Implement tap and hold gesture to color pick

Can be configured in the preferences. Currently only one-finger tap and
hold is implemented and only to summon the color picker with it, until
someone needs something else.

ChangeLog

@@ -25,7 +25,7 @@ Unreleased Version 2.2.2-pre
  * Fix: Clamp palette swatch sizes to more reasonable bounds. Thanks MachKerman for reporting.
  * Server Feature: Allow checking session, operator and server account passwords via the API. This can be used to password-protect recordings or similar. Thanks Meru for contributing.
  * Fix: Correct some UI scaling problems with brush outlines, canvas centering, dock toggling, pixel grid and transform handles. Thanks annoy for reporting.
- * Feature: Extended touch tap gestures, among them two-finger tap to undo and three-finger tap to redo. Can be configured in the preferences under the Touch tab. Thanks InconsolableCellist and many others for suggesting.
+ * Feature: Extended touch tap gestures, among them two-finger tap to undo, three-finger tap to redo and tap-and-hold to summon the color picker. Can be configured in the preferences under the Touch tab. Thanks InconsolableCellist and many others for suggesting.
  * Feature: Snap canvas rotation around 0° by default. If you don't want this, you can set the canvas shortcut or touch rotation to "free rotate canvas" instead.
  * Feature: Show a color preview when picking a color from the canvas.
 

src/desktop/dialogs/settingsdialog/touch.cpp

@@ -24,6 +24,8 @@ void Touch::setUp(desktop::settings::Settings &settings, QVBoxLayout *layout)
 	initTouchActions(settings, utils::addFormSection(layout));
 	utils::addFormSeparator(layout);
 	initTapActions(settings, utils::addFormSection(layout));
+	utils::addFormSeparator(layout);
+	initTapAndHoldActions(settings, utils::addFormSection(layout));
 }
 
 void Touch::initMode(desktop::settings::Settings &settings, QFormLayout *form)
@@ -82,6 +84,26 @@ void Touch::initTapActions(
 	form->addRow(tr("Four-finger tap:"), fourFingerTap);
 }
 
+void Touch::initTapAndHoldActions(
+	desktop::settings::Settings &settings, QFormLayout *form)
+{
+	QComboBox *oneFingerTapAndHold = new QComboBox;
+	for(QComboBox *tapAndHold : {oneFingerTapAndHold}) {
+		tapAndHold->addItem(
+			tr("No action"),
+			int(desktop::settings::TouchTapAndHoldAction::Nothing));
+		tapAndHold->addItem(
+			tr("Pick color"),
+			int(desktop::settings::TouchTapAndHoldAction::ColorPickMode));
+	}
+
+	settings.bindOneFingerTapAndHold(oneFingerTapAndHold, Qt::UserRole);
+
+	settings.bindTouchGestures(oneFingerTapAndHold, &QComboBox::setDisabled);
+
+	form->addRow(tr("One-finger tap and hold:"), oneFingerTapAndHold);
+}
+
 void Touch::initTouchActions(
 	desktop::settings::Settings &settings, QFormLayout *form)
 {

src/desktop/dialogs/settingsdialog/touch.h

@@ -29,6 +29,9 @@ class Touch final : public Page {
 	void
 	initTapActions(desktop::settings::Settings &settings, QFormLayout *form);
 
+	void initTapAndHoldActions(
+		desktop::settings::Settings &settings, QFormLayout *form);
+
 	void
 	initTouchActions(desktop::settings::Settings &settings, QFormLayout *form);
 };

src/desktop/scene/canvasview.cpp

@@ -178,6 +178,12 @@ CanvasView::CanvasView(QWidget *parent)
 	connect(
 		m_touch, &TouchHandler::touchTapActionActivated, this,
 		&CanvasView::touchTapActionActivated, Qt::DirectConnection);
+	connect(
+		m_touch, &TouchHandler::touchColorPicked, this,
+		&CanvasView::touchColorPick, Qt::DirectConnection);
+	connect(
+		m_touch, &TouchHandler::touchColorPickFinished, this,
+		&CanvasView::finishTouchColorPick, Qt::DirectConnection);
 }
 
