rg_display: Added on-screen battery icon when battery is low (<2%) (rel #188)

As of now there is no way to disable it, but I will add a toggle later, likely in the LED menu (and rename the menu to Indicators or something)..

Author: ducalex

components/retro-go/rg_display.c

@@ -10,7 +10,6 @@
 static rg_task_t *display_task_queue;
 static rg_display_counters_t counters;
 static rg_display_config_t config;
-// static rg_surface_t *osd;
 static rg_surface_t *border;
 static rg_display_t display;
 static int16_t map_viewport_to_source_x[RG_SCREEN_WIDTH + 1];
@@ -45,6 +44,38 @@ static inline void lcd_send_buffer(uint16_t *buffer, size_t length);
 #include "drivers/display/dummy.h"
 #endif
 
+static inline bool draw_on_screen_display(int y1, int y2)
+{
+    static unsigned area_dirty = 0;
+    rg_margins_t margins = rg_gui_get_safe_area();
+    int left = display.screen.width - margins.right - 28;
+    int top = margins.top + 4;
+    int border = 3;
+    int width = 20;
+    int height = 14;
+
+    // Check if the region contains OSD to draw
+    if (y2 < top || y1 > top + height)
+        return false;
+
+    // Low battery indicator
+    if (rg_system_get_indicator(RG_INDICATOR_POWER_LOW) && ((counters.totalFrames / 20) & 1))
+    {
+        rg_display_clear_rect(left, top, width, height, C_RED); // Main body
+        rg_display_clear_rect(left + width, top + height / 4, border, height / 2, C_RED); // The tab
+        rg_display_clear_rect(left + border, top + border, width - border * 2, height - border * 2, C_BLACK); // The fill
+        area_dirty |= 1 << RG_INDICATOR_POWER_LOW;
+    }
+    else if (area_dirty)
+    {
+        if (display.viewport.left || display.viewport.top)
+            rg_display_clear_rect(left, top, width + border, height, C_BLACK);
+        memset(&screen_line_checksum[top], 0, sizeof(uint32_t) * height);
+        area_dirty = 0;
+    }
+    return true;
+}
+
 static inline unsigned blend_pixels(unsigned a, unsigned b)
 {
     // Fast path (taken 80-90% of the time)
@@ -102,6 +133,7 @@ static inline void write_update(const rg_surface_t *update)
     int lines_remaining = draw_height;
     int lines_updated = 0;
     int window_top = -1;
+    int osd_threshold = 24;
 
     for (int y = 0; y < draw_height;)
     {
@@ -211,6 +243,13 @@ static inline void write_update(const rg_surface_t *update)
             lcd_send_buffer(line_buffer, 0);
         }
 
+        // if (draw_on_screen_display(draw_top + y - lines_to_copy, draw_top + y))
+        if (draw_top + y > osd_threshold && draw_on_screen_display(0, draw_top + y))
+        {
+            osd_threshold = 9999;
+            window_top = -1;
+        }
+
         lines_remaining -= lines_to_copy;
     }
 
@@ -328,7 +367,7 @@ static void display_task(void *arg)
         }
 
         write_update(msg.dataPtr);
-
+        // draw_on_screen_display(0, display.screen.height);
         rg_task_receive(&msg);
 
         lcd_sync();