CPFontManager convertFont:toFace:.

AppKit/CPFontManager.j

@@ -189,6 +189,20 @@ var CPSharedFontManager     = nil,
     return aFont;
 }
 
+- (CPFont)convertFont:(CPFont)aFont toFace:(CPString)aTypeface
+{
+    if (!aFont)
+        return nil;
+
+    var shouldBeBold = [aFont isBold],
+        shouldBeItalic = [aFont isItalic],
+        shouldBeSize = [aFont size];
+
+    aFont = [CPFont _fontWithName:aTypeface size:shouldBeSize bold:shouldBeBold italic:shouldBeItalic] || aFont;
+
+    return aFont;
+}
+
 - (@action)addFontTrait:(id)sender
 {
     _activeChange = [CPDictionary dictionaryWithObject:[sender tag] forKey:@"addTraits"];

Tests/AppKit/CPFontManagerTest.j

@@ -108,6 +108,18 @@
     [self assert:12.0 equals:[convertedFontB size] message:@"maintain size fontB with CPUnitalicFontMask"];
 }
 
+- (void)testConvertFont_toFace_
+{
+    fontB = [CPFont boldFontWithName:@"Helvetica" size:12.0 italic:YES];
+
+    convertedFontB = [[CPFontManager sharedFontManager] convertFont:fontB toFace:@"Arial"];
+
+    [self assertTrue:[convertedFontB isBold] message:@"maintain bold fontB"];
+    [self assertTrue:[convertedFontB isItalic] message:@"maintain italic fontB"];
+    [self assert:12.0 equals:[convertedFontB size] message:@"maintain size fontB"];
+    [self assert:@"Arial" equals:[convertedFontB familyName] message:@"change face fontB"];
+}
+
 - (@action)changeFont:(id)sender
 {
     convertedFontA = [sender convertFont:fontA];