{"id":7510,"date":"2018-05-01T01:33:03","date_gmt":"2018-04-30T17:33:03","guid":{"rendered":"http:\/\/www.zhangxinxu.com\/wordpress\/?p=7510"},"modified":"2018-05-01T13:47:07","modified_gmt":"2018-05-01T05:47:07","slug":"canvas-png-transparent-background-detect","status":"publish","type":"post","link":"https:\/\/www.zhangxinxu.com\/wordpress\/2018\/05\/canvas-png-transparent-background-detect\/","title":{"rendered":"JS\u68c0\u6d4bPNG\u56fe\u7247\u662f\u5426\u6709\u900f\u660e\u80cc\u666f\u3001\u62a0\u56fe\u7b49\u76f8\u5173\u5904\u7406"},"content":{"rendered":"<p>by <a href=\"http:\/\/www.zhangxinxu.com\/\">zhangxinxu<\/a> from <a href=\"http:\/\/www.zhangxinxu.com\/wordpress\/?p=7510\">http:\/\/www.zhangxinxu.com\/wordpress\/?p=7510<\/a><br \/>\n\u672c\u6587\u53ef\u5168\u6587\u8f6c\u8f7d\uff0c\u4f46\u9700\u8981\u4fdd\u7559\u539f\u4f5c\u8005\u548c\u51fa\u5904\uff0c\u6458\u8981\u5f15\u6d41\u5219\u968f\u610f\u3002<\/p>\n<h3>\u4e00\u3001JS\u68c0\u6d4bPNG\u56fe\u7247\u662f\u5426\u6709\u900f\u660e\u80cc\u666f<\/h3>\n<p>\u7528\u6237\u4e0a\u4f20\u56fe\u7247\uff0c\u5982\u679c\u662fPNG\u56fe\u7247\uff0c\u6709\u65f6\u5019\u6211\u4eec\u5e0c\u671b\u8fd9\u5f20PNG\u56fe\u7247\u80cc\u666f\u4e0d\u8981\u662f\u900f\u660e\u7684\uff0c\u4f8b\u5982\uff1a<\/p>\n<ol>\n<li>\u540e\u7aef\u4fdd\u5b58\u56fe\u7247\u65f6\u5019\u5e38\u5e38\u4f1a\u8f6c\u6210JPG\u683c\u5f0f\u7684\uff0c\u6b64\u65f6\uff0c\u5982\u679c\u540e\u7aef\u540c\u5b66\u4e0d\u52a0\u4ee5\u5224\u65ad\u548c\u5904\u7406\uff0c\u5219\u900f\u660e\u533a\u57df\u4f1a\u53d8\u6210\u9ed1\u8272\uff0c\u5f71\u54cd\u4f53\u9a8c\uff1b\n<p>\u4f8b\u5982\uff0c\u4e0b\u9762canvas\u5c06PNG\u56fe\u5f3a\u5236\u8f6c\u6362\u6210JPG\u540e\u7684\u5bf9\u6bd4\u6548\u679c\uff1a<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201804\/2018-04-30_211700.png\" width=\"333\" height=\"166\" alt=\"\u900f\u660e\u80cc\u666f\u8f6cjpg\u683c\u5f0f\u540e\u53d8\u9ed1\" class=\"alignnone\" \/><\/p>\n<p>\u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a<a href=\"http:\/\/www.zhangxinxu.com\/study\/201804\/canvas-png-to-jpg-black-bg.html\" rel=\"noopener\" target=\"_blank\">PNG\u900f\u660e\u80cc\u666f\u8f6cJPG\u540e\u53d8\u9ed1demo<\/a>\n<\/li>\n<li>\u8f6e\u64ad\u5e7f\u544a\u7684\u540e\u53f0\uff0c\u4e3a\u4e86\u663e\u793a\u8d28\u91cf\uff0c\u540e\u53f0\u5f80\u5f80\u662f\u76f4\u63a5\u5b58\u56fe\uff0c\u4fdd\u7559\u539f\u683c\u5f0f\u3002\u8fd9\u6837\u5c31\u6709\u8fd9\u6837\u4e00\u4e2a\u95ee\u9898\uff0c\u5982\u679c\u5e7f\u544a\u56fe\u662f\u4e0a\u4e0b\u5c42\u53e0\u5b9a\u4f4d\u7684\uff0c\u6b64\u65f6\u5982\u679c\u67d0\u4e2a\u5e7f\u544a\u56fe\u7f16\u8f91\u4f20\u7684\u662f\u90e8\u5206\u533a\u57df\u900f\u660e\u5ea6\u7684\u56fe\uff0c\u524d\u7aef\u53c8\u6ca1\u6709\u8003\u8651\u5230\u8fd9\u79cd\u573a\u666f\u