本文主要是介绍konva Image 对上报不同数据格式，客户端处理方式，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
vue3组件
<v-stageid="konva_stage":config="konvaConfig"ref="konvaStageRef"@wheel="wheelForScale($event)"><v-layer><v-group :config="group"><v-image:config="{image: pgmImage,}"/></v-group></v-layer></v-stage>
1. Blob 对象（推荐）
if (data instanceof Blob) {const url = URL.createObjectURL(data);pgmImage.value = new Image();pgmImage.value.src = url;pgmImage.value.onload = function () {console.log("pgmImage.width", pgmImage.value.naturalWidth);console.log("pgmImage.height", pgmImage.value.naturalHeight);};
}2.base64(此种方式，读取图片内容转换成base64格式会比原图片大大概1/3)
const base64Str = imgData; // imgData 从后端接口或者websocket 上报数据
pgmImage.value = new Image();
pgmImage.value.src = base64Str;
pgmImage.value.onload = ()=> {// 获取图片参数 参与逻辑操作
}3. pgm 这种非常不推荐pgm本身比其他图片格式大，且不能压缩处理，对图片较大情况下非常不友好！
解析接口传递过来的pgm 数据
const MapImage = function (data) {let exp = /^(\S+)\s+(\#.*?\n)*\s*(\d+)\s+(\d+)\s+(\d+)?\s*/;let match = data && data.match(exp);if (match) {let width = (this.width = parseInt(match[3], 10));let height = (this.height = parseInt(match[4], 10));let maxVal = parseInt(match[5], 10);let bytes = maxVal < 256 ? 1 : 2;let imgData = data.substr(match[0].length);switch (match[1]) {case "P1":this._parser = new ASCIIParser(maxVal + " " + imgData, bytes);this._formatter = new PBMFormatter(width, height);break;case "P2":this._parser = new ASCIIParser(imgData, bytes);this._formatter = new PGMFormatter(width, height, maxVal);break;case "P3":this._parser = new ASCIIParser(imgData, bytes);this._formatter = new PPMFormatter(width, height, maxVal);break;case "P4":this._parser = new BinaryParser(imgData, bytes);this._formatter = new PBMFormatter(width, height);break;case "P5":this._parser = new BinaryParser(imgData, bytes);this._formatter = new PGMFormatter(width, height, maxVal);break;case "P6":this._parser = new BinaryParser(data, bytes);this._formatter = new PPMFormatter(width, height, maxVal);break;default:throw new TypeError("Sorry, your file format is not supported. [" + match[1] + "]");}} else {throw new TypeError("Sorry, file does not appear to be a Netpbm file.");}
};MapImage.prototype.getInitMap = function (type = "image") {let canvas = this._formatter.getPainting(this._parser, type);return canvas;
};const BinaryParser = function (data, bytes) {this._data = data;this._bytes = bytes;this._pointer = 0;
};BinaryParser.prototype.getNextSample = function () {if (this._pointer >= this._data.length) return false;let val = 0;for (let i = 0; i < this._bytes; i++) {val = val * 255 + this._data.charCodeAt(this._pointer++);}return val;
};const ASCIIParser = function (data, bytes) {this._data = data.split(/\s+/);this._bytes = bytes;this._pointer = 0;
};ASCIIParser.prototype.getNextSample = function () {if (this._pointer >= this._data.length) return false;let val = 0;for (let i = 0; i < this._bytes; i++) {val = val * 255 + parseInt(this._data[this._pointer++], 10);}return val;
};const PPMFormatter = function (width, height, maxVal) {this._width = width;this._height = height;this._maxVal = maxVal;
