From 616ade56d7af7cfb3e8b76f2ca98e07357d8285d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20Madar=C3=A1sz?= <zaklaus@outlook.com>
Date: Sun, 10 Dec 2023 16:47:42 +0100
Subject: [PATCH] add font_metrics() method

---
 demos/01-font.c |  3 ++-
 engine/v4k.c    | 31 +++++++++++++++++++++++++++++++
 engine/v4k.h    | 16 ++++++++++++----
 3 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/demos/01-font.c b/demos/01-font.c
index 42511b1..fc73def 100644
--- a/demos/01-font.c
+++ b/demos/01-font.c
@@ -117,7 +117,8 @@ int main() {
             char *txt = "This is the first line.\nAnd now the second line.\nYou can do a third great line, too!\n";
             font_goto(pos.x, pos.y);
             vec2 size=font_rect(txt);
-            ddraw_aabb(vec3(pos.x,pos.y,0), vec3(pos.x+size.x,pos.y+size.y,0));
+            font_metrics_t m=font_metrics(txt);
+            ddraw_aabb(vec3(pos.x,pos.y,0), vec3(pos.x+size.x,pos.y+size.y-m.descent+m.linegap,0));
             font_print(txt);
             ddraw_pop_2d();
         }
diff --git a/engine/v4k.c b/engine/v4k.c
index d38b668..31fec2a 100644
--- a/engine/v4k.c
+++ b/engine/v4k.c
@@ -11050,6 +11050,37 @@ vec2 font_highlight(const char *text, const void *colors) {
 vec2 font_rect(const char *str) {
     return font_draw_ex(str, gotoxy, NULL, NULL);
 }
+
+font_metrics_t font_metrics(const char *text) {
+    font_metrics_t m={0};
+    int S = 3;
+    font_t *f = &fonts[0];
+
+    // utf8 to utf32
+    array(uint32_t) unicode = string32(text);
+
+    // parse string
+    for( int i = 0, end = array_count(unicode); i < end; ++i ) {
+        uint32_t ch = unicode[i];
+        if( ch >= 1 && ch <= 6 ) {
+            S = ch;
+            continue;
+        }
+        if( ch >= 0x1a && ch <= 0x1f ) {
+            if( fonts[ ch - 0x1a ].initialized) {
+                // change face
+                f = &fonts[ ch - 0x1a ];
+            }
+            continue;
+        }
+    }
+
+    m.ascent = f->ascent*f->factor*f->scale[S];
+    m.descent = f->descent*f->factor*f->scale[S];
+    m.linegap = f->linegap*f->factor*f->scale[S];
+    m.linedist = f->linedist*f->factor*f->scale[S];
+    return m;
+}
 #line 0
 
 #line 1 "v4k_gui.c"
diff --git a/engine/v4k.h b/engine/v4k.h
index 0ada3b9..b81c1f1 100644
--- a/engine/v4k.h
+++ b/engine/v4k.h
@@ -2182,6 +2182,13 @@ enum FONT_FLAGS {
     // FONT_DEFAULTS = FONT_512 | FONT_NO_OVERSAMPLE | FONT_ASCII,
 };
 
+typedef struct font_metrics_t {
+	float ascent;   // max distance above baseline for all glyphs
+    float descent;  // max distance below baseline for all glyphs
+    float linegap;  // distance betwen ascent of next line and descent of current line
+    float linedist; // distance between the baseline of two lines (ascent - descent + linegap)
+} font_metrics_t;
+
 // configures
 API void  font_face(const char *face_tag, const char *filename_ttf, float font_size, unsigned flags);
 API void  font_face_from_mem(const char *tag, const void *ttf_buffer, unsigned ttf_len, float font_size, unsigned flags);
@@ -2190,10 +2197,11 @@ API void  font_color(const char *color_tag, uint32_t color);
 API void  ui_font();
 
 // commands
-API vec2  font_xy();
-API void  font_goto(float x, float y);
-API vec2  font_print(const char *text);
-API vec2  font_rect(const char *text);
+API vec2  		   font_xy();
+API void  		   font_goto(float x, float y);
+API vec2  		   font_print(const char *text);
+API vec2  		   font_rect(const char *text);
+API font_metrics_t font_metrics(const char *text);
 //  void  font_clip(vec2 topleft, vec2 bottomright);
 //  void  font_wrap(vec2 topleft, vec2 bottomright);