 
@@ -2075,6 +2081,16 @@ void CanvasView::pickColor(const QPointF &point, const QPointF &posf)
 	m_pickingColor = m_scene->setColorPick(mapToScene(posf.toPoint()), color);
 }
 
+void CanvasView::touchColorPick(const QPointF &posf)
+{
+	pickColor(mapToCanvas(posf), posf);
+}
+
+void CanvasView::finishTouchColorPick()
+{
+	m_scene->setColorPick(QPointF(), QColor());
+}
+
 void CanvasView::updateCanvasTransform(const std::function<void()> &block)
 {
 	QPointF outlinePoint = fromCanvasTransform().map(m_prevoutlinepoint);

src/desktop/scene/canvasview.h

@@ -293,6 +293,8 @@ private slots:
 	//! Drag the view
 	void moveDrag(const QPoint &point);
 	void pickColor(const QPointF &point, const QPointF &posf);
+	void touchColorPick(const QPointF &posf);
+	void finishTouchColorPick();
 
 	QTransform fromCanvasTransform() const;
 	QTransform toCanvasTransform() const;

src/desktop/settings.h

@@ -85,6 +85,12 @@ enum class TouchTapAction : int {
 };
 Q_ENUM_NS(TouchTapAction)
 
+enum class TouchTapAndHoldAction : int {
+	Nothing,
+	ColorPickMode,
+};
+Q_ENUM_NS(TouchTapAndHoldAction)
+
 enum class ThemePalette : int {
 	System,
 	Light,

src/desktop/settings_table.h

@@ -189,6 +189,7 @@ SETTING(oneFingerTap              , OneFingerTap              , "settings/input/
 SETTING(twoFingerTap              , TwoFingerTap              , "settings/input/twofingertap"           , int(TouchTapAction::Undo))
 SETTING(threeFingerTap            , ThreeFingerTap            , "settings/input/threefingertap"         , int(TouchTapAction::Redo))
 SETTING(fourFingerTap             , FourFingerTap             , "settings/input/fourfingertap"          , int(TouchTapAction::HideDocks))
+SETTING(oneFingerTapAndHold       , OneFingerTapAndHold       , "settings/input/onefingertapandhold"    , int(TouchTapAndHoldAction::ColorPickMode))
 SETTING(tabletPressTimerDelay     , TabletPressTimerDelay     , "settings/input/tabletpresstimerdelay"  , 500)
 SETTING(touchGestures             , TouchGestures             , "settings/input/touchgestures"          , false)
 SETTING(onionSkinsFrameCount      , OnionSkinsFrameCount      , "onionskins/framecount"                 , 8)

src/desktop/utils/touchhandler.cpp

@@ -8,6 +8,7 @@ extern "C" {
 #include "libshared/util/qtcompat.h"
 #include <QDateTime>
 #include <QGestureEvent>
+#include <QTimer>
 
