o2 lable & pressure below graph,
+					print_y_offset[o2cyl][1]  = 0;
+					print_y_offset[dilcyl][0] = -7 * axisLog;  // and diluent lable above graph.
+					print_y_offset[dilcyl][1] = -0.5;	// and diluent pressure above graph.
+					align_dil = Qt::AlignTop;
+					align_o2  = Qt::AlignBottom;
+				}
+				offsets_initialised = true;
+			}
+
+			if (!seen_cyl[displayed_dive.oxygen_cylinder_index]) {	//For o2, on the left of profile, write lable and pressure
+				plotPressureValue(o2mbar, entry->sec, align_o2, print_y_offset[o2cyl][1]);
+				plotGasValue(o2mbar, entry->sec, displayed_dive.cylinder[displayed_dive.oxygen_cylinder_index].gasmix, align_o2, print_y_offset[o2cyl][0]);
 				seen_cyl[displayed_dive.oxygen_cylinder_index] = true;
 			}
 			last_pressure[displayed_dive.oxygen_cylinder_index] = o2mbar;
 			last_time[displayed_dive.oxygen_cylinder_index] = entry->sec;
+			alignVar = align_dil;
+		} else {
+			alignVar = Qt::AlignBottom;
+			align_dil = Qt::AlignTop;
 		}
 
-
 		if (!mbar)
 			continue;
-		if (cyl != entry->cylinderindex) {
-			cyl = entry->cylinderindex;
+
+		if (cyl != entry->cylinderindex) {	// Pressure value near the left hand edge of the profile - other cylinders:
+			cyl = entry->cylinderindex;	// For each other cylinder, write the gas lable and pressure
 			if (!seen_cyl[cyl]) {
-				plotPressureValue(mbar, entry->sec, Qt::AlignRight | Qt::AlignTop);
-				plotGasValue(mbar, entry->sec, Qt::AlignRight | Qt::AlignBottom,
-					     displayed_dive.cylinder[cyl].gasmix);
+				plotPressureValue(mbar, entry->sec, alignVar, print_y_offset[cyl][0]);
+				plotGasValue(mbar, entry->sec, displayed_dive.cylinder[cyl].gasmix, align_dil, print_y_offset[cyl][1]);
 				seen_cyl[cyl] = true;
 			}
 		}
 		last_pressure[cyl] = mbar;
 		last_time[cyl] = entry->sec;
 	}
+						// Now, for the cylinder pressure written near the right edge of the profile:
+	if ((o2cyl >= 0) && (dilcyl >= 0)) {	// At first, skip uninitialised values of o2cyl and dilcyl
+		if (last_pressure[o2cyl] > last_pressure[dilcyl]) { // If oxygen cyl pressure graph ends above diluent graph:
+			align_dil =  Qt::AlignTop;	// initialise to write diluent cyl end pressure underneath the graph
+			align_o2  =  Qt::AlignBottom;
+		} else {
+			align_dil =  Qt::AlignBottom;	// else initialise to write diluent cyl end pressure above the graph
+			align_o2  =  Qt::AlignTop;
+		}
+	}
 
-	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
+	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {	// For each cylinder, on right hand side of profile, write cylinder pressure
+		alignVar = ((o2cyl >= 0) && (cyl == displayed_dive.oxygen_cylinder_index)) ? align_o2 : align_dil;
 		if (last_time[cyl]) {
-			plotPressureValue(last_pressure[cyl], last_time[cyl], Qt::AlignLeft | Qt::AlignTop);
+			plotPressureValue(last_pressure[cyl], last_time[cyl], (alignVar | Qt::AlignLeft), print_y_offset[cyl][0]);
 		}
 	}
 }
 
-void DiveGasPressureItem::plotPressureValue(int mbar, int sec, QFlags<Qt::AlignmentFlag> flags)
+void DiveGasPressureItem::plotPressureValue(int mbar, int sec, QFlags<Qt::AlignmentFlag> align, double pressure_offset)
 {
 	const char *unit;
 	int pressure = get_pressure_units(mbar, &unit);
 	DiveTextItem *text = new DiveTextItem(this);
-	text->setPos(hAxis->posAtValue(sec), vAxis->posAtValue(mbar) - 0.5);
+	text->setPos(hAxis->posAtValue(sec), vAxis->posAtValue(mbar) + pressure_offset );
 	text->setText(QString("%1 %2").arg(pressure).arg(unit));
-	text->setAlignment(flags);
+	text->setAlignment(align);
 	text->setBrush(getColor(PRESSURE_TEXT));
 	texts.push_back(text);
 }
 
-void DiveGasPressureItem::plotGasValue(int mbar, int sec, QFlags<Qt::AlignmentFlag> flags, struct gasmix gasmix)
+void DiveGasPressureItem::plotGasValue(int mbar, int sec, struct gasmix gasmix, QFlags<Qt::AlignmentFlag> align, double gasname_offset)
 {
 	QString gas = gasToStr(gasmix);
 	DiveTextItem *text = new DiveTextItem(this);
-	text->setPos(hAxis->posAtValue(sec), vAxis->posAtValue(mbar));
+	text->setPos(hAxis->posAtValue(sec), vAxis->posAtValue(mbar) + gasname_offset );
 	text->setText(gas);
-	text->setAlignment(flags);
+	text->setAlignment(align);
 	text->setBrush(getColor(PRESSURE_TEXT));
 	texts.push_back(text);
 }
diff --git a/qt-ui/profile/diveprofileitem.h b/qt-ui/profile/diveprofileitem.h
index 096c1a3ce..a323e54ee 100644
--- a/qt-ui/profile/diveprofileitem.h
+++ b/qt-ui/profile/diveprofileitem.h
@@ -165,8 +165,8 @@ public:
 	virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0);
 
 private:
-	void plotPressureValue(int mbar, int sec, QFlags<Qt::AlignmentFlag> align);
-	void plotGasValue(int mbar, int sec, QFlags<Qt::AlignmentFlag> align, struct gasmix gasmix);
+	void plotPressureValue(int mbar, int sec, QFlags<Qt::AlignmentFlag> align, double offset);
+	void plotGasValue(int mbar, int sec, struct gasmix gasmix, QFlags<Qt::AlignmentFlag> align, double offset);
 	QVector<QPolygonF> polygons;
 };