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fix rational/s-rational EXIF parsing

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This commit is contained in:
cDc
2018-09-24 13:18:05 +03:00
parent ac39905f11
commit 8b383a2809
1 changed files with 7 additions and 4 deletions
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11
TinyEXIF.cpp
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@@ -157,6 +157,7 @@ public:
bool IsShort() const { return format == 3; } bool IsShort() const { return format == 3; }
bool IsLong() const { return format == 4; } bool IsLong() const { return format == 4; }
bool IsRational() const { return format == 5 || format == 10; } bool IsRational() const { return format == 5 || format == 10; }
bool IsSRational() const { return format == 10; }
bool IsFloat() const { return format == 11; } bool IsFloat() const { return format == 11; }
bool Fetch(std::string& val) const { bool Fetch(std::string& val) const {
@@ -198,13 +199,13 @@ public:
bool Fetch(double& val) const { bool Fetch(double& val) const {
if (!IsRational() || length == 0) if (!IsRational() || length == 0)
return false; return false;
val = parseRational(buf + GetSubIFD(), alignIntel); val = parseRational(buf + GetSubIFD(), alignIntel, IsSRational());
return true; return true;
} }
bool Fetch(double& val, uint32_t idx) const { bool Fetch(double& val, uint32_t idx) const {
if (!IsRational() || length <= idx) if (!IsRational() || length <= idx)
return false; return false;
val = parseRational(buf + GetSubIFD() + idx*8, alignIntel); val = parseRational(buf + GetSubIFD() + idx*8, alignIntel, IsSRational());
return true; return true;
} }
@@ -244,12 +245,14 @@ public:
i2f.i = parse32(buf, intel); i2f.i = parse32(buf, intel);
return i2f.f; return i2f.f;
} }
static double parseRational(const uint8_t* buf, bool intel) { static double parseRational(const uint8_t* buf, bool intel, bool isSigned) {
const uint32_t denominator = parse32(buf+4, intel); const uint32_t denominator = parse32(buf+4, intel);
if (denominator == 0) if (denominator == 0)
return 0.0; return 0.0;
const uint32_t numerator = parse32(buf, intel); const uint32_t numerator = parse32(buf, intel);
return (double)(int32_t)numerator/(double)(int32_t)denominator; return isSigned ?
(double)(int32_t)numerator/(double)(int32_t)denominator :
(double)numerator/(double)denominator;
} }
static std::string parseString(const uint8_t* buf, static std::string parseString(const uint8_t* buf,
unsigned num_components, unsigned num_components,