Snap canvas rotation around zero degrees

To make it easier to reset the rotation without having to faff around with the angle dial or use a separate shortcut. The snapping happens at +-5°, which should be a small enough value that it's not particularly useful to rotate the canvas by that amount, but large enough that it's reasonably easy to hit.
drawpile · Sep 27, 2024 · 6aec278 · 6aec278
1 parent a9a838f
commit 6aec278
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Showing 7 changed files with 68 additions and 8 deletions.
diff --git a/ChangeLog b/ChangeLog
@@ -26,6 +26,7 @@ Unreleased Version 2.2.2-pre
  * 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: 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.
 
 2024-08-09 Version 2.2.2-beta.3
  * Fix: Use more accurate timers for performance profiles if the platform supports it.

diff --git a/src/desktop/dialogs/canvasshortcutsdialog.cpp b/src/desktop/dialogs/canvasshortcutsdialog.cpp
@@ -31,6 +31,9 @@ CanvasShortcutsDialog::CanvasShortcutsDialog(
 	d->ui.actionCombo->addItem(tr("Pan Canvas"), CanvasShortcuts::CANVAS_PAN);
 	d->ui.actionCombo->addItem(
 		tr("Rotate Canvas"), CanvasShortcuts::CANVAS_ROTATE);
+	d->ui.actionCombo->addItem(
+		//: This refers to rotating the canvas without snapping around 0°.
+		tr("Free Rotate Canvas"), CanvasShortcuts::CANVAS_ROTATE_NO_SNAP);
 	d->ui.actionCombo->addItem(
 		//: This refers to rotating the canvas in 15° steps.
 		tr("Ratchet Rotate Canvas"), CanvasShortcuts::CANVAS_ROTATE_DISCRETE);
@@ -194,6 +197,7 @@ void CanvasShortcutsDialog::updateAction()
 	case CanvasShortcuts::CANVAS_PAN:
 	case CanvasShortcuts::CANVAS_ROTATE:
 	case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+	case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 	case CanvasShortcuts::CANVAS_ZOOM:
 	case CanvasShortcuts::TOOL_ADJUST:
 		showModifiers = true;

diff --git a/src/desktop/scene/canvasview.cpp b/src/desktop/scene/canvasview.cpp
@@ -586,6 +586,11 @@ void CanvasView::rotateStepCounterClockwise()
 	setRotation(rotation() - 5.0);
 }
 
