Factor axis tick calculation into reusable AxisTickInfo helper

Made-with: Cursor

Author: tegaidogun

include/ui/graph_widget.hpp

@@ -58,12 +58,20 @@ class GraphWidget : public QWidget {
     void leaveEvent(QEvent* event) override;
 
 private:
+    struct AxisTickInfo {
+        double min{};
+        double max{};
+        double step{};
+        double start{};
+    };
+
     void draw_axes(QPainter& painter);
     void draw_grid(QPainter& painter);
     void draw_graphs(QPainter& painter);
     void draw_axis_labels(QPainter& painter);
     void update_coordinates(const QPoint& pos);
     double calculate_grid_step(double range, int target_lines) const;
+    AxisTickInfo make_tick_info(double min, double max, int target_lines) const;
 
     graph::Graph* m_graph;
     graph::GraphConfig m_config;

src/ui/graph_widget.cpp

@@ -287,16 +287,11 @@ void GraphWidget::draw_grid(QPainter& painter) {
     painter.setPen(QPen(grid_color, 1, Qt::SolidLine));
 
     // Calculate appropriate grid spacing based on viewport
-    double x_range = x_max - x_min;
-    double y_range = y_max - y_min;
-    
-    // Smart grid spacing - adapt to zoom level
-    double x_step = calculate_grid_step(x_range, m_config.grid_spacing);
-    double y_step = calculate_grid_step(y_range, m_config.grid_spacing);
+    AxisTickInfo x_ticks = make_tick_info(x_min, x_max, m_config.grid_spacing);
+    AxisTickInfo y_ticks = make_tick_info(y_min, y_max, m_config.grid_spacing);
 
     // Vertical grid lines
-    double x_start = std::floor(x_min / x_step) * x_step;
-    for (double x = x_start; x <= x_max; x += x_step) {
+    for (double x = x_ticks.start; x <= x_ticks.max; x += x_ticks.step) {
         if (std::abs(x) < 1e-10) continue; // Skip origin (drawn as axis)
         int screen_x, screen_y;
         viewport.world_to_screen(x, y_min, width(), height(), screen_x, screen_y);
@@ -306,8 +301,7 @@ void GraphWidget::draw_grid(QPainter& painter) {
     }
 
     // Horizontal grid lines
-    double y_start = std::floor(y_min / y_step) * y_step;
-    for (double y = y_start; y <= y_max; y += y_step) {
+    for (double y = y_ticks.start; y <= y_ticks.max; y += y_ticks.step) {
         if (std::abs(y) < 1e-10) continue; // Skip origin (drawn as axis)
         int screen_x, screen_y;
         viewport.world_to_screen(x_min, y, width(), height(), screen_x, screen_y);
@@ -337,6 +331,22 @@ double GraphWidget::calculate_grid_step(double range, int target_lines) const {
     }
 }
 
+GraphWidget::AxisTickInfo GraphWidget::make_tick_info(double min, double max, int target_lines) const {
+    AxisTickInfo info;
+    info.min = min;
+    info.max = max;
+    const double range = max - min;
+    if (range <= 0.0 || target_lines <= 0) {
+        info.step = 1.0;
+        info.start = min;
+        return info;
+    }
+    
+    info.step = calculate_grid_step(range, target_lines);
+    info.start = std::floor(min / info.step) * info.step;
+    return info;
+}
+
 void GraphWidget::draw_axes(QPainter& painter) {
     if (!m_graph || !m_config.show_axes) return;
 
@@ -380,14 +390,13 @@ void GraphWidget::draw_axis_labels(QPainter& painter) {
 
     // X-axis labels
     if (y_min <= 0 && 0 <= y_max) {
-        double x_step = calculate_grid_step(x_max - x_min, 8);
-        double x_start = std::floor(x_min / x_step) * x_step;
-        for (double x = x_start; x <= x_max; x += x_step) {
+        AxisTickInfo x_ticks = make_tick_info(x_min, x_max, 8);
+        for (double x = x_ticks.start; x <= x_ticks.max; x += x_ticks.step) {
             if (std::abs(x) < 1e-10) continue; // Skip origin
             int screen_x, screen_y;
             viewport.world_to_screen(x, 0, width(), height(), screen_x, screen_y);
             if (screen_x >= 0 && screen_x <= width()) {
-                QString label = QString::number(x, 'f', x_step < 1.0 ? 1 : 0);
+                QString label = QString::number(x, 'f', x_ticks.step < 1.0 ? 1 : 0);
                 QFontMetrics fm(font);
                 QRect text_rect = fm.boundingRect(label);
                 text_rect.moveCenter(QPoint(screen_x, screen_y + 15));
@@ -398,14 +407,13 @@ void GraphWidget::draw_axis_labels(QPainter& painter) {
 
     // Y-axis labels
     if (x_min <= 0 && 0 <= x_max) {
-        double y_step = calculate_grid_step(y_max - y_min, 8);
-        double y_start = std::floor(y_min / y_step) * y_step;
-        for (double y = y_start; y <= y_max; y += y_step) {
+        AxisTickInfo y_ticks = make_tick_info(y_min, y_max, 8);
+        for (double y = y_ticks.start; y <= y_ticks.max; y += y_ticks.step) {
             if (std::abs(y) < 1e-10) continue; // Skip origin
             int screen_x, screen_y;
             viewport.world_to_screen(0, y, width(), height(), screen_x, screen_y);
             if (screen_y >= 0 && screen_y <= height()) {
-                QString label = QString::number(y, 'f', y_step < 1.0 ? 1 : 0);
+                QString label = QString::number(y, 'f', y_ticks.step < 1.0 ? 1 : 0);
                 QFontMetrics fm(font);
                 QRect text_rect = fm.boundingRect(label);
                 text_rect.moveCenter(QPoint(screen_x - 15, screen_y));