js -- canvas img 封装
鼠标 1.操作canvas 中的 img。 右键放大缩小，左键移动img。
2.拖动input type= range 改变图片的透明度
html 代码
<!DOCTYPE html>
<html lang="en" oncontextmenu="doNothing()">
<head>
<meta charset="UTF-8">
<title>图片已中心店的坐标缩放</title>
<style>
#box1 {
width: 500px;
height: 300px;
border: 1px solid black;
overflow: hidden;
float: left;
}
#box2 {
width: 500px;
height: 300px;
border: 1px solid black;
overflow: hidden;
float: left;
margin-left: 50px;
box-sizing: border-box;
}
</style>
<script type="text/javascript">function ss() {
if (event.button == 2) {
alert("aaaa");
}
document.onmousedown = ss;
}</script>
</head>
<body>
<div>
<div id="box1">
<canvas id="cas1" width="500" height="300"></canvas>
</div>
<div id='box2'>
<canvas id="cas2" width="500" height="300"></canvas>
</div>
<div style="clear: both"></div>
</div>
<input type="range" id="inp_d" value="0">
</body>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script src="./index.js"></script>
</html>js 代码
/**
* Created by Administrator on 2018/7/6.
*/
function doNothing() {
window.event.returnValue = false;
return false;
}
var imgX = 0;
var imgY = 0;
var imgScale = 1;
var val = 0;
window.onload = function (event) {
var count = [
{cas2: 'cas1', box2: '#box1,#box2', path: './2.jpg', callback: imgOnload_callbak, scale: methods,icon_img:'./4.jpg,./5.jpg',inp_id:'#inp_d,#inp_d'},
{cas2: 'cas2', box2: '#box1,#box2,',path: './3.jpg', callback: imgOnload_callbak, scale: methods,icon_img:'./5.jpg,./4.jpg',inp_id:'#inp_d,#inp_d'}
];
for (var i = 0; i < count.length; i++) {
getElement(count[i].cas2, count[i].box2, count[i].path, count[i].callback, count[i].scale,count[i].icon_img,count[i].inp_id)
}
};
function getElement(cas_id, box_id, img_src, imgOnload_call, methods,icon_img,inp_id) {
var canvas = document.getElementById(cas_id);
var box = document.getElementById(box_id);
var arr = box_id.split(',');
var context = canvas.getContext('2d');
var img = new Image();
var img1 = new Image();
var img1_arr = icon_img.split(',');
img.src = img_src;
for(var i = 0; i < img1_arr.length;i++){
img1.src = img1_arr[i];
}
imgOnload_call(img, context, canvas, img1);
methods(arr, canvas, context, img,img1);
inp_methods(inp_id,context,canvas,img,img1)
}
function imgOnload_callbak(img,context,canvas,img1) {
img.onload = function () {
context.globalAlpha = 1.0;
context.drawImage(img, 0, 0);
};
img1.onload = function (){
setTimeout(function(){
context.globalAlpha = 0;
context.drawImage(img1,0,0,img1.width,img1.height,0,0,img1.width,img1.height);
},50);
}
}
function methods(elements, canvas, context, img,img1) {
var img_y = 1;
elements.forEach(function (item, i) {
$(item).mousedown(function (event) {
console.log(val);
var e_btn = event.button;
if (e_btn == 2) {
var e_down_y = event.clientY;
$(item).mousemove(function (event) {
var e_move_y = event.clientY;
if (e_move_y < e_down_y) {
img_y *= 1.01;
} else {
img_y /= 1.01;
}
e_down_y = e_move_y;
img_y = (img_y > 1) ? img_y : 1;
canvas.style.transform = "scale(" + img_y + "," + img_y + ")"
});
$(item).mouseup(function () {
$(item).unbind('mousemove');
$(item).unbind('mouseup');
})
}
else if (e_btn == 0) {
var e_drag_down = {
x: event.clientX,
y: event.clientY
};
$(item).mousemove(function (event) {
var e_drag_move = {
x: event.clientX,
y: event.clientY
};
var e_drag_distance = {
x: e_drag_move.x - e_drag_down.x,
y: e_drag_move.y - e_drag_down.y
};
e_drag_down = e_drag_move;
imgX += e_drag_distance.x;
imgY += e_drag_distance.y;
context.clearRect(0, 0, canvas.width, canvas.height);
context.globalAlpha = 1.0;
context.drawImage(img, 0, 0, img.width, img.height, (imgX / 5), (imgY / 5), img.width * imgScale, img.height * imgScale);
context.globalAlpha = val;
context.drawImage(img1, 0, 0, img1.width, img1.height, (imgX / 5), (imgY / 5), img1.width * imgScale, img1.height * imgScale);
});
$(item).mouseup(function () {
$(item).unbind("mousemove");
$(item).unbind('mouseup');
})
}
})
})
}
function inp_methods(inp_id,context,canvas,img,img1){
var inp_id_arr = inp_id.split(',');
inp_id_arr.forEach(function(item,i){
$(item).on('input propertychange',function(){
val = $(item).val();
val = ( val < 0.1)? 0.1 : val/100;
context.clearRect(0,0,canvas.width,canvas.height);
context.globalAlpha = 1.0;
context.drawImage(img,0,0,img.width, img.height, (imgX / 5), (imgY / 5), img.width * imgScale, img.height * imgScale);
context.globalAlpha = val;
context.drawImage(img1,0,0,img1.width, img1.height, (imgX / 5), (imgY / 5), img1.width * imgScale, img1.height * imgScale);
})
});
}有错误的地方，请大家帮忙 指正一下。谢谢！
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原始发表：2018-07-12 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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