Function lvgl::widgets::img::buf_set_px_alpha

pub fn buf_set_px_alpha(
    dsc: *mut lv_img_dsc_t, 
    x: lv_coord_t, 
    y: lv_coord_t, 
    opa: lv_opa_t
) -> MynewtResult<()>

Set the alpha value of a pixel of an image. The color won't be affected

• dsc: pointer to an image descriptor
• x: x coordinate of the point to set
• y: x coordinate of the point to set
• opa: the desired opacity
• safe: true: check out of bounds