5219\u663e\u793a\u5c31\u4f1a\u51fa\u73b0\u95ee\u9898\uff0c\u900f\u51fa\u4e86\u4e0b\u9762\u4e00\u5f20\u56fe\u7cdf\u7cd5\u7684\u4f53\u9a8c\u95ee\u9898\uff1b<\/li>\n<\/ol>\n<p>\u6709\u65f6\u5019\uff0c\u6211\u4eec\u53c8\u5e0c\u671b\u4e0a\u4f20\u7684PNG\u56fe\u7247\u5e26\u900f\u660e\u7684\uff0c\u4f8b\u5982\uff1a<\/p>\n<ol>\n<li>\u67d0\u5e73\u53f0\u53ef\u4ee5\u81ea\u5b9a\u4e49\u83dc\u5355\uff0c\u5141\u8bb8\u7528\u6237\u7f16\u8f91\u6587\u5b57\u548c\u4e0a\u4f20\u56fe\u6807\uff0c\u5f88\u663e\u7136\uff0c\u8fd9\u4e2a\u56fe\u6807\u9700\u8981\u662f\u900f\u660e\u80cc\u666f\u7684\uff0c\u5426\u5219\u53ef\u80fdUI\u4f1a\u5f88\u7cdf\u7cd5\uff1b<\/li>\n<li>QQ\u90ae\u7bb1\u57df\u540d\u90ae\u7bb1\u53ef\u4ee5\u81ea\u5b9a\u4e49logo\u548c\u4e3b\u9898\uff0c\u5982\u679c\u4e0a\u4f20\u7684\u57df\u540dlogo\u56fe\u7247\u80cc\u666f\u4e0d\u662f\u900f\u660e\u7684\uff0c\u4e3b\u9898\u80cc\u666f\u989c\u8272\u4e5f\u4e0d\u4e00\u6837\uff0c\u540c\u6837\u4f1a\u51fa\u73b0\u6bd4\u8f83\u7cdf\u7cd5\u7684UI\uff0c\u5982\u4e0b\u622a\u56fe\uff1a\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201804\/2018-04-30_202134.png\" width=\"518\" height=\"224\" alt=\"\u81ea\u5b9a\u4e49logo\u548c\u80cc\u666f\u4e0d\u76f8\u7b26\u5408\" class=\"alignnone\" \/><\/li>\n<\/ol>\n<p>\u4ee5\u4e0a\u8fd9\u4e9b\u573a\u666f\u7684\u5904\u7406\u901a\u5e38\u8fd9\u6837\u7684\uff1a<\/p>\n<ul>\n<li>PNG\u80cc\u666f\u900f\u660e\u533a\u57df\u53d8\u9ed1\u8272 -> \u540e\u7aef\u9ed1\u8272\u7528\u767d\u8272\u4ee3\u66ff\uff1b<\/li>\n<li>\u5e7f\u544a\u56fe\u9542\u7a7a -> CSS\u7ed9<code>&lt;img&gt;<\/code>\u5143\u7d20\u8bbe\u7f6e\u4e2a\u80cc\u666f\u8272\uff1a\n<pre>img { background-color: #fff; }<\/pre>\n<p>\u4f46\uff0c\u5982\u679c\u56fe\u7247\u6e90\u7528\u5728\u591a\u4e2a\u5730\u65b9\uff0c\u5219\u6b64\u65b9\u6cd5\u5f88\u96be\u7f69\u4f4f\u6240\u6709\u573a\u666f\u3002<\/li>\n<li>\u4e0a\u4f20\u56fe\u6807\u9700\u900f\u660e -> \u5ffd\u7565\uff0c\u4ea4\u7ed9\u7528\u6237<\/li>\n<li>\u4e0a\u4f20logo\u9700\u900f\u660e -> \u5ffd\u7565\uff0c\u4ea4\u7ed9\u7528\u6237<\/li>\n<\/ul>\n<p>\u5b9e\u9645\u4e0a\uff0c\u4ee5\u4e0a\u6240\u6709\u7684\u5904\u7406\u90fd\u53ef\u4ee5\u5728\u4e0a\u4f20\u56fe\u7247\u7684\u65f6\u5019\u7531\u524d\u7aef\u4e00\u6b21\u6027\u89e3\u51b3\u3002<\/p>\n<p>\u5206\u4e24\u6b65\uff1a<\/p>\n<ul>\n<li>\u524d\u7aef\u83b7\u53d6\u4e0a\u4f20\u56fe\u7247\u4fe1\u606f\uff08\u5305\u62ec\u56fe\u7247\u7c7b\u578b\uff0c\u56fe\u7247\u6570\u636e\uff09\uff0cIE10+<\/li>\n<li>JS\u68c0\u6d4b\u56fe\u7247\u662f\u5426\u6709\u900f\u660e\u80cc\u666f\uff0cIE9+<\/li>\n<\/ul>\n<p>\u6211\u4eec\u5148\u770bdemo\uff0c\u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a<a