Conversions to and from COM VT_DATE types should no longer lose milli…

…seconds. Should fix #1385, fix #387
mhammond · mhammond · Nov 25, 2019 · Jan 26, 2018 · Mar 12, 2019 · Mar 12, 2019
commit 9c44c50475f8856b352adcd601b7df0ef38e5fe1
diff --git a/CHANGES.txt b/CHANGES.txt
@@ -6,6 +6,7 @@ However contributors are encouraged to add their own entries for their work.
 
 Since build 225:
 ----------------
+* Conversions to and from COM VT_DATE types should no longer lose milliseconds.
 
 Since build 224:
 ----------------

diff --git a/com/win32com/test/testDates.py b/com/win32com/test/testDates.py
@@ -0,0 +1,42 @@
+from __future__ import print_function
+
+from datetime import datetime
+import unittest
+
+import pywintypes
+import win32com.client
+import win32com.test.util
+import win32com.server.util
+from win32timezone import TimeZoneInfo
+
+# A COM object so we can pass dates to and from the COM boundary.
+class Tester:
+    _public_methods_ = [ 'TestDate' ]
+    def TestDate(self, d):
+        assert isinstance(d, datetime)
+        return d
+
+
+def test_ob():
+    return win32com.client.Dispatch(win32com.server.util.wrap(Tester()))
+
+class TestCase(win32com.test.util.TestCase):
+    def check(self, d, expected = None):
+        if not issubclass(pywintypes.TimeType, datetime):
+            self.skipTest("this is testing pywintypes and datetime")
+        got = test_ob().TestDate(d)
+        self.assertEqual(got, expected or d)
+
+    def testUTC(self):
+        self.check(datetime(year=2000, month=12, day=25, microsecond=500000, tzinfo=TimeZoneInfo.utc()))
+
+    def testLocal(self):
+        self.check(datetime(year=2000, month=12, day=25, microsecond=500000, tzinfo=TimeZoneInfo.local()))
+
+    def testMSTruncated(self):
+        # milliseconds are kept but microseconds are lost after rounding.
+        self.check(datetime(year=2000, month=12, day=25, microsecond=500500, tzinfo=TimeZoneInfo.utc()),
+                   datetime(year=2000, month=12, day=25, microsecond=500000, tzinfo=TimeZoneInfo.utc()))
+
+if __name__=='__main__':
+    unittest.main()
diff --git a/com/win32com/test/testDictionary.py b/com/win32com/test/testDictionary.py
@@ -1,25 +1,26 @@
 # testDictionary.py
 #
 import sys
+import datetime
+import time
 import win32com.server.util
 import win32com.test.util
 import win32com.client
 import traceback
 import pythoncom
 import pywintypes
 import winerror
+import win32timezone
 
 import unittest
 
-error = "dictionary test error"
-
 def MakeTestDictionary():
     return win32com.client.Dispatch("Python.Dictionary")
 
 def TestDictAgainst(dict,check):
-    for key, value in check.iteritems():
+    for key, value in check.items():
         if dict(key) != value:
-            raise error("Indexing for '%s' gave the incorrect value - %s/%s" % (repr(key), repr(dict[key]), repr(check[key])))
+            raise Exception("Indexing for '%s' gave the incorrect value - %s/%s" % (repr(key), repr(dict[key]), repr(check[key])))
 
 # Ensure we have the correct version registered.
 def Register(quiet):
@@ -32,7 +33,7 @@ def TestDict(quiet=None):
         quiet = not "-v" in sys.argv
     Register(quiet)
 
-    if not quiet: print "Simple enum test"
+    if not quiet: print("Simple enum test")
     dict = MakeTestDictionary()
     checkDict = {}
     TestDictAgainst(dict, checkDict)
@@ -45,31 +46,45 @@ def TestDict(quiet=None):
     del checkDict["NewKey"]
     TestDictAgainst(dict, checkDict)
 
+    if issubclass(pywintypes.TimeType, datetime.datetime):
+        now = win32timezone.now()
+        # We want to keep the milliseconds but discard microseconds as they
+        # don't survive the conversion.
+        now = now.replace(microsecond = round(now.microsecond / 1000) * 1000)
+    else:
+        now = pythoncom.MakeTime(time.gmtime(time.time()))
+    dict["Now"] = now
+    checkDict["Now"] = now
+    TestDictAgainst(dict, checkDict)
+
     if not quiet:
-        print "Failure tests"
+        print("Failure tests")
     try:
         dict()
-        raise error("default method with no args worked when it shouldnt have!")
-    except pythoncom.com_error, (hr, desc, exc, argErr):
+        raise Exception("default method with no args worked when it shouldnt have!")
+    except pythoncom.com_error as xxx_todo_changeme:
+        (hr, desc, exc, argErr) = xxx_todo_changeme.args
         if hr != winerror.DISP_E_BADPARAMCOUNT:
-            raise error("Expected DISP_E_BADPARAMCOUNT - got %d (%s)" % (hr, desc))
+            raise Exception("Expected DISP_E_BADPARAMCOUNT - got %d (%s)" % (hr, desc))
 
