Detect appropriate imagemagick convert command

src/videotoolkit/__init__.py

@@ -6,11 +6,54 @@
 from .tools import create_start_slide, create_end_slide
 from .utils import add_logo, generate_hex_grid, pdf_to_png
 
-__all__ = ['create_start_slide', 'create_end_slide', 'add_logo', 'generate_hex_grid', 'pdf_to_png']
 
 import logging
+import subprocess
 
 logging.basicConfig(
     level=logging.INFO,
     format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
 )
+
+logger = logging.getLogger(__name__)
+
+
+def detect_imagemagick_command():
+    """
+    Determine whether the appropriate ImageMagick command is `magick` (v7.x) or `convert` (v6.x).
+    :return: either `magick` or `convert` or, if not detected, `None`
+    """
+
+    magick_command = None
+
+    try:
+        result = subprocess.run(['magick', '--version'], stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+
+        if result.returncode == 0 and 'ImageMagick' in result.stdout:
+            magick_command = 'magick'
+    except (Exception,):
+        pass
+
+    if magick_command:
+        return magick_command
+
+    try:
+        result = subprocess.run(['convert', '--version'], stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+
+        if result.returncode == 0 and 'ImageMagick' in result.stdout:
+            magick_command = 'convert'
+    except (Exception,):
+        pass
+
+    if magick_command:
+        return magick_command
+
+    logger.warning(f'Could not detect ImageMagick either as `magick` or `convert`. Some functionality will not work.')
+    return None
+
+
+MAGICK_COMMAND = detect_imagemagick_command()
+logger.info(f'ImageMagick command detected as {MAGICK_COMMAND}')
+
+
+__all__ = ['create_start_slide', 'create_end_slide', 'add_logo', 'generate_hex_grid', 'pdf_to_png', MAGICK_COMMAND]

src/videotoolkit/utils.py

@@ -12,6 +12,8 @@
 import sys
 import subprocess
 
+import videotoolkit
+
 logger = logging.getLogger(__name__)
 
 
@@ -53,6 +55,10 @@ def draw_hexagon(c: canvas.Canvas, x: float, y: float, size: float):
 
 def pdf_to_png(pdf_path: str | Path) -> None:
 
+    if not videotoolkit.MAGICK_COMMAND:
+        logger.error(f'ImageMagick not found; required for {__name__}')
+        sys.exit(1)
+
     if isinstance(pdf_path, str):
         pdf_path = Path(pdf_path)
 
@@ -70,7 +76,7 @@ def pdf_to_png(pdf_path: str | Path) -> None:
     try:
         # Construct the command to call ImageMagick's convert
         command = [
-            'magick',
+            videotoolkit.MAGICK_COMMAND,
             '-density', '72',
             str(pdf_path),
             str(png_path)

tests/test_tools.py

@@ -27,3 +27,7 @@ def test_create_start_slide():
 def test_create_end_slide():
     """Placeholder test for create_end_slide"""
     assert True  # Replace with real test later
+
+
+def test_magick_command():
+    assert videotoolkit.MAGICK_COMMAND == 'magick' or videotoolkit.MAGICK_COMMAND == 'convert'