{"id":60,"date":"2009-03-27T13:11:15","date_gmt":"2009-03-27T05:11:15","guid":{"rendered":"http:\/\/leegorous.net\/?p=60"},"modified":"2012-03-03T20:41:52","modified_gmt":"2012-03-03T12:41:52","slug":"lines-in-canvas","status":"publish","type":"post","link":"http:\/\/leegorous.net\/blog\/2009\/03\/27\/lines-in-canvas\/","title":{"rendered":"\u7ed8\u5236\u76f4\u7ebf"},"content":{"rendered":"<p>\u5728\u4e86\u89e3 <a href=\"http:\/\/leegorous.net\/2009\/03\/25\/rectangle-in-canvas\/\" target=\"_blank\">\u5982\u4f55\u7ed8\u5236 canvas \u91cc\u552f\u4e00\u7684\u57fa\u672c\u5f62\u72b6\u2014\u2014\u77e9\u5f62<\/a> \u4e4b\u540e\uff0c\u73b0\u5728\u53ef\u4ee5\u8f6c\u5165\u4f7f\u7528\u8def\u5f84\u4e86\u3002\u8def\u5f84\u4e0d\u4ec5\u4ec5\u662f\u7ebf\u6761\uff0c\u53ea\u662f\u4e60\u60ef\u6027\u7684\u4f1a\u4ece\u7ebf\u6761\u5f00\u59cb\uff0c\u800c\u76f4\u7ebf\u53ef\u7b97\u662f\u6700\u7b80\u5355\u7684\u7ebf\u6761\u4e86\u3002<\/p>\n<p>\u4f7f\u7528\u8def\u5f84\uff0c\u662f\u6709\u5957\u8def\u7684\u3002<\/p>\n<p>\u521b\u5efa\u3001\u7ed8\u5236\u3001\u5173\u95ed\u548c\u586b\u5145\u6216\u8005\u52fe\u52d2\u5f62\u72b6\u3002<\/p>\n<pre name=\"code\" class=\"brush: js\">\r\nbeginPath()\r\n\/\/ actual drawing\r\nclosePath()\r\nstroke()\r\nfill()\r\n<\/pre>\n<p>\u4e24\u70b9\u786e\u5b9a\u4e00\u6761\u76f4\u7ebf\uff0c\u5728 canvas \u91cc\u4e5f\u4e0d\u4f8b\u5916\u7684\u3002<\/p>\n<pre name=\"code\" class=\"brush: js\">\r\nlineTo(x, y)\r\n<\/pre>\n<p>x, y \u53ea\u662f\u7ec8\u70b9\u7684\u5750\u6807\uff0c\u8d77\u70b9\u5750\u6807\u662f\u9690\u542b\u7684\uff0c\u5e76\u4e14\u53d6\u51b3\u4e8e\u524d\u4e00\u64cd\u4f5c\u3002\u7b80\u5355\u6765\u8bf4\uff0c\u4e0a\u4e00\u64cd\u4f5c\u7684\u7ec8\u70b9\u5c31\u662f\u5f53\u524d\u76f4\u7ebf\u7684\u8d77\u70b9\u3002\u65b0\u5efa canvas \u65f6\u8d77\u70b9\u5c31\u662f\u539f\u70b9\u3002\u53e6\u5916\u8fd8\u53ef\u4ee5\u901a\u8fc7\u8fd9\u4e2a\u65b9\u6cd5\uff1a<\/p>\n<pre name=\"code\" class=\"brush: js\">\r\nmoveTo(x, y)\r\n<\/pre>\n<p>\u6765\u79fb\u52a8\u8d77\u59cb\u5750\u6807\u3002moveTo \u987e\u540d\u601d\u4e49\u5c31\u662f\u79fb\u52a8\u5750\u6807\u7528\u7684\uff0c\u5b83\u4e00\u822c\u7528\u4e8e\u91cd\u8bbe\u8d77\u59cb\u5750\u6807\uff0c\u5927\u591a\u6570\u60c5\u51b5\u4e0b\u8def\u5f84\u90fd\u4e0d\u662f\u8d77\u4e8e\u539f\u70b9\u7684\uff0c\u800c\u4e14\u5728\u7ed8\u5236\u4e00\u4e9b\u4e0d\u8fde\u7eed\u7684\u8def\u5f84\u65f6\u975e\u5e38\u6709\u7528\u3002<\/p>\n<pre name=\"code\" class=\"brush: js\">\r\nvar x = 60;\r\nvar y = 20;\r\nvar r = 40;\r\nvar dy = Math.sqrt((r*2)*(r*2)-r*r);\r\n\r\nctx.beginPath();\r\nctx.moveTo(x, y);\r\nctx.lineTo(x-r, y+dy);\r\nctx.lineTo(x+r, y+dy);\r\nctx.fill();\r\n\r\nvar y = y + 