href=\"http:\/\/www.zhangxinxu.com\/study\/201804\/png-alpha-transparent-bg-detect.html\" rel=\"noopener\" target=\"_blank\">png\u56fe\u7247\u662f\u5426\u542b\u6709\u900f\u660e\u50cf\u7d20JS\u68c0\u6d4bdemo<\/a><\/p>\n<p>\u5982\u679c\u662f\u4e0d\u542b\u900f\u660e\u8272\u7684PNG\u56fe\u7247\uff0c\u5219\u4f1a\u63d0\u793a\u4e0d\u542b\u900f\u660e\uff1b\u5982\u679c\u662f\uff0c\u5219\u63d0\u793a\u542b\u900f\u660e\uff0c\u5982\u4e0b\u622a\u56fe\uff1a<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201804\/2018-04-30_221156.png\" width=\"331\" height=\"155\" alt=\"\u662f\u5426\u80cc\u666f\u900f\u660e\u7684\u68c0\u6d4b\" class=\"alignnone\" \/><\/p>\n<p>\u68c0\u6d4b\u539f\u7406\u662f\u501f\u52a9canvas\u7684<code>getImageData()<\/code>\u65b9\u6cd5\uff0c\u5173\u4e8e\u6b64\u65b9\u6cd5\u5177\u4f53API\u548c\u4f7f\u7528\uff0c\u53ef\u4ee5\u53c2\u89c1\u201c<a href=\"http:\/\/www.zhangxinxu.com\/wordpress\/2017\/12\/canvas-getimagedata-letter-shape-animation\/\">canvas getImageData\u4e0e\u4efb\u610f\u5b57\u7b26\u56fe\u5f62\u70b9\u3001\u7ebf\u52a8\u6548<\/a>\u201d\u8fd9\u7bc7\u6587\u7ae0\u201c\u50cf\u7d20\u70b9\u4fe1\u606f\u83b7\u53d6\u201d\u8fd9\u91cc\u7684\u8be6\u7ec6\u4ecb\u7ecd\u3002<\/p>\n<p>\u4e00\u53e5\u8bdd\u6982\u62ec\u5c31\u662f<code>getImageData()<\/code>\u65b9\u6cd5\u53ef\u4ee5\u83b7\u53d6canvas\u753b\u5e03\u4e0a\u6bcf\u4e00\u4e2a\u50cf\u7d20\u70b9\u7684\u989c\u8272\u4fe1\u606f\uff0c\u4e8e\u662f\uff0c\u6211\u4eec\u53ea\u8981\u628a\u4e0a\u4f20\u7684\u56fe\u7247\u7ed8\u5236\u5728canvas\u4e0a\uff0c\u7136\u540e\u68c0\u6d4b\u6709\u6ca1\u6709\u900f\u660e\u7684\u50cf\u7d20\u70b9\u4fe1\u606f\u5373\u53ef\u3002<\/p>\n<p>\u76f8\u5173\u68c0\u6d4bJS\u4ee3\u7801\u5982\u4e0b\uff08\u5b8c\u6574\u4ee3\u7801\u53c2\u89c1<a href=\"http:\/\/www.zhangxinxu.com\/study\/201804\/png-alpha-transparent-bg-detect.html\" target=\"_blank\">demo\u9875\u9762<\/a>\uff09\uff1a<\/p>\n<pre><span style=\"color:green;\">\/\/ \u56fe\u7247\u7ed8\u5236\u5728\u753b\u5e03\u4e0a<\/span>\ncontext.drawImage(img, 0, 0);\n<span style=\"color:green;\">\/\/ \u83b7\u53d6\u56fe\u7247\u50cf\u7d20\u4fe1\u606f<\/span>\nvar imageData = context.getImageData(0, 0, width, height).data;\n<span style=\"color:green;\">\/\/ \u68c0\u6d4b\u6709\u6ca1\u6709\u900f\u660e\u6570\u636e<\/span>\nvar isAlphaBackground = false;\nfor (var index = 3; index &amp;lt; imageData.length; index += 4) {\n    if (imageData[index] != 255) {\n        isAlphaBackground = true;\n        break;    \n    }\n}\n<span style=\"color:green;\">\/\/ isAlphaBackground\u5c31\u662f\u6700\u540e\u77f3\u5934\u6709\u900f\u660e\u6216\u534a\u900f\u660e\u80cc\u666f\u8272\u7684\u7ed3\u679c<\/span><\/pre>\n<p>\u4e0a\u9762<code>imageData<\/code>\u5c31\u662f\u6211\u4eec\u83b7\u53d6\u7684\u56fe\u7247\u50cf\u7d20\u4fe1\u606f\u6570\u7ec4\uff0c\u662f\u4e2a\u4e00\u7ef4\u6570\u7ec4\uff0c\u7c7b\u578b\u4e3aUint8ClampedArray\uff0c\u4e5f\u5c31\u662f\u6570\u7ec4\u4e2d\u6240\u6709\u7684\u503c\u8303\u56f4\u90fd\u662f0~255\uff0c\u6570\u7ec4\u4fe1\u606f\u8fd9\u6837\uff1a<\/p>\n<pre>[R,G,B,A,R,G,B,A,R,G,B,A,R,G,B,A,R,G,B,A,R,G,B,A,...]