add：添加字节数转可读字符串。

include/of_util.h

@@ -46,6 +46,7 @@ public:
 
 public:
     static ofString now_time();
+    static ofString get_file_size(long long bytes);
 };
 
 class CMutBuffer

src/of_util.cpp

@@ -85,6 +85,32 @@ ofString OfUtil::now_time()
 #endif
 }
 
+ofString OfUtil::get_file_size(long long bytes)
+{
+    constexpr long long gbblk = 1024 * 1024 * 1024;
+    constexpr long long mbblk = 1024 * 1024;
+
+    long long gb = bytes / gbblk;
+    bytes %= gbblk;
+
+    long long mb = bytes / mbblk;
+    bytes %= mbblk;
+
+    long long kb = bytes / 1024;
+
+    std::ostringstream oss;
+    if (gb > 0) {
+        oss << gb << ofT("GB");
+    }
+    if (mb > 0 || gb > 0) {
+        oss << mb << ofT("MB");
+    }
+    if (kb > 0 || mb > 0 || gb > 0) {
+        oss << kb << ofT("KB");
+    }
+    return oss.str();
+}
+
 #ifdef _WIN32
 std::string CCodec::u8ToGBK(const std::string& str)
 {