printing/units.cc

   1 // Copyright (c) 2011 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 #include "printing/print_job_constants.h"
   9
  10 namespace printing {
  11
  12 int ConvertUnit(int value, int old_unit, int new_unit) {
  13   DCHECK_GT(new_unit, 0);
  14   DCHECK_GT(old_unit, 0);
  15   // With integer arithmetic, to divide a value with correct rounding, you need
  16   // to add half of the divisor value to the dividend value. You need to do the
  17   // reverse with negative number.
  18   if (value >= 0) {
  19     return ((value * new_unit) + (old_unit / 2)) / old_unit;
  20   } else {
  21     return ((value * new_unit) - (old_unit / 2)) / old_unit;
  22   }
  23 }
  24
  25 double ConvertUnitDouble(double value, double old_unit, double new_unit) {
  26   DCHECK_GT(new_unit, 0);
  27   DCHECK_GT(old_unit, 0);
  28   return value * new_unit / old_unit;
  29 }
  30
  31 int ConvertMilliInchToHundredThousanthMeter(int milli_inch) {
  32   // 1" == 25.4 mm
  33   // 1" == 25400 um
  34   // 0.001" == 25.4 um
  35   // 0.001" == 2.54 cmm
  36   return ConvertUnit(milli_inch, 100, 254);
  37 }
  38
  39 int ConvertHundredThousanthMeterToMilliInch(int cmm) {
  40   return ConvertUnit(cmm, 254, 100);
  41 }
  42
  43 int ConvertPixelsToPoint(int pixels) {
  44   return ConvertUnit(pixels, kPixelsPerInch, kPointsPerInch);
  45 }
  46
  47 double ConvertPixelsToPointDouble(double pixels) {
  48   return ConvertUnitDouble(pixels, kPixelsPerInch, kPointsPerInch);
  49 }
  50
  51 double ConvertPointsToPixelDouble(double points) {
  52   return ConvertUnitDouble(points, kPointsPerInch, kPixelsPerInch);
  53 }
  54
  55 }  // namespace printing