AP_OSD: added OSD_FONT parameter

allow for user selection of font

libraries/AP_OSD/AP_OSD.cpp

@@ -76,6 +76,13 @@ const AP_Param::GroupInfo AP_OSD::var_info[] = {
     // @Bitmask: 0:UseDecimalPack
     // @User: Standard
     AP_GROUPINFO("_OPTIONS", 8, AP_OSD, options, OPTION_DECIMAL_PACK),
+
+    // @Param: _FONT
+    // @DisplayName: OSD Font
+    // @Description: This sets which OSD font to use. It is an integer from 0 to the number of fonts available
+    // @User: Standard
+    // @RebootRequired: True
+    AP_GROUPINFO("_FONT", 9, AP_OSD, font_num, 0),
     
     AP_GROUPEND
 };

libraries/AP_OSD/AP_OSD.h

@@ -161,6 +161,7 @@ public:
     AP_Int8 osd_type;
     AP_Int8 rc_channel;
     AP_Int8 sw_method;
+    AP_Int8 font_num;
 
     enum {
         OPTION_DECIMAL_PACK = 1U<<0,

libraries/AP_OSD/AP_OSD_Backend.h

@@ -52,6 +52,9 @@ public:
 protected:
     AP_OSD& _osd;
 
+    // get font choice
+    uint8_t get_font_num(void) const { return (uint8_t)_osd.font_num.get(); }
+
 };
 
 

libraries/AP_OSD/AP_OSD_MAX7456.cpp

@@ -155,7 +155,9 @@ bool AP_OSD_MAX7456::update_font()
 {
     uint32_t font_size;
     uint8_t updated_chars = 0;
-    uint8_t *font_data = AP_ROMFS::find_decompress("font0.bin", font_size);
+    char fontname[] = "font0.bin";
+    fontname[4] = get_font_num() + '0';
+    uint8_t *font_data = AP_ROMFS::find_decompress(fontname, font_size);
     if (font_data == nullptr || font_size != NVM_RAM_SIZE * 256) {
         return false;
     }

libraries/AP_OSD/AP_OSD_SITL.cpp

@@ -42,7 +42,9 @@ extern const AP_HAL::HAL &hal;
 void AP_OSD_SITL::load_font(void)
 {
     uint32_t font_size;
-    uint8_t *font_data = AP_ROMFS::find_decompress("font0.bin", font_size);
+    char fontname[] = "font0.bin";
+    fontname[4] = get_font_num() + '0';
+    uint8_t *font_data = AP_ROMFS::find_decompress(fontname, font_size);
     if (font_data == nullptr || font_size != 54 * 256) {
         AP_HAL::panic("Bad font file");
     }