本文介绍了画布，禁用图像下载的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在用 html5/js 制作游戏，地图上有战争迷雾.当您右键单击画布时，您可以将画布另存为图像，因此，您可以将整个地图保存为 jpg，但需要隐藏该地图.
有什么技巧可以禁用此功能吗?
我尝试在与地图相同的画布中创建我的战争迷雾，它可以工作，但移动迷雾更难，因为我需要为整个地图的每次移动创建.
谢谢.
解决方案
以下是适度模糊图像的方法:
它的工作原理是打乱您的地图，使临时用户无法轻松查看.
- 将您的图像垂直和水平切成许多部分.
- 将所有这些碎片打乱，然后根据它们创建一个新的打乱图像.
- 将该加扰图像提供给网页(用户无法识别该加扰图像).
- 将加扰顺序保存在 JSON 数组中，以便您以后可以对图像进行解扰.
混淆演示:>
混淆代码
去混淆代码
I'm making a game in html5/js, there is a map with a fog of war on it.When you right click on the canvas you can save the canvas as an image and so, you can have the whole map in a jpg, but that map need to be hidden.
Is there any trick to disable this ?
I tried to create my fog of war in the same canvas than the map, it works but it's harder to move the fog since i need to create for every move the entire map.
Thank you.
解决方案
Here’s how to moderately obfuscate your image:
It works by scrambling your map so the casual user cannot easily view it.
- Slice your image vertically and horizontally into many pieces.
- Scramble all those pieces and create a new scrambled image from them.
- Serve that scrambled image to the web page (this scrambled image is unrecognizable to the user).
- Save the scrambling order in a JSON array so you can later descramble the image.
Obfuscating Demo: http://jsfiddle.net/m1erickson/wWbt5/
When you need the image, unscramble it into an in-memory canvas that the user can’t see, but which you can programatically use in your game.
De-obfuscating Demo: http://jsfiddle.net/m1erickson/UtN6g/
Code for obfuscating
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; padding:20px;}
#obfuscated{border:1px solid blue;}
#canvas{border:1px solid red;}
</style>
<script>
$(function(){
var img=new Image();
img.onload=start;
img.crossOrigin="anonymous";
img.src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/obfuscated.png";
var verticalSlices=60;
var horizontalSlices=60;
var sliceCount=verticalSlices*horizontalSlices;
var sliceWidth,sliceHeight;
var slices=[];
var json;
function start(){
// vars for slice sizes
sliceWidth=img.width/verticalSlices;
sliceHeight=img.height/horizontalSlices;
// create a slices array to be used to scramble our image
for(var i=0;i<sliceCount;i++){ slices.push(i); }
slices=shuffle(slices);
// scramble the original image
var $obfuscatedImage=document.getElementById("obfuscated");
$obfuscatedImage.src=obfuscate(img,slices);
// create a JSON array used to descramble the image
slices.unshift(verticalSlices,horizontalSlices);
json=JSON.stringify(slices);
}
function obfuscate(img,slices){
var tempCanvas=document.createElement("canvas");
var tempCtx=tempCanvas.getContext('2d');
tempCanvas.width=img.width;
tempCanvas.height=img.height;
for(var i=0;i<slices.length;i++){
var s=slices[i];
var row=parseInt(s/verticalSlices);
var col=s-row*verticalSlices;
var x=col*sliceWidth;
var y=row*sliceHeight;
var canvasRow=parseInt(i/verticalSlices);
var canvasCol=i-canvasRow*verticalSlices;
var canvasX=canvasCol*sliceWidth;
var canvasY=canvasRow*sliceHeight;
tempCtx.drawImage(img,
x,y,sliceWidth,sliceHeight,
canvasX,canvasY,sliceWidth,sliceHeight);
}
return(tempCanvas.toDataURL());
}
function shuffle(array) {
var currentIndex = array.length,temporaryValue,randomIndex;
while (0 !== currentIndex) {
randomIndex = Math.floor(Math.random() * currentIndex);
currentIndex -= 1;
temporaryValue = array[currentIndex];
array[currentIndex] = array[randomIndex];
array[randomIndex] = temporaryValue;
}
return array;
}
}); // end $(function(){});
</script>
</head>
<body>
<p>Before scrambling</p>
