Server side support for BFont::IsFullAndHalfFixed().

Check a range of characters to see if they have the same width.

Change-Id: I9cef12f78d1e1d01acc6284eae90dbfb86166fc6
Reviewed-on: https://review.haiku-os.org/47
Reviewed-by: Adrien Destugues <[email protected]>
Reviewed-by: Jérôme Duval <[email protected]>

src/servers/app/font/FontStyle.cpp

@@ -37,7 +37,8 @@ FontStyle::FontStyle(node_ref& nodeRef, const char* path, FT_Face face)
 	fFamily(NULL),
 	fID(0),
 	fBounds(0, 0, 0, 0),
-	fFace(_TranslateStyleToFace(face->style_name))
+	fFace(_TranslateStyleToFace(face->style_name)),
+	fFullAndHalfFixed(false)
 {
 	fName.Truncate(B_FONT_STYLE_LENGTH);
 		// make sure this style can be found using the Be API
@@ -50,6 +51,26 @@ FontStyle::FontStyle(node_ref& nodeRef, const char* path, FT_Face face)
 	// calculate it because height = ascending + descending + leading
 	fHeight.leading = (double)(face->height - face->ascender + face->descender)
 		/ face->units_per_EM;
+
+	if (IsFixedWidth())
+		return;
+
+	// manually check if all applicable chars are the same width
+
+	FT_Int32 loadFlags = FT_LOAD_NO_SCALE | FT_LOAD_TARGET_NORMAL;
+	if (FT_Load_Char(face, (uint32)' ', loadFlags) != 0)
+		return;
+
+	int firstWidth = face->glyph->advance.x;
+	for (uint32 c = ' ' + 1; c <= 0x7e; c++) {
+		if (FT_Load_Char(face, c, loadFlags) != 0)
+			return;
+
+		if (face->glyph->advance.x != firstWidth)
+			return;
+	}
+
+	fFullAndHalfFixed = true;
 }
 
 

src/servers/app/font/FontStyle.h

@@ -82,7 +82,7 @@ class FontStyle : public ReferenceCounting, public Hashable {
 	\return false (for now)
 */
 		bool			IsFullAndHalfFixed() const
-							{ return false; };
+							{ return fFullAndHalfFixed; };
 
 /*!
 	\fn bool FontStyle::IsScalable(void)
@@ -171,6 +171,7 @@ class FontStyle : public ReferenceCounting, public Hashable {
 
 		font_height		fHeight;
 		uint16			fFace;
+		bool			fFullAndHalfFixed;
 };
 
 #endif	// FONT_STYLE_H_