Thanks for this hint. This could be a possibility, but I suppose it is rather slow on a big amount of pictures.
How do you think that Explorer retrieves this information ? Exactly in a similar manner
The only thing that explorer could perhaps do better (due to its integration) is caching the results in the background. That advantage is gone the moment you start to handle a big amount of files, as cache runs dry.
Now I installed the package: DExif and got the basic-example running - I get a heap-error closing the app. So I have no plan what to do?!
Post your project or create a simple example project showing that heaptrace error. You can publish your project inside lazarus and zip up the directory/files where you published the files into. You can attach that zip-file to a post on the forum
I made a simple example using FPC, based on the code you showed and i did not experience any leakage. That suggests that you have some leakage somewhere else inside your code and is probably not related to your use of DExif library.
fwiw: this is the output from my fpc test example (using the nokia test jpg that came with DExif):
> test
Camera Make : Nokia
Camera Model : 6300
Picture DateTime : 2017-09-11 09:57:02
Heap dump by heaptrc unit
1559 memory blocks allocated : 141850/158056
1559 memory blocks freed : 141850/158056
0 unfreed memory blocks : 0
True heap size : 163840 (96 used in System startup)
True free heap : 163744
Note that heaptrace does produce a message (i did not turned that off), but is telling that there are zero unfreed memory blocks (meaning everything went ok).