<\/pre>\n<p>\u56e0\u6b64\uff0c\u6211\u4eec\u53ea\u8981\u5224\u65ad\u6570\u7ec4\u4e2d\u7684A\u662f\u5426\u5168\u90e8\u90fd\u662f255\u5c31\u53ef\u4ee5\u5224\u65ad\u6709\u6ca1\u6709\u900f\u660e\u4fe1\u606f\u4e86\uff0c\u4e00\u4e2a<code>for<\/code>\u5faa\u73af\u5c31\u641e\u5b9a\u4e86\u3002<\/p>\n<p><strong>\u5982\u679c\u56fe\u7247\u5c3a\u5bf8\u5f88\u5927<\/strong><br \/>\ndemo\u9875\u9762\u65e8\u5728\u6f14\u793a\uff0c\u5982\u679c\u56fe\u7247\u5c3a\u5bf8\u5f88\u5927\uff0c\u6309\u7167demo\u9875\u9762\u7684\u5904\u7406\uff0c\u53ef\u80fd\u4f1a\u6bd4\u8f83\u8017\u65f6\u95f4\uff0c\u6211\u4eec\u53ef\u4ee5\u5728\u628acanvas\u753b\u5e03\u8fdb\u884c\u5c3a\u5bf8\u9650\u5236\uff0c\u4e5f\u5c31\u662f\u56fe\u7247\u5c3a\u5bf8\u538b\u7f29\uff0c\u8fd9\u4e2a\u4e0d\u4f1a\u5f71\u54cd\u5bf9\u662f\u5426\u6709\u900f\u660e\u80cc\u666f\u7684\u5224\u65ad\uff0c\u5177\u4f53\u64cd\u4f5c\u548c\u4ee3\u7801\u53ef\u4ee5\u53c2\u89c1\u8fd9\u7bc7\u6587\u7ae0\uff1a\u201c<a href=\"http:\/\/www.zhangxinxu.com\/wordpress\/2017\/07\/html5-canvas-image-compress-upload\/\">canvas\u5b9e\u73b0\u56fe\u7247\u524d\u7aefJS\u538b\u7f29\u5e76\u4e0a\u4f20<\/a>\u201d\u3002<\/p>\n<h4>\u80cc\u666f\u900f\u660e\u4e0e\u5426\u7684\u5b9e\u9645\u5904\u7406<\/h4>\n<p>\u5982\u679c\u7ad9\u5728\u89e3\u51b3\u5b9e\u9645\u95ee\u9898\u7684\u89d2\u5ea6\uff0c\u5224\u65ad\u662f\u5426\u80cc\u666f\u900f\u660e\u5e76\u4e0d\u4e00\u5b9a\u8981\u5f97\u5230\u3002<\/p>\n<ol>\n<li>\u5bf9\u4e8e\u4e0d\u9700\u8981\u900f\u660e\u80cc\u666f\u7684\u5904\u7406\uff0c\u6211\u4eec\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528canvas\u8865\u4e00\u4e2a\u80cc\u666f\u8272\uff0c\u65e0\u8bba\u56fe\u7247\u662f\u4e0d\u662f\u900f\u660e\u7684\u90fd\u4e0d\u9700\u8981\u5224\u65ad\u3002\u64cd\u4f5c\u5982\u4e0b\uff1a\n<ol>\n<li>canvas\u7ed8\u5236\u4e00\u4e2a\u5e95\u8272\uff0c\u901a\u5e38\u662f\u767d\u8272\uff1a\n<pre>context.fillStyle = '#ffffff';\ncontext.fillRect(0, 0, canvas.width, canvas.height);<\/pre>\n<\/li>\n<li>\u7ed8\u5236\u56fe\u7247\uff1a\n<pre>context.drawImage(img, 0, 0);<\/pre>\n<li>\u4e0a\u4f20canvas\u56fe\u7247\uff08\u8f6c\u6362\u6210base64\u540e\u8005blob\u6570\u636e\u90fd\u53ef\u4ee5\uff09\uff0c<code>canvas.toDataURL(file.type)<\/code>\u6216\u8005<code>canvas.toBlob(callback, file.type)<\/code>\u3002<\/li>\n<\/li>\n<\/ol>\n<\/li>\n<li>\u5982\u679c\u662f\u9700\u8981PNG\u80cc\u666f\u56fe\u7247\uff0c\u5219\u6211\u4eec\u5c31\u53ef\u4ee5\u5148\u8fdb\u884c\u524d\u7aef\u68c0\u6d4b\uff0c\u7136\u540e\uff1a\n<ul>\n<li>\u7b80\u5355\u7684\u5904\u7406\u662f\u76f4\u63a5\u63d0\u793a\u7528