 TouchHandler::TouchHandler(QObject *parent)
 	: QObject(parent)
@@ -19,8 +20,18 @@ TouchHandler::TouchHandler(QObject *parent)
 	, m_twoFingerTapAction(int(desktop::settings::TouchTapAction::Undo))
 	, m_threeFingerTapAction(int(desktop::settings::TouchTapAction::Redo))
 	, m_fourFingerTapAction(int(desktop::settings::TouchTapAction::HideDocks))
+	, m_oneFingerTapAndHoldAction(
+		  int(desktop::settings::TouchTapAndHoldAction::ColorPickMode))
 	, m_tapTimer(Qt::CoarseTimer)
+	, m_tapAndHoldTimer(new QTimer(this))
 {
+	m_tapAndHoldTimer->setTimerType(Qt::CoarseTimer);
+	m_tapAndHoldTimer->setSingleShot(true);
+	m_tapAndHoldTimer->setInterval(TAP_AND_HOLD_DELAY_MS);
+	connect(
+		m_tapAndHoldTimer, &QTimer::timeout, this,
+		&TouchHandler::triggerTapAndHold);
+
 	desktop::settings::Settings &settings = dpApp().settings();
 	settings.bindOneFingerTouch(this, &TouchHandler::setOneFingerTouchAction);
 	settings.bindTwoFingerPinch(this, &TouchHandler::setTwoFingerPinchAction);
@@ -29,6 +40,8 @@ TouchHandler::TouchHandler(QObject *parent)
 	settings.bindTwoFingerTap(this, &TouchHandler::setTwoFingerTapAction);
 	settings.bindThreeFingerTap(this, &TouchHandler::setThreeFingerTapAction);
 	settings.bindFourFingerTap(this, &TouchHandler::setFourFingerTapAction);
+	settings.bindOneFingerTapAndHold(
+		this, &TouchHandler::setOneFingerTapAndHoldAction);
 }
 
 bool TouchHandler::isTouchDrawEnabled() const
@@ -93,6 +106,7 @@ void TouchHandler::handleTouchBegin(QTouchEvent *event)
 	m_touchDrawBuffer.clear();
 	m_touchDragging = false;
 	m_touchRotating = false;
+	m_touchHeld = false;
 	m_maxTouchPoints = pointsCount;
 	m_tapTimer.setRemainingTime(TAP_MAX_DELAY_MS);
 	if(isTouchDrawEnabled() && pointsCount == 1 && !compat::isTouchPad(event)) {
@@ -105,7 +119,9 @@ void TouchHandler::handleTouchBegin(QTouchEvent *event)
 			qulonglong(event->timestamp()));
 		if(isTouchPanEnabled() || isTouchPinchOrTwistEnabled() ||
 		   m_oneFingerTapAction !=
-			   int(desktop::settings::TouchTapAction::Nothing)) {
+			   int(desktop::settings::TouchTapAction::Nothing) ||
+		   m_oneFingerTapAndHoldAction !=
+			   int(desktop::settings::TouchTapAndHoldAction::Nothing)) {
 			// Buffer the touch first, since it might end up being the
 			// beginning of an action that involves multiple fingers.
 			m_touchDrawBuffer.append(
@@ -127,6 +143,14 @@ void TouchHandler::handleTouchBegin(QTouchEvent *event)
 			qulonglong(event->timestamp()));
 		m_touchMode = TouchMode::Moving;
 	}
+
+	if(pointsCount == 1 && m_touchMode != TouchMode::Drawing &&
+	   m_oneFingerTapAndHoldAction !=
+		   int(desktop::settings::TouchTapAndHoldAction::Nothing)) {
+		m_tapAndHoldTimer->start();
+	} else {
+		m_tapAndHoldTimer->stop();
+	}
 }
 
 void TouchHandler::handleTouchUpdate(
@@ -138,10 +162,23 @@ void TouchHandler::handleTouchUpdate(
 		m_maxTouchPoints = pointsCount;
 	}
 
