[PATCH 2/2] kernel-shark: Always check if data is loaded before changing the graphs

["Yordan Karadzhov (VMware)" <y.karadz@gmail.com>]

We want all operations over the graphs (like Zoom or Scroll) to be
protected for the case when no data is loaded or no graphs are plotted.

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
---
 kernel-shark/src/KsGLWidget.cpp   | 22 ++++++++++++++++++++--
 kernel-shark/src/KsGLWidget.hpp   |  2 ++
 kernel-shark/src/KsTraceGraph.cpp |  9 +++++++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/kernel-shark/src/KsGLWidget.cpp b/kernel-shark/src/KsGLWidget.cpp
index ce68052..e930006 100644
--- a/kernel-shark/src/KsGLWidget.cpp
+++ b/kernel-shark/src/KsGLWidget.cpp
@@ -88,9 +88,11 @@ void KsGLWidget::paintGL()
 
 	glClear(GL_COLOR_BUFFER_BIT);
 
+	if (isEmpty())
+		return;
+
 	/* Draw the time axis. */
-	if(_data)
-		_drawAxisX(size);
+	_drawAxisX(size);
 
 	/* Process and draw all graphs by using the built-in logic. */
 	_makeGraphs(_cpuList, _taskList);
@@ -127,6 +129,13 @@ void KsGLWidget::reset()
 	_model.reset();
 }
 
+/** Check if the widget is empty (not showing anything). */
+bool KsGLWidget::isEmpty() const {
+	return !_data ||
+	       !_data->size() ||
+	       (!_cpuList.size() && !_taskList.size());
+}
+
 /** Reimplemented event handler used to receive mouse press events. */
 void KsGLWidget::mousePressEvent(QMouseEvent *event)
 {
@@ -198,6 +207,9 @@ void KsGLWidget::mouseMoveEvent(QMouseEvent *event)
 	size_t row;
 	bool ret;
 
+	if (isEmpty())
+		return;
+
 	if (_rubberBand.isVisible())
 		_rangeBoundStretched(_posInRange(event->pos().x()));
 
@@ -224,6 +236,9 @@ void KsGLWidget::mouseMoveEvent(QMouseEvent *event)
 /** Reimplemented event handler used to receive mouse release events. */
 void KsGLWidget::mouseReleaseEvent(QMouseEvent *event)
 {
+	if (isEmpty())
+		return;
+
 	if (event->button() == Qt::LeftButton) {
 		size_t posMouseRel = _posInRange(event->pos().x());
 		int min, max;
@@ -251,6 +266,9 @@ void KsGLWidget::wheelEvent(QWheelEvent * event)
 {
 	int zoomFocus;
 
+	if (isEmpty())
+		return;
+
 	if (_mState->activeMarker()._isSet &&
 	    _mState->activeMarker().isVisible()) {
 		/*
diff --git a/kernel-shark/src/KsGLWidget.hpp b/kernel-shark/src/KsGLWidget.hpp
index e141b0a..3d428b1 100644
--- a/kernel-shark/src/KsGLWidget.hpp
+++ b/kernel-shark/src/KsGLWidget.hpp
@@ -41,6 +41,8 @@ public:
 
 	void reset();
 
+	bool isEmpty() const;
+
 	/** Reprocess all graphs. */
 	void update() {resizeGL(width(), height());}
 
diff --git a/kernel-shark/src/KsTraceGraph.cpp b/kernel-shark/src/KsTraceGraph.cpp
index 324f36e..2e48372 100644
--- a/kernel-shark/src/KsTraceGraph.cpp
+++ b/kernel-shark/src/KsTraceGraph.cpp
@@ -234,6 +234,9 @@ void KsTraceGraph::_zoomOut()
 
 void KsTraceGraph::_quickZoomIn()
 {
+	if (_glWindow.isEmpty())
+		return;
+
 	/* Bin size will be 100 ns. */
 	_glWindow.model()->quickZoomIn(100);
 	if (_mState->activeMarker()._isSet &&
@@ -249,6 +252,9 @@ void KsTraceGraph::_quickZoomIn()
 
 void KsTraceGraph::_quickZoomOut()
 {
+	if (_glWindow.isEmpty())
+		return;
+
 	_glWindow.model()->quickZoomOut();
 }
 
@@ -646,6 +652,9 @@ void KsTraceGraph::_updateGraphs(GraphActions action)
 	double k;
 	int bin;
 
+	if (_glWindow.isEmpty())
+		return;
+
 	/*
 	 * Set the "Key Pressed" flag. The flag will stay set as long as the user
 	 * keeps the corresponding action button pressed.
-- 
2.20.1