+void CanvasView::setRotationSnap(qreal degrees)
+{
+	setRotation(qAbs(std::fmod(degrees, 360.0)) < 5.0 ? 0.0 : degrees);
+}
+
 void CanvasView::rotateByDiscreteSteps(int steps)
 {
 	constexpr qreal EPS = 0.01;
@@ -736,6 +741,7 @@ void CanvasView::resetCursor()
 													: Qt::OpenHandCursor);
 			break;
 		case CanvasShortcuts::CANVAS_ROTATE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 			setViewportCursor(m_rotatecursor);
 			break;
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
@@ -1111,6 +1117,7 @@ void CanvasView::penPressEvent(
 	case CanvasShortcuts::CANVAS_PAN:
 	case CanvasShortcuts::CANVAS_ROTATE:
 	case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+	case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 	case CanvasShortcuts::CANVAS_ZOOM:
 		if(m_dragmode != ViewDragMode::Started) {
 			m_dragmode = ViewDragMode::Prepared;
@@ -1142,6 +1149,7 @@ void CanvasView::penPressEvent(
 		m_dragButton = button;
 		m_dragModifiers = modifiers;
 		m_dragDiscreteRotation = 0.0;
+		m_dragSnapRotation = this->rotation();
 		resetCursor();
 	} else if(
 		(button == Qt::LeftButton || button == Qt::RightButton ||
@@ -1301,6 +1309,7 @@ void CanvasView::penReleaseEvent(
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_dragmode = ViewDragMode::Prepared;
@@ -1341,6 +1350,7 @@ void CanvasView::penReleaseEvent(
 			case CanvasShortcuts::CANVAS_PAN:
 			case CanvasShortcuts::CANVAS_ROTATE:
 			case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+			case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 			case CanvasShortcuts::CANVAS_ZOOM:
 				m_penmode = PenMode::Normal;
 				m_dragmode = ViewDragMode::Prepared;
@@ -1462,16 +1472,19 @@ void CanvasView::wheelEvent(QWheelEvent *event)
 		break;
 	case CanvasShortcuts::CANVAS_ROTATE:
 	case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+	case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 	case CanvasShortcuts::CANVAS_ZOOM: {
 		event->accept();
 		m_zoomWheelDelta += deltaY;
 		int steps = m_zoomWheelDelta / 120;
 		m_zoomWheelDelta -= steps * 120;
 		if(steps != 0) {
 			if(action == CanvasShortcuts::CANVAS_ROTATE) {
-				setRotation(rotation() + steps * 10);
+				setRotationSnap(rotation() + steps * 10);
 			} else if(action == CanvasShortcuts::CANVAS_ROTATE_DISCRETE) {
 				rotateByDiscreteSteps(steps);
+			} else if(action == CanvasShortcuts::CANVAS_ROTATE_NO_SNAP) {
+				setRotation(rotation() + steps * 10);
 			} else {
 				zoomStepsAt(steps, mapToCanvas(compat::wheelPosition(*event)));
 			}
@@ -1528,6 +1541,7 @@ void CanvasView::keyPressEvent(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_dragAction = mouseMatch.action();
@@ -1550,6 +1564,7 @@ void CanvasView::keyPressEvent(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_penmode = PenMode::Normal;
@@ -1562,6 +1577,7 @@ void CanvasView::keyPressEvent(QKeyEvent *event)
 			m_dragLastPoint = mapFromGlobal(QCursor::pos());
 			m_dragCanvasPoint = mapToCanvas(m_dragLastPoint);
 			m_dragDiscreteRotation = 0.0;
+			m_dragSnapRotation = rotation();
 			resetCursor();
 			break;
 		default:
@@ -1584,6 +1600,7 @@ void CanvasView::keyPressEvent(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 			m_penmode = PenMode::Normal;
 			m_dragmode = ViewDragMode::Prepared;
@@ -1632,6 +1649,7 @@ void CanvasView::keyReleaseEvent(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_dragmode = ViewDragMode::None;
@@ -1651,6 +1669,7 @@ void CanvasView::keyReleaseEvent(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_dragmode = ViewDragMode::Started;
@@ -1660,6 +1679,7 @@ void CanvasView::keyReleaseEvent(QKeyEvent *event)
 			m_dragInverted = mouseMatch.inverted();
 			m_dragSwapAxes = mouseMatch.swapAxes();
 			m_dragDiscreteRotation = 0.0;
+			m_dragSnapRotation = rotation();
 			resetCursor();
 			break;
 		default:
@@ -1681,6 +1701,7 @@ void CanvasView::keyReleaseEvent(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 			m_dragmode = ViewDragMode::Prepared;
 			m_dragAction = mouseMatch.action();
@@ -1988,16 +2009,18 @@ void CanvasView::moveDrag(const QPoint &point)
 		scrollBy(deltaX, deltaY);
 		break;
 	case CanvasShortcuts::CANVAS_ROTATE:
-	case CanvasShortcuts::CANVAS_ROTATE_DISCRETE: {
+	case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+	case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP: {
 		qreal hw = width() / 2.0;
 		qreal hh = height() / 2.0;
 		qreal a1 = qAtan2(hw - m_dragLastPoint.x(), hh - m_dragLastPoint.y());
 		qreal a2 = qAtan2(hw - point.x(), hh - point.y());
 		qreal ad = qRadiansToDegrees(a1 - a2);
 		qreal r = m_dragInverted ? -ad : ad;
 		if(m_dragAction == CanvasShortcuts::CANVAS_ROTATE) {
-			setRotation(rotation() + r);
-		} else {
+			m_dragSnapRotation += r;
+			setRotationSnap(m_dragSnapRotation);
+		} else if(m_dragAction == CanvasShortcuts::CANVAS_ROTATE_DISCRETE) {
 			m_dragDiscreteRotation += r;
 			qreal discrete = m_dragDiscreteRotation / ROTATION_STEP_SIZE;
 			if(discrete >= 1.0) {
@@ -2009,6 +2032,8 @@ void CanvasView::moveDrag(const QPoint &point)
 				m_dragDiscreteRotation += steps * -ROTATION_STEP_SIZE;
 				rotateByDiscreteSteps(steps);
 			}
+		} else {
+			setRotation(rotation() + r);
 		}
 		break;
 	}

