CLI improvements - autodiscover previews images, is more robust (#27)

* Preview continues past first error.

* Autodiscover previews images, and is more robust.

* cleaning up exception handling a bit.

* Bumping version to 0.4.5

* Automatically reformatting code with black and isort

* Woops - failed to fully refactor.

---------

Co-authored-by: Auto-format Bot <[email protected]>

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "framegrab"
-version = "0.4.4"
+version = "0.4.5"
 description = "Easily grab frames from cameras or streams"
 authors = ["Groundlight <[email protected]>"]
 license = "MIT"

src/framegrab/cli/autodiscover.py

@@ -1,12 +1,21 @@
+import traceback
+
 import click
 import yaml
+from imgcat import imgcat
 
 from framegrab import FrameGrabber
+from framegrab.cli.clitools import PREVIEW_COMMAND_CHOICES, preview_image
 
 
 @click.command()
-def autodiscover():
-    """Automatically Discover cameras connected to the current host (e.g. USB)."""
+@click.argument(
+    "preview",
+    type=click.Choice(PREVIEW_COMMAND_CHOICES, case_sensitive=False),
+    default="imgcat",
+)
+def autodiscover(preview: str):
+    """Automatically discover cameras connected to the current host (e.g. USB)."""
     # Print message to stderr
     click.echo("Discovering cameras...", err=True)
 
@@ -18,13 +27,22 @@ def autodiscover():
 
     # Get a frame from each camera
     for camera_name, grabber in grabbers.items():
-        frame = grabber.grab()
-
-        click.echo(f"Grabbed frame from {camera_name} with shape {frame.shape}", err=True)
-        click.echo(grabber.config, err=True)
-        yaml_config["image_sources"].append(grabber.config)
-
-        grabber.release()
+        try:
+            frame = grabber.grab()
+
+            yaml_config["image_sources"].append(grabber.config)
+            if frame is None:
+                click.echo(f"Failed to grab sample frame from {camera_name}.", err=True)
+                continue
+
+            click.echo(f"Grabbed sample frame from {camera_name} with shape {frame.shape}", err=True)
+            click.echo(grabber.config, err=True)
+            preview_image(frame, camera_name, preview)
+
+            grabber.release()
+        except Exception:
+            click.echo(f"Error while setting up {camera_name}.", err=True)
+            click.echo(traceback.format_exc(), err=True)
 
     # render the yaml config dict as yaml and print it
     click.echo("Rendering sample configuration file as YAML:\n", err=True)

src/framegrab/cli/clitools.py

@@ -0,0 +1,54 @@
+import ascii_magic
+import cv2
+from imgcat import imgcat
+from PIL import Image
+
+
+def imgcat_preview(name: str, frame):
+    """Displays the given frame in the terminal using imgcat."""
+    print(f"Previewing image from camera {name} in terminal. This requires an advanced terminal like iTerm2.")
+    frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
+    imgcat(frame_rgb)
+
+
+def cv2_preview(name: str, frame):
+    """Displays the given frame in a cv2 window, and wait for a key."""
+    cv2.imshow(name, frame)
+    print(f"Previewing image in cv2 window. Select the window and press any key to continue.")
+    _ = cv2.waitKey(0)
+    cv2.destroyAllWindows()
+
+
+def ascii_preview(name: str, frame):
+    """Displays the given frame in the terminal using ascii art."""
+    columns, _ = shutil.get_terminal_size()
+    frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
+    pil_image = Image.fromarray(frame_rgb)
+    out = ascii_magic.from_pillow_image(pil_image)
+    out.to_terminal(columns=columns)
+
+
+def null_preview(name: str, frame):
+    """Does nothing."""
+    pass
+
+
+_PREVIEW_COMMANDS = {
+    "imgcat": imgcat_preview,
+    "cv2": cv2_preview,
+    "ascii": ascii_preview,
+    "none": null_preview,
+}
+
+PREVIEW_COMMAND_CHOICES = list(_PREVIEW_COMMANDS.keys())
+
+
+def preview_image(frame, title: str, output_type: str):
+    """Displays the given frame using the given output method."""
+    if output_type not in PREVIEW_COMMAND_CHOICES:
+        raise ValueError(f"Invalid output method: {output_type}.  Valid options are {PREVIEW_COMMAND_CHOICES}.")
+    command = _PREVIEW_COMMANDS[output_type]
+    if frame is None:
+        print(f"Trying to preview None frame from {title}.")
+        return
+    command(title, frame)

src/framegrab/cli/preview.py

@@ -1,4 +1,5 @@
 import shutil
+import traceback
 
 import ascii_magic
 import click
@@ -8,30 +9,7 @@
 from PIL import Image
 
 from framegrab import FrameGrabber
-
-
-def imgcat_preview(name: str, frame):
-    """Displays the given frame in the terminal using imgcat."""
-    print(f"Previewing image from camera {name} in terminal. This requires an advanced terminal like iTerm2.")
-    frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
-    imgcat(frame_rgb)
-
-
-def cv2_preview(name: str, frame):
-    """Displays the given frame in a cv2 window, and wait for a key."""
-    cv2.imshow(name, frame)
-    print(f"Previewing image in cv2 window. Select the window and press any key to continue.")
-    _ = cv2.waitKey(0)
-    cv2.destroyAllWindows()
-
-
-def ascii_preview(name: str, frame):
-    """Displays the given frame in the terminal using ascii art."""
-    columns, _ = shutil.get_terminal_size()
-    frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
-    pil_image = Image.fromarray(frame_rgb)
-    out = ascii_magic.from_pillow_image(pil_image)
-    out.to_terminal(columns=columns)
+from framegrab.cli.clitools import PREVIEW_COMMAND_CHOICES, preview_image
 
 
 def get_image_sources_from_config(config: str) -> list:
@@ -47,7 +25,7 @@ def get_image_sources_from_config(config: str) -> list:
 @click.argument("config", type=click.Path(exists=True))
 @click.argument(
     "output",
-    type=click.Choice(["imgcat", "cv2", "ascii"], case_sensitive=False),
+    type=click.Choice(PREVIEW_COMMAND_CHOICES, case_sensitive=False),
     default="imgcat",
 )
 def preview(config: str, output: str):
@@ -57,18 +35,20 @@ def preview(config: str, output: str):
     image_sources = get_image_sources_from_config(config)
     grabbers = FrameGrabber.create_grabbers(image_sources)
 
-    preview_command = {
-        "imgcat": imgcat_preview,
-        "cv2": cv2_preview,
-        "ascii": ascii_preview,
-    }[output]
-
     try:
         # Get a frame from each camera
         for camera_name, grabber in grabbers.items():
-            frame = grabber.grab()
-            print(f"Grabbed frame from {camera_name}")
-            preview_command(camera_name, frame)
+            try:
+                frame = grabber.grab()
+            except Exception as e:
+                print(f"Error grabbing preview frame from {camera_name}: {e}")
+                traceback.print_exc()
+                continue
+            if frame is None:
+                print(f"Failed to grab preview frame from {camera_name}.")
+                continue
+            print(f"Grabbed preview frame from {camera_name}")
+            preview_image(frame, camera_name, output)
     finally:
         for grabber in grabbers.values():
             try: