Is the distance traveled while scrolling independent of screen resolution?

Question

Suppose you press the arrow keys for scrolling or use the mouse wheel.

If you just press an arrow key once or respectively scroll only one 'tick' with the mouse wheel - does the distance which is scrolled in px differ depending on what resolution the machine has that I'm currently on? Or is the scrolling distance a fixed distance?

Answer 1

...And, you can usually specify how many "lines" are to be scrolled per mouse wheel "click" in the mouse setup. Depending on the driver, it may be on the same dialog that lets you set how far the cursor moves with respect to how far you've moved the mouse (mouse cursor speed).

Lots of this is customizable in the mouse driver and in various programs (like web browsers), too.

When writing a program, in many languages you get to handle mouse movements and scroll wheel movements as well as what you do with up/down arrow keys, etc., within the program. So it isn't a fixed thing. It's largely up to the whim of the programmer writing whatever program you're running.

But getting to something else you may have been asking: The programs generally work with pixels or other relative distance units with regard to the screen. In a sense, the program may or may not care what your screen resolution is, and probably won't know at all what the physical size of the monitor is without going to fairly great lengths.

Keep in mind that screen resolution does not mean pixels per inch. It means total pixels available vertically or horizontally.

So I can have a monitor with a resolution of 1920 X 1080 that is 22" diagonally measured, and I can have another monitor that also has the same resolution (1920 X 1080) but is a 52" diagonal monitor. Both monitors have the same resolution. But the small one has a much finer "pitch" to its pixels. The pixels are closer together and smaller.

So using the large one, each mouse scroll will move the cursor (or whatever) by a much greater actual physical distance than it will when using the smaller monitor. But the effect is the same because both monitors are showing the same data. It's just presented smaller on the small monitor. The big one would make a good TV sitting 15 feet away. The smaller one would give the same "look" when placed only a few feet away from you (as on a desktop).

Same resolution. Same perceptual effect for each keypress or scroll wheel click. But different physical sizes and comfortable viewing distances.

This is often confusing to people when dealing with monitor or camera resolutions. Total pixels (resolution) does not equate to the same physical size because we also need to know how many pixels per inch the display or print is "mapped to".

A two megapixel image mapped to a 3.5" X 5" print will appear very smooth and with high quality. Map that same two megapixel (resolution) image onto a poster-sized print, and, viewed from up close, you'll see the individual pixels as small blocks. So it won't seem smooth or high quality. Yet both images have the same resolution and carry the same information. And if you step back from the poster, and look at it from a reasonable viewing distance, it will again look smooth and of good quality.

It's the same with a monitor. If you had a 52" TV with the same pixel pitch (spacing between pixels) as our 1920 X 1080 22" monitor, it would have a resolution that was about 5.6 times greater (because it has a surface area 5.6 times greater).

Our 1920 X 1080 monitor or TV is about 2 megapixels. It doesn't matter how big or small it is, it's still 2 megapixels. And that's what regular 1080p HDTV is.

But if we decided we wanted the same number of pixels per inch on our 52" TV as we have on our 22" computer monitor, then we'd end up with 5.6 times as many pixels so they'd cover that larger surface area with the same pixel pitch (spacing/size of pixels).

This would be a truly spectacular display. It would have a resolution of 4,538 X 2,553 pixels! That would be an 11.6 megapixel display. Pretty darned nice!

So the point is that there is no one physical relationship between size and resolution.

Resolution is the number of discrete steps into which we've divided something. But without knowing the overall size of that something, we can't say what the size of those steps is.

If we know the resolution AND the physical size, then we can compute the physical distance per step (pixels across a monitor in this case). And then, if we know how the operating system and program we're running will deal with mouse wheel clicks or presses of an arrow key, we can calculate the physical distance something will scroll or move on that one screen (whose size and resolution both are known).

That was probably boring enough. But hopefully it's useful for anyone who actually read it all. :)

Answer 2

It is far more complicated than that. Not only does it depend on the browser and customizable on some, the scrolling offset depends on the element being scrolled. There are many possibilities. Some elements scroll by a single text line, by a certain block-size or by pixel, for example.