Created attachment 87019 [details]
Patch imlpementing johannes solution

When you start zooming on the android client, the full image is sent over (This is a featrure to allow that you have a better resolution during zooming, while are fast during browsing). However, if the image is huge, then the image is not correctly loaded and instead it turns black. I've no idea what the exact limitation is, but it seems to depend on the device and be a limitation in OpenGL.

I don't see any error message in Qt code, only this line on stdout:
W/Adreno-ES20(13539): <core_glTexImage2D:514>: GL_INVALID_VALUE

Johannes Zarl analyzed the situation and came up with this report:
I've programatically created a batch of different resolution images to get 
some size-tag for the black-image-problem, but I'm not really getting a sharp 
conclusion:

I used the following command to create images for my test:

for dim in {5000..20000..1000} ; do \
  convert rose: -resize ${dim}x${dim}\! \
    /tmp/kphotoalbum-demo-zing/test-$dim.jpg \
;done

The biggest possible size was 6214x6214; the next one (6125x6125) did not 
work. 6124 squared corresponds to 37.5 MP

To me, this indicates:
 - The problem is not related to raw file size (not surprising, given that you 
said it's coming from somewhere within the OpenGL stack).

Not using square images changes the observed behaviour:

convert rose: -resize 8192x1024! pan-8192x1024.jpg
convert rose: -resize 8192x1024! pan-8193x1024.jpg

Produces two images, where the first one works, the second one (and bigger 
ones) not. This gives a image size of 8.3 MP. Interesting about that number is 
that 8192 = 2 * 4096.

I'm not entirely sure how to best determine when to split. In my own 
collection I've got one image with 8114x2731 pixels that works and a 8204x4795  
that doesn't work. So that seems to be consistent with my findings.

I don't really have that much time to do further testing for now, but I could 
imagine that there's actually two limiting factors: maximum pixel count 
(6124^2) and maximum dimension (8192).

Do you know how to get information about the graphics hardware in a tablet? It 
would be interesting to get something like maximum texture size and compare 
the value with my findings...


However, on my cell phone the limitation seems to be different, since I black out way earlier than with an image of the sizes he describes. 

Attached is a patch which limits the dimentions according to Johannes description. It does however, not work on my cell as mentioned.