Initial api to provide stateless read api for scanline things

This enables reading of scanlines in a "stateless" manner, where a
framebuffer does not have to be stored, then the call to readPixels
made.

Signed-off-by: Kimball Thurston <[email protected]>

src/lib/OpenEXR/ImfInputFile.cpp

@@ -77,10 +77,14 @@ struct InputFile::Data
     }
 
     void setFrameBuffer (const FrameBuffer& frameBuffer);
+    void lockedSetFrameBuffer (const FrameBuffer& frameBuffer);
 
     void readPixels (int scanline1, int scanline2);
     void bufferedReadPixels (int scanline1, int scanline2);
 
+    void readPixels (
+        const FrameBuffer& frameBuffer, int scanline1, int scanline2);
+
     void deleteCachedBuffer (void);
     void copyCachedBuffer (FrameBuffer::ConstIterator to,
                            FrameBuffer::ConstIterator from,
@@ -224,6 +228,13 @@ InputFile::readPixels (int scanLine)
     _data->readPixels (scanLine, scanLine);
 }
 
+void
+InputFile::readPixels (
+    const FrameBuffer& frameBuffer, int scanLine1, int scanLine2)
+{
+    _data->readPixels (frameBuffer, scanLine1, scanLine2);
+}
+
 void
 InputFile::rawPixelData (
     int firstScanLine, const char*& pixelData, int& pixelDataSize)
@@ -317,7 +328,12 @@ InputFile::Data::setFrameBuffer (const FrameBuffer& frameBuffer)
 #if ILMTHREAD_THREADING_ENABLED
     std::lock_guard<std::mutex> lk (_mx);
 #endif
+    lockedSetFrameBuffer (frameBuffer);
+}
 
+void
+InputFile::Data::lockedSetFrameBuffer (const FrameBuffer& frameBuffer)
+{
     if (_storage == EXR_STORAGE_TILED)
     {
         //
@@ -430,6 +446,30 @@ InputFile::Data::readPixels (int scanLine1, int scanLine2)
     else { _sFile->readPixels (scanLine1, scanLine2); }
 }
 
+void
+InputFile::Data::readPixels (
+    const FrameBuffer& frameBuffer, int scanLine1, int scanLine2)
+{
+    if (_compositor)
+    {
+#if ILMTHREAD_THREADING_ENABLED
+        std::lock_guard<std::mutex> lock (_mx);
+#endif
+        _compositor->setFrameBuffer (frameBuffer);
+        _compositor->readPixels (scanLine1, scanLine2);
+    }
+    else if (_storage == EXR_STORAGE_TILED)
+    {
+#if ILMTHREAD_THREADING_ENABLED
+        std::lock_guard<std::mutex> lock (_mx);
+#endif
+
+        lockedSetFrameBuffer (frameBuffer);
+        bufferedReadPixels (scanLine1, scanLine2);
+    }
+    else { _sFile->readPixels (frameBuffer, scanLine1, scanLine2); }
+}
+
 void
 InputFile::Data::bufferedReadPixels (int scanLine1, int scanLine2)
 {

src/lib/OpenEXR/ImfInputFile.h

@@ -200,6 +200,27 @@ class IMF_EXPORT_TYPE InputFile
     IMF_EXPORT
     void readPixels (int scanLine);
 
+    //----------------------------------------------
+    // Combines the setFrameBuffer and readPixels into a singular
+    // call. This does more than that in that it can, with the right
+    // conditions, not require a lock on the file, such that multiple
+    // (external to OpenEXR) threads can read at the same time on
+    // different framebuffers
+    //
+    // NB: if the underlying file is deep or tiled, that requires
+    // translation, so will not do the pass through, but will behave
+    // in a threadsafe manner (where the only way that was possible
+    // before was to have a larger framebuffer, set the framebuffer
+    // once, then call readPixels by the external threads, although
+    // that occured with a mutex and so the reads were serialized.
+    // There are reasons why that might still be serialized, such as a
+    // non-threadable stream.
+    //----------------------------------------------
+
+    IMF_EXPORT
+    void readPixels (
+        const FrameBuffer& frameBuffer, int scanLine1, int scanLine2);
+
     //----------------------------------------------
     // Read a block of raw pixel data from the file,
     // without uncompressing it (this function is

src/lib/OpenEXR/ImfInputPart.cpp

@@ -70,6 +70,13 @@ InputPart::readPixels (int scanLine)
     file->readPixels (scanLine);
 }
 
+void
+InputPart::readPixels (
+    const FrameBuffer& frameBuffer, int scanLine1, int scanLine2)
+{
+    file->readPixels (frameBuffer, scanLine1, scanLine2);
+}
+
 void
 InputPart::rawPixelData (
     int firstScanLine, const char*& pixelData, int& pixelDataSize)

src/lib/OpenEXR/ImfInputPart.h

@@ -41,6 +41,9 @@ class IMF_EXPORT_TYPE InputPart
     IMF_EXPORT
     void readPixels (int scanLine);
     IMF_EXPORT
+    void readPixels (
+        const FrameBuffer& frameBuffer, int scanLine1, int scanLine2);
+    IMF_EXPORT
     void rawPixelData (
         int firstScanLine, const char*& pixelData, int& pixelDataSize);
 

src/lib/OpenEXR/ImfMultiPartInputFile.h

@@ -99,7 +99,7 @@ class IMF_EXPORT_TYPE MultiPartInputFile
     //
     // used internally by 'Part' types to access individual parts of the multipart file
     //
-    // TODO: change these to value / reference semantics
+    // TODO: change these to value / reference semantics (smart ptr)
     template <class T> IMF_HIDDEN T* getInputPart (int partNumber);
     IMF_HIDDEN InputPartData*  getPart (int) const;
 

src/lib/OpenEXR/ImfScanLineInputFile.cpp

@@ -285,6 +285,13 @@ ScanLineInputFile::readPixels (int scanLine1, int scanLine2)
     _data->readPixels (frameBuffer (), scanLine1, scanLine2);
 }
 
+void
+ScanLineInputFile::readPixels (
+    const FrameBuffer& frame, int scanLine1, int scanLine2)
+{
+    _data->readPixels (frame, scanLine1, scanLine2);
+}
+
 ////////////////////////////////////////
 
 void

src/lib/OpenEXR/ImfScanLineInputFile.h

@@ -140,6 +140,18 @@ class IMF_EXPORT_TYPE ScanLineInputFile
     IMF_EXPORT
     void readPixels (int scanLine);
 
+    //----------------------------------------------
+    // Combines the setFrameBuffer and readPixels into a singular
+    // call. This does more than that in that it can, with the right
+    // conditions, not require a lock on the file, such that multiple
+    // (external to OpenEXR) threads can read at the same time on
+    // different framebuffers
+    //----------------------------------------------
+
+    IMF_EXPORT
+    void readPixels (
+        const FrameBuffer& frame, int scanLine1, int scanLine2);
+
     //----------------------------------------------
     // Read a block of raw pixel data from the file,
     // without uncompressing it (this function is