☰

Downbooru

danbooruに画像をダウンロードするボタンを追加する。画像にはタグ(XP Keywords)が付与される。Picasa3と相性抜群。

As of 18/05/2017. See the latest version.

// ==UserScript==
// @name         Downbooru
// @name:en      Downbooru
// @namespace    https://greasyfork.org/ja/scripts/29802-downbooru
// @version      2.1
// @description  danbooruに画像をダウンロードするボタンを追加する。画像にはタグ(XP Keywords)が付与される。Picasa3と相性抜群。
// @description  PNGはExifが無いためJPGに変換。サイズの大きい画像は縮小される。
// @description:en donwloads an image added tags from danbooru
// @author       You
// @match        http://danbooru.donmai.us$
// @match        *://danbooru.donmai.us$
// @match        *://danbooru.donmai.us/posts*
// @grant        none
// ==/UserScript==

//参考:canvas https://blog.agektmr.com/2013/09/canvas-png-blob.html
//参考:deferred http://hamalog.tumblr.com/post/5159447047/jquerydeferredって何
//参考:http://qiita.com/geek_duck/items/2db28daa9e27df9b861d
(function () {
    var host = window.location.host;
    (function () {
        var btn_prt = [];
        switch (host) {
            case 'danbooru.donmai.us':
                $('[data-id]').each(function () {
                    btn_prt.push($(this));
                });
        }

        for (var i in btn_prt) {
            setButton(btn_prt[i]);
        }
        return;
    })();

    function setButton(btn_prt) {
        var tag_name = btn_prt.get(0).tagName;
        var button = $('<button>');
        switch (tag_name) {
            case 'SECTION':
                button.text('Download');
                break;
            case 'ARTICLE':
                button.text('DL').attr('style', 'position:absolute; right:0; bottom:0; opacity:0.5;');
                button.hover(function () {
                    button.attr('style', 'position:absolute; right:0; bottom:0; opacity:1;');
                }, function () {
                    button.attr('style', 'position:absolute; right:0; bottom:0; opacity:0.5;');
                });
                break;
        }
        button.click(function () {
            switch (host) {
                case 'danbooru.donmai.us':
                    var src = btn_prt.attr('data-file-url');
                    var tags = btn_prt.attr('data-tags').split(' ');
                    var file = "danbooru" + btn_prt.attr('data-id') + ".jpg";
            }
            switch (tag_name) {
                case 'SECTION':
                    button.text('Generating...').attr("disabled", true);
                    break;
                case 'ARTICLE':
                    button.text('...').attr("disabled", true);
                    break;
            }

            downloadImageWithTags(src, tags, file);
            switch (tag_name) {
                case 'SECTION':
                    button.html('<s>Download</s>');
                    break;
                case 'ARTICLE':
                    button.html('<s>DL</s>').attr('style', 'position:absolute; right:0; bottom:0; opacity:1;');
                    break;
            }
        });
        btn_prt.append(button);
        return;
        debugger;
    }

    function downloadImageWithTags(src, tags, name) {
        var exif = createExif(tags);
        getImgDataurl(src).then(function (dataurl) {
            var blob = insertExif(exif, dataurl);
            var a = document.createElement('a');
            a.href = window.URL.createObjectURL(blob);
            a.download = name;
            a.click();
            return;
        });
    }

    function getImgDataurl(url) {
        var dfd = new $.Deferred();
        var img = new Image();
        img.src = url;
        var canvas = document.createElement('canvas');
        canvas.setAttribute('width', img.width);
        canvas.setAttribute('height', img.height);
        var ctx = canvas.getContext('2d');
        img.onload = function () {
            ctx.drawImage(img, 0, 0);
            var jpg_src = canvas.toDataURL('image/jpeg');
            //画像が大きすぎる場合、width850pxで再todataURL
            if (jpg_src.split(',')[1]) {
                dfd.resolve(jpg_src);
            } else {
                var smallWidth = 850;
                var smallheight = 850 * img.height / img.width;
                canvas.setAttribute('width', smallWidth);
                canvas.setAttribute('height', smallheight);
                ctx.drawImage(img, 0, 0, img.width, img.height, 0, 0, smallWidth, smallheight);
                jpg_src = canvas.toDataURL('image/jpeg');
                dfd.resolve(jpg_src);
            }
        };
        return dfd.promise();
    }

    function createExif(list) {
        var bim = "50686f746f73686f7020332e30003842494d040400000000";
        var hex_list = [];
        for (var i = 0; i < list.length; i++) {
            hex_list[i] = strToHex(list[i]);
        }

        var tags = "1c021900" + tagLength(hex_list[0]) + hex_list[0] + "1c020000020004";
        for (var i = 1; i < hex_list.length; i++) {
            tags = tags + "1c021900" + tagLength(hex_list[i]) + hex_list[i];
        }
        tags = wholeTagLength(tags) + tags;
        //XX XX [BIM] [TAGS]
        var seg_len = (2 + bim.length / 2 + tags.length / 2).toString(16);
        if (seg_len.length > 4) {
            console.log("タグのデータ量が限界を超えました");
            return;
        }
        seg_len = "000" + seg_len;
        seg_len = seg_len.slice(-4);
        var exif = "ffed" + seg_len + bim + tags;
        return exif;
    }

    function insertExif(exif, dataurl) {
        var bin = atob(dataurl.split(",")[1]);
        var buffer = new Uint8Array(bin.length + exif.length / 2);
        for (var i = 0; i < 20; i++) {
            buffer[i] = bin.charCodeAt(i);
        }
        for (var bf_i = 20, ex_j = 0; ex_j < exif.length / 2; bf_i++,
                ex_j++) {
            buffer[bf_i] = parseInt(exif.slice(ex_j * 2, ex_j * 2 + 2), 16);
        }
        for (var bf_i = 20 + exif.length / 2, bin_j = 20; bin_j < bin.length; bf_i++,
                bin_j++) {
            buffer[bf_i] = bin.charCodeAt(bin_j);
        }
        var blob = new Blob([buffer.buffer], {
            type: 'image/jpeg'
        });
        return blob;
    }

//引数はhexで
    function tagLength(str) {
        var len = (str.length / 2).toString(16);
        len = ("0" + len).slice(-2);
        return len;
    }

//引数はhexで
    function wholeTagLength(str) {
        var len = (str.length / 2).toString(16);
        len = ("000" + len).slice(-4);
        return len;
    }

    function strToHex(str) {
        var hex = "";
        for (var i = 0; i < str.length; i++) {
            hex = hex + str.charCodeAt(i).toString(16);
        }
        return hex;
    }

    function strToU8(str) {
        var buffer = new Uint8Array(str.length);
        for (var i = 0; i < buffer.length; i++) {
            buffer[i] = str.charCodeAt(i);
        }
        return buffer;
    }

    function hexToU8(str) {
        var buffer = new Uint8Array(str.length / 2);
        for (var i = 0; i < buffer.length; i++) {
            buffer[i] = parseInt(str.slice(i * 2, i * 2 + 2), 16);
        }
        return buffer;
    }

//テスト用 16進数文字列をアルファベットに変換する
    function hexToChar(str) {
        var char = "";
        for (var i = 0; i < str.length / 2; i++) {
//4a→74→J
            char = char + String.fromCharCode(parseInt(str.slice(i * 2, i * 2 + 2), 16));
        }
        return char;
    }
}
)();