Allow draging files to mod pane

HMCL/src/main/kotlin/org/jackhuang/hmcl/ui/ModController.kt

@@ -20,6 +20,8 @@ package org.jackhuang.hmcl.ui
 import com.jfoenix.effects.JFXDepthManager
 import javafx.fxml.FXML
 import javafx.scene.control.ScrollPane
+import javafx.scene.input.TransferMode
+import javafx.scene.layout.StackPane
 import javafx.scene.layout.VBox
 import javafx.stage.FileChooser
 import org.jackhuang.hmcl.i18n
@@ -29,12 +31,29 @@ import org.jackhuang.hmcl.task.task
 
 class ModController {
     @FXML lateinit var scrollPane: ScrollPane
-    @FXML lateinit var rootPane: VBox
+    @FXML lateinit var rootPane: StackPane
+    @FXML lateinit var contentPane: VBox
     private lateinit var modManager: ModManager
     private lateinit var versionId: String
 
     fun initialize() {
         scrollPane.smoothScrolling()
+
+        rootPane.setOnDragOver { event ->
+            if (event.gestureSource != rootPane && event.dragboard.hasFiles())
+                event.acceptTransferModes(*TransferMode.COPY_OR_MOVE)
+            event.consume()
+        }
+        rootPane.setOnDragDropped { event ->
+            val mods = event.dragboard.files
+                    ?.filter { it.extension in listOf("jar", "zip", "litemod") }
+            if (mods != null && mods.isNotEmpty()) {
+                mods.forEach { modManager.addMod(versionId, it) }
+                loadMods(modManager, versionId)
+                event.isDropCompleted = true
+            }
+            event.consume()
+        }
     }
 
     fun loadMods(modManager: ModManager, versionId: String) {
@@ -43,9 +62,9 @@ class ModController {
         task {
             modManager.refreshMods(versionId)
         }.subscribe(Scheduler.JAVAFX) {
-            rootPane.children.clear()
+            contentPane.children.clear()
             for (modInfo in modManager.getMods(versionId)) {
-                rootPane.children += ModItem(modInfo) {
+                contentPane.children += ModItem(modInfo) {
                     modManager.removeMods(versionId, modInfo)
                     loadMods(modManager, versionId)
                 }.apply {

HMCL/src/main/resources/assets/fxml/mod.fxml

@@ -6,14 +6,15 @@
 <?import com.jfoenix.controls.JFXButton?>
 <StackPane xmlns="http://javafx.com/javafx"
            xmlns:fx="http://javafx.com/fxml"
+           fx:id="rootPane"
            fx:controller="org.jackhuang.hmcl.ui.ModController">
     <ScrollPane fx:id="scrollPane" fitToWidth="true" fitToHeight="true">
-        <VBox fx:id="rootPane" spacing="10" style="-fx-padding: 20;">
+        <VBox fx:id="contentPane" spacing="10" style="-fx-padding: 20;">
 
         </VBox>
     </ScrollPane>
     <VBox style="-fx-padding: 15;" spacing="15" pickOnBounds="false" alignment="BOTTOM_RIGHT">
-        <JFXButton prefWidth="40" prefHeight="40" buttonType="RAISED" fx:id="btnAdd" onMouseClicked="#onAdd"
+        <JFXButton prefWidth="40" prefHeight="40" buttonType="RAISED" onMouseClicked="#onAdd"
                    style="-fx-background-color:#5264AE;-fx-background-radius: 50px;">
             <graphic>
                 <fx:include source="/assets/svg/plus.fxml" />

HMCLCore/src/main/kotlin/org/jackhuang/hmcl/mod/ModManager.kt

@@ -30,6 +30,7 @@ class ModManager(private val repository: GameRepository) {
     private val modCache = SimpleMultimap<String, ModInfo>(::HashMap, ::TreeSet)
 
     fun refreshMods(id: String): Collection<ModInfo> {
+        modCache.removeAll(id)
         val modsDirectory = repository.getRunDirectory(id).resolve("mods")
         val puter = { modFile: File -> ignoreException { modCache.put(id, ModInfo.fromFile(modFile)) } }
         modsDirectory.listFiles()?.forEach { modFile ->