On 05/10/2012 04:48 PM, Petr Kitashov wrote:
Hi,
I need just to display some region(any) from raster file. Seems like I
understand everything until rasterIO.
RasterIO fills(in my case) void* pData with raster info - that's
great, but how to display it?
I do it like this:
1) Call GDALRasterIO to get the part of interest into a 2D table of
floats or integers (ral_grid).
This happens in ral_grid_create_using_GDAL in
https://github.com/ajolma/geoinformatica/blob/master/libral/ral_grid_rw.c
2) Create a ral_pixbuf (each pixel has RGBA values) of the same size as
ral_grid.
3) Render the ral_grid onto the ral_pixbuf using current palette etc.
4) Convert the ral_pixbuf into GdkPixBuf.
5) Use the GdkPixBuf in a GTK+ image widget for display.
This happens in ral_pixbuf_create_from_grid, ral_render_integer_grid,
and ral_gdk_pixbuf in
https://github.com/ajolma/geoinformatica/blob/master/libral/ral_pixbuf.c
This is GTK+ specific. There are other Graphics toolkits.
Which data is stored there when I use GDALDataset::rasterIO, and which
in case of GDALRasterBand::RasterIO?
I.e. how to determine pixel values from pData?
I'm sorry if this question is stupid, but i spent a lot of time in
google and didn't find any solution.
I hope the above helps.
Ari
--
Best Regards,
Petr Kitashov
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