[Webkit-unassigned] [Bug 167597] New: ComplexTextController never worked if runs are non monotonic

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=167597

            Bug ID: 167597
           Summary: ComplexTextController never worked if runs are non
                    monotonic
    Classification: Unclassified
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Text
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: mmaxfield at apple.com
                CC: mmaxfield at apple.com

In ComplexTextController::advance(), we iterate through runs in string order. When we encounter a run, we append its paint advances into the GlyphBuffer and we increase the runWidthSoFar by its layout advance.

FontCascadeCocoa assumes that runs are adjacent. If the runs aren't adjacent or monotonic, our runWidthSoFar is meaningless because of this assumption.

Similarly, when we paint glyphs, we just paint them in the order they appear in the GlyphBuffer. If the runs aren't monotonic, then this order is completely busted and the results will be garbage.

Instead, since it never worked, we should just remove the logic about iterating to an arbitrary run in the middle of the ComplexTextController (inside advance()) and force monotonic iteration.

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