This is a horrible and yet not unexpected insight into the internals of Excel

To be fair this was Excell 25 years ago, may no longer be true.

One of the other bugs (the Quark/ATM one) was also because of the programmers were worried about writing over stuff that hadn't been completely erased, the Quark guys wrote a string with 2 spaces at the end through a box that masked the end of the string, the ATM font renderer saw it couldn't fit the text so it split it in half and tried again so it drew N/2 N/4 N/8 ... strings. It spent all it's time in the 68k's multiply instructions figuring out how wide the strings (and substrings) were, our fancy 24-bit character rendering hardware was an afterthought

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bathtub365 4 hours ago | parent | prev | next [-]

In all of the software you’ve written, are you aware of how many on-screen pixels you’ve overdrawn?

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trelbutate 3 hours ago | parent | prev [-]

> To be fair excel would erase places white that it wanted to write up to 9 times before it drew any black pixels

I feel like I'm having a stroke trying to read this, what does it mean??

	▲	Taniwha 37 minutes ago \| parent \| next [-]
		Well all they needed to do was erase the screen with white and draw on it, but their app's internal logic meant that they erased it more than once. I was capturing QuickDraw library calls - the low level graphics primitives, to figure out where the graphics time in apps was going and found out sometimes excel did it 9 times Of course users didn't see it more than once, but our hardware made all that wasted time run faster
	▲	NSUserDefaults 3 hours ago \| parent \| prev \| next [-]
		Several layers of white is what makes the black really pop. (Just kidding).
	▲	b112 3 hours ago \| parent \| prev \| next [-]
		It means they were time travellers! Secretly, they came from an alternate future where everyone used e-ink displays, and wanted Excel to be ready!
	▲	sixeyes 3 hours ago \| parent \| prev [-]
		before writing to some area, it would erase it (clearing with white) up to 9 times