[libcamera-devel] [PATCH v6 1/1] Fix Android adaptor thumbnail buffer lifetime

[Harvey Yang]

Previously the thumbnail buffer is destructed before even being used in
Exif. This patch moves the buffer into class Exif, so that the developer
won't need to worry about its lifetime.

Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
---
 src/android/jpeg/exif.cpp                | 10 ++++++----
 src/android/jpeg/exif.h                  | 10 ++++++++--
 src/android/jpeg/post_processor_jpeg.cpp |  6 ++----
 3 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
index 3220b458..584a29d0 100644
--- a/src/android/jpeg/exif.cpp
+++ b/src/android/jpeg/exif.cpp
@@ -435,11 +435,13 @@ void Exif::setOrientation(int orientation)
  * Failing to do so, might result in no thumbnail data being set even after a
  * call to Exif::setThumbnail().
  */
-void Exif::setThumbnail(Span<const unsigned char> thumbnail,
-			Compression compression)
+void Exif::setThumbnail(Compression compression)
 {
-	data_->data = const_cast<unsigned char *>(thumbnail.data());
-	data_->size = thumbnail.size();
+	if (thumbnail_raw_.empty())
+		return;
+
+	data_->data = const_cast<unsigned char *>(thumbnail_raw_.data());
+	data_->size = thumbnail_raw_.size();
 
 	setShort(EXIF_IFD_0, EXIF_TAG_COMPRESSION, compression);
 }
diff --git a/src/android/jpeg/exif.h b/src/android/jpeg/exif.h
index 2ff8fb78..4784496b 100644
--- a/src/android/jpeg/exif.h
+++ b/src/android/jpeg/exif.h
@@ -10,6 +10,7 @@
 #include <chrono>
 #include <string>
 #include <time.h>
+#include <vector>
 
 #include <libexif/exif-data.h>
 
@@ -60,8 +61,7 @@ public:
 
 	void setOrientation(int orientation);
 	void setSize(const libcamera::Size &size);
-	void setThumbnail(libcamera::Span<const unsigned char> thumbnail,
-			  Compression compression);
+	void setThumbnail(Compression compression);
 	void setTimestamp(time_t timestamp, std::chrono::milliseconds msec);
 
 	void setGPSDateTimestamp(time_t timestamp);
@@ -78,6 +78,10 @@ public:
 	libcamera::Span<const uint8_t> data() const { return { exifData_, size_ }; }
 	[[nodiscard]] int generate();
 
+	std::vector<unsigned char>& getThumbnailRaw() {
+		return thumbnail_raw_;
+	}
+
 private:
 	ExifEntry *createEntry(ExifIfd ifd, ExifTag tag);
 	ExifEntry *createEntry(ExifIfd ifd, ExifTag tag, ExifFormat format,
@@ -106,4 +110,6 @@ private:
 
 	unsigned char *exifData_;
 	unsigned int size_;
+
+	std::vector<unsigned char> thumbnail_raw_;
 };
diff --git a/src/android/jpeg/post_processor_jpeg.cpp b/src/android/jpeg/post_processor_jpeg.cpp
index d72ebc3c..506b00b9 100644
--- a/src/android/jpeg/post_processor_jpeg.cpp
+++ b/src/android/jpeg/post_processor_jpeg.cpp
@@ -163,10 +163,8 @@ void PostProcessorJpeg::process(Camera3RequestDescriptor::StreamBuffer *streamBu
 		resultMetadata->addEntry(ANDROID_JPEG_THUMBNAIL_QUALITY, quality);
 
 		if (thumbnailSize != Size(0, 0)) {
-			std::vector<unsigned char> thumbnail;
-			generateThumbnail(source, thumbnailSize, quality, &thumbnail);
-			if (!thumbnail.empty())
-				exif.setThumbnail(thumbnail, Exif::Compression::JPEG);
+			generateThumbnail(source, thumbnailSize, quality, &exif.getThumbnailRaw());
+			exif.setThumbnail(Exif::Compression::JPEG);
 		}
 
 		resultMetadata->addEntry(ANDROID_JPEG_THUMBNAIL_SIZE, data, 2);
-- 
2.37.0.170.g444d1eabd0-goog