Feature/help group by Czy014 · Pull Request #6 · Czy014/mono-pixel

Czy014 · 2026-03-29T05:36:30Z

No description provided.

…VG format

…uidance

Copilot

Pull request overview

This PR adds SVG export support to the mono-pixel exporter pipeline and improves CLI help output organization by grouping options into Rich help panels.

Changes:

Add export_to_svg() and route save_image() to SVG vs PNG based on output file extension.
Expand unit tests to cover SVG export and save_image(..., .svg) behavior.
Update CLI help text/panels and documentation to reflect .png vs .svg output.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
`src/mono_pixel/exporter.py`	Adds SVG export implementation and extension-based routing in `save_image()`.
`tests/test_exporter.py`	Adds unit tests validating SVG output structure and `save_image()` SVG behavior.
`src/mono_pixel/cli.py`	Groups CLI options into Rich help panels and updates output help text.
`src/mono_pixel/__init__.py`	Re-exports `export_to_svg` from the package top-level.
`docs/usage.md`	Documents `.svg` output behavior and shows usage examples for SVG export.

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Copilot · 2026-03-29T06:06:58Z

+        for y in range(height):
+            for x in range(width):
+                pixel = image.getpixel((x, y))
+                if isinstance(pixel, tuple) and len(pixel) >= 3:
+                    # Treat non-white pixels as foreground
+                    if pixel[:3] != (255, 255, 255):


SVG export treats any non-white RGB pixel as foreground (pixel[:3] != (255, 255, 255)), which breaks when the background color is not pure white (e.g., bg_color="black") and also breaks save_image(..., strict_binarize=True) because convert_to_monochrome produces an RGB image with a non-white background. Foreground detection should compare against the actual background color (or export from the 1-bit mask) so background pixels aren’t emitted as foreground rects.

Suggested change

for y in range(height):

for x in range(width):

pixel = image.getpixel((x, y))

if isinstance(pixel, tuple) and len(pixel) >= 3:

# Treat non-white pixels as foreground

if pixel[:3] != (255, 255, 255):

# Infer background color from the top-left pixel so we don't

# treat background pixels as foreground when the background

# is not pure white.

bg_pixel = image.getpixel((0, 0))

if isinstance(bg_pixel, tuple) and len(bg_pixel) >= 3:

bg_rgb = bg_pixel[:3]

else:

# Fallback to white to preserve previous behavior if we

# cannot determine a tuple-based background color.

bg_rgb = (255, 255, 255)

for y in range(height):

for x in range(width):

pixel = image.getpixel((x, y))

if isinstance(pixel, tuple) and len(pixel) >= 3:

# Treat pixels that differ from the background color as foreground

if pixel[:3] != bg_rgb:

Copilot · 2026-03-29T06:06:59Z

+
+    bg_svg = parse_color(bg_color)
+    fg_svg = parse_color(fg_color)
+


pixel_size is used to compute SVG dimensions and rect sizes but isn’t validated. A value of 0 or a negative value will generate an invalid SVG (zero/negative width/height and viewBox). Add an explicit validation (e.g., positive integer) in export_to_svg (and ideally also validate svg_pixel_size in save_image).

Suggested change

if not isinstance(pixel_size, int) or pixel_size <= 0:

raise ExportError(f"pixel_size must be a positive integer, got: {pixel_size}")

Copilot · 2026-03-29T06:06:59Z

+    else:
+        # Default to PNG
+        return export_to_png(processed_image, output_path, dpi, optimize)
+
+


save_image currently defaults to PNG for any non-.svg suffix, which can silently write PNG bytes to a path with an unrelated extension (e.g., .jpg). Consider validating supported output suffixes (.png/.svg) and either raising a clear error for others or normalizing/adding the correct extension to avoid confusing outputs.

Suggested change

else:

# Default to PNG

return export_to_png(processed_image, output_path, dpi, optimize)

if suffix == ".png" or suffix == "":

# Normalize paths without suffix to .png

if suffix == "":

output_path = output_path.with_suffix(".png")

return export_to_png(processed_image, output_path, dpi, optimize)

# Unsupported suffix: avoid writing PNG bytes to a misleading extension

raise ExportError(

f"Unsupported output format for '{output_path}'. "

"Supported extensions are: .png, .svg."

)

Copilot · 2026-03-29T06:06:59Z

+    # Get pixel data based on image mode
+    if image.mode == "1":
+        for y in range(height):
+            for x in range(width):
+                pixel = image.getpixel((x, y))
+                # For 1-bit images, 0 is foreground (black)
+                if pixel == 0:
+                    ET.SubElement(
+                        fg_group,
+                        "rect",
+                        {
+                            "x": str(x * pixel_size),
+                            "y": str(y * pixel_size),
+                            "width": str(pixel_size),
+                            "height": str(pixel_size),
+                        },
+                    )
+    elif image.mode == "L":
+        for y in range(height):
+            for x in range(width):
+                pixel = image.getpixel((x, y))
+                # For grayscale, treat dark pixels as foreground
+                if isinstance(pixel, int) and pixel < 128:
+                    ET.SubElement(
+                        fg_group,
+                        "rect",
+                        {
+                            "x": str(x * pixel_size),
+                            "y": str(y * pixel_size),
+                            "width": str(pixel_size),
+                            "height": str(pixel_size),
+                        },
+                    )


export_to_svg emits one <rect> per foreground pixel via nested for y/x loops and getpixel, which will be very slow and produce extremely large SVGs for bigger images (the test suite already uses 1024×1024 canvases). Consider compressing runs of pixels into fewer shapes (row-wise run-length rectangles, <path> segments), or at least using image.getdata() to avoid per-pixel getpixel overhead.

