update external headers

ios/include/imageio/HDRDecoder.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef IMAGE_HDRDECODER_H_
+#define IMAGE_HDRDECODER_H_
+
+#include <imageio/ImageDecoder.h>
+
+namespace image {
+
+class HDRDecoder : public ImageDecoder::Decoder {
+public:
+    static HDRDecoder* create(std::istream& stream);
+    static bool checkSignature(char const* buf);
+
+    HDRDecoder(const HDRDecoder&) = delete;
+    HDRDecoder& operator=(const HDRDecoder&) = delete;
+
+private:
+    explicit HDRDecoder(std::istream& stream);
+    ~HDRDecoder() override;
+
+    // ImageDecoder::Decoder interface
+    LinearImage decode() override;
+
+    static const char sigRadiance[];
+    static const char sigRGBE[];
+    std::istream& mStream;
+    std::streampos mStreamStartPos;
+};
+
+} // namespace image
+
+#endif /* IMAGE_IMAGEDECODER_H_ */