JAL-98 round when formatting dec places

[jalview.git] / src / jalview / util / Format.java

diff --git a/src/jalview/util/Format.java b/src/jalview/util/Format.java
index ffc80d3..20d228d 100755 (executable)
--- a/src/jalview/util/Format.java
+++ b/src/jalview/util/Format.java
@@ -1,6 +1,6 @@
 /*
- * Jalview - A Sequence Alignment Editor and Viewer (Version 2.9)
- * Copyright (C) 2015 The Jalview Authors
+ * Jalview - A Sequence Alignment Editor and Viewer ($$Version-Rel$$)
+ * Copyright (C) $$Year-Rel$$ The Jalview Authors
  * 
  * This file is part of Jalview.
  * 
@@ -947,4 +947,49 @@ public class Format
   {
     return formatString;
   }
+
+  /**
+   * Bespoke method to format percentage float value to the specified number of
+   * decimal places. Avoids use of general-purpose format parsers as a
+   * processing hotspot.
+   * 
+   * @param sb
+   * @param value
+   * @param dp
+   */
+  public static void appendPercentage(StringBuilder sb, float value, int dp)
+  {
+    /*
+     * rounding first
+     */
+    double d = value;
+    long factor = 1L;
+    for (int i = 0; i < dp; i++)
+    {
+      factor *= 10;
+    }
+    d *= factor;
+    d += 0.5;
+
+    /*
+     * integer part
+     */
+    value = (float) (d / factor);
+    sb.append((long) value);
+
+    /*
+     * decimal places
+     */
+    if (dp > 0)
+    {
+      sb.append(".");
+      while (dp > 0)
+      {
+        value = value - (int) value;
+        value *= 10;
+        sb.append((int) value);
+        dp--;
+      }
+    }
+  }
 }