Fix image extension

app/src/main/java/com/hippo/ehviewer/gallery/ArchiveGalleryProvider.java

@@ -157,6 +157,13 @@ public class ArchiveGalleryProvider extends GalleryProvider2 {
         return null;
     }
 
+    @NonNull
+    @Override
+    public String getImageFilenameWithExtension(int index) {
+        // TODO
+        return Integer.toString(index);
+    }
+
     private class ArchiveTask implements Runnable {
         @Override
         public void run() {

app/src/main/java/com/hippo/ehviewer/gallery/DirGalleryProvider.java

@@ -125,8 +125,33 @@ public class DirGalleryProvider extends GalleryProvider2 implements Runnable {
     @NonNull
     @Override
     public String getImageFilename(int index) {
-        // TODO
-        return Integer.toString(index);
+        UniFile[] fileList = mFileList.get();
+        if (null == fileList || index < 0 || index >= fileList.length) {
+            return Integer.toString(index);
+        }
+        UniFile src = fileList[index];
+        String name = src.getName();
+        if (name == null) {
+            return Integer.toString(index);
+        }
+        return name;
+    }
+
+    @NonNull
+    @Override
+    public String getImageFilenameWithExtension(int index) {
+        UniFile[] fileList = mFileList.get();
+        if (null == fileList || index < 0 || index >= fileList.length) {
+            return Integer.toString(index);
+        }
+        UniFile src = fileList[index];
+        String extension = FileUtils.getExtensionFromFilename(src.getName());
+        String name = src.getName();
+        if (name == null) {
+            return Integer.toString(index);
+        }
+        name = null != extension ? name + "." + extension : name;
+        return name;
     }
 
     @Override

app/src/main/java/com/hippo/ehviewer/gallery/EhGalleryProvider.java

@@ -77,6 +77,18 @@ public class EhGalleryProvider extends GalleryProvider2 implements SpiderQueen.O
         return String.format(Locale.US, "%d-%s-%08d", mGalleryInfo.gid, mGalleryInfo.token, index + 1);
     }
 
+    @NonNull
+    @Override
+    public String getImageFilenameWithExtension(int index) {
+        if (null != mSpiderQueen) {
+            String extension = mSpiderQueen.getExtension(index);
+            if (extension != null) {
+                return String.format(Locale.US, "%d-%s-%08d.%s", mGalleryInfo.gid, mGalleryInfo.token, index + 1, extension);
+            }
+        }
+        return String.format(Locale.US, "%d-%s-%08d", mGalleryInfo.gid, mGalleryInfo.token, index + 1);
+    }
+
     @Override
     public boolean save(int index, @NonNull UniFile file) {
         if (null != mSpiderQueen) {

app/src/main/java/com/hippo/ehviewer/gallery/GalleryProvider2.java

@@ -45,6 +45,12 @@ public abstract class GalleryProvider2 extends GalleryProvider {
     @NonNull
     public abstract String getImageFilename(int index);
 
+    /**
+     * @return with extension
+     */
+    @NonNull
+    public abstract String getImageFilenameWithExtension(int index);
+
     public abstract boolean save(int index, @NonNull UniFile file);
 
     /**

app/src/main/java/com/hippo/ehviewer/spider/SpiderQueen.java

@@ -629,6 +629,39 @@ public final class SpiderQueen implements Runnable {
         }
     }
 
+
+    @Nullable
+    public String getExtension(int index) {
+        int state = getPageState(index);
+        if (STATE_FINISHED != state) {
+            return null;
+        }
+
+        InputStreamPipe pipe = mSpiderDen.openInputStreamPipe(index);
+        if (null == pipe) {
+            return null;
+        }
+
+        OutputStream os = null;
+        try {
+            pipe.obtain();
+
+            // Get dst file
+            BitmapFactory.Options options = new BitmapFactory.Options();
+            options.inJustDecodeBounds = true;
+            BitmapFactory.decodeStream(pipe.open(), null, options);
+            pipe.close();
+
+            return MimeTypeMap.getSingleton().getExtensionFromMimeType(options.outMimeType);
+        } catch (IOException e) {
+            return null;
+        } finally {
+            pipe.close();
+            pipe.release();
+            IOUtils.closeQuietly(os);
+        }
+    }
+
     public int getStartPage() {
         SpiderInfo spiderInfo = readSpiderInfoFromLocal();
         if (spiderInfo != null) {

app/src/main/java/com/hippo/ehviewer/ui/GalleryActivity.java

@@ -785,7 +785,7 @@ public class GalleryActivity extends EhActivity implements SeekBar.OnSeekBarChan
             return;
         }
 
-        String filename = mGalleryProvider.getImageFilename(page);
+        String filename = mGalleryProvider.getImageFilenameWithExtension(page);
         String mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(
                 MimeTypeMap.getFileExtensionFromUrl(filename));
         if (TextUtils.isEmpty(mimeType)) {