Gdalada is a thin, low-level, auto-generated Ada bindings for the following subset of GDAL (Geospatial Data Abstraction Library):
- cpl_*.h: Common Portability Library C API
- gdal.h: Raster C API
- ogr_core.h, ogr_api.h: Vector C API
- gdal_alg.h: GDAL Algorithms C API
- ogr_srs_api.h: Spatial Reference System C API
- gdal_utils.h: GDAL Algorithms C API
Ada specifications were generated by gcc -fdump-ada-spec from the C headers of GDAL version 3.3.2.
The specification source code was amalgamated, slightly edited by hand and organized in the following Ada package hierarchy for convenience:
Gdalada
└───CPL
└───GDAL
└───GDAL_Alg
└───GDAL_Utils
└───OGR
└───OGR_SRS
└───Gdalwarper
You probably want to add something like that to your application's .gpr file to link with the system gdal library:
package Linker is
for Switches("Ada") use ("-lgdal");
end Linker;The following code is a rough translation of the GDAL ``Vector API tutorial'' example.
with Gdalada.GDAL; use Gdalada.GDAL;
with Gdalada.OGR; use Gdalada.OGR;
with Interfaces.C; use Interfaces.C;
with Interfaces.C.Strings; use Interfaces.C.Strings;
with System; use System;
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Assertions; use Ada.Assertions;
with Ada.Command_Line; use Ada.Command_Line;
procedure Gdal_Test is
Dataset : GDALDatasetH;
Layer : OGRLayerH;
Featuredefn : OGRFeatureDefnH;
Feature : OGRFeatureH;
begin
if Argument_Count /= 1 then
Put_Line ("Usage : " & Command_Name & " <file>");
return;
end if;
Put_Line ("Using file path: " & Argument (1));
GDALAllRegister;
Dataset :=
GDALOpenEx
(New_String (Argument (1)), GDAL_OF_VECTOR, Null_Address, Null_Address,
Null_Address);
Assert (Dataset /= Null_Address);
Layer := GDALDatasetGetLayer (Dataset, 0);
Assert (Layer /= Null_Address);
Put_Line ("Layer: " & Value (OGR_L_GetName (Layer)));
Featuredefn := OGR_L_GetLayerDefn (Layer);
OGR_L_ResetReading (Layer);
Features_Loop :
loop
Feature := OGR_L_GetNextFeature (Layer);
exit when Feature = Null_Address;
Put_Line ("Feature FID " & OGR_F_GetFID (Feature)'Image);
-- Look through all fields of the feature
Fields_Loop :
for I in 0 .. (OGR_FD_GetFieldCount (Featuredefn) - 1) loop
declare
Fielddefn : OGRFieldDefnH := OGR_FD_GetFieldDefn (Featuredefn, I);
begin
case OGR_Fld_GetType (Fielddefn) is
when OFTInteger =>
Put_Line
(" Integer field: " & OGR_F_GetFieldAsInteger (Feature, I)'Image);
when OFTInteger64 =>
Put_Line
(" Integer64 field: " &
OGR_F_GetFieldAsInteger64 (Feature, I)'Image);
when OFTReal =>
Put_Line
(" Real field: " & OGR_F_GetFieldAsDouble (Feature, I)'Image);
when OFTString =>
Put_Line
(" String field: " & Value (OGR_F_GetFieldAsString (Feature, I)));
when others =>
Put_Line
(" Other field: " & Value (OGR_F_GetFieldAsString (Feature, I)));
end case;
end;
end loop Fields_Loop;
-- Feature's geometry
declare
Geometry : OGRGeometryH := OGR_F_GetGeometryRef (Feature);
begin
if Geometry /= Null_Address and
OGR_GT_Flatten (OGR_G_GetGeometryType (Geometry)) = WkbPoint
then
Put_Line
(" " & OGR_G_GetX (Geometry, 0)'Image & ", " &
OGR_G_GetY (Geometry, 0)'Image);
else
Put_Line (" No point geometry");
end if;
end;
OGR_F_Destroy (Feature);
end loop Features_Loop;
GDALClose (Dataset);
end Gdal_Test;Unit tests are needed.
The library is Work-In-Progress.
Some functions from GDAL's CPL/VSI dealing with OS-specific types like time_t and stat that have no direct equivalent in standard Ada are commented out for now.