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import { IOBuffer } from 'iobuffer';
import { deflate } from 'pako';
import { writeCrc } from './helpers/crc';
import { writeSignature } from './helpers/signature';
import { encodetEXt } from './helpers/text';
import { InterlaceMethod, ColorType, CompressionMethod, FilterMethod, } from './internalTypes';
const defaultZlibOptions = {
level: 3,
};
export default class PngEncoder extends IOBuffer {
_png;
_zlibOptions;
_colorType;
_interlaceMethod;
constructor(data, options = {}) {
super();
this._colorType = ColorType.UNKNOWN;
this._zlibOptions = { ...defaultZlibOptions, ...options.zlib };
this._png = this._checkData(data);
this._interlaceMethod =
(options.interlace === 'Adam7'
? InterlaceMethod.ADAM7
: InterlaceMethod.NO_INTERLACE) ?? InterlaceMethod.NO_INTERLACE;
this.setBigEndian();
}
encode() {
writeSignature(this);
this.encodeIHDR();
if (this._png.palette) {
this.encodePLTE();
if (this._png.palette[0].length === 4) {
this.encodeTRNS();
}
}
this.encodeData();
if (this._png.text) {
for (const [keyword, text] of Object.entries(this._png.text)) {
encodetEXt(this, keyword, text);
}
}
this.encodeIEND();
return this.toArray();
}
// https://www.w3.org/TR/PNG/#11IHDR
encodeIHDR() {
this.writeUint32(13);
this.writeChars('IHDR');
this.writeUint32(this._png.width);
this.writeUint32(this._png.height);
this.writeByte(this._png.depth);
this.writeByte(this._colorType);
this.writeByte(CompressionMethod.DEFLATE);
this.writeByte(FilterMethod.ADAPTIVE);
this.writeByte(this._interlaceMethod);
writeCrc(this, 17);
}
// https://www.w3.org/TR/PNG/#11IEND
encodeIEND() {
this.writeUint32(0);
this.writeChars('IEND');
writeCrc(this, 4);
}
encodePLTE() {
const paletteLength = this._png.palette?.length * 3;
this.writeUint32(paletteLength);
this.writeChars('PLTE');
for (const color of this._png.palette) {
this.writeByte(color[0]);
this.writeByte(color[1]);
this.writeByte(color[2]);
}
writeCrc(this, 4 + paletteLength);
}
encodeTRNS() {
const alpha = this._png.palette.filter((color) => {
return color.at(-1) !== 255;
});
this.writeUint32(alpha.length);
this.writeChars('tRNS');
for (const el of alpha) {
this.writeByte(el.at(-1));
}
writeCrc(this, 4 + alpha.length);
}
// https://www.w3.org/TR/PNG/#11IDAT
encodeIDAT(data) {
this.writeUint32(data.length);
this.writeChars('IDAT');
this.writeBytes(data);
writeCrc(this, data.length + 4);
}
encodeData() {
const { width, height, channels, depth, data } = this._png;
const slotsPerLine = depth <= 8
? Math.ceil((width * depth) / 8) * channels
: Math.ceil((((width * depth) / 8) * channels) / 2);
const newData = new IOBuffer().setBigEndian();
let offset = 0;
if (this._interlaceMethod === InterlaceMethod.NO_INTERLACE) {
for (let i = 0; i < height; i++) {
newData.writeByte(0); // no filter
if (depth === 16) {
offset = writeDataUint16(data, newData, slotsPerLine, offset);
}
else {
offset = writeDataBytes(data, newData, slotsPerLine, offset);
}
}
}
else if (this._interlaceMethod === InterlaceMethod.ADAM7) {
// Adam7 interlacing
offset = writeDataInterlaced(this._png, data, newData, offset);
}
const buffer = newData.toArray();
const compressed = deflate(buffer, this._zlibOptions);
this.encodeIDAT(compressed);
}
_checkData(data) {
const { colorType, channels, depth } = getColorType(data, data.palette);
const png = {
width: checkInteger(data.width, 'width'),
