Patched LVGL 7.11.0 to support chart minor division lines and added them in two screens.

platformio/lib/lvgl.7.11.0/lvgl.h

@@ -16,7 +16,9 @@ extern "C" {
 #define LVGL_VERSION_MAJOR 7
 #define LVGL_VERSION_MINOR 11
 #define LVGL_VERSION_PATCH 0
-#define LVGL_VERSION_INFO ""
+// Patches:
+// June 2021 zapta - Added to lv_chart specification of minor division lines.
+#define LVGL_VERSION_INFO "7.11.0.patched"
 
 /*********************
  *      INCLUDES

platformio/lib/lvgl.7.11.0/src/lv_widgets/lv_chart.c

@@ -108,6 +108,12 @@ lv_obj_t * lv_chart_create(lv_obj_t * par, const lv_obj_t * copy)
 
     ext->hdiv_cnt              = LV_CHART_HDIV_DEF;
     ext->vdiv_cnt              = LV_CHART_VDIV_DEF;
+    // Patch(zapta): Lines whose index has a set bit here use
+    // an alternative line specification. Used to draw minor
+    // division lines.
+    ext->hdiv_minor_div_lines_mask    = 0;
+    ext->vdiv_minor_div_lines_mask    = 0;
+    //
     ext->point_cnt             = LV_CHART_PNUM_DEF;
     ext->type                  = LV_CHART_TYPE_LINE;
     ext->update_mode           = LV_CHART_UPDATE_MODE_SHIFT;
@@ -147,6 +153,8 @@ lv_obj_t * lv_chart_create(lv_obj_t * par, const lv_obj_t * copy)
         ext->type       = ext_copy->type;
         ext->hdiv_cnt   = ext_copy->hdiv_cnt;
         ext->vdiv_cnt   = ext_copy->vdiv_cnt;
+        ext->hdiv_minor_div_lines_mask  = ext_copy->hdiv_minor_div_lines_mask;
+        ext->vdiv_minor_div_lines_mask  = ext_copy->vdiv_minor_div_lines_mask;
         ext->point_cnt  = ext_copy->point_cnt;
         _lv_memcpy_small(ext->ymin, ext_copy->ymin, sizeof(ext->ymin));
         _lv_memcpy_small(ext->ymax, ext_copy->ymax, sizeof(ext->ymax));
@@ -312,6 +320,20 @@ void lv_chart_set_div_line_count(lv_obj_t * chart, uint8_t hdiv, uint8_t vdiv)
     lv_obj_invalidate(chart);
 }
 
+// Patch(zapta): Allows to specify division lines with alternative color, width,
+// etc.
+void lv_chart_set_minor_div_lines_masks(lv_obj_t * chart, uint32_t hdiv_mask, uint32_t vdiv_mask)
+{
+    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);
+
+    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
+
+    ext->hdiv_minor_div_lines_mask = hdiv_mask;
+    ext->vdiv_minor_div_lines_mask = vdiv_mask;
+
+    lv_obj_invalidate(chart);
+}
+
 /**
  * Set the minimal and maximal y values on an axis
  * @param chart pointer to a graph background object
@@ -1070,6 +1092,14 @@ static void draw_series_bg(lv_obj_t * chart, const lv_area_t * series_area, cons
     lv_coord_t x_ofs = series_area->x1;
     lv_coord_t y_ofs = series_area->y1;
 
+    // Patch(zapta): For minor division line specification we use
+    // the line specification from that chart's BG part.
+    lv_draw_line_dsc_t minor_line_dsc;
+    lv_draw_line_dsc_init(&minor_line_dsc);
+    lv_obj_init_draw_line_dsc(chart, LV_CHART_PART_BG, &minor_line_dsc);
+    //
+
+    // Normal division line specification comes from the series BG part.
     lv_draw_line_dsc_t line_dsc;
     lv_draw_line_dsc_init(&line_dsc);
     lv_obj_init_draw_line_dsc(chart, LV_CHART_PART_SERIES_BG, &line_dsc);
@@ -1088,10 +1118,12 @@ static void draw_series_bg(lv_obj_t * chart, const lv_area_t * series_area, cons
         p1.x = 0 + x_ofs;
         p2.x = w - 1 + x_ofs;
         for(div_i = div_i_start; div_i <= div_i_end; div_i++) {
-            p1.y = (int32_t)((int32_t)(h - line_dsc.width) * div_i) / (ext->hdiv_cnt + 1);
+            const bool is_minor = ext->hdiv_minor_div_lines_mask & (1u << div_i);
+            lv_draw_line_dsc_t* const l_dsc = is_minor ? &minor_line_dsc : &line_dsc;
+            p1.y = (int32_t)((int32_t)(h - l_dsc->width) * div_i) / (ext->hdiv_cnt + 1);
             p1.y += y_ofs;
             p2.y = p1.y;
-            lv_draw_line(&p1, &p2, clip_area, &line_dsc);
+            lv_draw_line(&p1, &p2, clip_area, l_dsc);
         }
     }
 
