openslide_read_region returns no picture data

[Stefan König]

hmm thanks a lot, now it works for me! i don't know exactly what i've
changed, but i created a new built, and now it works fine.

i can't say exactly what i've done, but maybe there was a mistaken
setting in cmake (can't believe this, but no other idea..)

2010/12/15 Adam Goode <adam at spicenitz.org>:
> Can you try the openslide-write-png program? Do something like this:
>
> openslide-write-png slide.mrxs 27500 27500 0 1000 1000 out.png
>
> By looking at the result, you might be able to determine where the
> problem is.
>
>
> Adam
>
>
> On 12/14/2010 04:46 AM, Stefan König wrote:
>> i tried it now with this call:
>>
>>        openslide_read_region(slideObject, dst, 27500, 27500, 0,
>> *width, *height);
>>
>> even if i set dimensions to 10000x1000 i get only (big) plane black
>> pictures, i tried some different mirax files right now, allways the
>> same thing.
>>
>> this produces a black image too
>>
>> 2010/12/10 Stefan König <blogdde at googlemail.com>:
>>> here is a part of my sample script to play bit arround with openslide,
>>> before i use this productive:
>>>
>>>        openslide_read_region(slideObject, dst, 0, 0, 1, *width, *height);
>>>
>>>        if(openslide_get_error(slideObject))
>>>                std::cout << openslide_get_error(slideObject) << std::endl;
>>>
>>>        argb8c_view_t gil = boost::gil::interleaved_view(*width, *height,
>>> (const argb8c_pixel_t*) (dst), (*width)*4);
>>>
>>>        rgb8_image_t exp(*width,*height);
>>>        copy_and_convert_pixels(gil, view(exp));
>>>
>>>        jpeg_write_view("C:\\readRegionTest.jpg", view(exp));
>>>
>>>        std::cout << "***************************************" << std::endl;
>>>        std::cout << "finished region read" << std::endl;
>>>        std::cout << "***************************************" << std::endl;
>>>
>>>
>>>        int64_t* w = new int64_t;
>>>        int64_t* h = new int64_t;
>>>        const char* name = openslide_get_associated_image_names(slideObject)[1];
>>>        openslide_get_associated_image_dimensions (slideObject, name, w, h);
>>>        uint32_t* dst2 = new uint32_t[(*w)*(*h)*4];
>>>        openslide_read_associated_image (slideObject, name, dst2);
>>>
>>>        if(openslide_get_error(slideObject))
>>>                std::cout << openslide_get_error(slideObject) << std::endl;
>>>
>>>        argb8c_view_t gil2 = boost::gil::interleaved_view(*w, *h, (const
>>> argb8c_pixel_t*) (dst2), *w*4);
>>>
>>>        rgb8_image_t exp2(*w,*h);
>>>        copy_and_convert_pixels(gil2, view(exp2));
>>>
>>>        jpeg_write_view("C:\\readAssociatedRegionTest.jpg", view(exp2));
>>>
>>>        std::cout << "***************************************" << std::endl;
>>>        std::cout << "finished associated region read" << std::endl;
>>>        std::cout << "***************************************" << std::endl;
>>>
>>> this is my output:
>>>
>>> the second picture is created successfully, the first one is only
>>> black (the dst pointer is empty.), i executed this script by using the
>>> mirax sample files from the openslide project page.
>>>
>>> ***************************************
>>> ***************************************
>>> finished region read
>>> ***************************************
>>> ***************************************
>>> finished associated region read
>>> ***************************************
>>>
>>>
>>> 2010/12/8 Stefan König <blogdde at googlemail.com>:
>>>> The error state is empty and a read_associated_image call works fine aber
>>>> calling read_region.
>>>>
>>>> I debugged inside the read_region code, I think there is something wrong
>>>> with some of the cairo calls painting to the buffer, but there is no proof
>>>> yet.
>>>>
>>>> Friday I'll take a further look, and I'll write here if I find something.
>>>>
>>>>
>>>> -----Ursprüngliche Nachricht-----
>>>> Von: openslide-users-bounces+blogdde=googlemail.com at lists.andrew.cmu.edu
>>>> [mailto:openslide-users-bounces+blogdde=googlemail.com at lists.andrew.cmu.edu]
>>>> Im Auftrag von Jan Harkes
>>>> Gesendet: Mittwoch, 8. Dezember 2010 17:13
>>>> An: openslide-users at lists.andrew.cmu.edu
>>>> Betreff: Re: openslide_read_region returns no picture data
>>>>
>>>> On 12/08/2010 10:21 AM, Stefan König wrote:
>>>>> Hi,
>>>>>
>>>>> i try to read a single region out of mirax file (just tried my own and
>>>>> the sample files from openslide.org), if i use
>>>>> openslide_get_associated_image_dimensions() i can extract my image and
>>>>> save work with them but if i try to extract a image by using
>>>>> openslide_read_region my dst pointer contains nothing and there is no
>>>>> exception either :(
>>>>>
>>>>>       *width = 256;
>>>>>       *height = 256;
>>>>>
>>>>>       uint32_t* dst = new uint32_t[(*width)*(*height)*4];
>>>>>       openslide_read_region(slideObject, dst, 0, 0, 1, *width, *height);
>>>>>
>>>>> if i understand the documentation right, it should take my slide
>>>>> object and write a 256x256 area begining at topleft from layer to dst?
>>>>
>>>> I believe that that should work. But it may be that the slideObject
>>>> handle got into an error state, you probably should check for errors by
>>>> calling 'openslide_get_error' after the call to openslide_read_region
>>>> and probably most other calls.
>>>>
>>>> According to the C api documentation, when the object is in error state
>>>> openslide_read_region will clear the dst buffer instead of painting to it.
>>>>
>>>> Jan
>>>>
>>>> _______________________________________________
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>>>> openslide-users at lists.andrew.cmu.edu
>>>> https://lists.andrew.cmu.edu/mailman/listinfo/openslide-users
>>>>
>>>>
>>>
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