Via visibility in composite renders - vias blend with copper color

[YouCanflyThruMostTheSun]

I'm working on a PCB viewer application using PyGerber's API to render composite board images. The rendering works, but vias are not visually distinct from copper traces - they appear the same color as the copper layer, making them effectively invisible.
Looking at the rendered image, I can see evidence that vias exist (there's a half-circle via visible at the board edge), but they blend in with the copper color scheme.

Color/Style API: What's the correct way to apply different colors to different layer types in v3.0.04a? I see the custom color maps documentation is not yet available.

Or am I doing something wrong and I should be displaying vias differently.

Current Approach
Main composite rendering:

from pygerber.gerber.api import (
    GerberFile, CompositeView, GerberJobFile, 
    FileTypeEnum, DEFAULT_ALPHA_COLOR_MAP
)

def _apply_alpha_color_map(gf: "GerberFile") -> None:
    """Use PyGerber's built-in alpha color map."""
    try:
        gf.set_color_map(DEFAULT_ALPHA_COLOR_MAP)
    except Exception:
        pass

def _group_by_type(files: list["GerberFile"]) -> dict[str, list["GerberFile"]]:
    """Bucket files by type for z-ordering."""
    grouped = {"copper": [], "mask": [], "silk": [], "edge": []}
    for f in files:
        # Extract filename from GerberFile repr
        rf = repr(f)
        name = rf.split("source='", 1)[1].split("'", 1)[0] if "source='" in rf else None
        ftype = _infer_type_from_name(str(name)) if name else None
        
        if FileTypeEnum and ftype == FileTypeEnum.MASK:
            grouped["mask"].append(f)
        elif FileTypeEnum and ftype == FileTypeEnum.SILK:
            grouped["silk"].append(f)
        elif FileTypeEnum and ftype == FileTypeEnum.PROFILE:
            grouped["edge"].append(f)
        else:
            grouped["copper"].append(f)
    return grouped

def _render_composite_pretty(files: list["GerberFile"], dpmm: int) -> PILImage.Image:
    """Render composite with proper z-ordering."""
    for gf in files:
        _apply_alpha_color_map(gf)
    
    grouped = _group_by_type(files)
    ordered = (
        grouped["copper"] + grouped["mask"] + grouped["silk"] + grouped["edge"]
    )
    
    cv = CompositeView(ordered)
    out = cv.render_with_pillow(dpmm=dpmm)
    return out.get_image()

Drill overlay attempt:

def _rasterize_excellon_overlay(drill_path: Path, canvas: PILImage.Image, dpmm: int) -> PILImage.Image:
    """Parse KiCad drill file and overlay holes."""
    W, H = canvas.size
    overlay = PILImage.new("RGBA", (W, H), (0, 0, 0, 0))
    draw = ImageDraw.Draw(overlay)

    tools_mm = {}
    cur_tool = None
    
    with open(drill_path, "r", errors="ignore") as f:
        for line in f:
            line = line.strip()
            if not line or line.startswith(';'):
                continue
                
            u = line.upper()
            
            # Tool definition: T1C0.310
            m = re.match(r"^T(\d+)C([\d\.]+)", u)
            if m:
                tools_mm[m.group(1)] = float(m.group(2))  # Already in mm for KiCad
                continue
                
            # Tool selection: T1
            m = re.match(r"^T(\d+)$", u)
            if m:
                cur_tool = m.group(1)
                continue
                
            # Coordinates: X139.827Y-91.084 (KiCad format)
            m = re.match(r"^X([+-]?[\d\.]+)Y([+-]?[\d\.]+)", u)
            if m and cur_tool and cur_tool in tools_mm:
                x_mm = float(m.group(1))
                y_mm = float(m.group(2))
                
                # Convert to pixels and center
                x_px = int(x_mm * dpmm) + W // 2
                y_px = int(-y_mm * dpmm) + H // 2  # Flip Y
                r_px = max(2, int((tools_mm[cur_tool] * dpmm) / 2.0))
                
                if 0 <= x_px < W and 0 <= y_px < H:
                    draw.ellipse([(x_px - r_px, y_px - r_px), 
                                 (x_px + r_px, y_px + r_px)],
                                fill=(255, 255, 255, 255))  # White holes
    return overlay
    ```
    
    How I'm using it:
    
    ```
# From .gbrjob processing
gerber_job = GerberJobFile.from_file(job_path)
project = gerber_job.to_project()

# Render top side
if project.top.files:
    top_pil = _render_composite_pretty(project.top.files, dpmm)
    
    # Add drill overlay
    drill_file = find_drill_file(extracted_dir)
    if drill_file:
        drill_overlay = _rasterize_excellon_overlay(drill_file, top_pil, dpmm)
        top_pil.alpha_composite(drill_overlay)
    
    top_pil.save("composite_top.png")
    ```
    

[Argmaster]

Hi

If vias are a separate layer and are tagged appropriately I think it should be possible to change their color with a color map.

For now please refer to the color map test case here for an example of how to set up a color map. You can also have a look at adjacent files for more.

If 3.0.0a4 is missing API from those examples then I guess I will have to finally deploy 3.0.0b1 or at least 3.0.0a5 to publish it. It is surely there in the dev version 😅

If vias are part of the copper layer and you don't have a separate Gerber file containing only them then as of now there will be no way to change colors of parts of a single layer.