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import base64js from 'base64-js'
import omggif from 'omggif'
/**
* Converts RGB array to named object
* @param {[]} item, a length 3 array containing 8 bit RGB value
*/
function rgb(item) {
return {
r: item[0],
g: item[1],
b: item[2]
}
}
/**
* Converts XY array to named object
* @param {[]} item, a 2 length array containing x and y values
*/
function xy(item) {
return {
x: item[0],
y: item[1]
}
}
/**
* Compares colors.
* Colors are either 3-element arrays [r, g, b]
* Or objects with .r .g .b members
*/
function colorEqual(item1, item2) {
if (!item1 || !item2) {
return false
}
if (Array.isArray(item1)) {
item1 = rgb(item1)
}
if (Array.isArray(item2)) {
item2 = rgb(item2)
}
return item1.r === item2.r
&& item1.g === item2.g
&& item1.b === item2.b
}
/**
* Compares 2 coordinate values
* @param { [x, y] or {x: y:} } item1
* @param { [x, y] or {x: y:} } item2
*/
function coordsEqual(item1, item2) {
if (!item1 || !item2) {
return false
}
if (Array.isArray(item1)) {
item1 = xy(item1)
}
if (Array.isArray(item2)) {
item2 = xy(item2)
}
return item1.x === item2.x
&& item1.y === item2.y
}
/**
* If I ever want to change the pixel format...
* I should really route all access to pixels through here.
* @param {number} x
* @param {number} y
* @param {[][][]} pixels
*/
function getPixel(x, y, pixels) {
let column = pixels[x]
if (!column) {
return
}
return column[y]
}
/**
* Finds contiguous regions of pixels of the same color.
* Returns an array of the x & y coordinates of every pixel in the region.
* Doesn't jump corners: only pixels that share a side are considered to
* join up.
*
* @param {number} x
* @param {number} y
* @param {[][]]} pixels
* @param {[]]} targetColor
* @param {[][]]} contiguousPixels
*/
function findContiguousPixels(x, y, pixels, targetColor = getPixel(x, y, pixels), contiguousPixels=[[x, y]]) {
let adjescent = [
[x-1, y],
[x+1, y],
[x, y-1],
[x, y+1]
]
adjescent.forEach((coord) => {
let px = xy(coord)
let pxCol = getPixel(px.x, px.y, pixels)
if (!pxCol) {
return
}
// add adjescents uniquely if they are the target color
let ix = contiguousPixels.findIndex((existingCoord) => coordsEqual(coord, existingCoord))
if (ix !== -1) {
return
}
if (!colorEqual(pxCol, targetColor)) {
return
}
contiguousPixels.push(coord)
let morePixels = findContiguousPixels(px.x, px.y, pixels, targetColor, contiguousPixels)
contiguousPixels.concat(morePixels)
})
return contiguousPixels
}
function rotatePixelsCounterClock(pixels) {
let rotateClock = (x, y, width, height) => {
return {
newx: -y + (width - 1),
newy : x
}
}
return transformPixels(pixels, rotateClock)
}
function rotatePixelsClock(pixels) {
let rotateClock = (x, y, width, height) => {
return {
newx: y,
newy : - x + (height - 1)
}
}
return transformPixels(pixels, rotateClock)
}
/**
* Apply an arbitrary transform to some pixels.
* Does not modify the original pixels, just returns the new ones
*
* @param {[][][]]} pixels
* @param {(x, y, width, height) => { newx: newy: }} transform
* @returns {[][][]} newPixels
*/
function transformPixels(pixels, transform) {
let width = pixels.length
let height = pixels[0].length
let newPixels = []
for (var x = 0; x < width; x++) {
let column = []
for (var y = 0; y < height; y++) {
column.push([0, 0, 0])
}
newPixels.push(column)
}
for (var x = 0; x < width; x++) {
for (var y = 0; y < height; y++) {
let px = getPixel(x, y, pixels)
let {newx, newy} = transform(x, y, width, height)
newPixels[newx][newy] = px
}
}
return newPixels
}
/**
* Reads all frames from a GIF image, returns them as 3d arrays (x, y, color component)
* @param {string} base64GifData The GIF image encoded as base64
*/
function readGifFrames(base64GifData) {
let imageBytes = base64js.toByteArray(base64GifData)
let gifReader = new omggif.GifReader(imageBytes)
let { width, height } = gifReader
let numFrames = gifReader.numFrames()
let frames = []
for (var i=0; i<numFrames; i++) {
let rawPixels = new Array(width * height * 4)
gifReader.decodeAndBlitFrameRGBA(i, rawPixels)
// Create the x, y array upfront
let pixels = new Array(width)
for (var y=0; y<height; y++) {
pixels[y] = new Array(height)
}
frames.push(pixels)
// Copy pixels to out array. The data provided is provided in rows
var ix = 0
for (var y=0; y<height; y++) {
for (var x=0; x<width; x++) {
let r = rawPixels[ix++]
let g = rawPixels[ix++]
let b = rawPixels[ix++]
// let a = rawPixels[ix++]
ix++ // Ignore the alpha component
pixels[x][y] = [r, g, b]
}
}
}
return frames
}
export {
xy,
rgb,
colorEqual,
coordsEqual,
findContiguousPixels,
getPixel,
rotatePixelsClock,
rotatePixelsCounterClock,
readGifFrames
}
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