add fallback for non-FileOutputStreams

chunky/src/java/se/llbit/chunky/renderer/export/Tiff32ExportFormat.java

@@ -19,7 +19,13 @@
 
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.OutputStream;
+import java.nio.channels.Channels;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
 
 import se.llbit.chunky.renderer.scene.AlphaBuffer;
 import se.llbit.chunky.renderer.scene.Scene;
@@ -59,15 +65,37 @@ public boolean wantsPostprocessing() {
 
   @Override
   public void write(OutputStream out, Scene scene, TaskTracker taskTracker) throws IOException {
-    assert(out instanceof FileOutputStream);
-    try (
-      TaskTracker.Task task = taskTracker.task("Writing TIFF");
-      TiffFileWriter writer = new TiffFileWriter(
-        ((FileOutputStream) out).getChannel(),
-        CompressionType.DEFLATE
-      )
-    ) {
-      writer.export(scene, task);
+    try (TaskTracker.Task task = taskTracker.task("Writing TIFF")) {
+      if (out instanceof FileOutputStream) {
+        write(((FileOutputStream) out).getChannel(), scene, task);
+      } else {
+        // fallback for the case, that the output stream was not created on a file
+        Path tempFile = Files.createTempFile(scene.name + "-", getExtension());
+        try (FileChannel fileChannel = FileChannel.open(tempFile, StandardOpenOption.DELETE_ON_CLOSE,
+          StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING,
+          StandardOpenOption.READ, StandardOpenOption.WRITE
+        )) {
+          write(fileChannel, scene, task);
+          // rewind channel
+          fileChannel.position(0);
+          try (InputStream inputStream = Channels.newInputStream(fileChannel)) {
+            // copy temp file to output
+            inputStream.transferTo(out);
+          }
+        }
+      }
     }
   }
+
+  /**
+   * Note: does not (!) close the file channel after writing
+   */
+  private void write(FileChannel fileChannel, Scene scene, TaskTracker.Task task) throws IOException {
+    TiffFileWriter writer = new TiffFileWriter(
+      fileChannel,
+      CompressionType.DEFLATE
+    );
+    writer.export(scene, task);
+    writer.doFinalization();
+  }
 }

chunky/src/java/se/llbit/imageformats/tiff/FinalizableBFCOutputStream.java

@@ -29,11 +29,22 @@ private <T extends UnfinalizedData<?>> T writeUnfinalized(T ud, int byteCount) t
     return ud;
   }
 
-  @Override
-  public void close() throws IOException {
+  /**
+   * writes remaining unfinalized data
+   */
+  public void doFinalization() throws IOException {
     for(UnfinalizedData<?> data : finalizationQueue) {
       data.write(this);
     }
+    finalizationQueue.clear();
+  }
+
+  /**
+   * does finalization, then closes the output stream
+   */
+  @Override
+  public void close() throws IOException {
+    doFinalization();
     super.close();
   }
 

chunky/src/java/se/llbit/imageformats/tiff/TiffFileWriter.java

@@ -43,6 +43,7 @@ public class TiffFileWriter implements AutoCloseable {
 
   private final FinalizableBFCOutputStream out;
   private final CompressionType compressionType;
+  private FinalizableBFCOutputStream.UnfinalizedData.Int nextIFDOffset;
 
   public TiffFileWriter(
     FileChannel fileChannel,
@@ -54,12 +55,17 @@ public TiffFileWriter(
     // - MM -> magic bytes
     // - \0* -> magic number 42 for big-endian byte order
     out.writeInt(0x4D4D002A);
+    nextIFDOffset = out.writeUnfinalizedInt();
   }
 
   public TiffFileWriter(FileOutputStream outputStream) throws IOException {
     this(outputStream.getChannel(), CompressionType.NONE);
   }
 
+  public void doFinalization() throws IOException {
+    out.doFinalization();
+  }
+
   @Override
   public void close() throws IOException {
     out.close();
@@ -68,11 +74,12 @@ public void close() throws IOException {
   /**
    * Export sample buffer as Baseline TIFF RGB image / TIFF Class R image
    * with 32 bits per color component.
+   *
+   * <p>Note: This method does not close the output stream, and can be called multiple times for multiple layers.
+   *       Use {@link #doFinalization()} to complete the export.
    */
   public void export(Scene scene, TaskTracker.Task task) throws IOException {
-    FinalizableBFCOutputStream.UnfinalizedData.Int ifdOffset = out.writeUnfinalizedInt();
-
-    writePrimaryIDF(ifdOffset, scene, task);
+    nextIFDOffset = writePrimaryIDF(nextIFDOffset, scene, task);
   }
 
   private static final DateTimeFormatter DATETIME_FORMAT = DateTimeFormatter.ofPattern("yyyy:MM:dd HH:mm:ss");