height: checkInteger(data.height, 'height'),
channels,
data: data.data,
depth,
text: data.text,
palette: data.palette,
};
this._colorType = colorType;
const expectedSize = depth < 8
? Math.ceil((png.width * depth) / 8) * png.height * channels
: png.width * png.height * channels;
if (png.data.length !== expectedSize) {
throw new RangeError(`wrong data size. Found ${png.data.length}, expected ${expectedSize}`);
}
return png;
}
}
function checkInteger(value, name) {
if (Number.isInteger(value) && value > 0) {
return value;
}
throw new TypeError(`${name} must be a positive integer`);
}
function getColorType(data, palette) {
const { channels = 4, depth = 8 } = data;
if (channels !== 4 && channels !== 3 && channels !== 2 && channels !== 1) {
throw new RangeError(`unsupported number of channels: ${channels}`);
}
const returnValue = {
channels,
depth,
colorType: ColorType.UNKNOWN,
};
switch (channels) {
case 4:
returnValue.colorType = ColorType.TRUECOLOUR_ALPHA;
break;
case 3:
returnValue.colorType = ColorType.TRUECOLOUR;
break;
case 1:
if (palette) {
returnValue.colorType = ColorType.INDEXED_COLOUR;
}
else {
returnValue.colorType = ColorType.GREYSCALE;
}
break;
case 2:
returnValue.colorType = ColorType.GREYSCALE_ALPHA;
break;
default:
throw new Error('unsupported number of channels');
}
return returnValue;
}
function writeDataBytes(data, newData, slotsPerLine, offset) {
for (let j = 0; j < slotsPerLine; j++) {
newData.writeByte(data[offset++]);
}
return offset;
}
function writeDataInterlaced(imageData, data, newData, offset) {
const passes = [
{ x: 0, y: 0, xStep: 8, yStep: 8 },
{ x: 4, y: 0, xStep: 8, yStep: 8 },
{ x: 0, y: 4, xStep: 4, yStep: 8 },
{ x: 2, y: 0, xStep: 4, yStep: 4 },
{ x: 0, y: 2, xStep: 2, yStep: 4 },
{ x: 1, y: 0, xStep: 2, yStep: 2 },
{ x: 0, y: 1, xStep: 1, yStep: 2 },
];
const { width, height, channels, depth } = imageData;
let pixelSize = 0;
if (depth === 16) {
pixelSize = (channels * depth) / 8 / 2;
}
else {
pixelSize = (channels * depth) / 8;
}
// Process each pass
for (let passIndex = 0; passIndex < 7; passIndex++) {
const pass = passes[passIndex];
const passWidth = Math.floor((width - pass.x + pass.xStep - 1) / pass.xStep);
const passHeight = Math.floor((height - pass.y + pass.yStep - 1) / pass.yStep);
if (passWidth <= 0 || passHeight <= 0)
continue;
const passLineBytes = passWidth * pixelSize;
// For each scanline in this pass
for (let y = 0; y < passHeight; y++) {
const imageY = pass.y + y * pass.yStep;
// Extract raw scanline data
const rawScanline = depth <= 8
? new Uint8Array(passLineBytes)
: new Uint16Array(passLineBytes);
let rawOffset = 0;
for (let x = 0; x < passWidth; x++) {
const imageX = pass.x + x * pass.xStep;
if (imageX < width && imageY < height) {
const srcPos = (imageY * width + imageX) * pixelSize;
for (let i = 0; i < pixelSize; i++) {
rawScanline[rawOffset++] = data[srcPos + i];
}
}
}
newData.writeByte(0); // no filter
if (depth === 8) {
newData.writeBytes(rawScanline);
}
else if (depth === 16) {
for (const value of rawScanline) {
newData.writeByte((value >> 8) & 0xff); // High byte
newData.writeByte(value & 0xff);
}
}
}
}
return offset;
}
function writeDataUint16(data, newData, slotsPerLine, offset) {
for (let j = 0; j < slotsPerLine; j++) {
newData.writeUint16(data[offset++]);
}
return offset;
}
//# sourceMappingURL=PngEncoder.js.map