Add GMT_IS_IMAGE case

[Chuan1937]

Add a GMT_IS_IMAGE branch to the gmtinit_get_region_from_data() function, read the image header information using the correct image type and GMT_CONTAINER_ONLY mode, extract the boundary coordinates, and then release the data structure.

Fixes #8878

[Chuan1937]

@joa-quim
I add a new case for this problem, and add a test for it.
I don't know if it can solve this problem in julia.

[joa-quim]

@Chuan1937 Thanks a lot for looking into this. However, I don't think it solves it.

Adding a GMT_IS_IMAGE branch doesn't help because in gmtinit_set_missing_R_from_grid() the call to gmtinit_get_region_from_data is always done with GMT_IS_GRID

if ((err = gmtinit_get_region_from_data (API, GMT_IS_GRID, exact, options, wesn, &API->GMT->common.R.aspect)))

and in fact this doesn't seem to be a problem because at the end the code flow ends up in the function that read an image. I have debugged this a bit further but still think there is something fundamentally broken in gmtinit_set_missing_R_from_grid. I think I can now force it to follow a path that should work but can't still base it in a robust logic.

And your test script. Yes, I guess it will work but it is not testing this case. Reading a file works fine, but reading one that is already loaded in memory (and you would need GMT.jl to test this) is where this keep failing.

[Chuan1937]

Can you give me the failed Julia Code?
I've installed Julia.@joa-quim

[joa-quim]

I smell the scent of a challenge 😃

When I have a easy to use Julia function I'll post instructions here (later today).

But your attempts are way off. A pre-loaded image is one that was already read and data is present in memory. That is what the wrappers do when they want to send in data already available. It has nothing to do files and extensions. Have a look at my attempt that almost worked
https://github.com/GenericMappingTools/gmt/pull/8883/changes

[joa-quim]

OK, you need to install the GMT.jl master version. You do that with:

] add GMT#master

than pick two images (whatever) and do

montage(["A.png", "A.png"], grid=(1,2))     # This works because it tells GMT to read the files
montage([gmtread("A.png"), gmtread("A.png")], grid=(1,2))     # This works because the montage function passes a -R under the hood in all commands
montage([gmtread("A.png"), gmtread("A.png")], grid=(1,2), noR=true)     # This fails due to issue of this issue