`lqr_rwindow_read`
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## Name

lqr_rwindow_read — read the content of a `LqrReadingWindow` object

## Synopsis

    #include <lqr.h>

`gfloat lqr_rwindow_read(` | LqrReadingWindow* rwindow,
| gint x,
| gint y,
| gint channel`)`;

## Description

The function `lqr_rwindow_read` returns the content of the reading window `rwindow` at point `x`, `y` and at channel `channel`.

The coordinates `x` and `y` are relative to the `rwindow` centre, and they both can range from `-radius` to `radius` (extremes included), where `radius` can be obtained with the function `lqr_rwindow_get_radius`(3).

The function returns `0` when the coordinates are out of range, either because they are beyond the `rwindow` radius or because they are outside the image boundary.

The `channel` parameter specifies which channel to read out; depending on the `rwindow` reader type, the range and meaning of this parameter changes: for the cases `LQR_ER_BRIGHTNESS` and `LQR_ER_LUMA` it must be `0`, because the readout consists of a single channel, for `LQR_ER_RGBA` it must be between `0` and `3` (and then the readout will contain the RGBA information), while for `LQR_ER_CUSTOM` it must be one of the original image channels.

## See also

`lqr_carver_set_energy_function`(3), `lqr_rwindow_get_read_t`(3), `lqr_rwindow_get_radius`(3), `lqr_rwindow_get_channels`(3)

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