[libcamera-devel] [PATCH 1/4] android: jpeg: exif: Fix and expand setRational

[Paul Elder]

setRational was not working properly for EXIF tags in the GPS IFD.
Manually specify the size of the EXIF entry to fix this. While at it,
add support for setting multiple rationals, as that is a common use case
for rational EXIF tags.

This allows the GPS altitude to be set properly, and is part of the fix
to allow the following CTS test to pass:
- android.hardware.cts.CameraTest#testJpegExif

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
---
 src/android/jpeg/exif.cpp | 13 +++++++++++--
 src/android/jpeg/exif.h   |  2 ++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
index fdd46070..e5a3e448 100644
--- a/src/android/jpeg/exif.cpp
+++ b/src/android/jpeg/exif.cpp
@@ -187,11 +187,20 @@ void Exif::setLong(ExifIfd ifd, ExifTag tag, uint32_t item)
 
 void Exif::setRational(ExifIfd ifd, ExifTag tag, ExifRational item)
 {
-	ExifEntry *entry = createEntry(ifd, tag);
+	ExifRational items[] = { item };
+	setRational(ifd, tag, 1, items);
+}
+
+void Exif::setRational(ExifIfd ifd, ExifTag tag, uint32_t count, ExifRational items[])
+{
+	ExifEntry *entry = createEntry(ifd, tag, EXIF_FORMAT_RATIONAL,
+				       count, count * sizeof(ExifRational));
 	if (!entry)
 		return;
 
-	exif_set_rational(entry->data, order_, item);
+	for (size_t i = 0; i < count; i++)
+		exif_set_rational(entry->data + i * sizeof(ExifRational),
+				  order_, items[i]);
 	exif_entry_unref(entry);
 }
 
diff --git a/src/android/jpeg/exif.h b/src/android/jpeg/exif.h
index b0d61402..e283d3fc 100644
--- a/src/android/jpeg/exif.h
+++ b/src/android/jpeg/exif.h
@@ -89,6 +89,8 @@ private:
 		       const std::string &item,
 		       StringEncoding encoding = NoEncoding);
 	void setRational(ExifIfd ifd, ExifTag tag, ExifRational item);
+	void setRational(ExifIfd ifd, ExifTag tag, uint32_t count,
+			 ExifRational items[]);
 
 	std::tuple<int, int, int> degreesToDMS(double decimalDegrees);
 	void setGPSDMS(ExifIfd ifd, ExifTag tag, int deg, int min, int sec);
-- 
2.27.0