@@ -1109,10 +1141,12 @@ static void draw_series_bg(lv_obj_t * chart, const lv_area_t * series_area, cons
         p1.y = 0 + y_ofs;
         p2.y = h + y_ofs - 1;
         for(div_i = div_i_start; div_i <= div_i_end; div_i++) {
+            const bool is_minor_line = ext->vdiv_minor_div_lines_mask & (1u << div_i);
+            lv_draw_line_dsc_t* const l_dsc = is_minor_line ? &minor_line_dsc : &line_dsc;
             p1.x = (int32_t)((int32_t)(w - line_dsc.width) * div_i) / (ext->vdiv_cnt + 1);
             p1.x += x_ofs;
             p2.x = p1.x;
-            lv_draw_line(&p1, &p2, clip_area, &line_dsc);
+            lv_draw_line(&p1, &p2, clip_area, l_dsc);
         }
     }
 }

platformio/lib/lvgl.7.11.0/src/lv_widgets/lv_chart.h

@@ -118,6 +118,9 @@ typedef struct {
     lv_chart_axis_cfg_t x_axis;
     lv_chart_axis_cfg_t secondary_y_axis;
     uint8_t update_mode : 1;
+    // Patch(zapta): Masks for identifying minor division lines.
+    uint32_t hdiv_minor_div_lines_mask;
+    uint32_t vdiv_minor_div_lines_mask;
 } lv_chart_ext_t;
 
 /*Parts of the chart*/
@@ -196,6 +199,8 @@ void lv_chart_hide_series(lv_obj_t * chart, lv_chart_series_t * series, bool hid
  */
 void lv_chart_set_div_line_count(lv_obj_t * chart, uint8_t hdiv, uint8_t vdiv);
 
+void lv_chart_set_minor_div_lines_masks(lv_obj_t * chart, uint32_t hdiv_mask, uint32_t vdiv_mask);
+
 /**
  * Set the minimal and maximal y values on an axis
  * @param chart pointer to a graph background object

platformio/src/ui/osciloscope_screen.cpp

@@ -7,15 +7,15 @@
 
 static const ui::ChartAxisConfigs kAxisConfigsNormal{
     .y_range = {.min = -2500, .max = 2500},
-    .x = {.labels = "0\n5ms\n10ms\n15ms\n20ms", .num_ticks = 5, .dividers = 3},
+    .x = {.labels = "0\n5ms\n10ms\n15ms\n20ms", .num_ticks = 5, .dividers = 19, .minor_div_lines_mask = 0xf7bde},
-    .y = {.labels = "2.5A\n0\n-2.5A", .num_ticks = 3, .dividers = 1}};
+    .y = {.labels = "2.5A\n0\n-2.5A", .num_ticks = 3, .dividers = 9, .minor_div_lines_mask = 0x03de}};
 
 static const ui::ChartAxisConfigs kAxisConfigsAlternative{
     .y_range = {.min = -2500, .max = 2500},
     .x = {.labels = "0\n20ms\n40ms\n60ms\n80ms\n100ms",
           .num_ticks = 6,
-          .dividers = 4},
+          .dividers = 19, .minor_div_lines_mask = 0xeeeee},
-    .y = {.labels = "2.5A\n0\n-2.5A", .num_ticks = 3, .dividers = 1}};
+    .y = {.labels = "2.5A\n0\n-2.5A", .num_ticks = 3, .dividers = 9, .minor_div_lines_mask = 0x03de}};
 
