[libcamera-devel] [PATCH v4 1/8] android: jpeg: exif: Expand setString to support different encodings
Paul Elder
paul.elder at ideasonboard.com
Mon Jan 25 08:14:37 CET 2021
GPSProcessingMethod and UserComment in EXIF tags can be in UTF-16.
Expand setString to take an encoding when the field type is undefined.
Update callers accordingly.
Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
Changes in v4:
- clean up switch
Changes in v3:
- use array to contain string encoding codes
- drop JIS and Undefined
- clean up setString a bit
- use the endianness of the exif
Changes in v2:
- moved from utils into exif
- support no-encoding
---
src/android/jpeg/exif.cpp | 77 +++++++++++++++++++++++++++++++++++++--
src/android/jpeg/exif.h | 11 +++++-
2 files changed, 84 insertions(+), 4 deletions(-)
diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
index 33b3fa7f..89343323 100644
--- a/src/android/jpeg/exif.cpp
+++ b/src/android/jpeg/exif.cpp
@@ -7,6 +7,9 @@
#include "exif.h"
+#include <map>
+#include <uchar.h>
+
#include "libcamera/internal/log.h"
#include "libcamera/internal/utils.h"
@@ -178,11 +181,18 @@ void Exif::setRational(ExifIfd ifd, ExifTag tag, ExifRational item)
exif_entry_unref(entry);
}
-void Exif::setString(ExifIfd ifd, ExifTag tag, ExifFormat format, const std::string &item)
+static const std::map<Exif::StringEncoding, std::array<uint8_t, 8>> stringEncodingCodes = {
+ { Exif::ASCII, { 0x41, 0x53, 0x43, 0x49, 0x49, 0x00, 0x00, 0x00 } },
+ { Exif::Unicode, { 0x55, 0x4e, 0x49, 0x43, 0x4f, 0x44, 0x45, 0x00 } },
+};
+
+void Exif::setString(ExifIfd ifd, ExifTag tag, ExifFormat format,
+ const std::string &item, StringEncoding encoding)
{
std::string ascii;
size_t length;
const char *str;
+ std::vector<uint8_t> buf;
if (format == EXIF_FORMAT_ASCII) {
ascii = utils::toAscii(item);
@@ -191,13 +201,46 @@ void Exif::setString(ExifIfd ifd, ExifTag tag, ExifFormat format, const std::str
/* Pad 1 extra byte to null-terminate the ASCII string. */
length = ascii.length() + 1;
} else {
- str = item.c_str();
+ std::u16string u16str;
+
+ auto encodingString = stringEncodingCodes.find(encoding);
+ if (encodingString != stringEncodingCodes.end()) {
+ buf = {
+ encodingString->second.begin(),
+ encodingString->second.end()
+ };
+ }
+
+ switch (encoding) {
+ case Unicode:
+ u16str = utf8ToUtf16(item);
+
+ buf.resize(8 + u16str.size() * 2);
+ for (size_t i = 0; i < u16str.size(); i++) {
+ if (order_ == EXIF_BYTE_ORDER_INTEL) {
+ buf[8 + 2 * i] = u16str[i] & 0xff;
+ buf[8 + 2 * i + 1] = (u16str[i] >> 8) & 0xff;
+ } else {
+ buf[8 + 2 * i] = (u16str[i] >> 8) & 0xff;
+ buf[8 + 2 * i + 1] = u16str[i] & 0xff;
+ }
+ }
+
+ break;
+
+ case ASCII:
+ case NoEncoding:
+ buf.insert(buf.end(), item.begin(), item.end());
+ break;
+ }
+
+ str = reinterpret_cast<const char *>(buf.data());
/*
* Strings stored in different formats (EXIF_FORMAT_UNDEFINED)
* are not null-terminated.
*/
- length = item.length();
+ length = buf.size();
}
ExifEntry *entry = createEntry(ifd, tag, format, length, length);
@@ -290,6 +333,34 @@ void Exif::setThumbnail(Span<const unsigned char> thumbnail,
setShort(EXIF_IFD_0, EXIF_TAG_COMPRESSION, compression);
}
+/**
+ * \brief Convert UTF-8 string to UTF-16 string
+ * \param[in] str String to convert
+ *
+ * \return \a str in UTF-16
+ */
+std::u16string Exif::utf8ToUtf16(const std::string &str)
+{
+ mbstate_t state{};
+ char16_t c16;
+ const char *ptr = str.data();
+ const char *end = ptr + str.size();
+
+ std::u16string ret;
+ while (size_t rc = mbrtoc16(&c16, ptr, end - ptr + 1, &state)) {
+ if (rc == static_cast<size_t>(-2) ||
+ rc == static_cast<size_t>(-1))
+ break;
+
+ ret.push_back(c16);
+
+ if (rc > 0)
+ ptr += rc;
+ }
+
+ return ret;
+}
+
[[nodiscard]] int Exif::generate()
{
if (exifData_) {
diff --git a/src/android/jpeg/exif.h b/src/android/jpeg/exif.h
index 5cab4559..8b84165b 100644
--- a/src/android/jpeg/exif.h
+++ b/src/android/jpeg/exif.h
@@ -26,6 +26,12 @@ public:
JPEG = 6,
};
+ enum StringEncoding {
+ NoEncoding = 0,
+ ASCII = 1,
+ Unicode = 2,
+ };
+
void setMake(const std::string &make);
void setModel(const std::string &model);
@@ -46,9 +52,12 @@ private:
void setShort(ExifIfd ifd, ExifTag tag, uint16_t item);
void setLong(ExifIfd ifd, ExifTag tag, uint32_t item);
void setString(ExifIfd ifd, ExifTag tag, ExifFormat format,
- const std::string &item);
+ const std::string &item,
+ StringEncoding encoding = NoEncoding);
void setRational(ExifIfd ifd, ExifTag tag, ExifRational item);
+ std::u16string utf8ToUtf16(const std::string &str);
+
bool valid_;
ExifData *data_;
--
2.27.0
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