Text to Image

Render text into an image and return a temporary local image file path, with optional data URI. Use when Clawhub or Codex needs to convert plain text, styled...

Use scripts/render_text_image.py to generate an image and return a local file path. The script can also include a data: image URL when needed.

Prefer the script over hand-writing image payloads. The script already handles:

• fixed image width and height
• output format: svg, png, jpg, jpeg
• temp file output by default under tmp/
• absolute and relative file paths in the response
• file path, file name, and file size in the response
• whole-text color
• partial text colors through friendly highlight fields or raw segments
• explicit font size
• automatic font-size fitting when font_size is omitted
• newline-aware wrapping
• transparent or solid backgrounds
• Windows and macOS font fallback

Input Shape

Pass a JSON spec through --spec-json or --spec-file.

Supported fields:

json

{
  "text": "Hello\nWorld",
  "highlight_ranges": [
    { "start": 0, "end": 5, "color": "#111111" },
    { "start": 6, "end": 11, "color": "#ff4d4f" }
  ],
  "highlight_texts": [
    { "match": "World", "color": "#1677ff", "occurrence": "all", "case_sensitive": true }
  ],
  "segments": [
    { "text": "Hello ", "color": "#111111" },
    { "text": "World", "color": "#ff4d4f" }
  ],
  "width": 1200,
  "height": 630,
  "format": "png",
  "font_size": 72,
  "min_font_size": 12,
  "default_color": "#111111",
  "background": "#ffffff",
  "padding": 48,
  "line_height": 1.2,
  "align": "center",
  "valign": "middle",
  "font_family": "Microsoft YaHei, PingFang SC, Arial, sans-serif"
}

Rules:

• Provide either text or segments. If both are present, segments wins.
• Prefer text + highlight_texts for simple "make this word red" requests.
• Use highlight_ranges when the caller knows character positions.
• Use segments only when the caller already has exact pieces split out.
• Keep \n when a hard line break is required.
• Omit font_size to make the script auto-fit the whole text inside the image.
• If font_size is provided, the script keeps that size and still wraps lines as needed.
• svg is the default format.
• Prefer png over jpg for text-heavy images.
• If format is jpg or jpeg, transparent background is converted to white.

Priority:

1. segments
2. text + highlight_ranges / highlight_texts
3. text only

Friendly highlight format:

json

{
  "text": "ClawHub makes text visible",
  "highlight_texts": [
    { "match": "ClawHub", "color": "#1677ff" },
    { "match": "visible", "color": "#fa541c" }
  ]
}

Range format:

json

{
  "text": "Hello World",
  "highlight_ranges": [
    { "start": 6, "end": 11, "color": "#ff4d4f" }
  ]
}

Recommended Workflow

1. Build the JSON spec from the user's request.
2. Run the script.
3. Return file_path to the caller when the next step is file upload.
4. Use image_url only when the caller explicitly needs a data URI.

Example:

powershell

@'
{
  "segments": [
    { "text": "Claw", "color": "#111111" },
    { "text": "Hub", "color": "#1677ff" }
  ],
  "width": 1024,
  "height": 512,
  "format": "png",
  "background": "#ffffff",
  "padding": 40
}
'@ | Set-Content spec.json

python scripts/render_text_image.py --spec-file spec.json --no-data-url

Output Contract

The script prints JSON:

json

{
  "file_path": "E:\\clawhub\\text-to-image\\tmp\\rendered-0000.png",
  "relative_file_path": "tmp/rendered-0000.png",
  "file_name": "rendered-0000.png",
  "file_size": 21550,
  "mime_type": "image/png",
  "format": "png",
  "width": 1024,
  "height": 512,
  "font_size": 96.0,
  "line_count": 1,
  "resolved_segments": [
    { "text": "Claw", "color": "#111111" },
    { "text": "Hub", "color": "#1677ff" }
  ]
}

Notes

• svg is lightweight, crisp, and ideal for text rendering.
• png is the best general-purpose bitmap choice for text images.
• jpg is supported for compatibility, but it is usually not the best default for text.
• Auto-fit uses width-aware wrapping and a font-size search; it is approximate but reliable for mixed Chinese and Latin text.
• The script writes files to the skill's own tmp/ folder by default.
• Pass --output path.ext to control where the file is written.
• Pass --no-data-url when the caller only needs upload-ready file metadata.
• On macOS the script tries system fonts such as PingFang and STHeiti before falling back.
• On Windows the script tries fonts such as Microsoft YaHei, SimHei, and Arial.
• Reusable sample specs live in testcases/, including 13-wrap-example.json for fixed-size wrapping.