\u6237\uff0c\u201c\u60a8\u4e0a\u4f20\u56fe\u7247\u4e3a\u5b9e\u8272\u80cc\u666f\uff0c\u6700\u7ec8\u6548\u679c\u53ef\u80fd\u4e0d\u597d\u770b\uff0c\u786e\u8ba4\u7ee7\u7eed\uff1f\u201d<\/li>\n<li>\u66f4\u597d\u7684\u5904\u7406\u5219\u662f\u53d1\u73b0\u7528\u6237\u4e0a\u4f20\u56fe\u7247\u4e0d\u662f\u900f\u660ePNG\u56fe\uff0c\u5219\u7acb\u5373\u5f39\u51fa\u4e2a\u5c0f\u7a97\u53e3\uff0c\u5728\u7ebf\u80cc\u666f\u53bb\u8272\u5c31\u597d\u4e86\uff01\u4e8e\u662f\u81ea\u7136\u5f15\u51fa\u4e86\u4e0b\u4e00\u90e8\u5206\u5185\u5bb9\uff0c\u5982\u4f55\u5b9e\u73b0\u56fe\u7247\u7684\u7b80\u6613\u62a0\u56fe\uff08\u80cc\u666f\u900f\u660e\uff09\u6548\u679c\uff1f<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<h3>\u4e8c\u3001\u5b9e\u73b0\u4e00\u4e2a\u7b80\u6613\u7684\u56fe\u7247\u80cc\u666f\u53bb\u8272\u6548\u679c<\/h3>\n<p>\u56fe\u7247\u53bb\u8272\u7f51\u4e0a\u5f88\u591a\u5728\u7ebf\u7684\u5de5\u5177\uff0c\u6709\u4e9b\u8fd8\u5f88\u5389\u5bb3\uff0c\u4f8b\u5982<a href=\"https:\/\/clippingmagic.com\" rel=\"nofollow\" target=\"_blank\">clippingmagic<\/a>\uff0c\u4f46\uff0c\u8fd9\u4e1c\u897f\u662f\u522b\u4eba\u7684\uff0c\u4e14\u6211\u4eec\u4e0d\u9700\u8981\u8fd9\u4e48\u590d\u6742\u4ea4\u4e92\uff0c\u5c31\u7b97\u4ee3\u7801\u722c\u8fc7\u6765\u4e5f\u6ca1\u4ec0\u4e48\u7528\uff0c\u8fd8\u662f\u81ea\u5df1\u5199\u5199\u529f\u80fd\u66f4\u5b9e\u5728\u3002<\/p>\n<p>\u597d\u5728\uff0c\u5982\u679c\u53ea\u662f\u60f3\u5b9e\u73b0\u4e00\u4e2a\u4e0d\u592a\u590d\u6742\u7684\u56fe\u7247\u80cc\u666f\u8272\u53bb\u8272\u6548\u679c\uff0c\u8fd8\u662f\u633a\u5bb9\u6613\u7684\u3002<\/p>\n<p>\u5b9e\u73b0\u7684\u5173\u952e\u4f9d\u7136\u662f<code>getImageData()<\/code>\u65b9\u6cd5\uff0c\u53bb\u8272\uff0c\u7136\u540e\u628a\u76f8\u4f3c\u989c\u8272\u53d8\u6210\u900f\u660e\u989c\u8272\u5c31\u53ef\u4ee5\u4e86\u3002<\/p>\n<p>\u60a8\u53ef\u4ee5\u72e0\u72e0\u5730\u70b9\u51fb\u8fd9\u91cc\uff1a<a href=\"http:\/\/www.zhangxinxu.com\/study\/201804\/background-color-replaced-by-transparent.html\" rel=\"noopener\" target=\"_blank\">\u501f\u52a9canvas\u5b9e\u73b0\u56fe\u7247\u80cc\u666f\u8272\u53bb\u8272demo<\/a><\/p>\n<p>\u4f8b\u5982\uff0c\u6211\u4eec\u70b9\u51fb\u5de6\u8fb9\u56fe\u7247\u7684\u767d\u8272\u533a\u57df\uff0c\u7136\u540e\u8bbe\u7f6e\u5bb9\u5dee\u503c\u662f20\uff0c\u70b9\u51fb\u201c\u6267\u884c\u53bb\u8272\u201d\u6309\u94ae\uff0c\u7ed3\u679c\u5982\u4e0b\u622a\u56fe\uff1a<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201805\/2018-05-01_004536.png\" width=\"434\" height=\"348\" alt=\"\u56fe\u7247\u80cc\u666f\u53bb\u8272\u53d8\u900f\u660e\u6548\u679c\u622a\u56fe\" class=\"alignnone\" \/><\/p>\n<p>\u5982\u679c\u6211\u4eec\u9009\u62e9\u7d2b\u8272\uff0c\u5219\u6548\u679c\u662f\uff1a<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201805\/2