[apps/shared] Prevent label method from being called on uninitialized chars

apps/shared/curve_view.cpp

@@ -190,6 +190,8 @@ int CurveView::numberOfLabels(Axis axis) const {
   float minLabel = std::ceil(min(axis)/labelStep);
   float maxLabel = std::floor(max(axis)/labelStep);
   int numberOfLabels = maxLabel - minLabel + 1;
+  // Assert labels are up to date
+  assert(m_drawnRangeVersion == m_curveViewRange->rangeChecksum());
   assert(numberOfLabels <= (axis == Axis::Horizontal ? k_maxNumberOfXLabels : k_maxNumberOfYLabels));
   return numberOfLabels;
 }
@@ -226,19 +228,24 @@ void CurveView::computeLabels(Axis axis) {
 
     if (axis == Axis::Horizontal) {
       if (labelBuffer[0] == 0) {
-        /* Some labels are too big and may overlap their neighbours. We write the
+        /* Some labels are too big and may overlap their neighbors. We write the
          * extrema labels only. */
         computeHorizontalExtremaLabels();
-        return;
+        break;
       }
       if (i > 0 && strcmp(labelBuffer, label(axis, i-1)) == 0) {
         /* We need to increase the number if significant digits, otherwise some
          * labels are rounded to the same value. */
         computeHorizontalExtremaLabels(true);
-        return;
+        break;
       }
     }
   }
+  int maxNumberOfLabels = (axis == Axis::Horizontal ? k_maxNumberOfXLabels : k_maxNumberOfYLabels);
+  // All remaining labels are empty. They shouldn't be accessed anyway.
+  for (int i = axisLabelsCount; i < maxNumberOfLabels; i++) {
+    label(axis, i)[0] = 0;
+  }
 }
 
 void CurveView::simpleDrawBothAxesLabels(KDContext * ctx, KDRect rect) const {

apps/shared/curve_view_range.cpp

@@ -10,8 +10,8 @@
 namespace Shared {
 
 uint32_t CurveViewRange::rangeChecksum() {
-  float data[4] = {xMin(), xMax(), yMin(), yMax()};
-  size_t dataLengthInBytes = 4*sizeof(float);
+  float data[7] = {xMin(), xMax(), yMin(), yMax(), xGridUnit(), yGridUnit(), offscreenYAxis()};
+  size_t dataLengthInBytes = 7*sizeof(float);
   assert((dataLengthInBytes & 0x3) == 0); // Assert that dataLengthInBytes is a multiple of 4
   return Ion::crc32Word((uint32_t *)data, dataLengthInBytes/sizeof(uint32_t));
 }

apps/shared/curve_view_range.h

@@ -12,7 +12,7 @@ public:
     X,
     Y
   };
-  virtual uint32_t rangeChecksum();
+  uint32_t rangeChecksum();
 
   virtual float xMin() const = 0;
   virtual float xMax() const = 0;

apps/shared/interactive_curve_view_range.cpp

@@ -19,13 +19,6 @@ void InteractiveCurveViewRange::setDelegate(InteractiveCurveViewRangeDelegate *
   }
 }
 
-uint32_t InteractiveCurveViewRange::rangeChecksum() {
-  float data[] = {xMin(), xMax(), yMin(), yMax()};
-  size_t dataLengthInBytes = sizeof(data);
-  assert((dataLengthInBytes & 0x3) == 0); // Assert that dataLengthInBytes is a multiple of 4
-  return Ion::crc32Word((uint32_t *)data, dataLengthInBytes/sizeof(uint32_t));
-}
-
 void InteractiveCurveViewRange::setZoomAuto(bool v) {
   if (m_zoomAuto == v) {
     return;

apps/shared/interactive_curve_view_range.h

@@ -29,7 +29,6 @@ public:
   bool isOrthonormal() const;
 
   void setDelegate(InteractiveCurveViewRangeDelegate * delegate);
-  uint32_t rangeChecksum() override;
 
   bool zoomAuto() const { return m_zoomAuto; }
   void setZoomAuto(bool v);