Implement TTF_GetFontBBox() which returns font's extremum bounding box

include/SDL3_ttf/SDL_ttf.h

@@ -844,6 +844,33 @@ extern SDL_DECLSPEC void SDLCALL TTF_SetFontKerning(TTF_Font *font, bool enabled
  */
 extern SDL_DECLSPEC bool SDLCALL TTF_GetFontKerning(const TTF_Font *font);
 
+/**
+ * Query the font's bounding box.
+ *
+ * The bounding box defines bounds large enough to contain any glyph from
+ * the font. It is expressed in pixel offsets from glyph's origin (0,0),
+ * with Y axis pointing upwards. Thus maxy offset may be seen as the
+ * "maximum ascender" and miny offset - as the "minimum descender".
+ *
+ * \param font the font to query.
+ * \param minx a pointer filled in with the minimum x coordinate of *any* glyph
+ *             in this font from it's origin. This value may be negative.
+ * \param maxx a pointer filled in with the maximum x coordinate of *any* glyph
+ *             in this font from it's origin.
+ * \param miny a pointer filled in with the minimum y coordinate of *any* glyph
+ *             in this font from it's origin. This value may be negative.
+ * \param maxy a pointer filled in with the maximum y coordinate of *any* glyph
+ *             in this font from it's origin.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety This function should be called on the thread that created the
+ *               font.
+ *
+ * \since This function is available since SDL_ttf 3.4.0.
+ */
+extern SDL_DECLSPEC bool SDLCALL TTF_GetFontBBox(const TTF_Font *font, int *minx, int *maxx, int *miny, int *maxy);
+
 /**
  * Query whether a font is fixed-width.
  *

src/SDL_ttf.c

@@ -5915,6 +5915,34 @@ bool TTF_GetFontKerning(const TTF_Font *font)
     return font->enable_kerning;
 }
 
+bool TTF_GetFontBBox(const TTF_Font *font, int *minx, int *maxx, int *miny, int *maxy)
+{
+    TTF_CHECK_FONT(font, false);
+
+    /* Bitmap fonts do not contain bbox information */
+    if (!FT_IS_SCALABLE(font->face)) {
+        return false;
+    }
+
+    const FT_Face face = font->face;
+    /* Recalculate FT_Face's bbox from font units to pixels */
+    FT_Fixed xscale = face->size->metrics.x_scale;
+    FT_Fixed yscale = face->size->metrics.y_scale;
+    if (minx) {
+        *minx = FT_CEIL(FT_MulFix(face->bbox.xMin, xscale));
+    }
+    if (maxx) {
+        *maxx = FT_CEIL(FT_MulFix(face->bbox.xMax, xscale));
+    }
+    if (miny) {
+        *miny = FT_CEIL(FT_MulFix(face->bbox.yMin, yscale));
+    }
+    if (maxy) {
+        *maxy = FT_CEIL(FT_MulFix(face->bbox.yMax, yscale));
+    }
+    return true;
+}
+
 int TTF_GetNumFontFaces(const TTF_Font *font)
 {
     TTF_CHECK_FONT(font, 0);

src/SDL_ttf.sym

@@ -119,5 +119,6 @@ SDL3_ttf_0.0.0 {
     TTF_WasInit;
     TTF_SetFontCharSpacing;
     TTF_GetFontCharSpacing;
+    TTF_GetFontBBox;
   local: *;
 };