018-05-01_005320.png\" width=\"380\" height=\"329\" alt=\"\u7d2b\u8272\u53bb\u8272\u540e\u7684\u6548\u679c\u622a\u56fe\" class=\"alignnone\" \/><\/p>\n<h4>\u5b9e\u73b0\u539f\u7406<\/h4>\n<p>\u5173\u952e2\u4e2a\u6b65\u9aa4\uff0c\u4e00\u662f\u53d6\u8272\uff0c\u4e8c\u662f\u53bb\u8272\u3002<\/p>\n<p><strong>1. \u53d6\u8272\u7684\u5b9e\u73b0<\/strong><\/p>\n<p>\u6839\u636e\u70b9\u51fb\u5750\u6807\uff0c\u53d6\u5f53\u524d\u70b9\u51fb\u4f4d\u7f6e\u50cf\u7d20\u70b9\u989c\u8272\u503c\u4fe1\u606f\u5373\u53ef\uff0c\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre>canvas.addEventListener('click', function (event) {\n    var rect = this.getBoundingClientRect();\n    var x = event.clientX - rect.left;\n    var y = event.clientY - rect.top;\n    <span style=\"color:green;\">\/\/ rgbaPicker\u5c31\u662f\u70b9\u51fb\u50cf\u7d20\u70b9\u7684\u989c\u8272\u4fe1\u606f<\/span>\n    rgbaPicker = context.getImageData(x, y, 1, 1).data;\n});<\/pre>\n<p><strong>2. \u53bb\u8272\u7684\u5b9e\u73b0<\/strong><\/p>\n<p>\u53bb\u8272\u5219\u662f\u66ff\u6362<code>getImageData()<\/code>\u7684\u4e00\u4e9b\u50cf\u7d20\u70b9\u8272\u503c\u4e3a\u900f\u660e\u5373\u53ef\uff0c\u8fd9\u4e2a\u4e0d\u96be\uff0c\u96be\u7684\u662f\u5982\u4f55\u5224\u522b\u4e24\u79cd\u8272\u503c\u662f\u76f8\u4f3c\u7684\u5462\uff1f<\/p>\n<p>\u8fd9\u91cc\u6709\u4e2a\u7b80\u6613\u7684\u989c\u8272\u8272\u503c\u76f8\u4f3c\u5ea6\u8ba1\u7b97\u7b97\u6cd5\uff1a<\/p>\n<pre>similar = Math.sqrt((r2 - r1) * (r2 - r1) + (g2 - g1) * (g2 - g1) + (b2 - b1) * (b2 - b1))<\/pre>\n<p>\u5176\u4e2d\uff0c<code>r2<\/code>,<code>r1<\/code>\u8868\u793aRGB\u4e2d\u7684\u7ea2\u8272red\uff0c<code>g2<\/code>,<code>g1<\/code>\u8868\u793aRGB\u4e2d\u7684\u7eff\u8272green\uff0c<code>b2<\/code>,<code>b1<\/code>\u8868\u793aRGB\u4e2d\u7684\u84dd\u8272blue\u3002<\/p>\n<p>OK\uff0c\u6709\u4e86\u76f8\u4f3c\u5ea6\u7b97\u6cd5\uff0c\u4e0b\u9762\u5c31\u662f\u7b80\u5355\u7684\u8272\u503c\u66ff\u6362\u5904\u7406\u4e86\uff1a<\/p>\n<pre><span style=\"color:green;\">\/\/ \u50cf\u7d20\u70b9\u8272\u503c<\/span>\nvar rgba = rgbaPicker;\n<span style=\"color:green;\">\/\/ \u5bb9\u5dee\u5927\u5c0f<\/span>\nvar tolerance = eleTolerance.value;\n<span style=\"color:green;\">\/\/ \u57fa\u4e8e\u539f\u59cb\u56fe\u7247\u6570\u636e\u5904\u7406\uff0c\n\/\/ \u5176\u4e2d\uff1a\n\/\/ imgData\u662f\u5de6\u56fe\u50cf\u7d20\u4fe1\u606f\uff0c\n\/\/ imgDataResult\u662f\u53f3\u56fe\u5904\u7406\u540e\u7684\u50cf\u7d20\u4fe1\u606f<\/span>\nfor (var index = 0; index &amp;lt; imgData.data.length; index += 4) {\n    var r = imgData.data[index];\n    var g = imgData.data[index + 1];\n    var b = imgData.data[index + 2];\n    \n    if (Math.sqrt(\n        (r - rgba[0]) * (r - rgba[0]) + \n        (g - rgba[1]) * (g - rgba[1]) + \n        (b - rgba[2]) * (b - rgba[2])) &lt;= tolerance\n    ) {\n        imgDataResult.data[index] = 0;\n        imgDataResult.data[index + 1] = 0;\n        imgDataResult.data[index + 2] = 0;\n        imgDataResult.data[index + 3] = 0;\n    } else {\n        imgDataResult.data[index] = r;\n        imgDataResult.data[index + 1] = g;\n        imgDataResult.data[index + 2] = b;\n        imgDataResult.data[index + 3] = imgData.data[index + 3];\n    }\n}\n<span style=\"color:green;\">\/\/ put\u6570\u636e<\/span>\ncontextResult.<span style=\"color:#cd0000;\">putImageData<\/span>(imgDataResult, 0, 0);<\/pre>\n<p>\u70b9\u775b\u4ee3\u7801\u5c31\u662f\u6700\u540e\u7684<code>putImageData()<\/code>\uff0c\u53ef\u4ee5\u8ba9\u753b\u5e03\u4f7f\u7528\u65b0\u6570\u636e\u8fdb\u884c\u56fe\u50cf\u5448\u73b0\uff0c\u5c31\u53ef\u4ee5\u770b\u5230\u53bb\u8272\u540e\u7684\u6548\u679c\u4e86\u3002<\/p>\n<p>\u4ee5\u4e0aJS\u4e3a\u7247\u6bb5\u622a\u53d6\uff0c\u5982\u679c\u770b\u4e0d\u900f\u5f7b\uff0c\u53ef\u4ee5\u524d\u5f80<a href=\"http:\/\/www.zhangxinxu.com\/study\/201804\/background-color-replaced-by-transparent.html\" rel=\"noopener\" target=\"_blank\">demo\u9875\u9762<\/a>\u67e5\u770b\u5b8c\u6574\u7684\u6e90\u4ee3\u7801\uff0c\u672a\u538b\u7f29\uff0c\u5c31\u5728\u9875\u9762\u4e0a\uff0c\u7b80\u6d01\u660e\u4e86\u65e0\u5e72\u6270\uff0c\u975e\u5e38\u9002\u5408\u5b66\u4e60\u3002<\/p>\n<p>\u4ee3\u7801\u91c7\u7528MIT\u534f\u8bae\uff0c\u53ef\u4ee5\u968f\u610f\u590d\u5236\uff0c\u5546\u4e1a\u4ea6\u53ef\uff0c\u4f46\u9700\u8981\u4fdd\u7559\u4ee3\u7801\u9876\u90e8\u7684\u4f5c\u8005\u548c\u539f\u51fa\u5904\u7248\u6743\u8bf4\u660e\u3002\u6240\u6709\u4ee3\u7801\u90fd\u662f\u81ea\u5df1\u952e\u76d8\u4e00\u4e2a\u4e00\u4e2a\u6572\u51fa\u6765\u7684\uff0c\u5c0a\u91cd\u8f9b\u52e4\u52b3\u52a8\uff0c\u5c0a\u91cd\u4ee3\u7801\u4f7f\u7528\u6388\u6743\u534f\u8bae\uff0c\u5171\u5efa\u548c\u8c10\u793e\u4f1a\u3002\u5982\u679c\u53d1\u73b0\u90fd\u662f\u5220\u6389\u534f\u8bae\u8bf4\u660e\u7684\u62ff\u6765\u4e3b\u4e49\uff0c\u6211\u60f3\u6211\u4f1a\u8003\u8651\u4f7f\u7528\u4ed8\u8d39\u3002<\/p>\n<h4>\u5176\u4ed6\u8bf4\u660e<\/h4>\n<p>\u8fd9\u91cc\u7684\u53bb\u8272\u6548\u679c\u662f\u6700\u7b80\u5355\u7684\u53bb\u8272\u6548\u679c\u4e86\uff0c\u5176\u5b9e\u6807\u51c6\u7684\u53bb\u8272\u529f\u80fd\uff0c\u8fd8\u9700\u8981\u4e00\u4e2a\u201c\u8fde\u7eed\u201d\u8fd8\u662f\u201c\u4e0d\u8fde\u7eed\u201d\u7684\u52fe\u9009\u529f\u80fd\u3002<\/p>\n<p>\u4f46\u662f\uff0c\u5bf9\u4e8e\u56fe\u6807\u548clogo\u8fd9\u4e9b\u53bb\u8272\u9700\u6c42\uff0c\u5f53\u524d\u7684\u6574\u4f53\u53bb\u8272\u5e94\u8be5\u8db3\u591f\uff0c\u201c\u8fde\u7eed\u201d\u529f\u80fd\u6709\u5174\u8da3\u7684\u5c0f\u4f19\u4f34\u53ef\u4ee5\u81ea\u5df1\u5c1d\u8bd5\u5b9e\u73b0\u4e0b\uff0c\u8003\u9a8c\u8fde\u7