printing/units.cc

   1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "printing/units.h"
   6
   7 #include "base/logging.h"
   8
   9 namespace printing {
  10
  11 int ConvertUnit(int value, int old_unit, int new_unit) {
  12   DCHECK_GT(new_unit, 0);
  13   DCHECK_GT(old_unit, 0);
  14   // With integer arithmetic, to divide a value with correct rounding, you need
  15   // to add half of the divisor value to the dividend value. You need to do the
  16   // reverse with negative number.
  17   if (value >= 0) {
  18     return ((value * new_unit) + (old_unit / 2)) / old_unit;
  19   } else {
  20     return ((value * new_unit) - (old_unit / 2)) / old_unit;
  21   }
  22 }
  23
  24 double ConvertUnitDouble(double value, double old_unit, double new_unit) {
  25   DCHECK_GT(new_unit, 0);
  26   DCHECK_GT(old_unit, 0);
  27   return value * new_unit / old_unit;
  28 }
  29
  30 int ConvertMilliInchToHundredThousanthMeter(int milli_inch) {
  31   // 1" == 25.4 mm
  32   // 1" == 25400 um
  33   // 0.001" == 25.4 um
  34   // 0.001" == 2.54 cmm
  35   return ConvertUnit(milli_inch, 100, 254);
  36 }
  37
  38 int ConvertHundredThousanthMeterToMilliInch(int cmm) {
  39   return ConvertUnit(cmm, 254, 100);
  40 }
  41
  42 int ConvertPixelsToPoint(int pixels) {
  43   return ConvertUnit(pixels, kPixelsPerInch, kPointsPerInch);
  44 }
  45
  46 double ConvertPixelsToPointDouble(double pixels) {
  47   return ConvertUnitDouble(pixels, kPixelsPerInch, kPointsPerInch);
  48 }
  49
  50 }  // namespace printing