html5canvas如何获取当前坐标

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一、事件的兼容：

1 functionbindEvent(obj, event, fn) {2 if (obj.attachEvent) { //ie

3 obj.attachEvent(\'on\' + event, function() {4 fn.call(obj);5 });6 } else{7 //chrome&ff

8 obj.addEventListener(event, fn, false);9 }10 }

上面兼容ie8以及修正this关键字在ie低版本的指向，下面兼容chrome和ff。其他更常用的封装可以参考我的javascript开源框架gdom

二、用立即表达式搭建一个基本的库

添加获取鼠标坐标的方法

1 ;(function(window) {2 window.G ={};3 functionbindEvent(obj, event, fn) {4 if (obj.attachEvent) { //ie

5 obj.attachEvent(\'on\' + event, function() {6 fn.call(obj);7 });8 } else{9 //chrome&ff

10 obj.addEventListener(event, fn, false);11 }12 }13

14 G.getPos = function( dom ){15 var oPos = { x : 0, y : 0};16 bindEvent( dom, \'mousemove\', function( ev ){17 var oEvent = ev ||event, x, y;18 if ( oEvent.pageX ||oEvent.pageY ){19 x =oEvent.pageX;20 y =oEvent.pageY;21 }else{22 x = oEvent.clientX + document.body.scrollLeft ||document.documentElement.scrollLeft;23 y = oEvent.clientX + document.body.scrollTop ||document.documentElement.scrollTop;24 }25 x -=dom.offsetLeft;26 y -=dom.offsetTop;27 oPos.x =x;28 oPos.y =y;29 } );30 returnoPos;31 };32

33 })(window);

三、引入封装的js库，绑定canvas为监听对象，打印当前鼠标的坐标

鼠标的坐标，我这里画了2根线，便于观察.

1

2

3

4 ;(function(window) {5 window.G ={};6 functionbindEvent(obj, event, fn) {7 if (obj.attachEvent) { //ie

8 obj.attachEvent(\'on\' + event, function() {9 fn.call(obj);10 });11 } else{12 //chrome&ff

13 obj.addEventListener(event, fn, false);14 }15 }16

17 G.getPos = function( dom ){18 var oPos = { x : 0, y : 0};19 bindEvent( dom, \'mousemove\', function( ev ){20 var oEvent = ev ||event, x, y;21 if ( oEvent.pageX ||oEvent.pageY ){22 x =oEvent.pageX;23 y =oEvent.pageY;24 }else{25 x = oEvent.clientX + document.body.scrollLeft ||document.documentElement.scrollLeft;26 y = oEvent.clientX + document.body.scrollTop ||document.documentElement.scrollTop;27 }28 x -=dom.offsetLeft;29 y -=dom.offsetTop;30 oPos.x =x;31 oPos.y =y;32 } );33 returnoPos;34 };35

36 })(window);37

38

39 #canvas{40 border:1px dashed #aaa;41 }42

43

44 window.onload = function(){45 var oCanvas = document.querySelector( "#canvas"),46 oGc = oCanvas.getContext( \'2d\'),47 width = oCanvas.width, height =oCanvas.height,48 oInfo = document.querySelector( "#info"),49 oPos =G.getPos( oCanvas );50 oCanvas.addEventListener( "mousemove", function(){51

52 oGc.clearRect( 0, 0, width, height );53 oGc.beginPath();54 oGc.moveTo( oPos.x, 0);55 oGc.lineTo( oPos.x, height );56 oGc.moveTo( 0, oPos.y );57 oGc.lineTo( width, oPos.y );58 oGc.closePath();59 oGc.strokeStyle = \'#09f\';60 oGc.stroke();61

62 oInfo.innerHTML = \'鼠标的当前坐标是:(\' + oPos.x + \',\' + oPos.y + \')\';63 }, false);64 }65

66

67

68

69

70

四、点击\'run code\'可以预览效果额

;(function (window) {

window.G = {};

function bindEvent(obj, event, fn) {

if (obj.attachEvent) { //ie

obj.attachEvent(\'on\' + event, function () {

fn.call(obj);

});

} else {

//chrome&ff

obj.addEventListener(event, fn, false);

}

}

G.getPos = function( dom ){

var oPos = { x : 0, y : 0 };

bindEvent( dom, \'mousemove\', function( ev ){

var oEvent = ev || event, x, y;

if ( oEvent.pageX || oEvent.pageY ){

x = oEvent.pageX;

y = oEvent.pageY;

}else {

x = oEvent.clientX + document.body.scrollLeft || document.documentElement.scrollLeft;

y = oEvent.clientX + document.body.scrollTop || document.documentElement.scrollTop;

}

x -= dom.offsetLeft;

y -= dom.offsetTop;

oPos.x = x;

oPos.y = y;

} );

return oPos;

};

})(window);

#canvas{

border:1px dashed #aaa;

}

window.onload = function(){

var oCanvas = document.querySelector( "#canvas" ),

oGc = oCanvas.getContext( \'2d\' ),

width = oCanvas.width, height = oCanvas.height,

oInfo = document.querySelector( "#info" ),

oPos = G.getPos( oCanvas );

oCanvas.addEventListener( "mousemove", function(){

oGc.clearRect( 0, 0, width, height );

oGc.beginPath();

oGc.moveTo( oPos.x, 0 );

oGc.lineTo( oPos.x, height );

oGc.moveTo( 0, oPos.y );

oGc.lineTo( width, oPos.y );

oGc.closePath();

oGc.strokeStyle = \'#09f\';

oGc.stroke();

oInfo.innerHTML = \'鼠标的当前坐标是:(\' + oPos.x + \',\' + oPos.y + \')\';

}, false );

}

以上是“html5 canvas如何获取当前坐标”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注创新互联行业资讯频道！