ppu-ocv/canvas-toolkit.js

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

export class CanvasToolkit{static instance=null;step=0;constructor(){}static getInstance(){if(!CanvasToolkit.instance){CanvasToolkit.instance=new CanvasToolkit}return CanvasToolkit.instance}crop(options){const{bbox,canvas}=options;let croppedCanvas=createCanvas(bbox.x1-bbox.x0,bbox.y1-bbox.y0);let croppedCtx=croppedCanvas.getContext("2d");croppedCtx.drawImage(canvas,bbox.x0,bbox.y0,bbox.x1-bbox.x0,bbox.y1-bbox.y0,0,0,croppedCanvas.width,croppedCanvas.height);return croppedCanvas}isDirty(options){const{canvas,threshold=127.5,majorColorThreshold=0.97}=options;let whiteCount=0;let blackCount=0;let borderlessCanvas=this.crop({bbox:{x0:canvas.width*0.1,y0:canvas.height*0.1,x1:canvas.width*0.9,y1:canvas.height*0.9},canvas});let ctx=borderlessCanvas.getContext("2d");let colorData=ctx.getImageData(0,0,borderlessCanvas.width,borderlessCanvas.height).data;for(let i=0;i<colorData.length;i+=4){let red=colorData[i];let green=colorData[i+1];let blue=colorData[i+2];if(red>=threshold&&green>=threshold&&blue>=threshold){whiteCount++}else{blackCount++}}let majorColorRatio=Math.max(whiteCount,blackCount)/(blackCount+whiteCount);return majorColorRatio<majorColorThreshold}saveImage(options){const{canvas,filename,path="out"}=options;let folderPath=join(process.cwd(),path);if(!existsSync(folderPath)){mkdirSync(folderPath,{recursive:true})}let filePath=join(folderPath,`${this.step++}. ${filename}.png`);let out=createWriteStream(filePath);let buffer=canvas.toBuffer("image/png");return new Promise((res,rej)=>{out.write(buffer,(err)=>{if(err){rej(err)}else{res()}})})}clearOutput(path="out"){let folderPath=join(process.cwd(),path);if(existsSync(folderPath)){let files=readdirSync(folderPath);for(let file of files){if(file===".gitignore")continue;let filePath=join(folderPath,file);unlinkSync(filePath)}}}drawLine(options){const{ctx,x,y,width,height,lineWidth=2,color="blue"}=options;ctx.beginPath();ctx.strokeStyle=color;ctx.lineWidth=lineWidth;ctx.strokeRect(x,y,width,height);ctx.closePath()}drawContour(options){const{ctx,contour,strokeStyle="red",lineWidth=2}=options;let pts=contour.data32S;if(pts.length<4)return;ctx.strokeStyle=strokeStyle;ctx.lineWidth=lineWidth;ctx.beginPath();ctx.moveTo(pts[0],pts[1]);for(let i=2;i<pts.length;i+=2){ctx.lineTo(pts[i],pts[i+1])}ctx.closePath();ctx.stroke()}}import{createCanvas}from"./index";import{createWriteStream,existsSync,mkdirSync,readdirSync,unlinkSync}from"fs";import{join}from"path";