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Add Proj::id_code and Proj::id_auth_name #204

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Add Proj::id_code and Proj::id_auth_name #204

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182dc0c
Add Proj::to_epsg
zwishing May 31, 2024
c655515
Add Proj::id_code and Proj::id_auth_name
zwishing Jun 1, 2024
6131e82
cargo fmt code
zwishing Jun 1, 2024
72cf6ab
Merge branch 'main' into main
zwishing Jun 20, 2024
fc1bd90
Merge branch 'main' into main
zwishing Sep 19, 2024
b7027b6
Merge branch 'georust:main' into main
zwishing Nov 10, 2024
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25 changes: 21 additions & 4 deletions src/proj.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,9 @@ use proj_sys::{
proj_context_destroy, proj_context_errno, proj_context_get_url_endpoint,
proj_context_is_network_enabled, proj_context_set_search_paths, proj_context_set_url_endpoint,
proj_create, proj_create_crs_to_crs, proj_destroy, proj_errno_string, proj_get_area_of_use,
proj_grid_cache_set_enable, proj_info, proj_normalize_for_visualization, proj_pj_info,
proj_trans, proj_trans_array, proj_trans_bounds, PJconsts, PJ_AREA, PJ_CONTEXT, PJ_COORD,
PJ_DIRECTION_PJ_FWD, PJ_DIRECTION_PJ_INV, PJ_INFO, PJ_LPZT, PJ_XYZT,
proj_get_id_code, proj_grid_cache_set_enable, proj_info, proj_normalize_for_visualization,
proj_pj_info, proj_trans, proj_trans_array, proj_trans_bounds, PJconsts, PJ, PJ_AREA,
PJ_CONTEXT, PJ_COORD, PJ_DIRECTION_PJ_FWD, PJ_DIRECTION_PJ_INV, PJ_INFO, PJ_LPZT, PJ_XYZT,
};
use std::{
convert, ffi,
Expand Down Expand Up @@ -584,6 +584,17 @@ impl Proj {
transform_epsg(ctx, from, to, area)
}

/// Returns epsg code for Proj
///
/// # Safety
/// This method contains unsafe code.
pub fn to_epsg(&self) -> Result<&str, str::Utf8Error> {
let pj = self.c_proj as *const PJ;
let c_char = unsafe { proj_get_id_code(pj, 0) };
let c_str = unsafe { CStr::from_ptr(c_char) };
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I believe there should be nullptr checking here as proj_get_id_code() might return null in case of error (typically if the CRS is custom and not tied to a known code), and https://doc.rust-lang.org/std/ffi/struct.CStr.html#method.from_ptr indicates the CStr::from_ptr() shouldn't be called with a null ptr

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When testing, I found that the Proj created by proj4str and esriwkt could not recognize the code and name。

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I found that the Proj created by proj4str and esriwkt could not recognize the code and name。

Yes, that's fully expected. Not all CRS representations contain an authority name and code

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If there are corresponding ideas or methods, converting them would be ideal.

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you can try using proj_identify() to find a known CRS that is identical to the current one, but there's no guarantee it will succeed. Custom CRS with custom projection parameter values are fully valid

c_str.to_str()
}

/// Set the bounding box of the area of use
///
/// This bounding box will be used to specify the area of use
Expand Down Expand Up @@ -1461,7 +1472,7 @@ mod test {
let usa_m = MyPoint::new(-115.797615, 37.2647978);
let usa_ft = to_feet.convert(usa_m).unwrap();
assert_relative_eq!(6693625.67217475, usa_ft.x());
assert_relative_eq!(3497301.5918027232, usa_ft.y(), epsilon=1e-8);
assert_relative_eq!(3497301.5918027232, usa_ft.y(), epsilon = 1e-8);
}

#[test]
Expand All @@ -1476,4 +1487,10 @@ mod test {
assert_eq!(area.north, 84.73);
assert!(name.contains("Europe"));
}
#[test]
fn test_to_epsg() {
let proj = Proj::new("EPSG:3059").unwrap();
let epsg = proj.to_epsg().unwrap();
assert_eq!(epsg, "3059")
}
}