diff --git a/src/desktop/scene/canvasview.h b/src/desktop/scene/canvasview.h
@@ -335,6 +335,7 @@ private slots:
 	void setViewportCursor(const QCursor &cursor);
 
 	void setZoomToFit(Qt::Orientations orientations);
+	void setRotationSnap(qreal degrees);
 	void rotateByDiscreteSteps(int steps);
 
 	void viewRectChanged();
@@ -386,6 +387,7 @@ private slots:
 	QPoint m_dragLastPoint;
 	QPointF m_dragCanvasPoint;
 	qreal m_dragDiscreteRotation;
+	qreal m_dragSnapRotation = 0.0;
 
 	//! Previous pointer location
 	canvas::Point m_prevpoint;

diff --git a/src/desktop/view/canvascontroller.cpp b/src/desktop/view/canvascontroller.cpp
@@ -701,16 +701,19 @@ void CanvasController::handleWheel(QWheelEvent *event)
 		break;
 	case CanvasShortcuts::CANVAS_ROTATE:
 	case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+	case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 	case CanvasShortcuts::CANVAS_ZOOM: {
 		event->accept();
 		m_zoomWheelDelta += deltaY;
 		int steps = m_zoomWheelDelta / 120;
 		m_zoomWheelDelta -= steps * 120;
 		if(steps != 0) {
 			if(action == CanvasShortcuts::CANVAS_ROTATE) {
-				setRotation(rotation() + steps * 10);
+				setRotationSnap(rotation() + steps * 10);
 			} else if(action == CanvasShortcuts::CANVAS_ROTATE_DISCRETE) {
 				rotateByDiscreteSteps(steps);
+			} else if(action == CanvasShortcuts::CANVAS_ROTATE_NO_SNAP) {
+				setRotation(rotation() + steps * 10);
 			} else {
 				zoomStepsAt(steps, mapPointToCanvasF(posf));
 			}
@@ -769,6 +772,7 @@ void CanvasController::handleKeyPress(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_dragAction = mouseMatch.action();
@@ -792,6 +796,7 @@ void CanvasController::handleKeyPress(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_penMode = PenMode::Normal;
@@ -804,6 +809,7 @@ void CanvasController::handleKeyPress(QKeyEvent *event)
 			m_dragLastPoint = mapPointFromGlobal(QCursor::pos());
 			m_dragCanvasPoint = mapPointToCanvasF(m_dragLastPoint);
 			m_dragDiscreteRotation = 0.0;
+			m_dragSnapRotation = rotation();
 			updateOutline();
 			resetCursor();
 			break;
@@ -823,6 +829,7 @@ void CanvasController::handleKeyPress(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 			m_penMode = PenMode::Normal;
 			m_dragMode = ViewDragMode::Prepared;
@@ -872,6 +879,7 @@ void CanvasController::handleKeyRelease(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_dragMode = ViewDragMode::None;
@@ -893,6 +901,7 @@ void CanvasController::handleKeyRelease(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_dragMode = ViewDragMode::Started;
@@ -902,6 +911,7 @@ void CanvasController::handleKeyRelease(QKeyEvent *event)
 			m_dragInverted = mouseMatch.inverted();
 			m_dragSwapAxes = mouseMatch.swapAxes();
 			m_dragDiscreteRotation = 0.0;
+			m_dragSnapRotation = rotation();
 			updateOutline();
 			resetCursor();
 			break;
@@ -924,6 +934,7 @@ void CanvasController::handleKeyRelease(QKeyEvent *event)
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 			m_dragMode = ViewDragMode::Prepared;
 			m_dragAction = mouseMatch.action();
@@ -1257,6 +1268,7 @@ void CanvasController::penPressEvent(
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 			if(m_dragMode != ViewDragMode::Started) {
 				m_dragMode = ViewDragMode::Prepared;
@@ -1289,6 +1301,7 @@ void CanvasController::penPressEvent(
 			m_dragButton = button;
 			m_dragModifiers = modifiers;
 			m_dragDiscreteRotation = 0.0;
+			m_dragSnapRotation = this->rotation();
 			resetCursor();
 
