do something more rebust abour EVLRs when piping to laszip

pylas/lasdatas/las14.py

@@ -7,6 +7,7 @@
 class LasData(LasBase):
     def __init__(self, *, header=None, vlrs=None, points=None, evlrs=None):
         super().__init__(header=header, vlrs=vlrs, points=points)
+        self.laszip_was_called = False
         self.evlrs = [] if evlrs is None else evlrs
 
     def update_header(self):
@@ -15,6 +16,7 @@ def update_header(self):
             self.header.global_encoding.wkt = 1
 
         self.header.start_of_waveform_data_packet_record = 0
+
         if len(self.points_data) > ctypes_max_limit(
                 self.header.__class__.legacy_point_count.size
         ):
@@ -23,20 +25,36 @@ def update_header(self):
             self.header.legacy_point_count = len(self.points_data)
 
     def write_to(self, out_stream, do_compress=False):
+        # When compressing data, we cannot know in advance the size of the compressed points
+        # LAS 1.4 may have evlrs located after the point data, and the header has a field
+        # that must give the offset to first evlr
+        # so in the case of writing compressed points we have to update the header
+        # written with seek + write
         start = out_stream.tell()
-        super().write_to(out_stream, do_compress=do_compress)
-
-        # when do_compress=True, and that the method to compress
-        # is piping data through laszip we will write evlrs 2 times
-        # once when we write the data (with do_compress=False)
-        # to laszip stdin and the other time after the data laszip returned us
-        # it's a bit a bit strange but should do no harm
-        raw_evlrs = evlrs.RawEVLRList.from_list(self.evlrs)
-        if len(self.evlrs) > 0:
-            self.header.start_of_first_evlr = out_stream.tell()
-            self.header.number_of_evlr = len(raw_evlrs)
-            self.header.update_evlrs_info_in_stream(self, out_stream, start)
-            out_stream.seek(self.header.start_of_first_evlr)
-
-        raw_evlrs.write_to(out_stream)
-        out_stream.seek(start)
+        if not do_compress:
+            if len(self.evlrs) > 0:
+                self.header.number_of_evlr = len(self.evlrs)
+                self.header.start_of_first_evlr = self.header.point_size * self.header.point_count
+
+            super().write_to(out_stream, do_compress=do_compress)
+            if len(self.evlrs) > 0:
+                raw_evlrs = evlrs.RawEVLRList.from_list(self.evlrs)
+                raw_evlrs.write_to(out_stream)
+        else:
+            super().write_to(out_stream, do_compress=do_compress)
+            # if laszip was called, the out_stream already contains the evlrs
+            # because we were called with write_to(laszip_sdtin, do_compress=False)
+            # and laszip has taken care of writting the LAZ file, so we do not have to
+            # write evlrs
+            if len(self.evlrs) > 0 and not self.laszip_was_called:
+                self.header.number_of_evlr = len(self.evlrs)
+                self.header.start_of_first_evlr = out_stream.tell()
+                self.header.update_evlrs_info_in_stream(self, out_stream, start)
+                out_stream.seek(self.header.start_of_first_evlr)
+                raw_evlrs = evlrs.RawEVLRList.from_list(self.evlrs)
+                raw_evlrs.write_to(out_stream)
+                self.laszip_was_called = False
+
+    def _compress_with_laszip_executable(self, out_stream):
+        super()._compress_with_laszip_executable(out_stream)
+        self.laszip_was_called = True