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      1 /*
      2  * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
      3  *
      4  * This library is free software; you can redistribute it and/or
      5  * modify it under the terms of the GNU Library General Public
      6  * License as published by the Free Software Foundation; either
      7  * version 2 of the License, or (at your option) any later version.
      8  *
      9  * This library is distributed in the hope that it will be useful,
     10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     12  * Library General Public License for more details.
     13  *
     14  * You should have received a copy of the GNU Library General Public License
     15  * along with this library; see the file COPYING.LIB.  If not, write to
     16  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     17  * Boston, MA 02110-1301, USA.
     18  *
     19  */
     20 
     21 #ifndef StepRange_h
     22 #define StepRange_h
     23 
     24 #include "platform/Decimal.h"
     25 #include "wtf/Forward.h"
     26 
     27 namespace WebCore {
     28 
     29 class HTMLInputElement;
     30 
     31 enum AnyStepHandling { RejectAny, AnyIsDefaultStep };
     32 
     33 class StepRange {
     34 public:
     35     enum StepValueShouldBe {
     36         StepValueShouldBeReal,
     37         ParsedStepValueShouldBeInteger,
     38         ScaledStepValueShouldBeInteger,
     39     };
     40 
     41     struct StepDescription {
     42         WTF_MAKE_FAST_ALLOCATED;
     43     public:
     44         int defaultStep;
     45         int defaultStepBase;
     46         int stepScaleFactor;
     47         StepValueShouldBe stepValueShouldBe;
     48 
     49         StepDescription(int defaultStep, int defaultStepBase, int stepScaleFactor, StepValueShouldBe stepValueShouldBe = StepValueShouldBeReal)
     50             : defaultStep(defaultStep)
     51             , defaultStepBase(defaultStepBase)
     52             , stepScaleFactor(stepScaleFactor)
     53             , stepValueShouldBe(stepValueShouldBe)
     54         {
     55         }
     56 
     57         StepDescription()
     58             : defaultStep(1)
     59             , defaultStepBase(0)
     60             , stepScaleFactor(1)
     61             , stepValueShouldBe(StepValueShouldBeReal)
     62         {
     63         }
     64 
     65         Decimal defaultValue() const
     66         {
     67             return defaultStep * stepScaleFactor;
     68         }
     69     };
     70 
     71     StepRange();
     72     StepRange(const StepRange&);
     73     StepRange(const Decimal& stepBase, const Decimal& minimum, const Decimal& maximum, const Decimal& step, const StepDescription&);
     74     Decimal alignValueForStep(const Decimal& currentValue, const Decimal& newValue) const;
     75     Decimal clampValue(const Decimal& value) const;
     76     bool hasStep() const { return m_hasStep; }
     77     Decimal maximum() const { return m_maximum; }
     78     Decimal minimum() const { return m_minimum; }
     79     static Decimal parseStep(AnyStepHandling, const StepDescription&, const String&);
     80     Decimal step() const { return m_step; }
     81     Decimal stepBase() const { return m_stepBase; }
     82     bool stepMismatch(const Decimal&) const;
     83 
     84     // Clamp the middle value according to the step
     85     Decimal defaultValue() const
     86     {
     87         return clampValue((m_minimum + m_maximum) / 2);
     88     }
     89 
     90     // Map value into 0-1 range
     91     Decimal proportionFromValue(const Decimal& value) const
     92     {
     93         if (m_minimum == m_maximum)
     94             return 0;
     95 
     96         return (value - m_minimum) / (m_maximum - m_minimum);
     97     }
     98 
     99     // Map from 0-1 range to value
    100     Decimal valueFromProportion(const Decimal& proportion) const
    101     {
    102         return m_minimum + proportion * (m_maximum - m_minimum);
    103     }
    104 
    105 private:
    106     StepRange& operator =(const StepRange&);
    107     Decimal acceptableError() const;
    108     Decimal roundByStep(const Decimal& value, const Decimal& base) const;
    109 
    110     const Decimal m_maximum; // maximum must be >= minimum.
    111     const Decimal m_minimum;
    112     const Decimal m_step;
    113     const Decimal m_stepBase;
    114     const StepDescription m_stepDescription;
    115     const bool m_hasStep;
    116 };
    117 
    118 }
    119 
    120 #endif // StepRange_h
    121