core/src/in/srain/cube/image/ImageTask.java
public static String joinSizeInfoToKey(String key, int w, int h) {
        if (w > 0 && h != Integer.MAX_VALUE && h > 0 && h != Integer.MAX_VALUE) {
            return new StringBuilder(key).append(SIZE_SP).append(w).append(SIZE_SP).append(h).toString();
        }
        return key;
    }
public static String joinSizeInfoToKey(String key, int w, int h) {
        if (w > 0 && h != Integer.MAX_VALUE && h > 0 && h != Integer.MAX_VALUE) {
            return new StringBuilder(key).append(SIZE_SP).append(w).append(SIZE_SP).append(h).toString();
        }
        return key;
    }
Join the key and the size information.

@param key
@param w
@param h
@return "$key" + "_" + "$w" + "_" + "$h"