Why every drawing app still looks like MacPaint

It's an app, you know, even if you've never used it.

40 years later, its influence is still everywhere.

Mac paint didn't just set the bar for digital paint programs. It taught you to click, drag, copy, and paste.

And somehow it managed to do all of this with 128kB of memory.

That's less memory than an iPhone photograph.

The original iPhone.

Achieving this meant solving what at times seemed like insurmountable problems, the first perhaps being that in 1984, a computer for most people was anything but a tool for artists.

The Apple II’s killer app was a spreadsheet called Visicalc.

And if you wanted to draw pictures, you could move a little turtle around the screen with a few lines of logo.

At least, that's what was available to the general public.

20 years earlier, in 1963, locked away in a lab that most people would never see.

Ivan Sutherland created sketchpad.

It's one of the most remarkable applications ever made by one person, no less.

Not only did it let you draw shapes directly with a light pen, you could tell sketchpad to do things like make all the selected lines parallel, or make changes to nested copies that would update when you change the original.

The problem was that sketchpad required a room sized computer to run.

Well, that and drawing on a vertical screen tends to make your arm fall asleep.

But it had a lasting influence, especially on the pioneers at Xerox Parc, who by the early 1970s had succeeded in creating the first personal computer with a graphical user interface.

Inspired by sketchpad, they saw the value of giving users direct tactile control over a computer instead of a light pen.

direct tactile control over a computer instead of a light pen.

They chose a mouse.

And instead of a rigid programing language, they developed Smalltalk, which was so flexible and easy to use that even children were able to create applications in it.

But the Alto was a research machine and it was very expensive.

believing he could turn this concept into a mass market product, believing he could turn this concept into a mass market product, and knowing that Xerox wanted in on Apple's upcoming IPO.

Steve Jobs let them by $1 million worth of pre-IPO Apple shares in exchange for a peek behind the curtains at Xerox Parc.

One of the people on that field trip was Bill Atkinson.

Atkinson's task was to make the Alto's innovations work on an affordable machine.

His Polaroids.

The only way you could take a screenshot back then document a series of developments that we take for granted today.

From pull down menus to overlapping windows to a basic drawing program called, fittingly, sketchpad.

When Atkinson passed away in 2025, Daring Fireball wrote that without hyperbole, It was heroic, monumental work, but the Apple Lisa was ultimately doomed.

Yes. Despite

these ads featuring the star of ‘Sizzle Beach, USA’ being an expensive commercial flop.

But before it had even launched, jobs had already moved on to take a second crack at building a computer with a graphical user interface.

The Macintosh.

The Macintosh wouldn't be cheap, but at a quarter of the price of the Lisa, it would require every ounce of creative engineering possible to make it all work.

Jobs pushed the team to think of themselves as artists.

Susan Kerr already was one.

Kare had been enlisted to develop the visual language of the Mac.

An icon editor didn't exist yet, so Kare designed the earliest icons on graph paper.

How do you convey meaning in 32 by 32 pixels?

Kare found inspiration in things like woven textiles and kanji, pictographs and logo graphs that convey meaning with an economy of lines.

As Kare’s whimsical design language took shape.

Atkinson turned his attention from Lisa to Macintosh, and Steve Jobs asked him Atkinson turned his attention from Lisa to Macintosh, and Steve Jobs asked him to build a drawing app, something along the lines of Mark Cutter's Lisa Draw.

to build a drawing app, something along the lines of Mark Cutter's Lisa Draw.

Lisa draw, and the alto draw that came before it were structured.

Drawing apps, think diagrams and floor plans.

They were powerful and similar in spirit to Ivan Sutherland's Sketchpad from the 1960s.

Atkinson wanted to do something more direct and immediate, something more like SuperPaint SuperPaint was a bitmap graphics editor – another invention of Xerox PARC It was full color, something neither the Alto nor the Mac could do, and it already had concepts like brushes and palettes.

It also required a room full of custom, expensive hardware.

Atkinson had already created a basic drawing app for Lisa.

Mostly is a way to test out his low level graphics framework that would become known as Quickdraw.

He ported it over and Mac Sketch was born.

Now the challenge was how to turn it into a polished, user friendly application.

A question user a question user interface designers had been wrestling with since the days of the Alto.

Was this concept of modes.

Word processors, for instance, would often force users into something like a delete mode.

And if you forgot where you were, it was easy to machine gun away an entire paragraph by mistake.

The Alto philosophy was to allow users to perform actions on selections.

Larry Tesler, a Xerox PARC alum and Apple engineering manager, was so emphatic about this point that he had a license plate reading no modes.

But Atkinson felt that in art making we do switch modes.

We pick up a pencil and draw with it, put it back down and maybe pick up an eraser.

Rather than a menu.

Mac paint would have a tool palette, an idea you'd first pitch to the Lisa team.

And unlike earlier drawing apps that mixed concepts like tools and actions, Mac paint would be ruthlessly organized around a simple question what happens when I click?

Your mode would always be visible as the selected tool line with and pattern.

The next challenge was how to make the app feel immediate.

If the user wanted to draw an oval or a rounded rectangle, Atkinson wanted them to be able to see the shape stretch as they dragged.

