[PATCH] Compute the height of a burndown chart

Signed-off-by: Paul Beckingham <paul@beckingham.net>

ChangeLog

@@ -169,6 +169,7 @@
  + Fixed bug that required the '%YAML' prologue in a YAML import.
  + Fixed bug that showed the 'due' date, under the heading 'until' date, in the
    info report (thanks to Michael McCann).
+ + Fixed burndown chart y-axis height calculation (thanks to Ben Boeckel).
 
 ------ old releases ------------------------------
 

src/util.cpp

@@ -29,6 +29,7 @@
 
 #include <iostream>
 #include <fstream>
+#include <limits>
 #include <sstream>
 #include <vector>
 #include <algorithm>
@@ -39,6 +40,7 @@
 #include <sys/wait.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -54,6 +56,12 @@
 
 extern Context context;
 
+////////////////////////////////////////////////////////////////////////////////
+static inline unsigned round_up_to (unsigned n, unsigned target)
+{
+  return n + target - (n % target);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Uses std::getline, because std::cin eats leading whitespace, and that means
 // that if a newline is entered, std::cin eats it and never returns from the
@@ -437,4 +445,43 @@ int execute(const std::string& executable, std::vector<std::string> arguments)
   }
 }
 
+// Collides with std::numeric_limits methods
+#undef max
+
 ////////////////////////////////////////////////////////////////////////////////
+unsigned burndown_size (unsigned ntasks)
+{
+  // Nearest 2
+  if (ntasks < 20)
+    return round_up_to (ntasks, 2);
+
+  // Nearest 10
+  if (ntasks < 50)
+    return round_up_to (ntasks, 10);
+
+  // Nearest 20
+  if (ntasks < 100)
+    return round_up_to (ntasks, 20);
+
+  // Choose the number from here rounded up to the nearest 10% of the next
+  // highest power of 10 or half of power of 10.
+  const unsigned count = (unsigned) log10 (std::numeric_limits<unsigned>::max ());
+  unsigned half = 500;
+  unsigned full = 1000;
+
+  // We start at two because we handle 5, 10, 50, and 100 above.
+  for (unsigned i = 2; i < count; ++i)
+  {
+    if (ntasks < half)
+      return round_up_to (ntasks, half / 10);
+
+    if (ntasks < full)
+      return round_up_to (ntasks, full / 10);
+
+    half *= 10;
+    full *= 10;
+  }
+
+  // Round up to max of unsigned.
+  return std::numeric_limits<unsigned>::max ();
+}

src/util.h

@@ -83,5 +83,7 @@ int execute (const std::string&, std::vector<std::string>);
 std::string compressIds (const std::vector <int>&);
 void combine (std::vector <int>&, const std::vector <int>&);
 
+unsigned burndown_size (unsigned ntasks);
+
 #endif
 ////////////////////////////////////////////////////////////////////////////////