无赖勇者的鬼畜美学,汉中电视台,珠宝网站
一.带隐藏文本信息的图片
通过rgb 分量值的小量变动,不影响对图片的识别。因此,我们可以在图片加入文字信息。
最终达到如下效果:
首先,在该组件中加入img用于显示图片
<canvas ref="canvas" v-show="0"></canvas> <img :src="imageurl" v-if="imageurl"/>
调用方法
encryptionimg({ width = '', height = '', content = '', }){ let img = this.img const imgratio = img.naturalwidth / img.naturalheight; const ctxwidth = width || img.naturalwidth; const ctxheight = height || ctxwidth / imgratio; this.canvas.width = ctxwidth; this.canvas.height = ctxheight; const ctx = this.ctx; ctx.font = '16px microsoft yahei'; ctx.textalign = 'left'; ctx.textbaseline = 'top'; ctx.filltext(content, 12, ctxheight/2, ctxwidth);17 const textdata = ctx.getimagedata(0, 0, ctxwidth, ctxheight); this.imageurl = this.mergedata(textdata.data, 'r',ctxwidth,ctxheight);19 }
把文字和图片整合成一张图
mergedata(newdata, color, width, height) { let img = this.img this.ctx.drawimage(img, 0, 0, width, height); this.originaldata = this.ctx.getimagedata(0, 0, width, height); var odata = this.originaldata.data; var bit, offset; switch (color) { case 'r': bit = 0; offset = 3; break; case 'g': bit = 1; offset = 2; break; case 'b': bit = 2; offset = 1; break; } for (var i = 0; i < odata.length; i++) { if (i % 4 == bit) { if (newdata[i + offset] === 0 && (odata[i] % 2 === 1)) { if (odata[i] === 255) { odata[i]-- } else { odata[i]++ } } else if (newdata[i + offset] !== 0 && (odata[i] % 2 === 0)) { if (odata[i] === 255) { odata[i]-- } else { odata[i]++ } } } } this.ctx.putimagedata(this.originaldata, 0, 0); return this.canvas.todataurl(); },
调用下面方法,解开图片信息
decryptimg(){ var data = this.originaldata.data; for(var i = 0; i < data.length; i++){ if(i % 4 == 0){ if(data[i] % 2 == 0){ data[i] = 0; } else { data[i] = 255; } } else if(i % 4 == 3){ continue; } else { data[i] = 0; } } this.ctx.putimagedata(this.originaldata, 0, 0); this.imageurl = this.canvas.todataurl(); },
二.图片水印
watermark({ content = '', container = '', width = '', height = '', position = 'bottom-right', font = '16px 微软雅黑', fillstyle = 'rgba(255, 255, 255, 1)', zindex = 11000, } = {}) { let img = this.img const imgratio = img.naturalwidth / img.naturalheight; const ctxwidth = width || img.naturalwidth; const ctxheight = height || ctxwidth / imgratio; this.canvas.width = ctxwidth; this.canvas.height = ctxheight; const ctx = this.ctx; ctx.drawimage(img, 0, 0, ctxwidth, ctxheight); ctx.shadowcolor = 'rgba(0, 0, 0, 0.2)'; ctx.shadowoffsetx = 2; ctx.shadowoffsety = 2; ctx.shadowblur = 2; ctx.font = font; ctx.fillstyle = fillstyle; if(position == 'center') { ctx.textalign = 'center'; ctx.textbaseline = 'middle'; ctx.filltext(content, ctxwidth / 2, ctxheight / 2, ctxwidth) }else if(position == 'bottom-right') { ctx.textalign = 'right'; ctx.textbaseline = 'alphabetic'; ctx.filltext(content, ctxwidth-12, ctxheight-12, ctxwidth) } const base64url = this.canvas.todataurl(); if(container) { const div = document.createelement('div'); div.setattribute('style', ` width: ${ctxwidth}px; height: ${ctxheight}px; z-index: ${zindex}; pointer-events: none; background-repeat: repeat; background-image: url('${base64url}')`); container.insertbefore(div, null); } this.imageurl = base64url }
参考
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