I recommend to to use the ini file for makeing the minimap size.

Let me explain how it works.

I implemented the ini file to have a refWidth and refHeight which is used to calculate the percentage value which is used by GTA to setup the viewport.

so width is divided by refWidth, height is divided by refHeight

Lets take [email protected]´s 1280x700

there you have HUD_RADAR 0.053,0.785 0.187,0.167 HUD_COLOUR_WHITE 150

where 0.187 is percentage width of you resolution so multiply that by 1280 which is 239.36

so in the ini file refWidth is 1280 and refHeight is 700

width is 239.36

we do the same for height which is then 116.9

so the ini file is

[minimap]
refWidth = 1280
refHeight = 700
width = 239.36
height = 116.9

So if you want the same size for 1280x1024 you just have to replace refWidth and refHeight. Then if the minimap is too big you can scale width and height down by multiply them with some values lets say 0.9.

so then the ini file is

[minimap]
refWidth = 1280
refHeight = 1024
width = 215.424
height = 105.21

I hope you understand that.