Scaling ratio of two different resolutions

I have two different resolutions, the original one is开发者_运维问答 567x756 (wXh), the one which I want to display is 768x1024 (wXh). How to find out the scaling ratio for these two resolutions? For example if the font size used in 567x756 resolution is 7 pts then what's the values I should multiply with the font size (7 pts) to display the text in 768x1024 resolution.

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Whenever you hear "scaling", think "proportions":

You can set up a proportion, here:

old width      new width
---------  =   --------
old font       new font

 567      768
----  =  -----
 7         x

567*x = 5376

x = 9.48

So your new font is about 9.48, or 9 if you only want integers.

Alternatively, you could also use the height-to-height proportion in your calculations instead of width-to-width. Or use the average font height you'd get from doing either. Or do old_area/old_font^2 = new_area/new_font^2

If you want a way to find the scaling factor for any arbitrary new width:

old width      new width
---------  =   --------
old font       new font

 567      w
----  =  ---
 7        x

567*x = 7*w

x = (7/567) * w

Given your new w (or h, or w/e), the new font size is (7/567) * w

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The aspect ratios are the same for both resolutions, so just take one dimension and use that as your scaling ratio, i.e.

1024/756

Which is about 1.35. Or if you want to scale in the other direction, 0.738