Fix "Copied to clipboard" message not showing in API 32 and lower

app/src/main/java/com/hippo/ehviewer/util/ClipboardUtil.kt

@@ -17,10 +17,12 @@
  */
 package com.hippo.ehviewer.util
 
+import android.app.Activity
 import android.content.ClipData
 import android.content.ClipDescription
 import android.content.ClipboardManager
 import android.content.Context
+import android.content.ContextWrapper
 import android.os.Build
 import android.view.textclassifier.TextClassifier
 import androidx.core.os.persistableBundleOf
@@ -49,8 +51,9 @@ fun Context.addTextToClipboard(text: CharSequence?, isSensitive: Boolean, useToa
     }
     // Avoid double notify user since system have done that on Tiramisu above
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU) {
-        if (this is MainActivity) {
-            showTip(R.string.copied_to_clipboard, BaseScene.LENGTH_SHORT, useToast)
+        val activity = findActivity()
+        if (activity is MainActivity) {
+            activity.showTip(R.string.copied_to_clipboard, BaseScene.LENGTH_SHORT, useToast)
         }
     }
 }
@@ -63,3 +66,15 @@ fun ClipboardManager.getUrlFromClipboard(context: Context): String? {
     val string = item?.coerceToText(context).toString()
     return string.ifEmpty { null }
 }
+
+/**
+ * Find the closest Activity in a given Context.
+ */
+internal fun Context.findActivity(): Activity {
+    var context = this
+    while (context is ContextWrapper) {
+        if (context is Activity) return context
+        context = context.baseContext
+    }
+    throw IllegalStateException("findActivity() should be called in the context of an Activity")
+}