Add an advanced pref to disable custom box-drawing code. Issue 6151

sources/iTermAdvancedSettingsModel.h

@@ -194,5 +194,6 @@
 + (CGFloat)verticalBarCursorWidth;
 + (BOOL)statusBarIcon;
 + (BOOL)sensitiveScrollWheel;
++ (BOOL)disableCustomBoxDrawing;
 @end

sources/iTermAdvancedSettingsModel.m

@@ -176,6 +176,7 @@ DEFINE_INT(adaptiveFrameRateThroughputThreshold, 10000, @"Drawing: Throughput th
 DEFINE_BOOL(dwcLineCache, YES, @"Drawing: Enable cache of double-width character locations?\nThis should improve performance. It is always on in nightly builds. You must restart iTerm2 for this setting to take effect.");
 DEFINE_BOOL(useGCDUpdateTimer, YES, @"Drawing: Use GCD-based update timer instead of NSTimer.\nThis should cause more regular screen updates. Restart iTerm2 after changing this setting.");
 DEFINE_BOOL(drawOutlineAroundCursor, NO, @"Drawing: Draw outline around underline and vertical bar cursors using background color.");
+DEFINE_BOOL(disableCustomBoxDrawing, NO, @"Drawing: Use your typeface’s box-drawing characters instead of iTerm2’s custom drawing code.\nYou must restart iTerm2 after changing this setting.");
 #pragma mark - Semantic History
 DEFINE_BOOL(ignoreHardNewlinesInURLs, NO, @"Semantic History: Ignore hard newlines for the purposes of locating URLs and file names for Semantic History.\nIf a hard newline occurs at the end of a line then cmd-click will not see it all unless this setting is turned on. This is useful for some interactive applications. Turning this on will remove newlines from the \\3 and \\4 substitutions.");

sources/iTermBoxDrawingBezierCurveFactory.m

@@ -7,6 +7,8 @@
 //
 #import "iTermBoxDrawingBezierCurveFactory.h"
+
+#import "iTermAdvancedSettingsModel.h"
 #import "charmaps.h"
 #import "NSArray+iTerm.h"
@@ -16,10 +18,14 @@
     static NSCharacterSet *sBoxDrawingCharactersWithBezierPaths;
     static dispatch_once_t onceToken;
     dispatch_once(&onceToken, ^{
-        sBoxDrawingCharactersWithBezierPaths =
+        if ([iTermAdvancedSettingsModel disableCustomBoxDrawing]) {
+            sBoxDrawingCharactersWithBezierPaths = [[NSCharacterSet characterSetWithCharactersInString:@""] retain];
+        } else {
+            sBoxDrawingCharactersWithBezierPaths =
             [[NSCharacterSet characterSetWithCharactersInString:@"─━│┃┌┍┎┏┐┑┒┓└┕┖┗┘┙┚┛├┝┞┟┠┡┢┣┤"
               @"┥┦┧┨┩┪┫┬┭┮┯┰┱┲┳┴┵┶┷┸┹┺┻┼┽┾┿╀╁╂╃╄╅╆╇╈╉╊╋═║╒╓╔╕╖╗╘╙╚╛╜╝╞╟╠╡╢╣╤╥╦╧╨╩╪╫╬╴╵╶╷╸╹╺╻╼╽╾╿"
               @"╯╮╰╭╱╲╳"] retain];
+        };
     });
     return sBoxDrawingCharactersWithBezierPaths;
 }