-	if(isTouchDrawEnabled() &&
-	   ((pointsCount == 1 && m_touchMode == TouchMode::Unknown) ||
-		m_touchMode == TouchMode::Drawing) &&
-	   !compat::isTouchPad(event)) {
+	if(pointsCount != 1) {
+		m_tapAndHoldTimer->stop();
+	}
+
+	m_touchPos = QPointF(0.0, 0.0);
+	for(const compat::TouchPoint &tp : compat::touchPoints(*event)) {
+		m_touchPos += compat::touchPos(tp);
+	}
+	m_touchPos /= pointsCount;
+
+	if(m_touchHeld) {
+		emit touchColorPicked(m_touchPos);
+	} else if(
+		isTouchDrawEnabled() &&
+		((pointsCount == 1 && m_touchMode == TouchMode::Unknown) ||
+		 m_touchMode == TouchMode::Drawing) &&
+		!compat::isTouchPad(event)) {
 		QPointF posf = compat::touchPos(compat::touchPoints(*event).first());
 		DP_EVENT_LOG(
 			"touch_draw_update x=%f y=%f touching=%d type=%d device=%s "
@@ -155,6 +192,7 @@ void TouchHandler::handleTouchUpdate(
 			if(m_touchMode == TouchMode::Drawing) {
 				emit touchMoved(QDateTime::currentMSecsSinceEpoch(), posf);
 			} else { // Shouldn't happen, but we'll deal with it anyway.
+				m_tapAndHoldTimer->stop();
 				m_touchMode = TouchMode::Drawing;
 				emit touchPressed(
 					event, QDateTime::currentMSecsSinceEpoch(), posf);
@@ -172,6 +210,7 @@ void TouchHandler::handleTouchUpdate(
 				m_touchDrawBuffer.append(
 					{QDateTime::currentMSecsSinceEpoch(), posf});
 			} else {
+				m_tapAndHoldTimer->stop();
 				m_touchMode = TouchMode::Drawing;
 				flushTouchDrawBuffer();
 				emit touchMoved(QDateTime::currentMSecsSinceEpoch(), posf);
@@ -180,17 +219,15 @@ void TouchHandler::handleTouchUpdate(
 	} else {
 		m_touchMode = TouchMode::Moving;
 
-		QPointF startCenter, lastCenter, center;
+		QPointF startCenter, lastCenter;
 		for(const compat::TouchPoint &tp : compat::touchPoints(*event)) {
 			QPointF startPos = compat::touchStartPos(tp);
 			startCenter += startPos;
 			lastCenter += compat::touchLastPos(tp);
-			QPointF pos = compat::touchPos(tp);
-			center += pos;
 			// This might be a tap gesture. Don't start a drag until there's
 			// been sufficient movement on any of the fingers.
 			if(!m_touchDragging &&
-			   squareDist(startPos - pos) > TAP_SLOP_SQUARED) {
+			   squareDist(startPos - compat::touchPos(tp)) > TAP_SLOP_SQUARED) {
 				m_touchDragging = true;
 			}
 		}
@@ -206,9 +243,10 @@ void TouchHandler::handleTouchUpdate(
 			}
 		}
 
+		m_tapAndHoldTimer->stop();
 		startCenter /= pointsCount;
 		lastCenter /= pointsCount;
-		center /= pointsCount;
+		QPointF center = m_touchPos;
 
 		DP_EVENT_LOG(
 			"touch_update x=%f y=%f touching=%d type=%d device=%s "
@@ -294,12 +332,16 @@ void TouchHandler::handleTouchEnd(QTouchEvent *event, bool cancel)
 {
 	event->accept();
 	const QList<compat::TouchPoint> &points = compat::touchPoints(*event);
-	if(isTouchDrawEnabled() &&
-	   ((m_touchMode == TouchMode::Unknown && !m_touchDrawBuffer.isEmpty() &&
-		 (m_touchDragging ||
-		  m_oneFingerTapAction ==
-			  int(desktop::settings::TouchTapAction::Nothing))) ||
-		m_touchMode == TouchMode::Drawing)) {
+	m_tapAndHoldTimer->stop();
+	if(m_touchHeld) {
+		emit touchColorPickFinished();
+	} else if(
+		isTouchDrawEnabled() &&
+		((m_touchMode == TouchMode::Unknown && !m_touchDrawBuffer.isEmpty() &&
+		  (m_touchDragging ||
+		   m_oneFingerTapAction ==
+			   int(desktop::settings::TouchTapAction::Nothing))) ||
+		 m_touchMode == TouchMode::Drawing)) {
 		DP_EVENT_LOG(
 			"touch_draw_%s touching=%d type=%d device=%s points=%s "
 			"timestamp=%llu",
@@ -474,6 +516,29 @@ void TouchHandler::setFourFingerTapAction(int fourFingerTapAction)
 	m_fourFingerTapAction = fourFingerTapAction;
 }
 
