Add a file-handler for .emf files

These can be embedded in slideshows and POI supports
some handling of them.

Also Tika uses this code to extract some textual information
from such images.

poi-integration/src/test/java/org/apache/poi/stress/FileHandlerKnown.java

@@ -29,6 +29,7 @@ public enum FileHandlerKnown {
     HSLF,
     HSMF,
     HSSF,
+    HEMF,
     HWMF,
     HWPF,
     OPC,

poi-integration/src/test/java/org/apache/poi/stress/HEMFFileHandler.java

@@ -0,0 +1,85 @@
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You 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.
+==================================================================== */
+package org.apache.poi.stress;
+
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+
+import java.awt.geom.Rectangle2D;
+import java.awt.image.BufferedImage;
+import java.io.BufferedInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.poi.hemf.record.emf.HemfRecord;
+import org.apache.poi.hemf.record.emf.HemfRecordType;
+import org.apache.poi.hemf.record.emf.HemfText;
+import org.apache.poi.hemf.usermodel.HemfPicture;
+import org.junit.jupiter.api.Test;
+
+public class HEMFFileHandler implements FileHandler {
+
+    @Override
+    public void handleExtracting(File file) throws Exception {
+        try (InputStream stream = new BufferedInputStream(new FileInputStream(file))) {
+            HemfPicture picture = new HemfPicture(stream);
+
+            // mimic a bit what e.g. Tika does to extract some information from .emf files
+            for (HemfRecord record : picture.getRecords()) {
+                if (record.getEmfRecordType().equals(HemfRecordType.extTextOutW)) {
+                    assertInstanceOf(HemfText.EmfExtTextOutW.class, record);
+                    HemfText.EmfExtTextOutW textOut = (HemfText.EmfExtTextOutW) record;
+                    textOut.getText(StandardCharsets.UTF_16LE);
+                } else if (record.getEmfRecordType().equals(HemfRecordType.extTextOutA)) {
+                    assertInstanceOf(HemfText.EmfExtTextOutA.class, record);
+                    HemfText.EmfExtTextOutA textOut = (HemfText.EmfExtTextOutA) record;
+                    textOut.getText(StandardCharsets.UTF_8);
+                }
+            }
+        }
+    }
+
+    @Override
+    public void handleAdditional(File file) throws Exception {
+        // no additional checks for now
+    }
+
+    @Override
+    public void handleFile(InputStream stream, String path) throws Exception {
+        HemfPicture picture = new HemfPicture(stream);
+
+        for (HemfRecord record : picture.getRecords()) {
+            record.getEmfRecordType();
+            record.getGenericRecordType();
+        }
+
+        BufferedImage dest = new BufferedImage(256, 256, BufferedImage.TYPE_INT_ARGB);
+        picture.draw(dest.createGraphics(), new Rectangle2D.Double(0, 0, 256, 256));
+    }
+
+    @Test
+    void test() throws Exception {
+        String file = "test-data/slideshow/wrench.emf";
+
+        try (InputStream stream = new BufferedInputStream(new FileInputStream(file))) {
+            handleFile(stream, file);
+        }
+
+        handleExtracting(new File(file));
+    }
+}