使用JavaScript向类中添加灰度fx?
我试图使用jQuery向每个具有类使用JavaScript向类中添加灰度fx?,javascript,jquery,html5-canvas,grayscale,Javascript,Jquery,Html5 Canvas,Grayscale,我试图使用jQuery向每个具有类灰度的图像添加灰度fx,但下面的方法似乎不起作用。有人知道为什么这可能不起作用吗 $(function(){ var imgObj = $('.greyscale'); var canvas = document.createElement('canvas'); var canvasContext = canvas.getContext('2d'); var imgW = im
灰度
的图像添加灰度fx,但下面的方法似乎不起作用。有人知道为什么这可能不起作用吗
$(function(){
var imgObj = $('.greyscale');
var canvas = document.createElement('canvas');
var canvasContext = canvas.getContext('2d');
var imgW = imgObj.width;
var imgH = imgObj.height;
canvas.width = imgW;
canvas.height = imgH;
canvasContext.drawImage(imgObj, 0, 0);
var imgPixels = canvasContext.getImageData(0, 0, imgW, imgH);
for(var y = 0; y < imgPixels.height; y++){
for(var x = 0; x < imgPixels.width; x++){
var i = (y * 4) * imgPixels.width + x * 4;
var avg = (imgPixels.data[i] + imgPixels.data[i + 1] + imgPixels.data[i + 2]) / 3;
imgPixels.data[i] = avg;
imgPixels.data[i + 1] = avg;
imgPixels.data[i + 2] = avg;
}
}
canvasContext.putImageData(imgPixels, 0, 0, 0, 0, imgPixels.width, imgPixels.height);
return canvas.toDataURL();
});
$(函数(){
var imgObj=$('.greyscale');
var canvas=document.createElement('canvas');
var canvasContext=canvas.getContext('2d');
var imgW=imgObj.宽度;
var imgH=imgObj.高度;
canvas.width=imgW;
canvas.height=imgH;
drawImage(imgObj,0,0);
var imgPixels=canvasContext.getImageData(0,0,imgW,imgH);
对于(变量y=0;y
您当前的错误是:
- 绘制jQuery对象而不是画布
- 在就绪处理程序中返回数据URL,这似乎毫无意义
- 迭代所有图像元素,对每个画布执行以下操作:
- 制作灰度版
- 将图像
设置为灰度画布的数据URLhref
$(窗口).load(函数(){//等待图像也加载
var imgObj=$('.greyscale');
返回imgObj.each(函数(){
var canvas=document.createElement('canvas');
var canvasContext=canvas.getContext('2d');
var imgW=此宽度;
var imgH=此高度;
canvas.width=imgW;
canvas.height=imgH;
drawImage(this,0,0);
var imgPixels=canvasContext.getImageData(0,0,imgW,imgH);
对于(变量y=0;y
我拥有的是一个灰度级的图像,我想将其移动到画布上,然后将画布转换为灰度级。请查看为什么您认为画布与图像不一样?@Chill Web Designs:您可以尝试使用$(窗口)。加载
而不是就绪处理程序吗?必须首先加载图像,ready
函数($(function(){})
)不等待图像,而只等待DOM。发现问题后,它会获得真实的图像大小,而不是CSS中指定的大小。请注意,如果页面未托管在服务器上,则getImageData将无法工作。
$(window).load(function() { // wait for images to load also
var imgObj = $('.greyscale');
return imgObj.each(function() {
var canvas = document.createElement('canvas');
var canvasContext = canvas.getContext('2d');
var imgW = this.width;
var imgH = this.height;
canvas.width = imgW;
canvas.height = imgH;
canvasContext.drawImage(this, 0, 0);
var imgPixels = canvasContext.getImageData(0, 0, imgW, imgH);
for(var y = 0; y < imgPixels.height; y++){
for(var x = 0; x < imgPixels.width; x++){
var i = (y * 4) * imgPixels.width + x * 4;
var avg = (imgPixels.data[i] + imgPixels.data[i + 1] + imgPixels.data[i + 2]) / 3;
imgPixels.data[i] = avg;
imgPixels.data[i + 1] = avg;
imgPixels.data[i + 2] = avg;
}
}
canvasContext.putImageData(imgPixels, 0, 0, 0, 0, imgPixels.width, imgPixels.height);
console.log(canvas.toDataURL())
this.src = canvas.toDataURL();
});
});