+void TouchHandler::setOneFingerTapAndHoldAction(int oneFingerTapAndHoldAction)
+{
+	m_oneFingerTapAndHoldAction = oneFingerTapAndHoldAction;
+}
+
+void TouchHandler::triggerTapAndHold()
+{
+	m_tapAndHoldTimer->stop();
+	if(m_maxTouchPoints == 1 && m_touchMode != TouchMode::Drawing) {
+		switch(m_oneFingerTapAndHoldAction) {
+		case int(desktop::settings::TouchTapAndHoldAction::ColorPickMode):
+			m_touchHeld = true;
+			emit touchColorPicked(m_touchPos);
+			break;
+		default:
+			qWarning(
+				"Unknown one finger tap and hold action %d",
+				m_oneFingerTapAndHoldAction);
+			break;
+		}
+	}
+}
+
 qreal TouchHandler::adjustTwistRotation(qreal degrees) const
 {
 	if(m_twoFingerTwistAction ==

src/desktop/utils/touchhandler.h

@@ -6,6 +6,7 @@
 #include <QPointF>
 
 class QGestureEvent;
+class QTimer;
 class QTouchEvent;
 
 class TouchHandler : public QObject {
@@ -38,10 +39,13 @@ class TouchHandler : public QObject {
 	void touchScrolledBy(qreal dx, qreal dy);
 	void touchZoomedRotated(qreal zoom, qreal rotation);
 	void touchTapActionActivated(int action);
+	void touchColorPicked(const QPointF &posf);
+	void touchColorPickFinished();
 
 private:
 	static constexpr qreal TAP_SLOP_SQUARED = 16.0 * 16.0;
 	static constexpr int TAP_MAX_DELAY_MS = 1000;
+	static constexpr int TAP_AND_HOLD_DELAY_MS = 400;
 	static constexpr int DRAW_BUFFER_COUNT = 20;
 
 	enum class TouchMode { Unknown, Drawing, Moving };
@@ -58,6 +62,9 @@ class TouchHandler : public QObject {
 	void setTwoFingerTapAction(int twoFingerTapAction);
 	void setThreeFingerTapAction(int threeFingerTapAction);
 	void setFourFingerTapAction(int fourFingerTapAction);
+	void setOneFingerTapAndHoldAction(int oneFingerTapAndHoldAction);
+
+	void triggerTapAndHold();
 
 	qreal adjustTwistRotation(qreal degrees) const;
 	void flushTouchDrawBuffer();
@@ -66,6 +73,7 @@ class TouchHandler : public QObject {
 	bool m_touching = false;
 	bool m_touchDragging = false;
 	bool m_touchRotating = false;
+	bool m_touchHeld = false;
 	bool m_anyTabletEventsReceived = false;
 	int m_oneFingerTouchAction;
 	int m_twoFingerPinchAction;
@@ -74,16 +82,19 @@ class TouchHandler : public QObject {
 	int m_twoFingerTapAction;
 	int m_threeFingerTapAction;
 	int m_fourFingerTapAction;
+	int m_oneFingerTapAndHoldAction;
 	int m_maxTouchPoints = 0;
 	TouchMode m_touchMode = TouchMode::Unknown;
 	QVector<QPair<long long, QPointF>> m_touchDrawBuffer;
 	QPointF m_touchStartPos;
 	qreal m_touchStartZoom = 0.0;
 	qreal m_touchStartRotate = 0.0;
+	QPointF m_touchPos;
 	QPointF m_gestureStartPos;
 	qreal m_gestureStartZoom = 0.0;
 	qreal m_gestureStartRotation = 0.0;
 	QDeadlineTimer m_tapTimer;
+	QTimer *m_tapAndHoldTimer;
 };
 
 #endif