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2.canvas像素计算pixel图解
3.less
* { margin: 0; padding: 0; #wrap { width: 600px; height: 800px; background: tomato; border: 2px solid white; border-radius: 5%; //这里不可使用position,会影响画布的坐标定位 left: 0; top: 0; right: 0; bottom: 0; margin: 5% auto; font: 20px "微软雅黑"; text-align: center; color: white; transition: 2s; &:hover { background: steelblue; } h1 { margin-top: 8%; } h2 { margin-left: 30%; margin-top: 100%; } #wrap-canvas { position: absolute; background: lightgoldenrodyellow; left: 0; top: 0; right: 0; bottom: 0; margin: auto; } }}4.js
/*canvas中可以使用ImageData对象操纵像素数据 * 1. getImageData():包含画布区域的对象像素数据,封装为ImageData对象 * |- getImageData(x,y,w,h) * x/y:被提取的图像数据,矩形区域的左上角x、y像素,单位是像素 * w/h:被提取的图像数据,矩形区域的宽度、高度,单位是像素 * |- data:Unit8ClampedArray类型的一维数组,包含RGBA格式的整型数据,范围在0-255(黑色到白色) A(0-255范围opacity)为不透明度 * 2. putImageData(imgData,x,y) 写入像素数据 * x/y:let、top坐标,默认左上角 * 3. createImageData(width,height) 创建像素数据 */$(function(){ var canvasNode=document.querySelector("#wrap-canvas"); if(canvasNode.getContext){ var canvasPen=canvasNode.getContext("2d"); canvasPen.save(); canvasPen.fillStyle="steelblue"; canvasPen.beginPath(); canvasPen.fillRect(0,0,100,100); canvasPen.restore(); //1.获取像素data:应该是100*100=10000个像素点,实际是Uint8ClampedArray(40000),rgba像素*4 var imageData=canvasPen.getImageData(0,0,50,50); console.log("steel blue的imageData-rgba:",imageData); /* 2.创建imageData * putImageData(imgData,x,y) 写入像素数据 * x/y:let、top坐标,默认左上角 * createImageData(width,height) 创建像素数据 */ canvasPen.save(); var newImageData=canvasPen.createImageData(100,100); canvasPen.beginPath(); for(var i=0;i<newImageData.data.length;i++){ newImageData.data[4*i+3]=100; }; canvasPen.putImageData(newImageData,100,100); canvasPen.restore(); //3.获取像素点 canvasPen.save(); canvasPen.fillStyle="tomato"; canvasPen.beginPath(); canvasPen.fillRect(200,200,100,100); canvasPen.restore(); var getImage=canvasPen.getImageData(200,200,canvasNode.width,canvasNode.height); //这里的(imagedata=get到的ImageData定位坐标,left:300=0 top:300=0 最高left/top=100,超出100即为0,0,0,0白色) var getImageColor=getPixelColor(getImage,50,50); console.log("tomato获取到的imageColor:",getImageColor);//[255, 99, 71, 255] //4.改变像素 canvasPen.save(); canvasPen.fillStyle="deepskyblue"; canvasPen.beginPath(); canvasPen.fillRect(300,300,100,100); //canvasPen.putImageData(setImage,300,300); canvasPen.restore(); //4.1获取画布宽度及图像位置 var setImage=canvasPen.getImageData(300,300,canvasNode.width,canvasNode.height); //4.2设置图像颜色 setPixelColor(setImage,50,50,[0,0,0,255]); //4.3放入图像:颜色点 //canvasPen.putImageData(setImage,300,300); //4.4整行/列替换颜色 for(var i=0;i<setImage.width;i++){ setPixelColor(setImage,i,50,[255,255,255,255]); } canvasPen.putImageData(setImage,300,300); console.log("set pixel color结果:",getImageColor); } //4.获取图像颜色 function getPixelColor(img,x,y){ var pixelColor=[]; var pixelData=img.data; var pixelWidth=img.width; //获取颜色偏移量位置:column(y)*width(w)+row(x) //r pixelColor[0]=pixelData[(y*pixelWidth+x)*4]; //g pixelColor[1]=pixelData[(y*pixelWidth+x)*4+1]; //b pixelColor[2]=pixelData[(y*pixelWidth+x)*4+2]; //a pixelColor[3]=pixelData[(y*pixelWidth+x)*4+3]; return pixelColor; } function setPixelColor(img,x,y,pixelColor){ var pixelData=img.data; var pixelWidth=img.width; pixelData[(y*pixelWidth+x)*4]=pixelColor[0]; pixelData[(y*pixelWidth+x)*4+1]=pixelColor[1]; pixelData[(y*pixelWidth+x)*4+2]=pixelColor[2]; pixelData[(y*pixelWidth+x)*4+3]=pixelColor[3]; }})5.html
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width,initial-scale=1.0,user-scalable=no" /> <title>canvas画布像素设置</title> </head> <link rel="stylesheet" href="../6-bootstrap/css/bootstrap.min.css" /> <link rel="stylesheet" href="css/16-canvas-pixel-up.css" /> <body> <div id="wrap"> <h1>canvas动画-像素pixel</h1> <canvas id="wrap-canvas" width="500px" height="500px"></canvas> <h2>PS:一刀coder</h2> </div> </body> <script type="text/javascript" src="../6-bootstrap/js/jquery.min.js"></script> <script type="text/javascript" src="../6-bootstrap/js/bootstrap.min.js"></script> <script type="text/javascript" src="js/16-canvas-pixel-up.js"></script></html>123456789101112131415161718192021226.效果图
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