Suggested change

# Get pixel data based on image mode

if image.mode == "1":

for y in range(height):

for x in range(width):

pixel = image.getpixel((x, y))

# For 1-bit images, 0 is foreground (black)

if pixel == 0:

ET.SubElement(

fg_group,

"rect",

{

"x": str(x * pixel_size),

"y": str(y * pixel_size),

"width": str(pixel_size),

"height": str(pixel_size),

},

)

elif image.mode == "L":

for y in range(height):

for x in range(width):

pixel = image.getpixel((x, y))

# For grayscale, treat dark pixels as foreground

if isinstance(pixel, int) and pixel < 128:

ET.SubElement(

fg_group,

"rect",

{

"x": str(x * pixel_size),

"y": str(y * pixel_size),

"width": str(pixel_size),

"height": str(pixel_size),

},

)

# Use fast pixel access and compress horizontal runs of foreground pixels

pixels = image.load()

if image.mode == "1":

# For 1-bit images, 0 is foreground (black)

for y in range(height):

x = 0

while x < width:

pixel = pixels[x, y]

if pixel == 0:

# Start of a run of foreground pixels

start_x = x

x += 1

while x < width and pixels[x, y] == 0:

x += 1

run_width = (x - start_x) * pixel_size

ET.SubElement(

fg_group,

"rect",

{

"x": str(start_x * pixel_size),

"y": str(y * pixel_size),

"width": str(run_width),

"height": str(pixel_size),

},

)

else:

x += 1

elif image.mode == "L":

# For grayscale, treat dark pixels as foreground

for y in range(height):

x = 0

while x < width:

pixel = pixels[x, y]

is_fg = isinstance(pixel, int) and pixel < 128

if is_fg:

# Start of a run of foreground pixels

start_x = x

x += 1

while x < width:

next_pixel = pixels[x, y]

if not (isinstance(next_pixel, int) and next_pixel < 128):

break

x += 1

run_width = (x - start_x) * pixel_size

ET.SubElement(

fg_group,

"rect",

{

"x": str(start_x * pixel_size),

"y": str(y * pixel_size),

"width": str(run_width),

"height": str(pixel_size),

},

)

else:

x += 1

Copilot · 2026-03-29T06:06:59Z

+    def test_export_custom_colors(self, tmp_path: Path):
+        """Custom colors work."""
+        canvas = create_canvas(50, 50, "white")
+        output_path = tmp_path / "output.svg"
+        result = export_to_svg(canvas, output_path, bg_color="red", fg_color="blue")
+


The new SVG tests don’t cover non-white backgrounds/foreground detection (e.g., bg_color="black", fg_color="white") which is where SVG pixel classification is most error-prone. Add a regression test that exports an image with a non-white background (and possibly a single foreground pixel) and asserts the SVG doesn’t emit foreground rects for background pixels.

Czy014 added 2 commits March 29, 2026 13:33

feat: add SVG export functionality and update save_image to support S…

a80af60

…VG format

feat: enhance command options with rich help panels for better user g…

09609ae

…uidance

Czy014 requested a review from Copilot March 29, 2026 05:36

Czy014 self-assigned this Mar 29, 2026

Czy014 added the enhancement New feature or request label Mar 29, 2026

Copilot started reviewing on behalf of Czy014 March 29, 2026 06:03 View session

Copilot AI reviewed Mar 29, 2026

View reviewed changes

Czy014 merged commit f00dc06 into main Apr 2, 2026
7 checks passed

Czy014 deleted the feature/help_group branch April 2, 2026 04:40

Czy014 restored the feature/help_group branch April 12, 2026 03:09

Czy014 deleted the feature/help_group branch April 12, 2026 03:10

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-        for y in range(height):
-            for x in range(width):
-                pixel = image.getpixel((x, y))
-                if isinstance(pixel, tuple) and len(pixel) >= 3:
-                    # Treat non-white pixels as foreground
-                    if pixel[:3] != (255, 255, 255):
+        # Infer background color from the top-left pixel so we don't
+        # treat background pixels as foreground when the background
+        # is not pure white.
+        bg_pixel = image.getpixel((0, 0))
+        if isinstance(bg_pixel, tuple) and len(bg_pixel) >= 3:
+            bg_rgb = bg_pixel[:3]
+        else:
+            # Fallback to white to preserve previous behavior if we
+            # cannot determine a tuple-based background color.
+            bg_rgb = (255, 255, 255)
+        for y in range(height):
+            for x in range(width):
+                pixel = image.getpixel((x, y))
+                if isinstance(pixel, tuple) and len(pixel) >= 3:
+                    # Treat pixels that differ from the background color as foreground
+                    if pixel[:3] != bg_rgb:


		bg_svg = parse_color(bg_color)
		fg_svg = parse_color(fg_color)



	if not isinstance(pixel_size, int) or pixel_size <= 0:
	raise ExportError(f"pixel_size must be a positive integer, got: {pixel_size}")

-    else:
-        # Default to PNG
-        return export_to_png(processed_image, output_path, dpi, optimize)
+    if suffix == ".png" or suffix == "":
+        # Normalize paths without suffix to .png
+        if suffix == "":
+            output_path = output_path.with_suffix(".png")
+        return export_to_png(processed_image, output_path, dpi, optimize)
+    # Unsupported suffix: avoid writing PNG bytes to a misleading extension
+    raise ExportError(
+        f"Unsupported output format for '{output_path}'. "
+        "Supported extensions are: .png, .svg."
+    )

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Pull request overview

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