キャンバス、画像のダウンロードを無効にする

debugcn 投稿 Dev

ジャックマン

html5 / jsでゲームを作っていますが、戦場の霧が描かれた地図があります。キャンバスを右クリックすると、キャンバスを画像として保存できるため、マップ全体をjpgで表示できますが、そのマップを非表示にする必要があります。

これを無効にするトリックはありますか？

マップと同じキャンバスに戦場の霧を作成しようとしましたが、機能しますが、マップ全体を移動するたびに作成する必要があるため、霧を移動するのは困難です。

ありがとうございました。

ブランド

画像を適度に難読化する方法は次のとおりです。

それはあなたの地図をスクランブルすることによって機能するので、カジュアルなユーザーはそれを簡単に見ることができません。

画像を垂直方向と水平方向に多くの部分にスライスします。
それらすべてのピースをスクランブルし、それらから新しいスクランブル画像を作成します。
そのスクランブルされた画像をWebページに提供します（このスクランブルされた画像はユーザーには認識されません）。
スクランブル順序をJSON配列に保存して、後で画像のスクランブルを解除できるようにします。

難読化デモ：http：//jsfiddle.net/m1erickson/wWbt5/

ここに画像の説明を入力してください

画像が必要な場合は、ユーザーには表示されないが、プログラムでゲームで使用できるメモリ内のキャンバスに画像をスクランブル解除します。

難読化解除のデモ：http：//jsfiddle.net/m1erickson/UtN6g/

難読化するためのコード

<!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>

難読化を解除するためのコード

<!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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2733,1269,1283,413,1999,2568,1692,867,1829,559,106,2135,3554,2019,3418,2808,3570,28,2826,2648,1505,454,2047,2632,1647,2417,1481,3059,2107,1330,1138,1491,2679,905,2218,1896,1199,564,2811,1406,1564,450,3153,2270,680,2068,951,601,1054,808,2830,1548,1765,3170,113,3367,2116,565,2326,3160,2497,1730,88,1863,2878,1989,24,375,294,278,2529,2013,1781,232,1733,2742,580,2457,3332,26,1490,3115,1309,1065,598,3351,1770,3466,970,1395,1821,3350,3167,514,735,3046,3255,2905,1348,1172,1747,2920,147,2471,1769,2790,2139,2041,20,1952,891,2300,795,1864,1285,613,2176,638,2388,1196,1622,2473,676,612,2582,623,1811,2416,1670,396,2413,1356,1572,74,2157,3558,2411,3338,2707,2682,2110,2318,1337,918,2561,1519,1705,669,2164,1351,1604,2432,3416,1207,982,1665,2151,1063,3138,1523,2713,3235,1024,3575,972,2642,2879,3448,3495,3328,1982,2530,1627,1959,744,3240,3434,2129,1805,1723,1417,3280,2723,1493,2894,1713,76,900,2975,2433,854,10,760,100,3355,568,2546,1089,2147,2909,789,531,1415,46,307,3480,507,3164,2677,2419,3189,622,895,2488,2704,1174,3471,2465,1975,485,3248,3379,300,279,3474,1688,1192,170,286,2986,903,3303,3263,1128,2220,712,3315,2828,1621,1144,2343,491,2565,1305,578,729,3076,251,2483,1302,2767,818,3574,1164,2919,2946,1640,3267,525,1526,961,1004,857,2576,2917,470,2913,437,2496,723,144,1973,3210,2368,2282,2741,2651,2694,1512,2263,518,1605,381,3008,1201,95,225,2899,761,1699,368,1632,2251,2745,1502,3134,1991,640,1072,349,1511,1102,778,2802,852,388,1338,1051,1740,3450,1325,1114,1162,2153,2276,1845,3439,227,3464,3588,1549,252,2908,2669,2204,3286,1372,2540,2883,2523,3145,2146,946,1047,326,2558,238,724,889,3250,230,823,1154,2140,2199,1450,2575,511,1106,499,1361,1118,1389,3599,270,3538,3010,3256,253,2900,911,1865,102,515,1261,3311,3162,2093,1117,3431,264,3412,361,2230,2817,2403,208,3198,1693,1998,3274,2938,2267,473,3258,1055,842,2581,1541,148,2422,164,2702,379,79,1168,3215,1546,2535,1645,1466,261,855,1591,376,374]";

    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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