看圖：
有木有很可愛呀？
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>Char Picture</title>
<style>
#show{
font-family: Courier New;
font-size: 10px;
line-height: 8px;
}
</style>
<script>
/**
* Created by Roger on 16/1/2.
*/
var map=getCharsMap();
/*
* this function can convert the image in canvas to a char-picture(string)
* cotext:the canvas context;width:the image width;height:the image height; rowChars:how many chars in one row.
*/
function toChars(context, width, height, rowChars) {
var pixels = [],
output = "",
imageData = context.getImageData(0, 0, width, height),
rowChars = width < rowChars ? width : rowChars,
char_h = width / rowChars,
char_w = char_h,
rows = height / char_h,
cols = rowChars,
//to get a block of pixiels average gray-value.
getBlockGray = function (x, y, w, h) {
var sumGray = 0, pixels;
for (var row = 0; row < w; row++) {
for (var col = 0; col < h; col++) {
var cx = x + col, //current position x
cy = y + row, //current positon y
index = (cy * imageData.width + cx) * 4, //current index in rgba data array
data = imageData.data,
R = data[index],
G = data[index + 1],
B = data[index + 2],
gray = ~~(R * 0.3 + G * 0.59 + B * 0.11);
sumGray += gray;
}
}
pixels = w * h;
return ~~(sumGray / pixels);
};
for (var r = 0; r < rows; r++) {
for (var c = 0; c < cols; c++) {
var pos_x = ~~(c * char_h),
pos_y = ~~(r * char_h),
avg = getBlockGray(pos_x, pos_y, ~~char_w, ~~char_h),
ch = map[avg];
output += ch;
}
output += '\r\n';
}
;
return output;
}
function getCharsMap() {
var chars = ['@', 'w', '#', '$', 'k', 'd', 't', 'j', 'i', '.', ' '];
var step = 25,
map = {};
for (var i = 0; i < 256; i++) {
var index = ~~(i / 25)
map[i] = chars[index];
}
;
return map;
}
</script>
</head>
<body>
<input type="file" id="file"><button type="button" onclick="showImage()">展示</button><br>
<img src="" style="width: 100px"/>
<pre id="show"></pre>
<script>
var map=getCharsMap(),show=document.getElementById("show"),
img=document.getElementsByTagName("img")[0],
canvas = document.createElement("canvas");
function showImage(){
var file = document.getElementById('file').files[0],
ctx = canvas.getContext('2d'),
url = URL.createObjectURL(file);
if(!file){
alert("請先選擇文件");
}
img.src = url;
img.onload=function(){
canvas.width=img.naturalWidth;
canvas.height=img.naturalHeight;
ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
show.innerText=toChars(ctx,canvas.width,canvas.height,100);
}
}
</script>
</body>
</html>