[gdal-dev] Interleave Bands with RasterIO?

[legeochen]

This is how i do it. I hope it is what you want:)
    GByte *myGdalScanData=(GByte *)
CPLMalloc(theRasterViewport->drawableAreaXDim*theRasterViewport->drawableAreaYDim*4);
    if (myGdalScanData == NULL)
    {
        std::cout<<"scan data is null! ";
    }
    else
    {
        CPLErr myErr = GDALRasterIO( myGdalRedBand, GF_Read,
                                    theRasterViewport->rectXOffset,
                                    theRasterViewport->rectYOffset,
                                    theRasterViewport->clippedWidth,
                                    theRasterViewport->clippedHeight,
                                    myGdalScanData+0,
                                    theRasterViewport->drawableAreaXDim,
                                    theRasterViewport->drawableAreaYDim,
                                    GDT_Byte,
4,theRasterViewport->drawableAreaXDim *4  );
        myErr = GDALRasterIO( myGdalGreenBand, GF_Read,
                                    theRasterViewport->rectXOffset,
                                    theRasterViewport->rectYOffset,
                                    theRasterViewport->clippedWidth,
                                    theRasterViewport->clippedHeight,
                                    myGdalScanData+1,
                                    theRasterViewport->drawableAreaXDim,
                                    theRasterViewport->drawableAreaYDim,
                                    GDT_Byte,
4,theRasterViewport->drawableAreaXDim* 4 );
        myErr = GDALRasterIO( myGdalBlueBand, GF_Read,
                                    theRasterViewport->rectXOffset,
                                    theRasterViewport->rectYOffset,
                                    theRasterViewport->clippedWidth,
                                    theRasterViewport->clippedHeight,
                                    myGdalScanData+2,
                                    theRasterViewport->drawableAreaXDim,
                                    theRasterViewport->drawableAreaYDim,
                                    GDT_Byte,
4,theRasterViewport->drawableAreaXDim * 4 );
        myErr = GDALRasterIO( myGdalBlueBand, GF_Read,
                                    theRasterViewport->rectXOffset,
                                    theRasterViewport->rectYOffset,
                                    theRasterViewport->clippedWidth,
                                    theRasterViewport->clippedHeight,
                                    myGdalScanData+3,
                                    theRasterViewport->drawableAreaXDim,
                                    theRasterViewport->drawableAreaYDim,
                                    GDT_Byte,
4,theRasterViewport->drawableAreaXDim * 4 );
        if (myErr != CPLE_None)
        {
            std::cout<< "RaterIO  error: " << CPLGetLastErrorMsg();
        }
    }

2008/10/19 <craig.miller at spatialminds.com>

> I have a BGRA buffer in memory, and a multi-band RGBA TIF image.  Is it
> possible to use RasterIO to read in values from each band and neatly
> interleave them in my buffer.
>
> For example if I was loading an RGBA image I am hoping to be able to make 4
> separate RasterIO calls.
>
> Assuming a BGRA image looks like:
>
> 0 - blue byte
> 8 - green byte
> 16 - red byte
> 24 - alpha byte
> 32 - blue byte
> 40 - green byte
> 48 - red byte
> 56 - alpha byte
> 64 - ....
>
> The first RasterIO call would read in the blue values and insert them at 0,
> 32, 64, etc making it look like:
>
> 0 - blue byte
> 8 -
> 16 -
> 24 -
> 32 - blue byte
> 40 -
> 48 -
> 56 -
> 64 - ....
>
> The second RasterIO call would read the green values and insert them at 8,
> 40, etc making it look like:
>
> 0 - blue byte
> 8 - green byte
> 16 -
> 24 -
> 32 - blue byte
> 40 - green byte
> 48 -
> 56 -
> 64 - ....
>
> Rinse and repeat for red and alpha.
>
> Is this possible, or is there a much much simpler way that I'm
> overlooking?  I've been looking at the paramaters for RasterIO but can't
> seem to get it to work.  I do understand that I can just read the values
> into a separate buffer and memcpy them over to my image buffer.  I was
> trying to minimize the total number of times the same data has to be copied.
>
> Thanks for the help.
>
> Craig
>
>
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/gdal-dev/attachments/20081019/8528aab1/attachment-0001.html