Delete empty annotations automatically

After switching away from having one selected, since people often
accidentally create empty annotations and leave them strewn around. If
the user wanted to keep the annotation, they can hit undo and to make it
come back.

Implements #1351.

src/libclient/canvas/paintengine.cpp

@@ -291,6 +291,19 @@ uint16_t PaintEngine::findAvailableAnnotationId(uint8_t forUser) const
 	return 0;
 }
 
+drawdance::Annotation PaintEngine::getAnnotationById(int annotationId) const
+{
+	drawdance::AnnotationList annotations = viewCanvasState().annotations();
+	int count = annotations.count();
+	for(int i = 0; i < count; ++i) {
+		drawdance::Annotation annotation = annotations.at(i);
+		if(annotation.id() == annotationId) {
+			return annotation;
+		}
+	}
+	return drawdance::Annotation::null();
+}
+
 drawdance::Annotation
 PaintEngine::getAnnotationAt(int x, int y, int expand) const
 {

src/libclient/canvas/paintengine.h

@@ -131,6 +131,9 @@ class PaintEngine final : public QObject {
 	//! Find an unused ID for a new annotation
 	uint16_t findAvailableAnnotationId(uint8_t forUser) const;
 
+	//! Get the annotation at the given point
+	drawdance::Annotation getAnnotationById(int annotationId) const;
+
 	//! Get the annotation at the given point
 	drawdance::Annotation getAnnotationAt(int x, int y, int expand) const;
 

src/libclient/document.cpp

@@ -142,6 +142,10 @@ Document::Document(
 	connect(
 		this, &Document::buildStreamResetImageFinished, this,
 		&Document::startSendingStreamResetSnapshot, Qt::QueuedConnection);
+
+	connect(
+		m_toolctrl, &tools::ToolController::deleteAnnotationRequested, this,
+		&Document::deleteAnnotation);
 }
 
 void Document::initCanvas()
@@ -1627,6 +1631,16 @@ void Document::fillArea(const QColor &color, DP_BlendMode mode, float opacity)
 	m_messageBuffer.clear();
 }
 
+void Document::deleteAnnotation(int annotationId)
+{
+	unsigned int contextId = m_client->myId();
+	net::Message msgs[] = {
+		net::makeUndoPointMessage(contextId),
+		net::makeAnnotationDeleteMessage(contextId, annotationId),
+	};
+	m_client->sendMessages(2, msgs);
+}
+
 void Document::removeEmptyAnnotations()
 {
 	if(!m_canvas) {

src/libclient/document.h

@@ -294,6 +294,7 @@ public slots:
 	void copyLayer();
 	void cutLayer();
 
+	void deleteAnnotation(int annotationId);
 	void removeEmptyAnnotations();
 	void clearArea();
 	void fillArea(const QColor &color, DP_BlendMode mode, float opacity);

src/libclient/tools/toolcontroller.cpp

@@ -143,6 +143,14 @@ void ToolController::setActiveTool(Tool::Type tool)
 void ToolController::setActiveAnnotation(uint16_t id)
 {
 	if(m_activeAnnotation != id) {
+		if(m_activeAnnotation != 0) {
+			drawdance::Annotation a =
+				m_model->paintEngine()->getAnnotationById(m_activeAnnotation);
+			if(!a.isNull() && a.textBytes().isEmpty()) {
+				emit deleteAnnotationRequested(a.id());
+			}
+		}
+
 		m_activeAnnotation = id;
 		emit activeAnnotationChanged(id);
 	}

src/libclient/tools/toolcontroller.h

@@ -230,6 +230,7 @@ public slots:
 	void toolSwitchRequested(tools::Tool::Type tool);
 	void showMessageRequested(const QString &message);
 	void toolNoticeRequested(const QString &text);
+	void deleteAnnotationRequested(int annotationId);
 
 	void floodFillStateChanged(bool running, bool pending);
 	void toolStateChanged(int state);