// ==UserScript==
// @name         Picture Auto-Resize on Chrome
// @name:zh-cn    图片在Chrome中自动缩放
// @namespace    https://greasyfork.org/users/2646
// @version      0.3
// @description  Auto-Resize on Chrome Picture Preview Tab
// @description:zh-cn  让大图在Chrome窗体内自动调整到适合的缩放大小，一览图片全貌（不会影响图片保存）
// @author       2016+, CLE
// @include      *
// @grant        none
// @downloadURL none
// ==/UserScript==

if( ! document.contentType.match(/^image\//i) ) return;

var img = document.getElementsByTagName("img")[0];

function defsize(){
    img.height = img.naturalHeight;
    img.width = img.naturalWidth;
}

function autoresize() {
    if ( img.naturalHeight > window.innerHeight || img.naturalWidth > window.innerWidth ) {
		var hb = 0; var zb = 0; var rat = 0;
		
		if(img.naturalWidth > window.innerWidth) hb = img.naturalWidth / window.innerWidth;
		if(img.naturalHeight > window.innerHeight) zb = img.naturalHeight / window.innerHeight;
		
		if(hb !== 0 && zb !== 0){
			if(hb >= zb) rat = hb; else rat = zb;
		} else if (hb !==0) {
			rat = hb;
		} else if (zb !==0) {
			rat = zb;
		}
		
		if (rat !==0 ){
			img.width = img.naturalWidth / rat;
			img.height = img.naturalHeight / rat;
		}
    }
}

autoresize();
window.onresize = autoresize;


var defm = false;
window.onkeydown = function(event){
    switch(event.keyCode) {
        case 13:
            if(defm){
                window.onresize = autoresize;
                autoresize();
            }else{
                window.onresize = null;
                defsize();
            }
            defm = !defm;
            break;
        case 27:
            window.close();
            break;
    }
};