 void OsciloscopeScreen::setup(uint8_t screen_num) {
   ui::create_screen(&screen_);

platformio/src/ui/phase_screen.cpp

@@ -10,8 +10,8 @@ static lv_point_t points[analyzer::kCaptureBufferSize];
 
 static const ui::ChartAxisConfigs kAxisConfigs{
     .y_range = {.min = -2500, .max = 2500},
-    .x = {.labels = "-2.5A\n0\n2.5A", .num_ticks = 3, .dividers = 1},
+    .x = {.labels = "-2.5A\n0\n2.5A", .num_ticks = 3, .dividers = 9,  .minor_div_lines_mask = 0x03de},
-    .y = {.labels = "2.5A\n0\n-2.5A", .num_ticks = 3, .dividers = 1}};
+    .y = {.labels = "2.5A\n0\n-2.5A", .num_ticks = 3, .dividers = 9,  .minor_div_lines_mask = 0x03de}};
 
 void PhaseScreen::setup(uint8_t screen_num) {
   ui::create_screen(&screen_);

platformio/src/ui/ui.cpp

@@ -117,17 +117,22 @@ static void common_lv_chart_bg_style(lv_style_t* bg_style) {
 static void init_chart_styles() {
   // Background style
   lv_style_init(&chart_styles.bg);
-
   common_lv_chart_bg_style(&chart_styles.bg);
+  // Patch(zapta): Specifciation of minor division lines.
+  lv_style_set_line_color(&chart_styles.bg, LV_STATE_DEFAULT,
+                          LV_COLOR_MAKE(0x20, 0x20, 0x20));  // dark gray
+  lv_style_set_line_width(&chart_styles.bg, LV_STATE_DEFAULT, 1);
 
-  // Series style
+
+  // Series style (graph)
   lv_style_init(&chart_styles.series);
   lv_style_set_size(&chart_styles.series, LV_STATE_DEFAULT, 0);
   lv_style_set_line_width(&chart_styles.series, LV_STATE_DEFAULT, 2);
 
-  // Series bg style
+  // Series bg style (grid lines)
   lv_style_init(&chart_styles.series_bg);
   lv_style_set_line_dash_gap(&chart_styles.series_bg, LV_STATE_DEFAULT, 0);
+  lv_style_set_line_width(&chart_styles.series_bg, LV_STATE_DEFAULT, 1);
   lv_style_set_line_color(&chart_styles.series_bg, LV_STATE_DEFAULT,
                           LV_COLOR_MAKE(0x00, 0x40, 0x00));  // dark green
 }
@@ -138,6 +143,11 @@ static void init_polar_chart_styles() {
 
   common_lv_chart_bg_style(&polar_chart_styles.bg);
 
+  // Patch(zapta): Specifciation of minor division lines.
+  lv_style_set_line_color(&polar_chart_styles.bg, LV_STATE_DEFAULT,
+                           LV_COLOR_MAKE(0x20, 0x20, 0x20));  // dark gray
+  lv_style_set_line_width(&polar_chart_styles.bg, LV_STATE_DEFAULT, 1);
+
   // Series bg style (grid)
   lv_style_init(&polar_chart_styles.series_bg);
   lv_style_set_line_dash_gap(&polar_chart_styles.series_bg, LV_STATE_DEFAULT,
@@ -372,6 +382,7 @@ void set_chart_scale(lv_obj_t* lv_chart, const ChartAxisConfigs& axis_configs) {
   // include the frame.
   lv_chart_set_div_line_count(lv_chart, axis_configs.y.dividers,
                               axis_configs.x.dividers);
+  lv_chart_set_minor_div_lines_masks(lv_chart, axis_configs.y.minor_div_lines_mask, axis_configs.x.minor_div_lines_mask);
 
   lv_chart_set_y_tick_length(lv_chart, 0, 0);
   lv_chart_set_x_tick_length(lv_chart, 0, 0);

platformio/src/ui/ui.h

@@ -85,6 +85,7 @@ struct ChartAxisConfig {
   uint8_t num_ticks = 0;
   // Vertical or horizontal internal grid lines.
   uint8_t dividers;
+  uint32_t minor_div_lines_mask = 0;
   bool is_enabled() const { return num_ticks > 0 && labels != nullptr; }
 };