gg: allow fonts loaded with $embed_file() to be used (#8263)

vlib/gg/gg.v

@@ -60,6 +60,11 @@ pub:
 	font_path             string
 	custom_bold_font_path string
 	ui_mode               bool // refreshes only on events to save CPU usage
+	// font bytes for embedding
+	font_bytes_normal []byte
+	font_bytes_bold   []byte
+	font_bytes_mono   []byte
+	font_bytes_italic []byte
 }
 
 pub struct Context {
@@ -131,14 +136,25 @@ fn gg_init_sokol_window(user_data voidptr) {
 		g.font_inited = true
 	} else {
 		if !exists {
-			sfont := system_font_path()
-			eprintln('font file "$g.config.font_path" does not exist, the system font was used instead.')
-			g.ft = new_ft(
-				font_path: sfont
-				custom_bold_font_path: g.config.custom_bold_font_path
-				scale: sapp.dpi_scale()
-			) or { panic(err) }
-			g.font_inited = true
+			if g.config.font_bytes_normal.len > 0 {
+				g.ft = new_ft(
+					bytes_normal: g.config.font_bytes_normal
+					bytes_bold: g.config.font_bytes_bold
+					bytes_mono: g.config.font_bytes_mono
+					bytes_italic: g.config.font_bytes_italic
+					scale: sapp.dpi_scale()
+				) or { panic(err) }
+				g.font_inited = true
+			} else {
+				sfont := system_font_path()
+				eprintln('font file "$g.config.font_path" does not exist, the system font was used instead.')
+				g.ft = new_ft(
+					font_path: sfont
+					custom_bold_font_path: g.config.custom_bold_font_path
+					scale: sapp.dpi_scale()
+				) or { panic(err) }
+				g.font_inited = true
+			}
 		}
 	}
 	//
@@ -237,7 +253,7 @@ pub fn new_context(cfg Config) &Context {
 		width: cfg.width
 		height: cfg.height
 		config: cfg
-		render_text: cfg.font_path != ''
+		render_text: cfg.font_path != '' || cfg.font_bytes_normal.len > 0
 		ft: 0
 		ui_mode: cfg.ui_mode
 	}

vlib/gg/text_rendering.v

@@ -29,11 +29,51 @@ struct FTConfig {
 	custom_bold_font_path string
 	scale                 f32 = 1.0
 	font_size             int
+	bytes_normal          []byte
+	bytes_bold            []byte
+	bytes_mono            []byte
+	bytes_italic          []byte
 }
 
 fn new_ft(c FTConfig) ?&FT {
 	if c.font_path == '' {
-		// Load default font
+		if c.bytes_normal.len > 0 {
+			fons := sfons.create(512, 512, 1)
+			bytes_normal := c.bytes_normal
+			bytes_bold := if c.bytes_bold.len > 0 {
+				c.bytes_bold
+			} else {
+				debug_font_println('setting bold variant to normal')
+				bytes_normal
+			}
+			bytes_mono := if c.bytes_mono.len > 0 {
+				c.bytes_mono
+			} else {
+				debug_font_println('setting mono variant to normal')
+				bytes_normal
+			}
+			bytes_italic := if c.bytes_italic.len > 0 {
+				c.bytes_italic
+			} else {
+				debug_font_println('setting italic variant to normal')
+				bytes_normal
+			}
+
+			return &FT{
+				fons: fons
+				font_normal: C.fonsAddFontMem(fons, 'sans', bytes_normal.data, bytes_normal.len,
+					false)
+				font_bold: C.fonsAddFontMem(fons, 'sans', bytes_bold.data, bytes_bold.len,
+					false)
+				font_mono: C.fonsAddFontMem(fons, 'sans', bytes_mono.data, bytes_mono.len,
+					false)
+				font_italic: C.fonsAddFontMem(fons, 'sans', bytes_italic.data, bytes_italic.len,
+					false)
+				scale: c.scale
+			}
+		} else {
+			// Load default font
+		}
 	}
 	$if !android {
 		if c.font_path == '' || !os.exists(c.font_path) {
@@ -144,7 +184,8 @@ pub fn (ctx &Context) text_width(s string) int {
 	mut buf := [4]f32{}
 	C.fonsTextBounds(ctx.ft.fons, 0, 0, s.str, 0, buf)
 	if s.ends_with(' ') {
-		return int((buf[2] - buf[0]) / ctx.scale) + ctx.text_width('i') // TODO fix this in fontstash?
+		return int((buf[2] - buf[0]) /
+			ctx.scale) + ctx.text_width('i') // TODO fix this in fontstash?
 	}
 	return int((buf[2] - buf[0]) / ctx.scale)
 }