small image generator improve

www/js/beauty.js

@@ -23,9 +23,10 @@ if ($('#image_site').get(0)) {
     //需要浏览器支持naturalWidth
     var saveSmallImg = function(imgEl, cateId) {
         var width = imgEl.width,
+            height = imgEl.height,
             naturalWidth = imgEl.naturalWidth,
             naturalHeight = imgEl.naturalHeight;
-        if (!naturalWidth || naturalWidth - width < 100 ||
+        if (!naturalWidth || naturalWidth < 600 || naturalHeight < 500 ||
             (typeof(disableSmallImage) != 'undefined' && disableSmallImage)
         ) {
             return false;
@@ -33,8 +34,14 @@ if ($('#image_site').get(0)) {
 
         var aspect = naturalHeight / naturalWidth;
         var canvas = document.createElement('canvas');
-        canvas.width = width * 1.5;
+
+        if (naturalWidth <= naturalHeight) {
+            canvas.width = width * 2.5 <= 600 ? width * 2.5 : 600;
             canvas.height = canvas.width * aspect;
+        }else {
+            canvas.height = height * 2.5 <= 500 ? height * 2.5 : 500;
+            canvas.width = canvas.height / aspect;
+        }
 
         var ctx = canvas.getContext('2d');
         ctx.drawImage( imgEl, 0, 0, canvas.width, canvas.height );