Support use of custom fonts in miniui

Bug: 29547343
Change-Id: I398160c85daac90ffab2fa9bb2e96795b9e9885a
diff --git a/minui/minui.h b/minui/minui.h
index fb0bbe1..23156b6 100644
--- a/minui/minui.h
+++ b/minui/minui.h
@@ -33,6 +33,12 @@
     unsigned char* data;
 };
 
+struct GRFont {
+    GRSurface* texture;
+    int char_width;
+    int char_height;
+};
+
 int gr_init();
 void gr_exit();
 
@@ -45,10 +51,14 @@
 void gr_clear();  // clear entire surface to current color
 void gr_color(unsigned char r, unsigned char g, unsigned char b, unsigned char a);
 void gr_fill(int x1, int y1, int x2, int y2);
-void gr_text(int x, int y, const char *s, bool bold);
+
 void gr_texticon(int x, int y, GRSurface* icon);
-int gr_measure(const char *s);
-void gr_font_size(int *x, int *y);
+
+const GRFont* gr_sys_font();
+int gr_init_font(const char* name, GRFont* dest);
+void gr_text(const GRFont* font, int x, int y, const char *s, bool bold);
+int gr_measure(const GRFont* font, const char *s);
+void gr_font_size(const GRFont* font, int *x, int *y);
 
 void gr_blit(GRSurface* source, int sx, int sy, int w, int h, int dx, int dy);
 unsigned int gr_get_width(GRSurface* surface);