<img src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/koolaidman.png"><br>
<p>After scrambling</p>
<img id="obfuscated" width=300 height=300>
</body>
</html>
Code for de-obfuscating
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; padding:20px; }
#obfuscated{border:1px solid red;}
#clarify{margin:10px;}
canvas{border:1px solid blue;}
p{margin:10px;}
</style>
<script>
$(function(){
// this json would be downloaded from the server
// first 2 elements are images width,height
// next 2 elements are #vertical,#horizontal slices
var json="[60,60,734,418,14,393,2863,1779,3555,1208,1300,2715,2380,130,2082,2004,2882,2610,2816,2537,1578,815,571,1188,806,2554,2115,683,923,2049,2180,2429,1799,1185,1827,522,3061,1856,554,1455,1731,3140,831,2022,2983,3203,2350,1586,2320,3494,1946,2628,1424,1900,1027,791,1373,257,3501,1094,1458,3419,2122,858,2515,2312,3521,2795,224,2711,77,2885,1239,2035,1545,1370,2787,468,3579,780,504,2070,2584,1698,2652,898,2111,2305,2901,2929,2482,2193,725,134,2781,2871,2342,2621,2930,3370,169,3107,2695,2862,963,1099,2775,997,2850,1252,2667,1782,1917,61,2645,2788,879,1377,1663,2522,517,2595,166,2815,2510,2835,2538,3551,2011,2942,30,3308,285,2933,1758,2029,2569,220,1105,445,931,2017,153,1728,3407,1057,2163,1636,296,920,2663,995,51,1840,25,1030,3117,1935,840,986,1387,1084,1832,728,37,1551,3361,533,1927,2771,109,3428,2123,2265,277,2643,3587,2764,549,65,785,2943,1643,2453,2467,2906,2335,540,626,3021,1802,2984,1547,284,2125,860,383,2292,2264,350,3141,2670,1722,1440,203,250,2813,1470,1901,2893,1197,2206,3535,2583,1787,1659,1130,541,2524,1435,380,770,161,3038,1607,3257,2240,1175,3176,2750,3304,759,67,993,2964,1497,173,2155,2948,1695,384,472,991,838,1798,977,334,219,2425,2030,269,3206,2423,1925,2202,2099,2721,1087,3508,635,3078,2987,2045,292,3029,2279,2845,2659,2379,492,523,674,1825,887,2169,1328,81,2585,382,2572,2793,1464,3590,453,1134,2067,949,983,1620,2818,6,1820,821,295,1116,2976,544,1913,2562,3406,864,675,2002,967,2985,2710,1784,427,2495,1590,1721,3381,610,3373,3339,1803,1041,2087,1465,1390,1014,1289,1868,2221,1068,2498,183,1680,805,1703,3504,2656,894,1671,2928,3595,825,3068,1053,2109,1292,691,2271,1100,3578,2451,1344,771,3384,2526,692,2336,2037,570,1233,2566,1477,3192,479,3353,1639,1378,3447,2973,3136,2148,588,3042,131,3070,2574,214,2743,3239,1058,1844,1019,3041,656,1893,3193,1902,2065,1449,3470,2608,2655,1708,1374,987,3166,3055,2327,1234,1678,1980,71,807,2228,3033,779,218,1625,405,215,3253,652,3086,1810,1602,1536,2174,2371,1916,2219,3151,410,1683,2442,1195,1141,54,532,3479,1319,733,3365,762,2680,3536,3507,117,1701,68,3148,1904,2782,320,1706,1078,629,2727,3275,649,268,625,885,2796,2660,2358,3177,2962,458,2594,2903,1056,1872,1499,1970,2545,1808,2294,1236,3548,902,3028,2797,3005,1801,3040,3254,1610,2245,2196,695,3322,696,3224,3344,198,901,2431,1657,2323,1486,1874,727,835,355,2322,2356,29,2534,1736,3114,2809,2046,3415,2458,366,3152,2508,2803,1050,2950,2077,409,1525,2108,1073,2939,2470,3489,2722,553,3268,2927,3269,338,3119,1682,477,1543,3238,1841,247,3318,1245,1444,3472,2066,1419,2829,3292,1885,2814,2178,2536,3460,524,1022,1745,2870,3414,2746,196,3534,2765,503,2776,2398,1474,3382,1290,1381,3232,459,1488,1018,63,3317,2159,2491,1186,2246,332,3082,3399,2191,152,828,2755,3106,2034,2484,2044,837,3486,2095,1760,1672,3511,667,737,1270,489,3410,2958,1459,1447,658,2365,1155,406,2000,339,236,560,870,1855,984,1386,158,1230,1170,1184,3226,1190,2063,1986,3185,1365,1988,457,1069,1472,699,959,682,3374,665,1329,1891,331,713,1923,3325,133,801,1366,1354,1569,2362,1272,2587,2926,814,755,768,883,