2*(Math.sqrt(4\/3)*r);\r\n\r\nctx.beginPath();\r\nctx.moveTo(x, y);\r\nctx.lineTo(x-r, y-dy);\r\nctx.lineTo(x+r, y-dy);\r\nctx.closePath();\r\nctx.stroke(); \r\n<\/pre>\n<p><figure style=\"width: 120px\" class=\"wp-caption alignright\"><img loading=\"lazy\" title=\"2-triangles\" src=\"http:\/\/farm4.static.flickr.com\/3639\/3389367046_1e11826d1a_o.png\" alt=\"2-triangles\" width=\"120\" height=\"124\" \/><figcaption class=\"wp-caption-text\">2-triangles<\/figcaption><\/figure><br \/>\n\u4e0a\u9762\u7684\u4ee3\u7801\u7ed8\u5236\u51fa\u516d\u89d2\u661f\uff0cmoveTo \u8fd9\u91cc\u662f\u79fb\u52a8\u8d77\u59cb\u5750\u6807\u53c8\u7528\u4e8e\u521b\u5efa\u4e24\u6761\u4e0d\u8fde\u7eed\u7684\u4e09\u89d2\u8def\u5f84\u3002<\/p>\n<p>\u4e09\u89d2\u51e0\u4f55\u7684\u5185\u5bb9\u5c31\u4e0d\u89e3\u6790\u4e86\uff0c\u91cd\u70b9\u662f\u4f7f\u7528\u586b\u5145\u548c\u63cf\u8fb9\u7684\u533a\u522b\u3002\u586b\u5145\u662f\u4f1a\u89e6\u53d1\u8def\u5f84\u7684\u81ea\u52a8\u95ed\u5408\u7684\uff0c\u800c\u63cf\u8fb9\u5219\u4e0d\u4f1a\u3002<\/p>\n<p>\u8fd9\u91cc\u53ef\u4ee5\u770b\u51fa\u5728\u8fd9\u4e2a\u5957\u8def\u91cc closePath \u4e0d\u662f\u5fc5\u987b\u7684\u3002\u5982\u679c\u63cf\u8fb9\u4e4b\u524d\u4e0d\u95ed\u5408\u8def\u5f84\uff0c\u6240\u52fe\u753b\u51fa\u6765\u7684\u5c06\u4f1a\u662f\u5f00\u653e\u7684\u8def\u5f84\uff0c\u5728\u8fd9\u4e2a\u6848\u4f8b\u91cc\u5c31\u662f\u53ea\u753b\u4e24\u8fb9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728\u4e86\u89e3 \u5982\u4f55\u7ed8\u5236 canvas \u91cc\u552f\u4e00\u7684\u57fa\u672c\u5f62\u72b6\u2014\u2014\u77e9\u5f62 \u4e4b\u540e\uff0c\u73b0\u5728\u53ef\u4ee5\u8f6c\u5165\u4f7f\u7528\u8def\u5f84\u4e86\u3002\u8def\u5f84\u4e0d\u4ec5\u4ec5\u662f\u7ebf\u6761\uff0c\u53ea\u662f &hellip; <\/p>\n<p class=\"link-more\"><a href=\"http:\/\/leegorous.net\/blog\/2009\/03\/27\/lines-in-canvas\/\" class=\"more-link\">\u7ee7\u7eed\u9605\u8bfb<span class=\"screen-reader-text\">\u201c\u7ed8\u5236\u76f4\u7ebf\u201d<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[3],"tags":[5,4,9],"_links":{"self":[{"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/posts\/60"}],"collection":[{"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/comments?post=60"}],"version-history":[{"count":5,"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/posts\/60\/revisions"}],"predecessor-version":[{"id":1077,"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/posts\/60\/revisions\/1077"}],"wp:attachment":[{"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/media?parent=60"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/categories?post=60"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/leegorous.net\/blog\/wp-json\/wp\/v2\/tags?post=60"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}