Overview
Introduction
This tool recreates the classic 'placeholder.com'-style dummy image locally: a solid-color rectangle with its own dimensions stamped in the middle, generated as a real downloadable PNG.
It's useful anywhere you'd otherwise hotlink to a third-party placeholder image service, but want a self-contained file with no external dependency.
What Is Placeholder PNG Creator?
A placeholder image generator that fills a buffer with a solid background color, then stamps the text 'WIDTHxHEIGHT' in the center using a hand-rolled 5x7 bitmap font (since pure, DOM-free functions can't call canvas text APIs).
The text is automatically centered, scaled up for larger images, and colored independently from the background.
How Placeholder PNG Creator Works
First, a solid PixelBuffer is built at the requested size and background color; then the label text is computed from the width and height themselves and its pixel scale is derived from the smaller of the two dimensions (larger images get bigger text, up to 4x scale).
The text's total rendered width and height are computed from the bitmap font's fixed glyph size, then used to calculate a centered (x, y) position before handing off to the shared text-stamping function that clips any pixels that fall outside the canvas.
When To Use Placeholder PNG Creator
Use it whenever you need a quick dummy image for a wireframe, mockup, or test fixture that clearly shows its own dimensions at a glance.
It's also handy for front-end development, filling image slots in a layout before real assets are ready.
Often used alongside Single-color PNG Generator, PNG Text Adder and Empty PNG Creator.
Features
Advantages
- Self-contained: produces a real PNG file with no dependency on a third-party placeholder image service or network request.
- The stamped label makes it immediately obvious what size the image is, useful when debugging layout issues.
- Background and text colors are fully customizable to match a design system.
Limitations
- The built-in bitmap font only supports uppercase letters and digits, so only the dimension label (always digits and 'X') can be rendered, not arbitrary custom text.
- At very small sizes the stamped label can be partially or fully clipped since there isn't enough room for even the smallest text scale.
Examples
Best Practices & Notes
Best Practices
- Choose a background/text color pair with enough contrast so the dimension label stays legible.
- Match the placeholder's aspect ratio to the real image slot it's standing in for, to catch layout issues early.
Developer Notes
generatePlaceholderPng is a pure function that builds a background PixelBuffer, then delegates the actual glyph rasterization to addTextToPng from png-text-adder.ts, keeping this file free of any font logic; no DOM or canvas access happens until the client component paints the returned buffer.
Placeholder PNG Creator Use Cases
- Filling empty image slots in a wireframe or mockup
- Generating test fixture images with a known, labeled size
- Replacing hotlinked placeholder.com images with a self-hosted equivalent
Common Mistakes
- Expecting arbitrary custom text — this tool only ever stamps the image's own computed WIDTHxHEIGHT label.
- Using a very small size and being surprised the label text is clipped rather than shrunk indefinitely; the minimum text scale is 1.
Tips
- Pick a background close to your final image's dominant color for a more realistic layout preview.
- Generate at your exact target dimensions so the stamped label doubles as a sanity check when you inspect the layout.