profile: implement panning of profile

When zoomed in, the profile position was moved by hovering with
the mouse. What a horrible user experience. This is especially
useless if we want to implement an interactive profile on mobile.

Instead, let the user start the panning with a mouse click. The
code is somewhat nasty, because the position is given as a
real in the [0,1] range, which represents all possible positions
from completely to the left to completely to the right.

This commit also removes the restriction that the planner handles
can only be moved when fully zoomed out. It is not completely
clear what the implications are. Let's see.

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

CHANGELOG.md

@@ -1,4 +1,6 @@
 import: allow import of divesites without UUID
+profile: implement panning of the profile
+planner: allow handle manipulation in zoomed in state
 divelist: do not include planned versions of a dive if there is real data
 desktop: fix key composition in tag widgets and dive site widget
 desktop: use combobox for moving sensor between cylinders

profile-widget/divecartesianaxis.cpp

@@ -436,6 +436,16 @@ double DiveCartesianAxis::valueAt(const QPointF &p) const
 	return fraction * (max - min) + min;
 }
 
+double DiveCartesianAxis::deltaToValue(double delta) const
+{
+	QLineF m = line();
+	double screenSize = position == Position::Bottom ? m.x2() - m.x1()
+							 : m.y2() - m.y1();
+	double axisSize = max - min;
+	double res = delta * axisSize / screenSize;
+	return ((position == Position::Bottom) == inverted) ? -res : res;
+}
+
 double DiveCartesianAxis::posAtValue(double value, double max, double min) const
 {
 	QLineF m = line();

profile-widget/divecartesianaxis.h

@@ -31,6 +31,7 @@ public:
 	std::pair<double, double> screenMinMax() const;
 	double valueAt(const QPointF &p) const;
 	double posAtValue(double value) const;
+	double deltaToValue(double delta) const; // For panning: turn a screen distance to delta-value
 	void setPosition(const QRectF &rect);
 	double screenPosition(double pos) const; // 0.0 = begin, 1.0 = end of axis, independent of represented values
 	double pointInRange(double pos) const; // Point on screen is in range of axis

profile-widget/profilescene.cpp

@@ -12,6 +12,7 @@
 #include "core/pref.h"
 #include "core/profile.h"
 #include "core/qthelper.h"	// for decoMode()
+#include "core/subsurface-float.h"
 #include "core/subsurface-string.h"
 #include "core/settings/qPrefDisplay.h"
 #include "qt-models/diveplannermodel.h"
@@ -491,11 +492,9 @@ void ProfileScene::plotDive(const struct dive *dIn, int dcIn, DivePlannerPointsM
 	percentageAxis->updateTicks(animSpeed);
 	animatedAxes.push_back(percentageAxis);
 
-	if (calcMax) {
-		double relStart = (1.0 - 1.0/zoom) * zoomedPosition;
-		double relEnd = relStart + 1.0/zoom;
-		timeAxis->setBounds(round(relStart * maxtime), round(relEnd * maxtime));
-	}
+	double relStart = (1.0 - 1.0/zoom) * zoomedPosition;
+	double relEnd = relStart + 1.0/zoom;
+	timeAxis->setBounds(round(relStart * maxtime), round(relEnd * maxtime));
 
 	// Find first and last plotInfo entry
 	int firstSecond = lrint(timeAxis->minimum());
@@ -627,3 +626,19 @@ void ProfileScene::draw(QPainter *painter, const QRect &pos,
 	}
 	painter->drawImage(pos, image);
 }
+
+// Calculate the new zoom position when the mouse is dragged by delta.
+// This is annoyingly complex, because the zoom position is given as
+// a real between 0 and 1.
+double ProfileScene::calcZoomPosition(double zoom, double originalPos, double delta)
+{
+	double factor = 1.0 - 1.0/zoom;
+	if (nearly_0(factor))
+		return 0.0;
+	double relStart = factor * originalPos;
+	double start = relStart * maxtime;
+	double newStart = start + timeAxis->deltaToValue(delta);
+	double newRelStart = newStart / maxtime;
+	double newPos = newRelStart / factor;
+	return std::clamp(newPos, 0.0, 1.0);
+}

profile-widget/profilescene.h

@@ -48,6 +48,7 @@ public:
 	void draw(QPainter *painter, const QRect &pos,
 		  const struct dive *d, int dc,
 		  DivePlannerPointsModel *plannerModel = nullptr, bool inPlanner = false);
+	double calcZoomPosition(double zoom, double originalPos, double delta);
 
 	const struct dive *d;
 	int dc;

profile-widget/profilewidget2.cpp

@@ -40,8 +40,12 @@
 // We might add more constants here for easier customability.
 static const double thumbnailBaseZValue = 100.0;
 
-// Base of exponential zoom function: one wheel-click will increase the zoom by 15%.
-static const double zoomFactor = 1.15;
+static double calcZoom(int zoomLevel)
+{
+	// Base of exponential zoom function: one wheel-click will increase the zoom by 15%.
+	constexpr double zoomFactor = 1.15;
+	return zoomLevel == 0 ? 1.0 : pow(zoomFactor, zoomLevel);
+}
 
