New Style option: Overlap

If this option is enable, the blenfont check for overlap characters, like
one of my previous commit but now it's optional and disable by default.
(This fix the "Fi" or other case when the characters are too close)

Enable/disable from:
Outliner -> User Preferences -> Styles -> Panel Font -> Overlap

(also for other styles, Group Label, Widget, Widget Label)

source/blender/blenfont/BLF_api.h

@@ -135,6 +135,7 @@ void BLF_dir_free(char **dirs, int count);
 #define BLF_FONT_KERNING (1<<2)
 #define BLF_USER_KERNING (1<<3)
 #define BLF_SHADOW (1<<4)
+#define BLF_OVERLAP_CHAR (1<<5)
 
 /* font->mode. */
 #define BLF_MODE_TEXTURE 0

source/blender/blenfont/intern/blf_font.c

@@ -146,20 +146,22 @@ void blf_font_draw(FontBLF *font, char *str)
 
 			if (FT_Get_Kerning(font->face, g_prev_index, glyph_index, FT_KERNING_UNFITTED, &delta) == 0) {
 				pen_x += delta.x >> 6;
-/*
-				if (pen_x < old_pen_x)
-					pen_x= old_pen_x;
-*/
+
+				if (font->flags & BLF_OVERLAP_CHAR) {
+					if (pen_x < old_pen_x)
+						pen_x= old_pen_x;
+				}
 			}
 		}
 
 		if (font->flags & BLF_USER_KERNING) {
 			old_pen_x= pen_x;
 			pen_x += font->kerning;
-/*
-			if (pen_x < old_pen_x)
-				pen_x= old_pen_x;
-*/
+
+			if (font->flags & BLF_OVERLAP_CHAR) {
+				if (pen_x < old_pen_x)
+					pen_x= old_pen_x;
+			}
 		}
 
 		/* do not return this loop if clipped, we want every character tested */
@@ -228,20 +230,22 @@ void blf_font_boundbox(FontBLF *font, char *str, rctf *box)
 
 			if (FT_Get_Kerning(font->face, g_prev_index, glyph_index, FT_KERNING_UNFITTED, &delta) == 0) {
 				pen_x += delta.x >> 6;
-/*
-				if (pen_x < old_pen_x)
-					old_pen_x= pen_x;
-*/
+
+				if (font->flags & BLF_OVERLAP_CHAR) {
+					if (pen_x < old_pen_x)
+						pen_x= old_pen_x;
+				}
 			}
 		}
 
 		if (font->flags & BLF_USER_KERNING) {
 			old_pen_x= pen_x;
 			pen_x += font->kerning;
-/*
-			if (pen_x < old_pen_x)
-				old_pen_x= pen_x;
-*/
+
+			if (font->flags & BLF_OVERLAP_CHAR) {
+				if (pen_x < old_pen_x)
+					pen_x= old_pen_x;
+			}
 		}
 
 		gbox.xmin= g->box.xmin + pen_x;

source/blender/blenfont/intern/blf_glyph.c

@@ -500,6 +500,8 @@ int blf_glyph_texture_render(FontBLF *font, GlyphBLF *g, float x, float y)
 	float color[4];
 
 	gt= g->tex_data;
+	xo= 0.0f;
+	yo= 0.0f;
 
 	if (font->flags & BLF_SHADOW) {
 		xo= x;

source/blender/editors/interface/interface_style.c

@@ -92,6 +92,7 @@ static uiStyle *ui_style_new(ListBase *styles, const char *name)
 	style->paneltitle.uifont_id= UIFONT_DEFAULT;
 	style->paneltitle.points= 13;
 	style->paneltitle.kerning= 0.0;
+	style->paneltitle.overlap= 0;
 	style->paneltitle.shadow= 5;
 	style->paneltitle.shadx= 2;
 	style->paneltitle.shady= -2;
@@ -101,6 +102,7 @@ static uiStyle *ui_style_new(ListBase *styles, const char *name)
 	style->grouplabel.uifont_id= UIFONT_DEFAULT;
 	style->grouplabel.points= 12;
 	style->grouplabel.kerning= 0.0;
+	style->grouplabel.overlap= 0;
 	style->grouplabel.shadow= 3;
 	style->grouplabel.shadx= 1;
 	style->grouplabel.shady= -1;
@@ -109,6 +111,7 @@ static uiStyle *ui_style_new(ListBase *styles, const char *name)
 	style->widgetlabel.uifont_id= UIFONT_DEFAULT;
 	style->widgetlabel.points= 11;
 	style->widgetlabel.kerning= 0.0;
+	style->widgetlabel.overlap= 0;
 	style->widgetlabel.shadow= 3;
 	style->widgetlabel.shadx= 1;
 	style->widgetlabel.shady= -1;
@@ -171,10 +174,15 @@ void uiStyleFontDraw(uiFontStyle *fs, rcti *rect, char *str)
 		BLF_shadow_offset(fs->shadx, fs->shady);
 	}
 
+	if (fs->overlap)
+		BLF_enable(BLF_OVERLAP_CHAR);
+
 	BLF_draw(str);
 	BLF_disable(BLF_CLIPPING);
 	if (fs->shadow)
 		BLF_disable(BLF_SHADOW);
+	if (fs->overlap)
+		BLF_disable(BLF_OVERLAP_CHAR);
 }
 
 /* ************** helpers ************************ */

source/blender/makesdna/DNA_userdef_types.h

@@ -67,7 +67,8 @@ typedef struct uiFontStyle {
 	short uifont_id;		/* saved in file, 0 is default */
 	short points;			/* actual size depends on 'global' dpi */
 	float kerning;			/* kerning space between characters. */
-	float pad;
+	short overlap;			/* check overlaped characters. */
+	short pad;
 	short italic, bold;		/* style hint */
 	short shadow;			/* value is amount of pixels blur */
 	short shadx, shady;		/* shadow offset in pixels */

source/blender/makesrna/intern/rna_userdef.c

@@ -139,7 +139,12 @@ static void rna_def_userdef_theme_ui_font_style(BlenderRNA *brna)
 
 	prop= RNA_def_property(srna, "kerning", PROP_FLOAT, PROP_NONE);
 	RNA_def_property_range(prop, -5.0, 5.0);
-	RNA_def_property_ui_text(prop, "Kerning", "");
+	RNA_def_property_ui_text(prop, "Kerning", "User kerning value in pixels");
+	RNA_def_property_update(prop, NC_WINDOW, NULL);
+
+	prop= RNA_def_property(srna, "overlap", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "overlap", 1);
+	RNA_def_property_ui_text(prop, "Overlap", "Check for overlap characters");
 	RNA_def_property_update(prop, NC_WINDOW, NULL);
 
 	prop= RNA_def_property(srna, "shadow", PROP_INT, PROP_NONE);