};PPMFormatter.prototype.getPainting = function (parser, type) {let paintData = null;let canvas = null;let ctx = null;let img = null;if (type === "canvas") {canvas = document.createElement("canvas");ctx = canvas.getContext("2d");canvas.width = ctx.width = this._width;canvas.height = ctx.height = this._height;paintData = ctx.getImageData(0, 0, this._width, this._height);} else {paintData = new Uint8ClampedArray(this._width * this._height * 4);}let dataArr = type === "canvas" ? paintData.data : paintData;for (let row = 0; row < this._height; row++) {for (let col = 0; col < this._width; col++) {let factor = 255 / this._maxVal;let r = factor * parser.getNextSample();let g = factor * parser.getNextSample();let b = factor * parser.getNextSample();let pos = (row * this._width + col) * 4;dataArr[pos] = r;dataArr[pos + 1] = g;dataArr[pos + 2] = b;dataArr[pos + 3] = 255;}}if (type === "canvas") {ctx.putImageData(paintData, 0, 0);return canvas;} else {img = new ImageData(paintData, this._width, this._height);return img;}
};const PGMFormatter = function (width, height, maxVal) {this._width = width;this._height = height;this._maxVal = maxVal;
};PGMFormatter.prototype.getPainting = function (parser, type) {let paintData = null;let canvas = null;let ctx = null;let img = null;if (type === "canvas") {canvas = document.createElement("canvas");ctx = canvas.getContext("2d");canvas.width = ctx.width = this._width;canvas.height = ctx.height = this._height;paintData = ctx.getImageData(0, 0, this._width, this._height);} else {paintData = new Uint8ClampedArray(this._width * this._height * 4);}let dataArr = type === "canvas" ? paintData.data : paintData;for (let row = 0; row < this._height; row++) {for (let col = 0; col < this._width; col++) {let d = parser.getNextSample() * (255 / this._maxVal);let pos = (row * this._width + col) * 4;dataArr[pos] = d;dataArr[pos + 1] = d;dataArr[pos + 2] = d;dataArr[pos + 3] = 255;}}if (type === "canvas") {ctx.putImageData(paintData, 0, 0);return canvas;} else {img = new ImageData(paintData, this._width, this._height);return img;}
};const PBMFormatter = function (width, height) {this._width = width;this._height = height;
};PBMFormatter.prototype.getPainting = function (parser, type) {let paintData = null;let canvas = null;let ctx = null;let img = null;if (type === "canvas") {canvas = document.createElement("canvas");ctx = canvas.getContext("2d");canvas.width = ctx.width = this._width;canvas.height = ctx.height = this._height;paintData = ctx.getImageData(0, 0, this._width, this._height);}if (parser instanceof BinaryParser) {let data = "";let byte = null;let bytesPerLine = Math.ceil(this._width / 8);for (let i = 0; i < this._height; i++) {let line = parser._data.substr(i * bytesPerLine, bytesPerLine);let lineData = "";for (let j = 0; j < line.length; j++)lineData += ("0000000" + line.charCodeAt(j).toString(2)).substr(-8);data += lineData.substr(0, this._width);}while ((byte = parser.getNextSample()) !== false) {data += ("0000000" + byte.toString(2)).substr(-8);}parser = new ASCIIParser(data.split("").join(" "), 1);}let dataArr = type === "canvas" ? paintData.data : paintData;for (let row = 0; row < this._height; row++) {for (let col = 0; col < this._width; col++) {let d = (1 - parser.getNextSample()) * 255;let pos = (row * this._width + col) * 4;dataArr[pos] = d;dataArr[pos + 1] = d;dataArr[pos + 2] = d;dataArr[pos + 3] = 255;}}if (type === "canvas") {ctx.putImageData(paintData, 0, 0);return canvas;} else {img = new ImageData(paintData, this._width, this._height);return img;}
};export { MapImage };
vue2 使用方式：
if (pgmImageData) { //pgmImageData 接口返回let img = new MapImage(pgmImageData);let canvasImg = img.getInitMap("canvas");// canvasImg.width, canvasImg.heightthis.konvaConfig.pgmImage = new Image();this.konvaConfig.pgmImage.src = canvasImg.toDataURL();
}这篇关于konva Image 对上报不同数据格式，客户端处理方式的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
