From 478e49b8a602c2240de1367e631ab5f1f09525c6 Mon Sep 17 00:00:00 2001
From: Mirco Miranda <mirco.miranda@systemceramics.com>
Date: Mon, 25 Sep 2023 20:55:53 +0000
Subject: [PATCH] raw: fix multi image load

Fixes not loading a second image in the file. This patch allow code like the following.

QImageReader r(file);
do {
    auto qi = r.read();
    if (!qi.isNull()) {
        qi.save(QString("/tmp/%1_%2.tif")
                .arg(QFileInfo(file).baseName())
                .arg(r.currentImageNumber()));
    }
}
while (r.jumpToNextImage());

m_startPos is used to reposition the device if you decide to do a subsequent read: libraw wants it to be at the beginning of the RAW stream

(cherry picked from commit 18ea0492bc5b6689c9523c84dd716b3c50dc918f)
---
 src/imageformats/raw.cpp | 16 ++++++++++++++--
 src/imageformats/raw_p.h |  6 ++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/imageformats/raw.cpp b/src/imageformats/raw.cpp
index c8888fe..3b40d6b 100644
--- a/src/imageformats/raw.cpp
+++ b/src/imageformats/raw.cpp
@@ -443,7 +443,9 @@ void setParams(QImageIOHandler *handler, LibRaw *rawProcessor)
     auto &&rawparams = rawProcessor->imgdata.rawparams;
 #endif
     // Select one raw image from input file (0 - first, ...)
-    rawparams.shot_select = handler->currentImageNumber();
+    if (handler->currentImageNumber() > -1) {
+        rawparams.shot_select = handler->currentImageNumber();
+    }
 
     // *** Set processing parameters
 
@@ -723,6 +725,7 @@ RAWHandler::RAWHandler()
     : m_imageNumber(0)
     , m_imageCount(0)
     , m_quality(-1)
+    , m_startPos(-1)
 {
 }
 
@@ -739,6 +742,15 @@ bool RAWHandler::read(QImage *image)
 {
     auto dev = device();
 
+    // set the image position after the first run.
+    if (!dev->isSequential()) {
+        if (m_startPos < 0) {
+            m_startPos = dev->pos();
+        } else {
+            dev->seek(m_startPos);
+        }
+    }
+
     // Check image file format.
     if (dev->atEnd()) {
         return false;
@@ -820,7 +832,7 @@ bool RAWHandler::jumpToNextImage()
 
 bool RAWHandler::jumpToImage(int imageNumber)
 {
-    if (imageNumber >= imageCount()) {
+    if (imageNumber < 0 || imageNumber >= imageCount()) {
         return false;
     }
     m_imageNumber = imageNumber;
diff --git a/src/imageformats/raw_p.h b/src/imageformats/raw_p.h
index 30e8357..b4c5451 100644
--- a/src/imageformats/raw_p.h
+++ b/src/imageformats/raw_p.h
@@ -78,6 +78,12 @@ private:
      * @note It is safe to set both W and A: W is used if camera white balance is found, otherwise A is used.
      */
     qint32 m_quality;
+
+    /*!
+     * \brief m_startPos
+     * The initial device position to allow multi image load (cache value).
+     */
+    qint64 m_startPos;
 };
 
 class RAWPlugin : public QImageIOPlugin