But drawing straight to the screen and redrawing every time the mouse move would cause the image to flicker.

The solution was to compose frames off screen, swapping them at the last second.

as a bonus.

This gave Mac Paint undo basically for free.

Some of the best ideas come to us when we step away from the computer, and it was one such evening at a pub in Los Gatos that Bill Atkinson and it was one such evening at a pub in Los Gatos that Bill Atkinson discovered a solution to a problem that had been bugging him.

How to represent selections in Mac Paint.

You could invert the image, but in black and white, especially with a more complicated picture that could get confusing.

That's when Atkinson looked up and saw Hamm's beer That's when Atkinson looked up and saw Hamm's beer sign on the wall.

It had an animated waterfall, but as he stared at it, he realized the water wasn't actually moving.

There was a rotating mask underneath that caused the water to shimmer in a way that read like movement.

And it hit him that this simple technique could be used to represent selections.

The Marching Ants effect was born.

But rectangular selections alone wouldn't cut it.

Users would need to be able to select irregularly shaped objects.

The answer was hiding in another problem that Atkinson had been working on.

The paint bucket tool.

Ah, the paint bucket, whatever drawing app you grew up with.

You probably remember the thrill the first time you click the paint bucket to flood a canvas.

But how does it work?

Well, the simple version is that when you click, an algorithm checks the neighboring pixels to see if they're the same as the one you clicked, checks the neighboring pixels to see if they're the same as the one you clicked, and if they are, it fills them in..

Then it repeats the process for each of those pixels, and so on, expanding outwards until it hits the edges.

It's elegant, but wasteful.

At each step, you have to keep more and more state in memory, which is already pretty stretched on a machine with only 128kB of it.

A faster approach was the scanline method.

Starting from your seed pixel, you would expand left and right until you hit the edges and then repeat the process row But Atkinson pushed it one step further.

He realized that a lot of the times you were filling big, empty regions, and you didn't need to check those one pixel at a time.

You could just set all of those bits at once.

And for areas that were more complex, you'd fall back to the other algorithm of checking them individually.

It's the kind of solution that emerges from an intimate relationship with the machine itself.

And here's where it gets clever.

That fill algorithm spreading outwards until you hit a boundary.

It turned out to be the solution to the selection problem in reverse.

When you draw a loop with the Lasso Tool, Mac paint fills inwards until it finds the edges of the object you're trying to select.

The selection shrinks onto the object like plastic wrap.

You don't have to trace anything. Precisely.

You just gesture around it, and the algorithm takes The Lasso tool is a true Atkinson original, still copied to this day.

One final challenge was vexing Atkinson how to let users edit text.

If you've ever used a bitmap graphics editor, you know the problem.

Once you've typed text, it becomes baked into the image.

uneditable.

Atkinson decided to try something absurd, teaching Mac paint to turn pixels back into characters.

It worked by a check summing each character's pixels against tables of the fonts.

The same trick your computer uses to verify files.

And it worked.

And users could edit what it found.

But wait, you still can't do that in most paint programs today.

What gives?

well, after all that work, Atkinson, to his team's astonishment, decided to cut the feature.

He worried that he worried that people would use Mac paint as a kind of word processor, and that it would be a pretty lousy one.

Better to simplify and be better to simplify and be a great paint program.

But as impressive and lasting as all these achievements were.

Atkinson needed to see how Mac paint would click in the hands of a real artist.

Working mostly from home, Atkinson would bring his latest work into Apple to show Susan Kare and then watch her discover the program strengths He’d go back home, make improvements and rinse and repeat.

In this way, through constant iteration and testing, Mac paint became more and more polished.

Atkinson would later credit Kare as co-designer of Mac Payne.

Their collaboration wasn't just about how Mac paint looked.

Kare also saved Atkinson from an indelicate named menu.

He had tucked a set of extras into something called the Aids menu.

It was the early 1980s, and like most of the public, Atkinson had yet to become aware of the emerging public health crisis of the same name.

Kare flagged it.

The rest of the team confirmed it and it was renamed the Goodies Menu.

Inside that goodies menu is another innovative feature called Fat Bits.

It was basically a magnification tool that let you paint pixel by pixel.

It included a mini map that showed you where you were in the larger document, a feature that you could still see in many apps today.

Fat bits inspired Andy Herzfeld, Macintosh software architect and resident wizard, to create an icon editor for Kare, who at this point was still creating them on graph paper.

Kare had taken Atkinson's rough icons and turned them into the timelessly recognizable ones we know today.

She did so much more than just paint pixels.

She created the visual vocabulary of the personal computer.

None of this was planned, nor was it accidental.

The guiding principle of the Macintosh team was to think like artists, and that enthusiasm could be felt in every aspect of the machine, from the light hearted human touch of the user interface to the circuit board signed by its creators.

Mac paint shipped with every Macintosh, and for millions of people, it was their first contact with the mouse.

It wasn't just a vehicle for creative expression.

It taught you how to click, drag, copy, and paste.

Many critics dismiss the Mac as a toy, but over the years it helped spark the desktop publishing revolution, and Mac paints influence can still be felt across countless creative apps today.

Fun, it turns out, is good for business.