node-ejs-renderer/node_modules/pngjs/lib/format-normaliser.js
2024-06-09 13:55:01 -04:00

94 lines
2.3 KiB
JavaScript

"use strict";
function dePalette(indata, outdata, width, height, palette) {
let pxPos = 0;
// use values from palette
for (let y = 0; y < height; y++) {
for (let x = 0; x < width; x++) {
let color = palette[indata[pxPos]];
if (!color) {
throw new Error("index " + indata[pxPos] + " not in palette");
}
for (let i = 0; i < 4; i++) {
outdata[pxPos + i] = color[i];
}
pxPos += 4;
}
}
}
function replaceTransparentColor(indata, outdata, width, height, transColor) {
let pxPos = 0;
for (let y = 0; y < height; y++) {
for (let x = 0; x < width; x++) {
let makeTrans = false;
if (transColor.length === 1) {
if (transColor[0] === indata[pxPos]) {
makeTrans = true;
}
} else if (
transColor[0] === indata[pxPos] &&
transColor[1] === indata[pxPos + 1] &&
transColor[2] === indata[pxPos + 2]
) {
makeTrans = true;
}
if (makeTrans) {
for (let i = 0; i < 4; i++) {
outdata[pxPos + i] = 0;
}
}
pxPos += 4;
}
}
}
function scaleDepth(indata, outdata, width, height, depth) {
let maxOutSample = 255;
let maxInSample = Math.pow(2, depth) - 1;
let pxPos = 0;
for (let y = 0; y < height; y++) {
for (let x = 0; x < width; x++) {
for (let i = 0; i < 4; i++) {
outdata[pxPos + i] = Math.floor(
(indata[pxPos + i] * maxOutSample) / maxInSample + 0.5
);
}
pxPos += 4;
}
}
}
module.exports = function (indata, imageData) {
let depth = imageData.depth;
let width = imageData.width;
let height = imageData.height;
let colorType = imageData.colorType;
let transColor = imageData.transColor;
let palette = imageData.palette;
let outdata = indata; // only different for 16 bits
if (colorType === 3) {
// paletted
dePalette(indata, outdata, width, height, palette);
} else {
if (transColor) {
replaceTransparentColor(indata, outdata, width, height, transColor);
}
// if it needs scaling
if (depth !== 8) {
// if we need to change the buffer size
if (depth === 16) {
outdata = Buffer.alloc(width * height * 4);
}
scaleDepth(indata, outdata, width, height, depth);
}
}
return outdata;
};