我正在开发一个产品,它可以接收用户上传的图片,并将图像信息叠加在上面。由于明暗度不同,这些图片需要使用不同的文本颜色。是否有办法用JavaScript实现这个功能?
编辑:我找到了一个类似问题的解决方案,jsfiddle给出了一个解决方案(http://jsfiddle.net/xLF38/818)。不过我在我的网站中使用jQuery。如何将原始的JavaScript代码转换为jQuery呢?
var rgb = getAverageRGB(document.getElementById('i'));
document.body.style.backgroundColor = 'rgb(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ')';
function getAverageRGB(imgEl) {
var blockSize = 5, // only visit every 5 pixels
defaultRGB = {
r: 0,
g: 0,
b: 0
}, // for non-supporting envs
canvas = document.createElement('canvas'),
context = canvas.getContext && canvas.getContext('2d'),
data, width, height,
i = -4,
length,
rgb = {
r: 0,
g: 0,
b: 0
},
count = 0;
if (!context) {
return defaultRGB;
}
height = canvas.height = imgEl.naturalHeight || imgEl.offsetHeight || imgEl.height;
width = canvas.width = imgEl.naturalWidth || imgEl.offsetWidth || imgEl.width;
context.drawImage(imgEl, 0, 0);
try {
data = context.getImageData(0, 0, width, height);
} catch (e) {
/* security error, img on diff domain */
alert('x');
return defaultRGB;
}
length = data.data.length;
while ((i += blockSize * 4) < length) {
++count;
rgb.r += data.data[i];
rgb.g += data.data[i + 1];
rgb.b += data.data[i + 2];
}
// ~~ used to floor values
rgb.r = ~~ (rgb.r / count);
rgb.g = ~~ (rgb.g / count);
rgb.b = ~~ (rgb.b / count);
return rgb;
}
text-shadow
怎么样? - Wesley Murch