ppu-ocv/canvas-processor.js

A type-safe, modular, chainable image processing library built on top of OpenCV.js with a fluent API leveraging pipeline processing.

export class CanvasProcessor{_canvas;constructor(source){this._canvas=source}get width(){return this._canvas.width}get height(){return this._canvas.height}resize(options){const{width,height}=options;let dst=getPlatform().createCanvas(width,height);dst.getContext("2d").drawImage(this._canvas,0,0,width,height);this._canvas=dst;return this}grayscale(){const{width,height}=this._canvas;let imageData=this._canvas.getContext("2d").getImageData(0,0,width,height);let d=imageData.data;for(let i=0;i<d.length;i+=4){let luma=Math.round(0.299*(d[i]??0)+0.587*(d[i+1]??0)+0.114*(d[i+2]??0));d[i]=luma;d[i+1]=luma;d[i+2]=luma}let dst=getPlatform().createCanvas(width,height);dst.getContext("2d").putImageData(imageData,0,0);this._canvas=dst;return this}convert(options={}){const{alpha=1,beta=0}=options;if(alpha===1&&beta===0)return this;const{width,height}=this._canvas;let imageData=this._canvas.getContext("2d").getImageData(0,0,width,height);let d=imageData.data;for(let i=0;i<d.length;i+=4){d[i]=Math.round((d[i]??0)*alpha+beta);d[i+1]=Math.round((d[i+1]??0)*alpha+beta);d[i+2]=Math.round((d[i+2]??0)*alpha+beta)}let dst=getPlatform().createCanvas(width,height);dst.getContext("2d").putImageData(imageData,0,0);this._canvas=dst;return this}invert(){const{width,height}=this._canvas;let imageData=this._canvas.getContext("2d").getImageData(0,0,width,height);let d=imageData.data;for(let i=0;i<d.length;i+=4){d[i]=255-(d[i]??0);d[i+1]=255-(d[i+1]??0);d[i+2]=255-(d[i+2]??0)}let dst=getPlatform().createCanvas(width,height);dst.getContext("2d").putImageData(imageData,0,0);this._canvas=dst;return this}threshold(options={}){const{thresh=127,maxValue=255}=options;const{width,height}=this._canvas;let imageData=this._canvas.getContext("2d").getImageData(0,0,width,height);let d=imageData.data;for(let i=0;i<d.length;i+=4){let luma=d[i]===d[i+1]&&d[i+1]===d[i+2]?d[i]??0:Math.round(0.299*(d[i]??0)+0.587*(d[i+1]??0)+0.114*(d[i+2]??0));let val=luma>thresh?maxValue:0;d[i]=val;d[i+1]=val;d[i+2]=val}let dst=getPlatform().createCanvas(width,height);dst.getContext("2d").putImageData(imageData,0,0);this._canvas=dst;return this}border(options={}){const{size=10,color="white"}=options;const{width,height}=this._canvas;let dst=getPlatform().createCanvas(width+size*2,height+size*2);let ctx=dst.getContext("2d");ctx.fillStyle=color;ctx.fillRect(0,0,dst.width,dst.height);ctx.drawImage(this._canvas,size,size);this._canvas=dst;return this}rotate(options){const{angle,cx=this._canvas.width/2,cy=this._canvas.height/2}=options;if(angle===0)return this;const{width,height}=this._canvas;let dst=getPlatform().createCanvas(width,height);let ctx=dst.getContext("2d");ctx.save();ctx.translate(cx,cy);ctx.rotate(-angle*Math.PI/180);ctx.drawImage(this._canvas,-cx,-cy);ctx.restore();this._canvas=dst;return this}findRegions(options={}){const{width,height}=this._canvas;let data=this._canvas.getContext("2d").getImageData(0,0,width,height).data;return detectRegions(data,width,height,options)}toCanvas(){return this._canvas}static async prepareCanvas(file){return bufferToCanvas(file)}static async prepareBuffer(canvas){return canvasToBuffer(canvas)}}import{getPlatform}from"./canvas-factory.js";import{bufferToCanvas,canvasToBuffer}from"./canvas-io.js";import{detectRegions}from"./canvas-regions.js";