 ProfileWidget2::ProfileWidget2(DivePlannerPointsModel *plannerModelIn, double dpr, QWidget *parent) : QGraphicsView(parent),
 	profileScene(new ProfileScene(dpr, false, false)),
@@ -55,6 +59,7 @@ ProfileWidget2::ProfileWidget2(DivePlannerPointsModel *plannerModelIn, double dp
 	d(nullptr),
 	dc(0),
 	empty(true),
+	panning(false),
 #ifndef SUBSURFACE_MOBILE
 	mouseFollowerVertical(new DiveLineItem()),
 	mouseFollowerHorizontal(new DiveLineItem()),
@@ -202,7 +207,7 @@ void ProfileWidget2::plotDive(const struct dive *dIn, int dcIn, int flags)
 	DivePlannerPointsModel *model = currentState == EDIT || currentState == PLAN ? plannerModel : nullptr;
 	bool inPlanner = currentState == PLAN;
 
-	double zoom = zoomLevel == 0 ? 1.0 : pow(zoomFactor, zoomLevel);
+	double zoom = calcZoom(zoomLevel);
 	profileScene->plotDive(d, dc, model, inPlanner, flags & RenderFlags::Instant,
 			       flags & RenderFlags::DontRecalculatePlotInfo,
 			       shouldCalculateMax, zoom, zoomedPosition);
@@ -267,24 +272,22 @@ void ProfileWidget2::resizeEvent(QResizeEvent *event)
 #ifndef SUBSURFACE_MOBILE
 void ProfileWidget2::mousePressEvent(QMouseEvent *event)
 {
-	if (zoomLevel)
-		return;
 	QGraphicsView::mousePressEvent(event);
-	if (currentState == PLAN || currentState == EDIT)
-		shouldCalculateMax = false;
+
+	if (!event->isAccepted()) {
+		panning = true;
+		panningOriginalMousePosition = mapToScene(event->pos()).x();
+		panningOriginalProfilePosition = zoomedPosition;
+	}
 }
 
 void ProfileWidget2::divePlannerHandlerClicked()
 {
-	if (zoomLevel)
-		return;
 	shouldCalculateMax = false;
 }
 
 void ProfileWidget2::divePlannerHandlerReleased()
 {
-	if (zoomLevel)
-		return;
 	if (currentState == EDIT)
 		emit stopMoved(1);
 	shouldCalculateMax = true;
@@ -293,9 +296,8 @@ void ProfileWidget2::divePlannerHandlerReleased()
 
 void ProfileWidget2::mouseReleaseEvent(QMouseEvent *event)
 {
-	if (zoomLevel)
-		return;
 	QGraphicsView::mouseReleaseEvent(event);
+	panning = false;
 	if (currentState == PLAN || currentState == EDIT) {
 		shouldCalculateMax = true;
 		replot();
@@ -306,12 +308,6 @@ void ProfileWidget2::mouseReleaseEvent(QMouseEvent *event)
 void ProfileWidget2::setZoom(int level)
 {
 	zoomLevel = level;
-	if (zoomLevel == 0) {
-		zoomedPosition = 0.0;
-	} else {
-		double pos = mapToScene(mapFromGlobal(QCursor::pos())).x();
-		zoomedPosition = pos / profileScene->width();
-	}
 	plotDive(d, dc, RenderFlags::DontRecalculatePlotInfo);
 }
 
@@ -320,6 +316,8 @@ void ProfileWidget2::wheelEvent(QWheelEvent *event)
 {
 	if (!d)
 		return;
+	if (panning)
+		return;	// No change in zoom level while panning.
 	if (event->buttons() == Qt::LeftButton)
 		return;
 	if (event->angleDelta().y() > 0 && zoomLevel < 20)
@@ -348,13 +346,17 @@ void ProfileWidget2::mouseMoveEvent(QMouseEvent *event)
 	QGraphicsView::mouseMoveEvent(event);
 
 	QPointF pos = mapToScene(event->pos());
-	toolTipItem->refresh(d, mapToScene(mapFromGlobal(QCursor::pos())), currentState == PLAN);
-
-	if (zoomLevel != 0) {
-		zoomedPosition = pos.x() / profileScene->width();
-		plotDive(d, dc, RenderFlags::Instant | RenderFlags::DontRecalculatePlotInfo); // TODO: animations don't work when scrolling
+	if (panning) {
+		double oldPos = zoomedPosition;
+		zoomedPosition = profileScene->calcZoomPosition(calcZoom(zoomLevel),
+								panningOriginalProfilePosition,
+								panningOriginalMousePosition - pos.x());
+		if (oldPos != zoomedPosition)
+			plotDive(d, dc, RenderFlags::Instant | RenderFlags::DontRecalculatePlotInfo); // TODO: animations don't work when scrolling
 	}
 
+	toolTipItem->refresh(d, mapToScene(mapFromGlobal(QCursor::pos())), currentState == PLAN);
+
 	if (currentState == PLAN || currentState == EDIT) {
 		QRectF rect = profileScene->profileRegion;
 		auto [miny, maxy] = profileScene->profileYAxis->screenMinMax();

profile-widget/profilewidget2.h

@@ -142,6 +142,9 @@ private:
 	const struct dive *d;
 	int dc;
 	bool empty; // No dive shown.
+	bool panning; // Currently panning.
+	double panningOriginalMousePosition;
+	double panningOriginalProfilePosition;
 #ifndef SUBSURFACE_MOBILE
 	DiveLineItem *mouseFollowerVertical;
 	DiveLineItem *mouseFollowerHorizontal;