Converting screen pixels into percent.

[Nickydude]

Hi guys.

My maths is non existent so I'm hoping one of you boffins might be able to help.

I have an object that can be dragged around on screen, the very center of the object is the anchor point and I need some way of converting the x and y co ordinates from pixel to percent.

Let's say, for example, I have a 800 x 600 screen, the very center would be 400 x 300 which would be 50% x 50%. if the object was dragged to 400 x 200 then that would be 50% x 33% (I think).

Does anyone have a formula that can do this, even if the resolution changed (to say 1024 x 768)? Any help would be appreciated.

[UrbanMonk]

Take the x position and divide it by the x size of the screen and multiply that by 100

so if the screen is 800 and the object is at 123 then the formula would be "(123/800)*100"

But you should do "floor(123*1.0/800*1.0)*100" for a more accurate measurement

Do the same for the y.

[Nickydude]

Thank you very much That is greatly appreciated.

[Anders]

A good way of remembering percentage is that you want the outcome to be 0% or 0.0 when the object is as position 0 (no matter the screen resolution) and 100% or 1.0 when the object is at the same position as the screen size. Think of it in "reverse". If the object is at position 800 and your screen size is 800, how do we get 1.0 out of it? From very basic math you know that any number divided with itself is 1 so that is a good start.

800 (object position)
--- = 1.0
800 (screen size)

1.0 is the equivalent of 100%.


If the object were half the way on the screen:

400 (object position)
--- = 0.5
800 (screen size)

which looks very much like 50% of the way