gn-rtf.js/src/emfjs/Bitmap.ts

Render RTF documents in HTML. This also includes rendering WMF and EMF images which are often contained in RTF documents.

/*

The MIT License (MIT)

Copyright (c) 2016 Tom Zoehner
Copyright (c) 2018 Thomas Bluemel

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

*/

import { Blob } from "./Blob";
import { Helper } from "./Helper";

interface Bitmap {
    getWidth(): number

    getHeight(): number
}

class BitmapCoreHeader {
    public width: number;
    public height: number;
    public planes: number;
    public bitcount: number;

    constructor(reader: Blob, skipsize: boolean) {
        if (skipsize) {
            reader.skip(4);
        }
        this.width = reader.readUint16();
        this.height = reader.readUint16();
        this.planes = reader.readUint16();
        this.bitcount = reader.readUint16();
    }

    public colors(): number {
        return this.bitcount <= 8 ? 1 << this.bitcount : 0;
    }
}

class BitmapInfoHeader {
    public width: number;
    public height: number;
    public planes: number;
    public bitcount: number;
    public compression: number;
    public sizeimage: number;
    public xpelspermeter: number;
    public ypelspermeter: number;
    public clrused: number;
    public clrimportant: number;

    constructor(reader: Blob, skipsize: boolean) {
        if (skipsize) {
            reader.skip(4);
        }
        this.width = reader.readInt32();
        this.height = reader.readInt32();
        this.planes = reader.readUint16();
        this.bitcount = reader.readUint16();
        this.compression = reader.readUint32();
        this.sizeimage = reader.readUint32();
        this.xpelspermeter = reader.readInt32();
        this.ypelspermeter = reader.readInt32();
        this.clrused = reader.readUint32();
        this.clrimportant = reader.readUint32();
    }

    public colors(): number {
        if (this.clrused !== 0) {
            return this.clrused < 256 ? this.clrused : 256;
        } else {
            return this.bitcount > 8 ? 0 : 1 << this.bitcount;
        }
    }
}

export class BitmapInfo implements Bitmap {
    private _usergb: boolean;
    private _infosize: number;
    private _header: BitmapCoreHeader | BitmapInfoHeader;

    constructor(reader: Blob, usergb: boolean) {
        this._usergb = usergb;
        const hdrsize = reader.readUint32();
        this._infosize = hdrsize;
        if (hdrsize === Helper.GDI.BITMAPCOREHEADER_SIZE) {
            this._header = new BitmapCoreHeader(reader, false);
            this._infosize += this._header.colors() * (usergb ? 3 : 2);
        } else {
            this._header = new BitmapInfoHeader(reader, false);
            const masks = (this._header as BitmapInfoHeader).compression
            === Helper.GDI.BitmapCompression.BI_BITFIELDS ? 3 : 0;
            if (hdrsize <= Helper.GDI.BITMAPINFOHEADER_SIZE + (masks * 4)) {
                this._infosize = Helper.GDI.BITMAPINFOHEADER_SIZE + (masks * 4);
            }
            this._infosize += this._header.colors() * (usergb ? 4 : 2);
        }
    }

    public getWidth(): number {
        return this._header.width;
    }

    public getHeight(): number {
        return Math.abs(this._header.height);
    }

    public infosize(): number {
        return this._infosize;
    }

    public header(): BitmapCoreHeader | BitmapInfoHeader {
        return this._header;
    }
}

export class DIBitmap implements Bitmap {
    private _reader: Blob;
    private _offset: number;
    private _location: any;
    private _info: BitmapInfo;

    constructor(reader: Blob, bitmapInfo?: any) {
        this._reader = reader;
        this._offset = reader.pos;
        this._location = bitmapInfo;
        this._info = new BitmapInfo(reader, true);
    }

    public getWidth(): number {
        return this._info.getWidth();
    }

    public getHeight(): number {
        return this._info.getHeight();
    }

    public totalSize(): number {
        return this._location.header.size + this._location.data.size;
    }

    public makeBitmapFileHeader(): string {
        const buf = new ArrayBuffer(14);
        const view = new Uint8Array(buf);
        view[0] = 0x42;
        view[1] = 0x4d;
        Helper._writeUint32Val(view, 2, this.totalSize() + 14);
        Helper._writeUint32Val(view, 10, this._info.infosize() + 14);
        return Helper._blobToBinary(view);
    }

    public base64ref(): string {
        const prevpos = this._reader.pos;
        this._reader.seek(this._offset);
        let mime = "image/bmp";
        const header = this._info.header();
        let data;
        if (header instanceof BitmapInfoHeader && header.compression != null) {
            switch (header.compression) {
                case Helper.GDI.BitmapCompression.BI_JPEG:
                    mime = "data:image/jpeg";
                    break;
                case Helper.GDI.BitmapCompression.BI_PNG:
                    mime = "data:image/png";
                    break;
                default:
                    data = this.makeBitmapFileHeader();
                    break;
            }
        } else {
            data = this.makeBitmapFileHeader();
        }

        this._reader.seek(this._location.header.offset);
        if (data != null) {
            data += this._reader.readBinary(this._location.header.size);
        } else {
            data = this._reader.readBinary(this._location.header.size);
        }

        this._reader.seek(this._location.data.offset);
        data += this._reader.readBinary(this._location.data.size);

        const ref = "data:" + mime + ";base64," + btoa(data);
        this._reader.seek(prevpos);
        return ref;
    }
}