bitmap-sdf

Calculate SDF for image/bw-data/array

Downloads in past

Stats

StarsIssuesVersionUpdatedCreatedSize
bitmap-sdf
1.0.43 months ago5 years agoMinified + gzip package size for bitmap-sdf in KB

Readme

bitmap-sdf unstable
Calculate signed distance field for an image / bw-data. Fork of tiny-sdf with reduced API. bitmap-sdf Demo

Usage

npm install bitmap-sdf ```js let calcSdf = requrie('bitmap-sdf') //draw image let canvas = document.body.appendChild(document.createElement('canvas')) let w = canvas.width = 200, h = canvas.height = 200 let ctx = canvas.getContext('2d') ctx.fillStyle = 'white' ctx.font = 'bold 30px sans-serif' ctx.fillText('X', 20, 20) //calculate distances let distances = calcSdf(canvas) //show distances let imgArr = new Uint8ClampedArray(wh4) for (let i = 0; i < w; i++) {
for (let j = 0; j < h; j++) {
imgArr[j*w*4 + i*4 + 0] = arr[j*w+i]*255
imgArr[j*w*4 + i*4 + 1] = arr[j*w+i]*255
imgArr[j*w*4 + i*4 + 2] = arr[j*w+i]*255
imgArr[j*w*4 + i*4 + 3] = 255
}
} var data = new ImageData(imgArr, w, h) ctx.putImageData(data, 0, 0) ```

dist = calcSdf(source, options?)

Calculate distance field for the input source data, based on options. Returns 1-channel array with distance values from 0..1 range.

Source:

Type | Meaning ---|--- Canvas, Context2D | Calculates sdf for the full canvas image data based on options.channel, by default 0, ie. red channel. ImageData | Calculates sdf for the image data based on options.channel Uint8ClampedArray, Uint8Array | Handles raw pixel data, requires options.width and options.height. Stride is detected from width and height. Float32Array, Array | Handles raw numbers from 0..1 range, requires options.width and options.height. Stride is detected from width and height.

Options:

Property | Default | Meaning ---|---|--- cutoff | 0.25 | Cutoff parameter, balance between SDF inside 1 and outside 0 of glyph radius | 10 | Max length of SDF, ie. the size of SDF around the cutoff width | canvas.width | Width of input data, if array height | canvas.height | Height of input data, if array channel | 0 | Channel number, 0 is red, 1 is green, 2 is blue, 3 is alpha. stride | null | Explicitly indicate number of channels per pixel. Not needed if height and width are provided.

See also

  • tiny-sdf − fast glyph signed distance field generation.

Alternatives

License

(c) 2017 Dima Yv. MIT License Development supported by plot.ly.