From bc54748634695aaef80a426ba02e00df1b7a66a4 Mon Sep 17 00:00:00 2001
From: Andreas Huggel <ahuggel@gmx.net>
Date: Thu, 22 Jul 2010 02:41:02 +0000
Subject: [PATCH] #711: Added FloatValue to deal with TIFF Float values. (Nice
 one! :)

---
 src/types.cpp | 14 ++++++++++++++
 src/types.hpp |  7 +++++++
 src/value.cpp |  4 +++-
 src/value.hpp | 27 +++++++++++++++++++++++++++
 4 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/src/types.cpp b/src/types.cpp
index 3116136f..f3b740bf 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -235,6 +235,13 @@ namespace Exiv2 {
         return std::make_pair(nominator, denominator);
     }
 
+    float getFloat(const byte* buf, ByteOrder byteOrder)
+    {
+        assert(sizeof(float) == 4);
+        uint32_t ul = getULong(buf, byteOrder);
+        return *reinterpret_cast<float*>(&ul);
+    }
+
     long us2Data(byte* buf, uint16_t s, ByteOrder byteOrder)
     {
         if (byteOrder == littleEndian) {
@@ -309,6 +316,13 @@ namespace Exiv2 {
         return o;
     }
 
+    long f2Data(byte* buf, float f, ByteOrder byteOrder)
+    {
+        assert(sizeof(float) == 4);
+        uint32_t ul = *reinterpret_cast<uint32_t*>(&f);
+        return ul2Data(buf, ul, byteOrder);
+    }
+
     void hexdump(std::ostream& os, const byte* buf, long len, long offset)
     {
         const std::string::size_type pos = 8 + 16 * 3 + 2;
diff --git a/src/types.hpp b/src/types.hpp
index af4d8aa9..0dcfa5c4 100644
--- a/src/types.hpp
+++ b/src/types.hpp
@@ -366,6 +366,8 @@ namespace Exiv2 {
     EXIV2API int32_t getLong(const byte* buf, ByteOrder byteOrder);
     //! Read an 8 byte signed rational value from the data buffer
     EXIV2API Rational getRational(const byte* buf, ByteOrder byteOrder);
+    //! Read a 4 byte single precision floating point value (IEEE 754 binary32) from the data buffer
+    EXIV2API float getFloat(const byte* buf, ByteOrder byteOrder);
 
     //! Output operator for our fake rational
     EXIV2API std::ostream& operator<<(std::ostream& os, const Rational& r);
@@ -406,6 +408,11 @@ namespace Exiv2 {
              return number of bytes written.
      */
     EXIV2API long r2Data(byte* buf, Rational l, ByteOrder byteOrder);
+    /*!
+      @brief Convert a single precision floating point (IEEE 754 binary32) float
+             to data, write the data to the buffer, return number of bytes written.
+     */
+    EXIV2API long f2Data(byte* buf, float f, ByteOrder byteOrder);
 
     /*!
       @brief Print len bytes from buf in hex and ASCII format to the given
diff --git a/src/value.cpp b/src/value.cpp
index 7aa6051a..6e101e6d 100644
--- a/src/value.cpp
+++ b/src/value.cpp
@@ -76,7 +76,6 @@ namespace Exiv2 {
         case invalidTypeId:
         case signedByte:
         case unsignedByte:
-        case tiffFloat:
         case tiffDouble:
             value = AutoPtr(new DataValue(typeId));
             break;
@@ -105,6 +104,9 @@ namespace Exiv2 {
         case signedRational:
             value = AutoPtr(new ValueType<Rational>);
             break;
+        case tiffFloat:
+            value = AutoPtr(new ValueType<float>);
+            break;
         case string:
             value = AutoPtr(new StringValue);
             break;
diff --git a/src/value.hpp b/src/value.hpp
index d47c3450..e8d1248e 100644
--- a/src/value.hpp
+++ b/src/value.hpp
@@ -1209,6 +1209,8 @@ namespace Exiv2 {
     template<> inline TypeId getType<int32_t>() { return signedLong; }
     //! Specialization for a signed rational
     template<> inline TypeId getType<Rational>() { return signedRational; }
+    //! Specialization for a float
+    template<> inline TypeId getType<float>() { return tiffFloat; }
 
     // No default implementation: let the compiler/linker complain
     // template<typename T> inline TypeId getType() { return invalid; }
@@ -1321,6 +1323,8 @@ namespace Exiv2 {
     typedef ValueType<int32_t> LongValue;
     //! Signed rational value type
     typedef ValueType<Rational> RationalValue;
+    //! Float value type
+    typedef ValueType<float> FloatValue;
 
 // *****************************************************************************
 // free functions, template and inline definitions
@@ -1373,6 +1377,12 @@ namespace Exiv2 {
     {
         return getRational(buf, byteOrder);
     }
+    // Specialization for a 4 byte float value.
+    template<>
+    inline float getValue(const byte* buf, ByteOrder byteOrder)
+    {
+        return getFloat(buf, byteOrder);
+    }
 
     /*!
       @brief Convert a value of type T to data, write the data to the data buffer.
@@ -1441,6 +1451,15 @@ namespace Exiv2 {
     {
         return r2Data(buf, t, byteOrder);
     }
+    /*!
+      @brief Specialization to write a float to the data buffer.
+             Return the number of bytes written.
+     */
+    template<>
+    inline long toData(byte* buf, float t, ByteOrder byteOrder)
+    {
+        return f2Data(buf, t, byteOrder);
+    }
 
     template<typename T>
     ValueType<T>::ValueType()
@@ -1640,6 +1659,14 @@ namespace Exiv2 {
         ok_ = true;
         return Rational(value_[n].first, value_[n].second);
     }
+    // Specialization for float.
+    template<>
+    inline Rational ValueType<float>::toRational(long n) const
+    {
+        ok_ = true;
+        // Warning: This is a very simple conversion, see floatToRationalCast()
+        return floatToRationalCast(value_[n]);
+    }
 
     template<typename T>
     long ValueType<T>::sizeDataArea() const