Convert all PageLoader to kotlin

app/src/main/java/com/hippo/ehviewer/gallery/EhPageLoader.kt

@@ -39,9 +39,8 @@ class EhPageLoader(private val mGalleryInfo: GalleryInfo) : PageLoader2(), OnSpi
         SimpleHandler.getInstance().postDelayed(ReleaseTask(mSpiderQueen), 3000)
     }
 
-    override fun getStartPage(): Int {
-        return mSpiderQueen.startPage
-    }
+    override val startPage
+        get() = mSpiderQueen.startPage
 
     override fun getImageFilename(index: Int): String {
         return String.format(

app/src/main/java/com/hippo/ehviewer/gallery/PageLoader2.kt

@@ -13,49 +13,36 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+package com.hippo.ehviewer.gallery
 
-package com.hippo.ehviewer.gallery;
+import com.hippo.unifile.UniFile
+import eu.kanade.tachiyomi.ui.reader.loader.PageLoader
 
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
+abstract class PageLoader2 : PageLoader() {
+    open val startPage: Int
+        get() = 0
 
-import com.hippo.unifile.UniFile;
-
-import eu.kanade.tachiyomi.ui.reader.loader.PageLoader;
-
-public abstract class PageLoader2 extends PageLoader {
-
-    // With dot
-    public static final String[] SUPPORT_IMAGE_EXTENSIONS = {
-            ".jpg", // Joint Photographic Experts Group
-            ".png", // Portable Network Graphics
-            ".gif", // Graphics Interchange Format
-    };
-
-    public int getStartPage() {
-        return 0;
-    }
-
-    public void putStartPage(int page) {
-    }
+    open fun putStartPage(page: Int) {}
 
     /**
      * @return without extension
      */
-    @NonNull
-    public abstract String getImageFilename(int index);
+    abstract fun getImageFilename(index: Int): String
 
     /**
      * @return with extension
      */
-    @NonNull
-    public abstract String getImageFilenameWithExtension(int index);
-
-    public abstract boolean save(int index, @NonNull UniFile file);
+    abstract fun getImageFilenameWithExtension(index: Int): String
+    abstract fun save(index: Int, file: UniFile): Boolean
 
     /**
      * @param filename without extension
      */
-    @Nullable
-    public abstract UniFile save(int index, @NonNull UniFile dir, @NonNull String filename);
+    abstract fun save(index: Int, dir: UniFile, filename: String): UniFile?
 }
+
+val SUPPORT_IMAGE_EXTENSIONS = arrayOf(
+    ".jpg",  // Joint Photographic Experts Group
+    ".png",  // Portable Network Graphics
+    ".gif"
+)

app/src/main/java/com/hippo/ehviewer/spider/SpiderDen.kt

@@ -31,6 +31,7 @@ import com.hippo.ehviewer.client.data.GalleryInfo
 import com.hippo.ehviewer.coil.edit
 import com.hippo.ehviewer.coil.read
 import com.hippo.ehviewer.gallery.PageLoader2
+import com.hippo.ehviewer.gallery.SUPPORT_IMAGE_EXTENSIONS
 import com.hippo.image.Image.CloseableSource
 import com.hippo.unifile.RawFile
 import com.hippo.unifile.UniFile
@@ -103,8 +104,8 @@ class SpiderDen(private val mGalleryInfo: GalleryInfo) {
      * @param extension with dot
      */
     private fun fixExtension(extension: String): String {
-        return extension.takeIf { PageLoader2.SUPPORT_IMAGE_EXTENSIONS.contains(it) }
-            ?: PageLoader2.SUPPORT_IMAGE_EXTENSIONS[0]
+        return extension.takeIf { SUPPORT_IMAGE_EXTENSIONS.contains(it) }
+            ?: SUPPORT_IMAGE_EXTENSIONS[0]
     }
 
     private fun copyFromCacheToDownloadDir(index: Int): Boolean {
@@ -335,7 +336,7 @@ class SpiderDen(private val mGalleryInfo: GalleryInfo) {
                 ).build()
         }
 
-        private val COMPAT_IMAGE_EXTENSIONS = PageLoader2.SUPPORT_IMAGE_EXTENSIONS + ".jpeg"
+        private val COMPAT_IMAGE_EXTENSIONS = SUPPORT_IMAGE_EXTENSIONS + ".jpeg"
 
         fun getGalleryDownloadDir(gid: Long): UniFile? {
             val dir = Settings.getDownloadLocation()