1691,3334,604,2657,1985,636,434,412,2133,3503,3433,359,3319,498,2786,1198,1015,596,2521,1003,443,1000,231,154,2306,1253,86,3490,347,2532,3385,341,1220,2339,115,221,2303,3455,87,2089,2837,1786,973,5,3026,2003,1582,3309,2623,1293,2644,439,2101,681,2579,2205,2907,992,2284,487,1035,3050,841,969,1127,786,2898,1807,1759,1392,563,2661,2839,1738,1911,2598,1598,1751,1132,2079,243,2844,2401,2434,2461,1644,1775,1107,619,2249,2040,2578,738,547,1343,1400,53,1221,1043,1651,140,3024,1737,3518,3421,3549,1360,1081,3083,2773,1243,3337,888,631,1023,240,505,416,2728,2188,904,1550,2696,2647,1984,72,2406,108,606,2481,3444,1249,804,2996,3388,2410,1850,1158,3454,3506,1238,2236,589,1422,1847,2293,2724,3347,1567,3483,2812,849,899,941,2462,2091,537,2012,632,543,594,1306,132,546,1060,2223,3516,1697,816,3345,2145,1848,436,2671,155,1889,2048,2262,3559,3532,138,1299,2020,1957,2974,1715,643,3487,1317,2714,2162,1355,1067,926,732,1924,2783,1712,2636,3393,3112,2672,3499,2998,1726,3517,1594,3378,494,2059,1282,372,3313,0,1217,469,47,2445,1573,3459,2673,2273,249,2924,3529,2653,1397,2993,2506,810,2033,1049,2607,736,3429,1498,3403,162,265,1036,297,2260,3163,2447,659,2408,1148,146,1336,2678,3002,3048,288,1382,1597,1596,1969,1313,1681,35,1570,1445,3289,1363,2693,1561,3446,988,1968,2274,426,317,151,2945,435,283,3213,2697,1304,915,2332,3488,1987,3052,3411,1599,2509,1884,2730,2143,2444,2965,209,2131,2217,597,2438,2717,2593,1476,874,1714,844,471,1711,2076,2861,730,2698,2136,1965,3044,2914,2010,395,2396,342,176,2208,404,2254,702,2860,1656,3387,1906,3165,2549,1990,402,2421,233,2977,1260,3181,668,1140,177,3510,2051,1244,1818,2119,276,1858,2807,1146,739,1725,689,1092,1205,62,1646,1061,2552,21,69,2347,2649,3074,763,3266,1291,2539,1592,2126,2156,85,1314,124,1413,1574,2859,2798,1418,255,262,3231,1534,2307,2602,3496,1066,703,129,990,976,3121,293,3178,2016,3586,1664,690,3564,3214,2664,2235,2469,1839,1468,1817,2688,3364,2519,1266,2075,280,2142,1052,1806,3468,3354,1204,2875,2616,2542,2426,462,767,1504,1967,186,1031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var keys=JSON.parse(json);
$button=document.getElementById("clarify");
$button.style.display="none";
var img=new Image();
img.onload=function(){
$button.style.display="block";
}
img.src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/obfuscated.png";
function deobfuscate(obfuscatedImage,keys){
var tempCanvas=document.createElement("canvas");
var tempCtx=tempCanvas.getContext('2d');
tempCanvas.width=obfuscatedImage.width;
tempCanvas.height=obfuscatedImage.height;
var verticalSlices=keys.shift();
var horizontalSlices=keys.shift();
var sliceWidth=tempCanvas.width/verticalSlices;
var sliceHeight=tempCanvas.height/horizontalSlices;
for(var i=0;i<keys.length;i++){
var s=keys[i];
var row=parseInt(s/verticalSlices);
var col=s-row*verticalSlices;
var x=col*sliceWidth;
var y=row*sliceHeight;
var canvasRow=parseInt(i/verticalSlices);
var canvasCol=i-canvasRow*verticalSlices;
var canvasX=canvasCol*sliceWidth;
var canvasY=canvasRow*sliceHeight;
tempCtx.drawImage(obfuscatedImage,
canvasX,canvasY,sliceWidth,sliceHeight,
x,y,sliceWidth,sliceHeight);
}
return(tempCanvas);
}
$("#clarify").click(function(){
var canvas=deobfuscate(img,keys);
document.body.appendChild(canvas);
});
}); // end $(function(){});
</script>
</head>
<body>
<button id="clarify">De-obfuscate</button>
<p>The obfuscated image</p>
<img id="obfuscated" src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/obfuscated.png">
<p>The de-obfuscated canvas</p><br>
</body>
</html>
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