JPEGR Decoder: Add XMP data parsing

Parse XMP packet and get Range Scaling Factor

Test: build
Bug: b/252835416
Change-Id: Id05269286e0a32f789a26e2af2ce3ebc4c89b4a6
diff --git a/libs/jpegrecoverymap/recoverymaputils.cpp b/libs/jpegrecoverymap/recoverymaputils.cpp
index f8549f1..fe46cba 100644
--- a/libs/jpegrecoverymap/recoverymaputils.cpp
+++ b/libs/jpegrecoverymap/recoverymaputils.cpp
@@ -16,16 +16,138 @@
 
 #include <jpegrecoverymap/recoverymaputils.h>
 #include <jpegrecoverymap/recoverymap.h>
+#include <image_io/xml/xml_reader.h>
+#include <image_io/base/message_handler.h>
+#include <image_io/xml/xml_element_rules.h>
+#include <image_io/xml/xml_handler.h>
+#include <image_io/xml/xml_rule.h>
+
+#include <string>
+#include <sstream>
+
+using namespace photos_editing_formats::image_io;
+using namespace std;
 
 namespace android::recoverymap {
 
+
+// Extremely simple XML Handler - just searches for interesting elements
+class XMPXmlHandler : public XmlHandler {
+public:
+
+    XMPXmlHandler() : XmlHandler() {
+        rangeScalingFactorState = NotStrarted;
+    }
+
+    enum ParseState {
+        NotStrarted,
+        Started,
+        Done
+    };
+
+    virtual DataMatchResult StartElement(const XmlTokenContext& context) {
+        string val;
+        if (context.BuildTokenValue(&val)) {
+            if (!val.compare(rangeScalingFactorName)) {
+                rangeScalingFactorState = Started;
+            } else {
+                if (rangeScalingFactorState != Done) {
+                    rangeScalingFactorState = NotStrarted;
+                }
+            }
+        }
+        return context.GetResult();
+    }
+
+    virtual DataMatchResult FinishElement(const XmlTokenContext& context) {
+        if (rangeScalingFactorState == Started) {
+            rangeScalingFactorState = Done;
+        }
+        return context.GetResult();
+    }
+
+    virtual DataMatchResult ElementContent(const XmlTokenContext& context) {
+        string val;
+        if (rangeScalingFactorState == Started) {
+            if (context.BuildTokenValue(&val)) {
+                rangeScalingFactorStr.assign(val);
+            }
+        }
+        return context.GetResult();
+    }
+
+    bool getRangeScalingFactor(float* scaling_factor) {
+        if (rangeScalingFactorState == Done) {
+            stringstream ss(rangeScalingFactorStr);
+            float val;
+            if (ss >> val) {
+                *scaling_factor = val;
+                return true;
+            } else {
+                return false;
+            }
+        } else {
+            return false;
+        }
+    }
+
+    bool getTransferFunction(jpegr_transfer_function* transfer_function) {
+        *transfer_function = JPEGR_TF_HLG;
+        return true;
+    }
+
+private:
+    static const string rangeScalingFactorName;
+    string              rangeScalingFactorStr;
+    ParseState          rangeScalingFactorState;
+};
+
+const string XMPXmlHandler::rangeScalingFactorName = "GContainer:rangeScalingFactor";
+
+
 bool getMetadataFromXMP(uint8_t* xmp_data, size_t xmp_size, jpegr_metadata* metadata) {
-    // TODO: Parse XMP Data
-    (void)xmp_data;
-    (void)xmp_size;
-    metadata->rangeScalingFactor = 0.0708864;
-    metadata->transferFunction = JPEGR_TF_HLG;
+    string nameSpace = "http://ns.adobe.com/xap/1.0/\0";
+
+    if (xmp_size < nameSpace.size()+2) {
+        // Data too short
+        return false;
+    }
+
+    if (strncmp(reinterpret_cast<char*>(xmp_data), nameSpace.c_str(), nameSpace.size())) {
+        // Not correct namespace
+        return false;
+    }
+
+    // Position the pointers to the start of XMP XML portion
+    xmp_data += nameSpace.size()+1;
+    xmp_size -= nameSpace.size()+1;
+    XMPXmlHandler handler;
+
+    // We need to remove tail data until the closing tag. Otherwise parser will throw an error.
+    while(xmp_data[xmp_size-1]!='>' && xmp_size > 1) {
+        xmp_size--;
+    }
+
+    string str(reinterpret_cast<const char*>(xmp_data), xmp_size);
+    MessageHandler msg_handler;
+    unique_ptr<XmlRule> rule(new XmlElementRule);
+    XmlReader reader(&handler, &msg_handler);
+    reader.StartParse(std::move(rule));
+    reader.Parse(str);
+    reader.FinishParse();
+    if (reader.HasErrors()) {
+        // Parse error
+        return false;
+    }
+
+    if (!handler.getRangeScalingFactor(&metadata->rangeScalingFactor)) {
+        return false;
+    }
+
+    if (!handler.getTransferFunction(&metadata->transferFunction)) {
+        return false;
+    }
     return true;
 }
 
-}
\ No newline at end of file
+} // namespace android::recoverymap
\ No newline at end of file