图片拾色器

我会带着你远行 2022-06-03 05:16 237阅读 0赞

如果要获取这张图片的所有颜色：[https://segmentfault.com/a/1190000009345753][https_segmentfault.com_a_1190000009345753]   预览效果：

[http://jsrun.net/DjkKp/edit][http_jsrun.net_DjkKp_edit]

使用的插件来自[http://www.jq22.com/jquery-info5319][http_www.jq22.com_jquery-info5319]，说明：不支持IE8等低版本浏览器，Chrome本地预览会出现canvas跨域问题，请换用其它浏览器或在服务器环境下测试。

结构：

<canvas id="canvas" width="400px" height="286px">Sorry, your browser dose not support canvas.</canvas>  
<hr />  
<div class="info" id="currentColor">点击上面的canvas来查看效果</div>  
<div id="cursor"></div>

引入的js内容：

if (typeof HTMLElement == 'undefined')\{  
var HTMLElement = function()\{\};  
if (window.webkit) document.createElement("iframe"); //fixes safari  
HTMLElement.prototype = (window.webkit) ? window\["\[\[DOMElement.prototype\]\]"\] : \{\};  
\}  
HTMLElement.prototype.getPixelColor = function(x, y)\{  
var thisContext = this.getContext("2d");  
var imageData = thisContext.getImageData(x, y, 1, 1);  
// 获取该点像素数据  
var pixel = imageData.data;  
var r = pixel\[0\];  
var g = pixel\[1\];  
var b = pixel\[2\];  
var a = pixel\[3\] / 255  
a = Math.round(a \* 100) / 100;  
var rHex = r.toString(16);  
r < 16 && (rHex = "0" + rHex);  
var gHex = g.toString(16);  
g < 16 && (gHex = "0" + gHex);  
var bHex = b.toString(16);  
b < 16 && (bHex = "0" + bHex);  
var rgbaColor = "rgba(" + r + "," + g + "," + b + "," + a + ")";  
var rgbColor = "rgb(" + r + "," + g + "," + b + ")";  
var hexColor = "\#" + rHex + gHex + bHex;  
return \{  
rgba : rgbaColor,  
rgb : rgbColor,  
hex : hexColor,  
r : r,  
g : g,  
b : b,  
a : a  
\};  
\}

调用的js：  
  
<script type="text/javascript">  
var draw = function(img) \{  
var canvas = document.getElementById("canvas");  
var context = canvas.getContext("2d");  
context.shadowBlur = 20;  
context.shadowColor = "\#000000";  
context.drawImage(img, 0, 0);  
  
  
canvas = $("\#canvas");  
canvas.click(function (e) \{  
var canvasOffset = canvas.offset();  
var canvasX = Math.floor(e.pageX - canvasOffset.left);  
var canvasY = Math.floor(e.pageY - canvasOffset.top);  
var colorData = document.getElementById("canvas").getPixelColor(canvasX, canvasY);  
// 获取该点像素的数据  
console.log(colorData);  
var color = colorData.hex;  
$("\#currentColor").html("当前像素(" + canvasX + "," + canvasY + ")颜色为: " + color);  
var cursorX = (e.pageX - 5) + "px";  
var cursorY = (e.pageY - 5) + "px";  
$("\#cursor").stop(true, true).css(\{  
"display" : "inline-block",  
"left" : cursorX,  
"top" : cursorY  
\}).fadeOut(2500);  
\});  
\}  
$(document).ready(function () \{  
var img = new Image();  
img.src = "images/demo.jpg";  
$(img).load(function () \{  
draw(img);  
\});  
\});  
</script>

结果展示：

![20171219161127158][]

\*如果图片不是同域下的，会报跨域错误，暂时没有没有找到解决办法。

[https_segmentfault.com_a_1190000009345753]: https://segmentfault.com/a/1190000009345753
[http_jsrun.net_DjkKp_edit]: http://jsrun.net/DjkKp/edit
[http_www.jq22.com_jquery-info5319]: http://www.jq22.com/jquery-info5319
[20171219161127158]: /images/20220603/dc9a627dbdbf48b1a0dc31c30a28d015.png