inno wizard page size differs between XP and Win7 causing background image issue

Question

inno wizard page size differs between XP and Win7, its 100pix narrow in xp

is there exact knownledge how this works?

Should I have the different backgound images for xp and 7, the strech feature makes BMP image look bad

Answer 1

The different size you saw caused by different default value of DPI (Dots Per Inch) in both OSes. Windows XP and vista set the default value of logical DPI equal to 96 regardless your monitor size, but starting from Windows 7, the default value of DPI calculated by Windows automatically based on your monitor size. It will become a long explanation if I explain all DPI concept in this place. So, you are likely to see the background is bigger in Windows 7, right? because Windows 7 dpi value tends to be larger than 96, it could 120, 150, or even 192 dpi. Windows 7 will automatically decide it depends on your monitor size.

So, the best solution to your problem is by creating different background images for every possible dpi values you might encounter, then use GetDeviceCaps(..., LOGPIXELSX) to get the current dpi value used by Windows.