eed\u533a\u57df\u7b97\u6cd5\u3002<\/p>\n<h3>\u4e09\u3001\u7ed3\u675f\u8bed<\/h3>\n<p>\u672c\u6587\u7b2c\u4e00\u6bb5\u201c\u68c0\u6d4b\u900f\u660e\u201d\uff0c\u548c\u7b2c\u4e8c\u6bb5\u201c\u53bb\u8272\u53d8\u900f\u660e\u201d\u672c\u6765\u8ba1\u5212\u662f\u4e24\u7bc7\u6587\u7ae0\u7684\uff0c\u56e0\u4e3a\u4ee5\u524d\u5f88\u591a\u6587\u7ae0\u597d\u591a\u597d\u4e1c\u897f\u90fd\u6574\u5728\u4e00\u4e2a\u6587\u7ae0\u91cc\uff0c\u7ed3\u679c\u5f88\u5bb9\u6613\u5c31\u6e6e\u6ca1\u4e86\uff0c\u65e0\u4eba\u95ee\u6d25\uff0c\u751a\u662f\u53ef\u60dc\uff1b\u52a0\u4e0a\u6587\u7ae0\u7bc7\u5e45\u53d8\u5f97\u5f88\u957f\uff0c\u5927\u5bb6\u53c8\u90fd\u5f88\u5fd9\uff0c\u6ca1\u6709\u90a3\u4e48\u591a\u8010\u5fc3\u901a\u8bfb\u957f\u6587\uff0c\u4e5f\u5f88\u5bb9\u6613\u9519\u8fc7\u7a00\u7f3a\u4f18\u8d28\u5185\u5bb9\u3002<\/p>\n<p>\u4f46\u662f\u5199\u7740\u5199\u7740\u8fd8\u662f\u63a7\u5236\u4e0d\u4f4f\u81ea\u5df1\u7684\u624b\uff0c\u8fd8\u662f\u5408\u5728\u4e86\u4e00\u8d77\uff0c\u5176\u5b9e\u6211\u4e5f\u4e0d\u660e\u767d\u6211\u7684\u6267\u5ff5\u5728\u54ea\u91cc\uff01\u867d\u7136\u5206\u5f00\u603b\u4f53\u9605\u8bfb\u7c7b\u80af\u5b9a\u6bd4\u4e00\u7bc7\u8981\u591a\uff0c\u641c\u7d22\u6548\u679c\u4e5f\u66f4\u597d\uff0cPV\u6570\u636e\u4e5f\u4f1a\u597d\u770b\u4e9b\uff0c\u8fd9\u4e2a\u6708\u53d1\u6587\u6587\u7ae0\u6570\u91cf\u4e5f\u4f1a\u4e0a\u53bb\uff0c\u4f46\u662f\uff0c\u4e00\u60f3\u5230\u8981\u5206\u5f00\u53d8\u6210\u4e24\u7bc7\u4e5f\u4e0d\u9519\u7684\u6587\u7ae0\uff0c\u6211\u5c31\u5fc3\u91cc\u96be\u53d7\uff0c\u96be\u9053\u662f\u8ddf\u6d01\u7656\u4e00\u6837\u7684\u5fc3\u7406\u75be\u75c5\u2014\u2014\u201c\u6587\u7ae0\u5927\u800c\u5168\u5408\u4f53\u7efc\u5408\u5f81\u201d\uff0c\u65e0\u6cd5\u653e\u5f03\u53bb\u5b8c\u7f8e\u54c1\u8d28\u6587\u7ae0\u7684\u8ffd\u6c42\u3002<\/p>\n<p>\u5ffd\u7565\u773c\u524d\u5229\u76ca\u7684\u6781\u81f4\u8ffd\u6c42\uff0c\u6216\u8bb8\u662f\u81ea\u5df1\u5370\u523b\u5728\u9aa8\u5b50\u91cc\u7684\u7279\u8d28\u5427\uff0c\u4e5f\u662f\u81ea\u5df1\u80fd\u591f\u6210\u957f\u5230\u73b0\u5728\u8fd9\u4e2a\u6837\u5b50\u7684\u539f\u56e0\u6240\u5728\u3002<\/p>\n<p>\u611f\u8c22\u9605\u8bfb\uff0c\u6b22\u8fce\u4ea4\u6d41\uff01<\/p>\n<p><img decoding=\"async\" src=\"http:\/\/image.zhangxinxu.com\/image\/blog\/201611\/14.png\" align=\"absmiddle\"><\/p>\n<p>\u672c\u6587\u4e3a\u539f\u521b\u6587\u7ae0\uff0c\u4f1a\u7ecf\u5e38\u66f4\u65b0\u77e5\u8bc6\u70b9\u4ee5\u53ca\u4fee\u6b63\u4e00\u4e9b\u9519\u8bef\uff0c\u56e0\u6b64\u8f6c\u8f7d\u8bf7\u4fdd\u7559\u539f\u51fa\u5904\uff0c\u65b9\u4fbf\u6eaf\u6e90\uff0c\u907f\u514d\u9648\u65e7\u9519\u8bef\u77e5\u8bc6\u7684\u8bef\u5bfc\uff0c\u540c\u65f6\u6709\u66f4\u597d\u7684\u9605\u8bfb\u4f53\u9a8c\u3002<br \/>\n\u672c\u6587\u5730\u5740\uff1a<a 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