 		} else if(
@@ -1353,6 +1366,7 @@ void CanvasController::penReleaseEvent(
 		case CanvasShortcuts::CANVAS_PAN:
 		case CanvasShortcuts::CANVAS_ROTATE:
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 		case CanvasShortcuts::CANVAS_ZOOM:
 		case CanvasShortcuts::TOOL_ADJUST:
 			m_dragMode = ViewDragMode::Prepared;
@@ -1394,6 +1408,7 @@ void CanvasController::penReleaseEvent(
 			case CanvasShortcuts::CANVAS_PAN:
 			case CanvasShortcuts::CANVAS_ROTATE:
 			case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+			case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 			case CanvasShortcuts::CANVAS_ZOOM:
 				m_penMode = PenMode::Normal;
 				m_dragMode = ViewDragMode::Prepared;
@@ -1470,7 +1485,8 @@ void CanvasController::moveDrag(const QPoint &point)
 		scrollBy(deltaX, deltaY);
 		break;
 	case CanvasShortcuts::CANVAS_ROTATE:
-	case CanvasShortcuts::CANVAS_ROTATE_DISCRETE: {
+	case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
+	case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP: {
 		QSizeF halfSize = viewSizeF() / 2.0;
 		qreal hw = halfSize.width();
 		qreal hh = halfSize.height();
@@ -1479,8 +1495,9 @@ void CanvasController::moveDrag(const QPoint &point)
 		qreal ad = qRadiansToDegrees(a1 - a2);
 		qreal r = m_dragInverted ? -ad : ad;
 		if(m_dragAction == CanvasShortcuts::CANVAS_ROTATE) {
-			setRotation(rotation() + r);
-		} else {
+			m_dragSnapRotation += r;
+			setRotationSnap(m_dragSnapRotation);
+		} else if(m_dragAction == CanvasShortcuts::CANVAS_ROTATE_DISCRETE) {
 			m_dragDiscreteRotation += r;
 			qreal discrete = m_dragDiscreteRotation / DISCRETE_ROTATION_STEP;
 			if(discrete >= 1.0) {
@@ -1492,6 +1509,8 @@ void CanvasController::moveDrag(const QPoint &point)
 				m_dragDiscreteRotation += steps * -DISCRETE_ROTATION_STEP;
 				rotateByDiscreteSteps(steps);
 			}
+		} else {
+			setRotation(rotation() + r);
 		}
 		break;
 	}
@@ -1531,6 +1550,7 @@ void CanvasController::resetCursor()
 													: Qt::OpenHandCursor);
 			break;
 		case CanvasShortcuts::CANVAS_ROTATE:
+		case CanvasShortcuts::CANVAS_ROTATE_NO_SNAP:
 			setViewportCursor(m_rotateCursor);
 			break;
 		case CanvasShortcuts::CANVAS_ROTATE_DISCRETE:
@@ -1973,6 +1993,11 @@ void CanvasController::setZoomToFit(Qt::Orientations orientations)
 	}
 }
 
+void CanvasController::setRotationSnap(qreal degrees)
+{
+	setRotation(qAbs(std::fmod(degrees, 360.0)) < 5.0 ? 0.0 : degrees);
+}
+
 void CanvasController::rotateByDiscreteSteps(int steps)
 {
 	constexpr qreal EPS = 0.01;

diff --git a/src/desktop/view/canvascontroller.h b/src/desktop/view/canvascontroller.h
@@ -294,6 +294,7 @@ class CanvasController : public QObject {
 	bool isRotationInverted() const { return m_mirror ^ m_flip; }
 
 	void setZoomToFit(Qt::Orientations orientations);
+	void setRotationSnap(qreal degrees);
 	void rotateByDiscreteSteps(int steps);
 
 	void emitTransformChanged();
@@ -399,6 +400,7 @@ class CanvasController : public QObject {
 	QPoint m_dragLastPoint;
 	QPointF m_dragCanvasPoint;
 	qreal m_dragDiscreteRotation = 0.0;
+	qreal m_dragSnapRotation = 0.0;
 	int m_zoomWheelDelta = 0;
 
 	bool m_canvasSizeChanging = false;