Allow custom mime type determination

To allow library users to influence the file type
determination process, this commit refactors the
ft-detection and image dimension determination logic
so that `ImageStrategy` can be filled with a custom
file type detector.

build.gradle

@@ -8,7 +8,7 @@ plugins {
 }
 
 group 'com.docutools'
-version = '1.5.12'
+version = '1.6.0-alpha.1'
 
 sourceCompatibility = JavaVersion.VERSION_17
 targetCompatibility = JavaVersion.VERSION_17

src/main/java/com/docutools/jocument/image/DefaultImageStrategy.java

@@ -1,11 +1,11 @@
 package com.docutools.jocument.image;
 
-import com.docutools.jocument.impl.word.WordImageUtils;
 import java.awt.Dimension;
 import java.awt.geom.AffineTransform;
 import java.awt.image.AffineTransformOp;
 import java.awt.image.BufferedImage;
 import java.io.IOException;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Iterator;
 import javax.imageio.ImageIO;
@@ -22,15 +22,15 @@ public final class DefaultImageStrategy implements ImageStrategy {
   private static final Object MUTEX = new Object();
 
   //https://stackoverflow.com/a/7855774/4786733
-  private static volatile ImageStrategy INSTANCE;
+  private static volatile DefaultImageStrategy INSTANCE;
 
   /**
    * Gets the singleton instance of the defualt {@link ImageStrategy} prefered by jocument.
    *
    * @return the default {@link ImageStrategy}
    */
-  public static ImageStrategy instance() {
-    ImageStrategy localRef = INSTANCE;
+  public static DefaultImageStrategy instance() {
+    DefaultImageStrategy localRef = INSTANCE;
     if (localRef == null) {
       synchronized (MUTEX) {
         localRef = INSTANCE;
@@ -73,7 +73,7 @@ public ImageReference scale(ImageReference original, double scaleBy) {
   // https://stackoverflow.com/a/12164026/4786733
   public Dimension getDimensions(Path path) throws IOException {
     log.trace("Getting image dimensions of '{}'", path);
-    var mimeType = WordImageUtils.probeContentTypeSafely(path).orElseThrow(() -> new IOException("Could not determine File Type"));
+    var mimeType = getMimeType(path);
     Iterator<ImageReader> iter = ImageIO.getImageReadersByMIMEType(mimeType);
     while (iter.hasNext()) {
       ImageReader reader = iter.next();
@@ -90,4 +90,9 @@ public Dimension getDimensions(Path path) throws IOException {
     }
     throw new IOException("Not a known image file: " + path.toAbsolutePath());
   }
+
+  @Override
+  public String getMimeType(Path path) throws IOException {
+    return Files.probeContentType(path);
+  }
 }

src/main/java/com/docutools/jocument/image/ImageStrategy.java

@@ -53,4 +53,5 @@ public interface ImageStrategy {
    */
   Dimension getDimensions(Path path) throws IOException;
 
+  String getMimeType(Path path) throws IOException;
 }

src/main/java/com/docutools/jocument/impl/word/WordImageUtils.java

@@ -57,7 +57,7 @@ public static XWPFPicture insertImage(XWPFParagraph paragraph, Path path, ImageS
         .map(pictureDimensions -> scaleToTargetDimensions(pictureDimensions, targetDimensions))
         .map(WordImageUtils::toEmu)
         .orElse(DEFAULT_DIM);
-    var contentType = probeImageType(path);
+    var contentType = probeImageType(path, imageStrategy);
 
     try (var in = Files.newInputStream(path, StandardOpenOption.READ)) {
       logger.debug("Adding picture from path {} with content type {} and dimensions {} {}", path, contentType, dim.width, dim.height);
@@ -110,16 +110,20 @@ private static Dimension scale(Dimension dim, int maxHeight, int maxWidth) {
   }
 
   /**
-   * Get the XWPF integer representing the image type of the file at the provided {@link Path},
-   * returning `DEFAULT_XWPF_CONTENT_TYPE` if it can not be determined.
+   * Get the XWPF integer representing the image type of the file at the provided {@link Path}, returning `DEFAULT_XWPF_CONTENT_TYPE` if it can not be
+   * determined.
    *
-   * @param path the path to the image file
+   * @param path          the path to the image file
+   * @param imageStrategy the image strategy containing a file type resolving function
    * @return the {@link int} representing the image type in the xwpf system.
    */
-  public static int probeImageType(Path path) {
-    return probeContentTypeSafely(path)
-        .map(WordImageUtils::toPoiType)
-        .orElse(DEFAULT_XWPF_CONTENT_TYPE);
+  public static int probeImageType(Path path, ImageStrategy imageStrategy) {
+    try {
+      String mimeType = imageStrategy.getMimeType(path);
+      return WordImageUtils.toPoiType(mimeType);
+    } catch (IOException e) {
+      return DEFAULT_XWPF_CONTENT_TYPE;
+    }
   }
 
   private static int toPoiType(String mimeType) {
@@ -138,21 +142,4 @@ private static int toPoiType(String mimeType) {
       default -> Document.PICTURE_TYPE_JPEG;
     };
   }
-
-  /**
-   * Get the mime type of the file at the provided {@link Path}.
-   *
-   * @param path the path to the file to examine
-   * @return an optional containing the mime type of the file if it can be determined, or {@link Optional#empty()} if not
-   */
-  public static Optional<String> probeContentTypeSafely(Path path) {
-    try {
-      return Optional.ofNullable(Files.probeContentType(path))
-          .filter(contentType -> !contentType.isBlank());
-    } catch (Exception e) {
-      logger.warn("Failed to probe content type of path %s".formatted(path), e);
-      return Optional.empty();
-    }
-  }
-
 }