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MainActivity: fix einkUpdate/hapticFeedback crash when called from NativeThread #596

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backcountrymountains wants to merge 2 commits into from
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MainActivity: fix einkUpdate/hapticFeedback crash when called from NativeThread #596

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8d33c36
android: pre-cache epdRootView to fix EPD updates from NativeThread
backcountrymountains Jun 17, 2026
0ca81a5
MainActivity: refresh epdRootView in surfaceCreated
backcountrymountains Jun 17, 2026
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14 changes: 11 additions & 3 deletions app/src/main/java/org/koreader/launcher/MainActivity.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,9 @@ class MainActivity : NativeActivity(), LuaInterface,

// surface used on devices that need a view
private var view: NativeSurfaceView? = null

// cached root view for EPD mode calls from NativeThread (avoids window.decorView on non-UI thread)
private var epdRootView: android.view.View? = null
private class NativeSurfaceView(context: Context): SurfaceView(context),
SurfaceHolder.Callback {
init { holder.addCallback(this) }
Expand Down Expand Up @@ -133,6 +136,10 @@ class MainActivity : NativeActivity(), LuaInterface,
}
Log.v(TAG_SURFACE, "Using $surfaceKind implementation")

// Cache root view for EPD calls from NativeThread (window.decorView must not be
// accessed from a non-UI thread; pre-cache it here on the main thread instead).
epdRootView = view ?: window.decorView.findViewById(android.R.id.content)

@Suppress("DEPRECATION")
screenIsLandscape = windowManager.defaultDisplay.width > windowManager.defaultDisplay.height

Expand Down Expand Up @@ -165,6 +172,7 @@ class MainActivity : NativeActivity(), LuaInterface,

override fun surfaceCreated(holder: SurfaceHolder) {
super.surfaceCreated(holder)
epdRootView = view ?: window.decorView.rootView
drawSplashScreen(holder)
}

Expand Down Expand Up @@ -314,7 +322,7 @@ class MainActivity : NativeActivity(), LuaInterface,
}

override fun einkUpdate(mode: Int) {
val rootView = view ?: window.decorView.findViewById<View>(android.R.id.content)
val rootView = epdRootView ?: return
val modeName = when (mode) {
1 -> "EPD_FULL"
2 -> "EPD_PART"
Expand All @@ -332,7 +340,7 @@ class MainActivity : NativeActivity(), LuaInterface,
}

override fun einkUpdate(mode: Int, delay: Long, x: Int, y: Int, width: Int, height: Int) {
val rootView = view ?: window.decorView.findViewById<View>(android.R.id.content)
val rootView = epdRootView ?: return
Log.v(tag, String.format(Locale.US,
"requesting epd update, mode:%d, delay:%d, [x:%d, y:%d, w:%d, h:%d]",
mode, delay, x, y, width, height))
Expand Down Expand Up @@ -645,7 +653,7 @@ class MainActivity : NativeActivity(), LuaInterface,
}

override fun performHapticFeedback(constant: Int, force: Int) {
val rootView = view ?: window.decorView.findViewById<View>(android.R.id.content)
val rootView = epdRootView ?: return
hapticFeedback(constant, force > 0, rootView)
}

Expand Down