how to resize an image mantaining aspect ratio.

[dcelso]

  hello to all. I have program to load a image on a timage. The image can be any known format of timage can load.

I need put a preview of the image in a 50x50 container so i want resize it maintaining aspect ratio. The result will be a 50x? Image or ?x50 image.
 what is the better method to do it.?

[User137]

Use math and logics. You get the relative size by Width/Height. For example 400x200 would give you 2, also that 200x200 image would result 1. So if x>1, then image is horizontally bigger. Same relation number can be used as a multiplier.
For example if you draw image horizontally, you can
image.width := 50;
image.height := 50 / x;

[dcelso]

Yes. I know it. But what function and image container can i use in Lazarus? For example Tlazimginterfaz has methods to do it?

[User137]

TPanel and TImage in it for example. TImage has Stretch property which you could use in this case.

[dcelso]

 , thanx i will try it