possible to export bwipp_ functions

[lublak]

currently i can only use BwipJs export.
To improve the performance of the size caulculation (#281) i need to write my own BWIPJs Object and call bwipp_encode.
It woould be usefull to get an: BwipJs.bwipp.bwipp_encode etc.

[metafloor]

I am not sure what you are asking. Please provide a code sketch of what you would like to do.

[lublak]

@metafloor
currently i created somthing like this so i can auto scale a barcode.
But it would be faster if i create my own BwipJs class.
So i can remove all code which is not needed to calculate the size.

class CalculateSize implements DrawingOption<{width:number, height:number}> {
    width:number = 0;
    height:number = 0;
    constructor() {

    }
    scale(sx: number, sy: number): [number, number] | null {
        return null;
    }
    measure(str: string, font: string, fwidth: number, fheight: number): { width: number; ascent: number; descent: number; } {
        width = fwidth|0;
        fheight = fheight|0;

        var fontid = FontLib.lookup(font);
        var width = 0;
        var ascent = 0;
        var descent = 0;
        for (var i = 0; i < str.length; i++) {
            var ch = str.charCodeAt(i);
            var glyph = FontLib.getpaths(fontid, ch, fwidth, fheight);
            if (!glyph) {
                continue;
            }
            ascent  = Math.max(ascent, glyph.ascent);
            descent = Math.max(descent, -glyph.descent);
            width  += glyph.advance;
        }
        return { width, ascent, descent };
    }
    init(width: number, height: number): void {
        this.width = width;
        this.height = height;
    }
    line(x0: number, y0: number, x1: number, y1: number, lw: number, rgb: string): void {
        
    }
    polygon(pts: [number, number][]): void {
        
    }
    hexagon(pts: [[number, number], [number, number], [number, number], [number, number], [number, number]]): void {
        
    }
    ellipse(x: number, y: number, rx: number, ry: number, ccw: boolean): void {
        
    }
    fill(rgb: string): void {
        
    }
    text(x: number, y: number, str: string, rgb: string, font: { name: string; width: number; height: number; dx: number; }): void {
        
    }
    end(): {width:number, height:number} {
        return {
            width: this.width,
            height: this.height,
        }
    }
}
 const size = BwipJs.render({
    bcid: data.type,
    text: data.data,
    includetext: !!text,
    alttext: text
 }, new CalculateSize());

const ratio = Math.floor(width / size.width);
BwipJs.toCanvas({
    bcid: data.type,
    text: data.data,
    includetext: !!text,
    alttext: text,
    scale: ration
})

[metafloor]

I am finishing up the version 4 release of bwip-js and its biggest change is the ability to pass in user-provided drawing objects to the named exports. This will allow tree-shaking with custom drawing, which the current version does not support. I believe that is what you are asking for here. Please correct me if I misunderstand.

But your request also shows the need to include a built-in drawing object that just returns size. I will add that to the new release.

[lublak]

@metafloor yes :) this is it! Thanks!

[metafloor]

Version 4 is just released and includes the ability to supply custom drawing objects to the named exports. See here for the announcement: #299