AP_OSD: allow for loading fonts from sdcard

user can put fontN.bin on their sdcard and it will replace the font in
romfs. This makes for easy font development, and allows for multiple
languages

This replaces #15668

libraries/AP_OSD/AP_OSD_Backend.cpp

@@ -51,3 +51,26 @@ void AP_OSD_Backend::write(uint8_t x, uint8_t y, bool blink, const char *fmt, ..
     va_end(ap);
 #endif
 }
+
+/*
+  load a font from sdcard or ROMFS
+ */
+FileData *AP_OSD_Backend::load_font_data(uint8_t font_num)
+{
+    FileData *fd;
+
+    // first try from microSD
+    char fontname[] = "font0.bin";
+    fontname[4] = font_num + '0';
+
+    fd = AP::FS().load_file(fontname);
+    if (fd == nullptr) {
+        char fontname_romfs[] = "@ROMFS/font0.bin";
+        fontname_romfs[7+4] = font_num + '0';
+        fd = AP::FS().load_file(fontname_romfs);
+    }
+    if (fd == nullptr) {
+        GCS_SEND_TEXT(MAV_SEVERITY_ERROR, "OSD: Failed to load font %u", font_num);
+    }
+    return fd;
+}

libraries/AP_OSD/AP_OSD_Backend.h

@@ -18,6 +18,7 @@
 
 #include <AP_HAL/HAL.h>
 #include <AP_OSD/AP_OSD.h>
+#include <AP_Filesystem/AP_Filesystem.h>
 
 
 class AP_OSD_Backend
@@ -72,6 +73,9 @@ protected:
         return (_osd.options & option) != 0;
     }
 
+    // load a font from sdcard or ROMFS
+    FileData *load_font_data(uint8_t font_num);
+
     int8_t blink_phase;
 
     enum vid_format {

libraries/AP_OSD/AP_OSD_MAX7456.cpp

@@ -22,7 +22,8 @@
 #include <AP_HAL/Util.h>
 #include <AP_HAL/Semaphores.h>
 #include <AP_HAL/Scheduler.h>
-#include <AP_ROMFS/AP_ROMFS.h>
+#include <AP_Filesystem/AP_Filesystem.h>
+#include <GCS_MAVLink/GCS.h>
 
 #include <utility>
 
@@ -157,13 +158,19 @@ bool AP_OSD_MAX7456::init()
 
 bool AP_OSD_MAX7456::update_font()
 {
-    uint32_t font_size;
     uint8_t updated_chars = 0;
-    char fontname[] = "font0.bin";
     last_font = get_font_num();
-    fontname[4] = last_font + '0';
-    const uint8_t *font_data = AP_ROMFS::find_decompress(fontname, font_size);
-    if (font_data == nullptr || font_size != NVM_RAM_SIZE * 256) {
+    FileData *fd = load_font_data(last_font);
+
+    if (fd == nullptr) {
+        return false;
+    }
+
+    const uint8_t *font_data = fd->data;
+    uint32_t font_size = fd->length;
+    if (font_size != NVM_RAM_SIZE * 256) {
+        GCS_SEND_TEXT(MAV_SEVERITY_ERROR, "AP_OSD: bad font size %u\n", unsigned(font_size));
+        delete fd;
         return false;
     }
 
@@ -173,18 +180,13 @@ bool AP_OSD_MAX7456::update_font()
         if (!check_font_char(chr, chr_font_data)) {
             //update char inside max7456 NVM
             if (!update_font_char(chr, chr_font_data)) {
-                hal.console->printf("AP_OSD: error during font char update\n");
-                AP_ROMFS::free(font_data);
+                delete fd;
                 return false;
             }
             updated_chars++;
         }
     }
-    if (updated_chars > 0) {
-        hal.console->printf("AP_OSD: updated %d symbols.\n", updated_chars);
-    }
-    hal.console->printf("AP_OSD: osd font is up to date.\n");
-    AP_ROMFS::free(font_data);
+    delete fd;
     return true;
 }
 

libraries/AP_OSD/AP_OSD_SITL.cpp

@@ -43,21 +43,13 @@ extern const AP_HAL::HAL &hal;
  */
 void AP_OSD_SITL::load_font(void)
 {
-    uint32_t font_size;
-    char fontname[] = "font0.bin";
     last_font = get_font_num();
-    fontname[4] = last_font + '0';
-    const uint8_t *font_data = AP_ROMFS::find_decompress(fontname, font_size);
-    if (font_data == nullptr && last_font != 0) {
-        last_font = 0;
-        fontname[4] = last_font + '0';
-        font_data = AP_ROMFS::find_decompress(fontname, font_size);
-    }
-    if (font_data == nullptr || font_size != 54 * 256) {
+    FileData *fd = load_font_data(last_font);
+    if (fd == nullptr || fd->length != 54 * 256) {
         AP_HAL::panic("Bad font file");
     }
     for (uint16_t i=0; i<256; i++) {
-        const uint8_t *c = &font_data[i*54];
+        const uint8_t *c = &fd->data[i*54];
         // each pixel is 4 bytes, RGBA
         sf::Uint8 *pixels = new sf::Uint8[char_width * char_height * 4];
         if (!font[i].create(char_width, char_height)) {
@@ -97,7 +89,7 @@ void AP_OSD_SITL::load_font(void)
         }
         font[i].update(pixels);
     }
-    AP_ROMFS::free(font_data);
+    delete fd;
 }
 
 void AP_OSD_SITL::write(uint8_t x, uint8_t y, const char* text)

libraries/AP_OSD/AP_OSD_Screen.cpp

@@ -1777,17 +1777,15 @@ void AP_OSD_Screen::draw_callsign(uint8_t x, uint8_t y)
 #if HAVE_FILESYSTEM_SUPPORT
     if (!callsign_data.load_attempted) {
         callsign_data.load_attempted = true;
-        int fd = AP::FS().open("callsign.txt", O_RDONLY);
-        if (fd != -1) {
-            char s[20] {};
-            int32_t len = AP::FS().read(fd, s, sizeof(s)-1);
+        FileData *fd = AP::FS().load_file("callsign.txt");
+        if (fd != nullptr) {
+            uint32_t len = fd->length;
             // trim off whitespace
-            while (len > 0 && isspace(s[len-1])) {
-                s[len-1] = 0;
+            while (len > 0 && isspace(fd->data[len-1])) {
                 len--;
             }
-            AP::FS().close(fd);
-            callsign_data.str = strdup(s);
+            callsign_data.str = strndup((const char *)fd->data, len);
+            delete fd;
         }
     }
     if (callsign_data.str != nullptr) {