download: Add support to an user defined progress bar

This commit just introduces a new argument to the download function: `bar`.
The argument let the person who is developing code define his own progress
bar using whatever he wants to. It also requires the pattern of passing
the current size of the downloaded chunk. This callable function respects the
tqdm API.

Signed-off-by: Julio Faracco <[email protected]>

gdown/download.py

@@ -124,6 +124,7 @@ def download(
     format=None,
     user_agent=None,
     log_messages=None,
+    bar=None,
 ):
     """Download file from URL.
 
@@ -165,6 +166,10 @@ def download(
         Log messages to customize. Currently it supports:
         - 'start': the message to show the start of the download
         - 'output': the message to show the output filename
+    bar: type
+        A user defined progress bar. It should be followed by the argument
+        of the current chunk size downloaded. The total size should be defined
+        previously in order to make the API consistent to tqdm.
 
     Returns
     -------
@@ -180,6 +185,8 @@ def download(
         user_agent = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36"  # NOQA: E501
     if log_messages is None:
         log_messages = {}
+    if bar is not None and not callable(bar):
+        raise ValueError("Parameter bar should be callable and respect arguments of cur_size")
 
     url_origin = url
 
@@ -362,19 +369,25 @@ def download(
         total = res.headers.get("Content-Length")
         if total is not None:
             total = int(total) + start_size
-        if not quiet:
+        if not quiet and bar is None:
             pbar = tqdm.tqdm(total=total, unit="B", initial=start_size, unit_scale=True)
+
+        percent = 0.0
         t_start = time.time()
         for chunk in res.iter_content(chunk_size=CHUNK_SIZE):
             f.write(chunk)
             if not quiet:
-                pbar.update(len(chunk))
+                if bar is None:
+                    pbar.update(len(chunk))
+                else:
+                    bar(len(chunk))
+            percent += len(chunk) / total
             if speed is not None:
-                elapsed_time_expected = 1.0 * pbar.n / speed
+                elapsed_time_expected = 1.0 * percent / speed
                 elapsed_time = time.time() - t_start
                 if elapsed_time < elapsed_time_expected:
                     time.sleep(elapsed_time_expected - elapsed_time)
-        if not quiet:
+        if not quiet and bar is None:
             pbar.close()
         if tmp_file:
             f.close()