{"id":349,"date":"2020-07-25T10:43:08","date_gmt":"2020-07-25T01:43:08","guid":{"rendered":"https:\/\/blog.wsd.sh\/?p=349"},"modified":"2020-07-25T10:43:08","modified_gmt":"2020-07-25T01:43:08","slug":"08-09-javascript-%e5%a4%89%e6%9b%b4","status":"publish","type":"post","link":"https:\/\/blog.wsd.sh\/?p=349","title":{"rendered":"08->09 JavaScript \u5909\u66f4"},"content":{"rendered":"<p>1. canvas.js<br \/>\n1.1 canvas\u306e\u521d\u671f\u5316<\/p>\n<p>before:<\/p>\n<pre>\r\nvar\tcanvas\t=\tdocument.getElementById(\"canvas\");\r\n<\/pre>\n<p>after:<\/p>\n<pre>\r\nroot = {\r\n        \/\/ context\r\n        \"ctx\":null,\r\n        \"canvas\":null,\r\n\r\n        \/\/ canvas\u306e\u521d\u671f\u5316\r\n        \"init\":function () {\r\n                this.canvas = document.getElementById('canvas');\r\n                this.ctx = this.canvas.getContext('2d');\r\n        },\r\n<\/pre>\n<p>1.2 \u30de\u30a6\u30b9\u62bc\u4e0b\u958b\u59cb\u3001\u30de\u30a6\u30b9\u62bc\u4e0b\u7d42\u4e86<br \/>\nbefore:<\/p>\n<pre>\r\n        canvas.onmousedown = function(e){\r\n                \/\/ \u30de\u30a6\u30b9\u62bc\u4e0b\u958b\u59cb\r\n                root.drawStart(e.offsetX, e.offsetY, cnvBold, cnvColor);\r\n                canvas.addEventListener(\"mousemove\" , _mouseMove, false);\r\n        }\r\n        canvas.onmouseup = function(){\r\n                \/\/ \u30de\u30a6\u30b9\u62bc\u4e0b\u7d42\u4e86\r\n                canvas.removeEventListener(\"mousemove\" , _mouseMove, false);\r\n        }\r\n<\/pre>\n<p>after:<\/p>\n<pre>\r\n        root.canvas.onmousedown = function(e){\r\n                \/\/ \u30de\u30a6\u30b9\u62bc\u4e0b\u958b\u59cb\r\n                root.drawStart(e.offsetX, e.offsetY, cnvBold, cnvColor);\r\n                root.canvas.addEventListener(\"mousemove\" , _mouseMove, false);\r\n        }\r\n        root.canvas.onmouseup = function(){\r\n                \/\/ \u30de\u30a6\u30b9\u62bc\u4e0b\u7d42\u4e86\r\n                root.canvas.removeEventListener(\"mousemove\" , _mouseMove, false);\r\n        }\r\n<\/pre>\n<p>1.3 canvas\u3092\u753b\u50cf\u3067\u4fdd\u5b58<br \/>\nbefore:<\/p>\n<pre>\r\n\r\n     \/\/ canvas\u3092\u753b\u50cf\u3067\u4fdd\u5b58\r\n        var download = document.getElementById(\"download\");\r\n        download.onclick = function(){\r\n                canvas = document.getElementById('canvas');\r\n                var base64 = canvas.toDataURL(\"image\/jpeg\");\r\n                document.getElementById(\"download\").href = base64;\r\n        }\r\n<\/pre>\n<p>after:<\/p>\n<pre>\r\n    \/\/ canvas\u3092\u753b\u50cf\u3067\u4fdd\u5b58\r\n        var download = document.getElementById(\"download\");\r\n        download.onclick = function(){\r\n                var base64 = root.canvas.toDataURL(\"image\/jpeg\");\r\n                document.getElementById(\"download\").href = base64;\r\n        }\r\n<\/pre>\n<p>1.4 canvas\u306e\u521d\u671f\u5316<br \/>\nbefore:<\/p>\n<pre>\r\n\r\n        \/\/ ccanvas\u306e\u521d\u671f\u5316\r\n        \"init\":function () {\r\n                var cnvs = document.getElementById('canvas');\r\n                this.ctx = cnvs.getContext('2d');\r\n        },\r\n<\/pre>\n<p>after:<\/p>\n<pre>\r\n\r\n        \/\/ ccanvas\u306e\u521d\u671f\u5316\r\n        \"init\":function () {\r\n                this.canvas = document.getElementById('canvas');\r\n                this.ctx = this.canvas.getContext('2d');\r\n        },\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>1. canvas.js 1.1 canvas\u306e\u521d\u671f\u5316 before: var canvas = document.getElementById(&#8220;canvas&#8221;); after: root = { \/\/ context&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false},"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=\/wp\/v2\/posts\/349"}],"collection":[{"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=349"}],"version-history":[{"count":1,"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=\/wp\/v2\/posts\/349\/revisions"}],"predecessor-version":[{"id":350,"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=\/wp\/v2\/posts\/349\/revisions\/350"}],"wp:attachment":[{"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=349"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=349"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.wsd.sh\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=349"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}