Doesn't print with "wireless direct print" (Test your IQ)?

Question

iOS

Good afternoon.
An interesting and strange problem.
Background - Does not print photos from WhatsApp and Photo galleries in Iphone (and not all photos).
Task:
Given:
1. Photo A - size 160 kb, 940x1280px
2. Photo B - Size 170 kb, 650x1280px
3. Photo C - Size 2.2 MB, 650x1280px
4. Printer HP LaserJet Pro MFP127FW
Also given 4 phones:
2 Apple (IOS 11.x and higher)
2 Android (xs what version is there, but not the old one)
Task:
Print photo A via Iphone, using "wireless direct printing"
We take Iphone 5s and 10.
Select photo A in WhatsApp and try to print photo - dick with oil.
Select photo B in WhatsApp and try printing photo-prints.
Select photo B in WhatsApp and try printing a photo - prints.
Hmmm. Ok maybe WhatsApp is buggy:
Select photo A in the Photo Gallery and try printing photo - dick with oil.
Select photo B in the Photo Gallery and try printing photo-prints.
We select photo B in the Photo Gallery and try to print the photo - it prints.
We take photos in Android devices:
Select photo A in the Photo Gallery and WhatsApp and try to print the photo - prints.
We select photo B in the Photo Gallery and WhatsApp and try to print the photo - prints.
We select photo B in the Photo Gallery and WhatsApp and try to print the photo - prints.
Solution attempts:
1. Printer firmware? Have you requested
2. Reset the printer? Reset, configured
3. Restart the printer, phone? Reloaded
4. Print on another printer? Tried (Tried on HP MFP1217, everything is ok), with IOS all 3 photos are printed. 5. Is there a problem with the printer? Then why does everything print on Android. The printer is not friendly (stopped) with IOS? Everything was working a week ago.
5. Photo problem? Which? Converted 940 pixels (width) to centimeters = about 25 cm, 640 pixels = 17 cm ... exceeds the size of the A4 width ... ok, cut it less than the A4 width, tried it, zero emotions.
6. Long file name? Ok, renamed - zero emotions.
7. Convert jpg photo to another format? Ok, remade - zero emotions.
8. File size? OK, more than 2 mb files are printed, and this one is 160 kb ....
In general, somehow it selectively prints photos. Some without problems, some with oil.
What is the jamb? Where to dig? Flash IOS? :D
To sin on the printer? So with androyd it prints everything ...
Sin on IOS? So everything prints on the other, and it printed on this too ...
On IOS, there is something like a print manager when you start a file for printing. The photo that he wants to print, spins like 1 of 1, prints and prints. "Problem" photo he quickly so "Completed" .......
Already thoughts of a conspiracy! Maybe WhatsApp or IOS imposes some kind of "grid" on the file, marked "important" and the printers do not understand what kind of garbage is sent to us =)
In general, I'm tired of writing (I need some details, I'll let you know, I seem to have painted everything) ..... that still try, xs .... fresh ideas, thoughts are needed .....

Answer 1

On the fingers, how printing is arranged in android.
The program on the phone itself generates a pdf file or accesses its servers by transferring the document
in its original format, and in return receives a ready-made pdf.
This pdf is framed as a print job to android print service.
The print service allows the user to select a printer from the configured plug-ins for the print service.
For example, the Google Cloud Print plugin.
Having received the task, it forwards it to its servers.
The printer, which can connect to the GPC itself, checks every 30 seconds
if there are new jobs.
The PDF is rendered on the printer itself.
And now you know that the cant can be not only in WhatsApp.
About what kind of adventures on the apple, alas, I don’t know.
Try printing to pdf. If there is. You may notice some error in the format.
And also there may be an error in the printer driver on the phone.
If the driver prepares the raster itself, then there may be an error in the pdf rendering library.
Maybe there is not enough memory or an incomprehensible glitch like this
#00 pc 000000000013ade8 /system/lib/libpdfium.so (_ZN13CFX_MemoryMgr5AllocEji+8)
#01 pc 000000000007397c /system/lib/libpdfium.so (FPDF_LoadCustomDocument+16)
#02 pc 00000000 lib/libandroid_runtime.so
this happens in the android kernel. I can't fix. Over the past 30 days, there were 11 cases per 18,000 users.