[apps/shared] Create a class Range1D

apps/shared/Makefile

@@ -52,6 +52,7 @@ app_shared_src = $(addprefix apps/shared/,\
   parameter_text_field_delegate.cpp \
   post_and_hardware_tests.cpp \
   range_parameter_controller.cpp \
+  range_1D.cpp \
   regular_table_view_data_source.cpp \
   round_cursor_view.cpp \
   scrollable_exact_approximate_expressions_cell.cpp \

apps/shared/range_1D.cpp

@@ -0,0 +1,48 @@
+#include "range_1D.h"
+#include <assert.h>
+#include <ion.h>
+
+namespace Shared {
+
+static inline float minFloat(float x, float y) { return x < y ? x : y; }
+static inline float maxFloat(float x, float y) { return x > y ? x : y; }
+
+void Range1D::setMin(float min, float lowerMaxFloat, float upperMaxFloat) {
+  min = clipped(min, false, lowerMaxFloat, upperMaxFloat);
+  if (std::isnan(min)) {
+    return;
+  }
+  m_min = min;
+  if (m_min >= m_max) {
+    m_max = min + defaultRangeLengthFor(min);
+  }
+  if (m_max - min < k_minFloat) {
+    m_max = clipped(min + k_minFloat, true, lowerMaxFloat, upperMaxFloat);
+  }
+}
+
+void Range1D::setMax(float max, float lowerMaxFloat, float upperMaxFloat) {
+  max = clipped(max, true, lowerMaxFloat, upperMaxFloat);
+  if (std::isnan(max)) {
+    return;
+  }
+  m_max = max;
+  if (m_min >= m_max) {
+    m_min = max - defaultRangeLengthFor(max);
+  }
+  if (max-m_min < k_minFloat) {
+    m_min = clipped(max - k_minFloat, false, lowerMaxFloat, upperMaxFloat);
+  }
+}
+
+float Range1D::defaultRangeLengthFor(float position) {
+  return std::pow(10.0f, std::floor(std::log10(std::fabs(position)))-1.0f);
+}
+
+float Range1D::clipped(float x, bool isMax, float lowerMaxFloat, float upperMaxFloat) {
+  float maxF = isMax ? upperMaxFloat : lowerMaxFloat;
+  float minF = isMax ? -lowerMaxFloat : -upperMaxFloat;
+  return maxFloat(minF, minFloat(x, maxF));
+}
+
+}

apps/shared/range_1D.h

@@ -0,0 +1,31 @@
+#ifndef SHARED_RANGE_1D_H
+#define SHARED_RANGE_1D_H
+
+#include <cmath>
+#include <float.h>
+
+namespace Shared {
+
+class Range1D {
+public:
+  constexpr static float k_minFloat = 1E-4f;
+  Range1D(float min = -10.0f, float max = 10.0f) :
+    m_min(min),
+    m_max(max)
+  {}
+  float min() const { return m_min; }
+  float max() const { return m_max; }
+  void setMin(float f, float lowerMaxFloat = INFINITY, float upperMaxFloat = INFINITY);
+  void setMax(float f, float lowerMaxFloat = INFINITY, float upperMaxFloat = INFINITY);
+  static float clipped(float x, bool isMax, float lowerMaxFloat, float upperMaxFloat);
+  static float defaultRangeLengthFor(float position);
+private:
+  float m_min;
+  float m_max;
+};
+
+static_assert(Range1D::k_minFloat >= FLT_EPSILON, "InteractiveCurveViewRange's minimal float range is lower than float precision, it might draw uglily curves such as cos(x)^2+sin(x)^2");
+
+}
+
+#endif