     try:
         dict("hi", "there")
-        raise error("multiple args worked when it shouldnt have!")
-    except pythoncom.com_error, (hr, desc, exc, argErr):
+        raise Exception("multiple args worked when it shouldnt have!")
+    except pythoncom.com_error as xxx_todo_changeme1:
+        (hr, desc, exc, argErr) = xxx_todo_changeme1.args
         if hr != winerror.DISP_E_BADPARAMCOUNT:
-            raise error("Expected DISP_E_BADPARAMCOUNT - got %d (%s)" % (hr, desc))
+            raise Exception("Expected DISP_E_BADPARAMCOUNT - got %d (%s)" % (hr, desc))
 
     try:
         dict(0)
-        raise error("int key worked when it shouldnt have!")
-    except pythoncom.com_error, (hr, desc, exc, argErr):
+        raise Exception("int key worked when it shouldnt have!")
+    except pythoncom.com_error as xxx_todo_changeme2:
+        (hr, desc, exc, argErr) = xxx_todo_changeme2.args
         if hr != winerror.DISP_E_TYPEMISMATCH:
-            raise error("Expected DISP_E_TYPEMISMATCH - got %d (%s)" % (hr, desc))
+            raise Exception("Expected DISP_E_TYPEMISMATCH - got %d (%s)" % (hr, desc))
 
     if not quiet:
-        print "Python.Dictionary tests complete."
+        print("Python.Dictionary tests complete.")
 
 class TestCase(win32com.test.util.TestCase):
     def testDict(self):

diff --git a/win32/src/PyTime.cpp b/win32/src/PyTime.cpp
@@ -13,6 +13,9 @@
 #include "tchar.h"
 #include "math.h"
 
+// Each second as stored in a DATE.
+const double ONETHOUSANDMILLISECONDS = 0.00001157407407407407407407407407;
+
 PyObject *PyWin_NewTime(PyObject *timeOb);
 
 BOOL PyWinTime_Check(PyObject *ob)
@@ -737,10 +740,22 @@ BOOL PyWinObject_AsDATE(PyObject *ob, DATE *pDate)
     SYSTEMTIME st;
     if (!PyWinObject_AsSYSTEMTIME(ob, &st))
         return FALSE;
-    if (!SystemTimeToVariantTime(&st, pDate)) {
+    // Extra work to get milliseconds, via
+    // https://www.codeproject.com/Articles/17576/SystemTime-to-VariantTime-with-Milliseconds
+    WORD wMilliseconds = st.wMilliseconds;
+    // not clear why we need to zero this since we always seem to get ms ignored
+    // but...
+    st.wMilliseconds = 0;
+
+    double dWithoutms;
+    if (!SystemTimeToVariantTime(&st, &dWithoutms)) {
         PyWin_SetAPIError("SystemTimeToVariantTime");
         return FALSE;
     }
+    // manually convert the millisecond information into variant
+    // fraction and add it to system converted value
+    double OneMilliSecond = ONETHOUSANDMILLISECONDS / 1000;
+    *pDate = dWithoutms + (OneMilliSecond * wMilliseconds);
     return TRUE;
 }
 
@@ -956,12 +971,41 @@ PyObject *PyWin_NewTime(PyObject *timeOb)
         return new PyTime(t);
 #endif
     }
+
+#ifdef PYWIN_HAVE_DATETIME_CAPI
+    static double round(double Value, int Digits)
+    {
+        assert(Digits >= -4 && Digits <= 4);
+        int Idx = Digits + 4;
+        double v[] = {1e-4, 1e-3, 1e-2, 1e-1, 1, 10, 1e2, 1e3, 1e4};
+        return floor(Value * v[Idx] + 0.5) / (v[Idx]);
+    }
+#endif
+
     PyObject *PyWinObject_FromDATE(DATE t)
     {
 #ifdef PYWIN_HAVE_DATETIME_CAPI
+        // via https://www.codeproject.com/Articles/17576/SystemTime-to-VariantTime-with-Milliseconds
+        // (in particular, see the comments)
+        double fraction = t - (int)t;  // extracts the fraction part
+        double hours = (fraction - (int)fraction) * 24.0;
+        double minutes = (hours - (int)hours) * 60.0;
+        double seconds = round((minutes - (int)minutes) * 60.0, 4);
+        double milliseconds = round((seconds - (int)seconds) * 1000.0, 0);
+        // assert(milliseconds>=0.0 && milliseconds<=999.0);
+
+        // Strip off the msec part of time
+        double TimeWithoutMsecs = t - (ONETHOUSANDMILLISECONDS / 1000.0 * milliseconds);
+
+        // Let the OS translate the variant date/time
         SYSTEMTIME st;
-        if (!VariantTimeToSystemTime(t, &st))
+        if (!VariantTimeToSystemTime(TimeWithoutMsecs, &st)) {
             return PyWin_SetAPIError("VariantTimeToSystemTime");
+        }
+        if (milliseconds > 0.0) {
+            // add the msec part to the systemtime object
+            st.wMilliseconds = (WORD)milliseconds;
+        }
         return PyWinObject_FromSYSTEMTIME(st);
 #endif  // PYWIN_HAVE_DATETIME_CAPI
-Original file line number
+Diff line change
@@ Expand Up @@
     Since build 225:
     ----------------
+    * Conversions to and from COM VT_DATE types should no longer lose milliseconds.
     Since build 224:
     ----------------
@@ Expand Down @@