rt_band_get_pixel()

rt_errorstate rt_band_get_pixel	(	rt_band	band,
		int	x,
		int	y,
		double *	value,
		int *	nodata
	)

Get pixel value.

If band's isnodata flag is TRUE, value returned will be the band's NODATA value

Parameters

band	: the band to get pixel value from
x	: pixel column (0-based)
y	: pixel row (0-based)
*value	: pixel value
*nodata	: 0 if pixel is not NODATA

Returns

ES_NONE on success, ES_ERROR on error

If band's isnodata flag is TRUE, value returned will be the band's NODATA value

Parameters

band	: the band to set nodata value to
x	: x ordinate (0-based)
y	: x ordinate (0-based)
*value	: pixel value
*nodata	: 0 if pixel is not NODATA

Returns

0 on success, -1 on error (value out of valid range).

Definition at line 1088 of file rt_band.c.

References ovdump::data, ES_ERROR, ES_NONE, rt_band_t::hasnodata, rt_band_t::height, rt_band_t::isnodata, rt_band_t::nodataval, rt_band_t::pixtype, PT_16BSI, PT_16BUI, PT_1BB, PT_2BUI, PT_32BF, PT_32BSI, PT_32BUI, PT_4BUI, PT_64BF, PT_8BSI, PT_8BUI, PT_END, RASTER_DEBUG, rt_band_clamped_value_is_nodata(), rt_band_get_data(), rterror(), rtwarn(), and rt_band_t::width.

Referenced by _rti_raster_get_band_perimeter(), RASTER_dumpValues(), RASTER_getPixelPolygons(), RASTER_getPixelValue(), RASTER_mapAlgebra2(), RASTER_mapAlgebraExpr(), RASTER_mapAlgebraFct(), RASTER_mapAlgebraFctNgb(), RASTER_nearestValue(), RASTER_neighborhood(), RASTER_setPixelValuesArray(), RASTER_setPixelValuesGeomval(), rt_band_check_is_nodata(), rt_band_get_nearest_pixel(), rt_band_get_pixel_of_value(), rt_band_get_quantiles_stream(), rt_band_get_summary_stats(), rt_band_get_value_count(), rt_band_reclass(), rt_band_set_pixel_line(), rt_raster_gdal_rasterize(), rt_raster_intersects(), rt_raster_intersects_algorithm(), rt_raster_iterator(), rt_raster_to_gdal_mem(), test_band_metadata(), test_band_pixtype_16BSI(), test_band_pixtype_16BUI(), test_band_pixtype_1BB(), test_band_pixtype_2BUI(), test_band_pixtype_32BF(), test_band_pixtype_32BSI(), test_band_pixtype_32BUI(), test_band_pixtype_4BUI(), test_band_pixtype_64BF(), test_band_pixtype_8BSI(), test_band_pixtype_8BUI(), test_band_reclass(), test_gdal_to_raster(), test_gdal_warp(), test_pixel_set_to_array(), test_raster_colormap(), and test_raster_wkb().

  {
        rt_pixtype pixtype = PT_END;
        uint8_t* data = NULL;
        uint32_t offset = 0;

        assert(NULL != band);
        assert(NULL != value);

        /* set nodata to 0 */
        if (nodata != NULL)
                *nodata = 0;

        if (
                x < 0 || x >= band->width ||
                y < 0 || y >= band->height
        ) {
                rtwarn("Attempting to get pixel value with out of range raster coordinates: (%d, %d)", x, y);
                return ES_ERROR;
        }

        /* band is NODATA */
        if (band->isnodata) {
                RASTER_DEBUG(3, "Band's isnodata flag is TRUE. Returning NODATA value");
                *value = band->nodataval;
                if (nodata != NULL) *nodata = 1;
                return ES_NONE;
        }

        data = rt_band_get_data(band);
        if (data == NULL) {
                rterror("rt_band_get_pixel: Cannot get band data");
                return ES_ERROR;
        }

        /* +1 for the nodata value */
        offset = x + (y * band->width);

        pixtype = band->pixtype;

        switch (pixtype) {
                case PT_1BB:
#ifdef OPTIMIZE_SPACE
                        {
                                int byteOffset = offset / 8;
                                int bitOffset = offset % 8;
                                data += byteOffset;

                                /* Bit to set is bitOffset into data */
                                *value = getBits(data, val, 1, bitOffset);
                                break;
                        }
#endif
                case PT_2BUI:
#ifdef OPTIMIZE_SPACE
                        {
                                int byteOffset = offset / 4;
                                int bitOffset = offset % 4;
                                data += byteOffset;

                                /* Bits to set start at bitOffset into data */
                                *value = getBits(data, val, 2, bitOffset);
                                break;
                        }
#endif
                case PT_4BUI:
#ifdef OPTIMIZE_SPACE
                        {
                                int byteOffset = offset / 2;
                                int bitOffset = offset % 2;
                                data += byteOffset;

                                /* Bits to set start at bitOffset into data */
                                *value = getBits(data, val, 2, bitOffset);
                                break;
                        }
#endif
                case PT_8BSI: {
                        int8_t val = data[offset];
                        *value = val;
                        break;
                }
                case PT_8BUI: {
                        uint8_t val = data[offset];
                        *value = val;
                        break;
                }
                case PT_16BSI: {
                        int16_t *ptr = (int16_t*) data; /* we assume correct alignment */
                        *value = ptr[offset];
                        break;
                }
                case PT_16BUI: {
                        uint16_t *ptr = (uint16_t*) data; /* we assume correct alignment */
                        *value = ptr[offset];
                        break;
                }
                case PT_32BSI: {
                        int32_t *ptr = (int32_t*) data; /* we assume correct alignment */
                        *value = ptr[offset];
                        break;
                }
                case PT_32BUI: {
                        uint32_t *ptr = (uint32_t*) data; /* we assume correct alignment */
                        *value = ptr[offset];
                        break;
                }
                case PT_32BF: {
                        float *ptr = (float*) data; /* we assume correct alignment */
                        *value = ptr[offset];
                        break;
                }
                case PT_64BF: {
                        double *ptr = (double*) data; /* we assume correct alignment */
                        *value = ptr[offset];
                        break;
                }
                default: {
                        rterror("rt_band_get_pixel: Unknown pixeltype %d", pixtype);
                        return ES_ERROR;
                }
        }

        /* set NODATA flag */
        if (band->hasnodata && nodata != NULL) {
                if (rt_band_clamped_value_is_nodata(band, *value))
                        *nodata = 1;
        }

        return ES_NONE;
}

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