Add devtool overlay for heap memory usage

app/src/main/java/dev/patrickgold/florisboard/ime/core/FlorisBoard.kt

@@ -57,7 +57,7 @@ import dev.patrickgold.florisboard.ime.theme.Theme
 import dev.patrickgold.florisboard.ime.theme.ThemeManager
 import dev.patrickgold.florisboard.setup.SetupActivity
 import dev.patrickgold.florisboard.util.*
-import kotlinx.coroutines.launch
+import kotlinx.coroutines.*
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.Transient
@@ -84,6 +84,7 @@ class FlorisBoard : InputMethodService(), LifecycleOwner, FlorisClipboardManager
     private val serviceLifecycleDispatcher: ServiceLifecycleDispatcher = ServiceLifecycleDispatcher(this)
     private val uiScope: LifecycleCoroutineScope
         get() = lifecycle.coroutineScope
+    private var devtoolsOverlaySyncJob: Job? = null
 
     /**
      * The theme context for the UI. Must only be used for inflating/creating Views for the keyboard UI, else the IME
@@ -393,6 +394,17 @@ class FlorisBoard : InputMethodService(), LifecycleOwner, FlorisClipboardManager
         onSubtypeChanged(activeSubtype)
         setActiveInput(R.id.text_input)
 
+        if (prefs.devtools.enabled && prefs.devtools.showHeapMemoryStats) {
+            devtoolsOverlaySyncJob?.cancel()
+            devtoolsOverlaySyncJob = uiScope.launch(Dispatchers.Default) {
+                while (true) {
+                    if (!isActive) break
+                    withContext(Dispatchers.Main) { inputView?.invalidate() }
+                    delay(1000)
+                }
+            }
+        }
+
         eventListeners.toList().forEach { it?.onWindowShown() }
     }
 
@@ -406,6 +418,9 @@ class FlorisBoard : InputMethodService(), LifecycleOwner, FlorisClipboardManager
         }
         isWindowShown = false
 
+        devtoolsOverlaySyncJob?.cancel()
+        devtoolsOverlaySyncJob = null
+
         eventListeners.toList().forEach { it?.onWindowHidden() }
     }
 

app/src/main/java/dev/patrickgold/florisboard/ime/core/InputView.kt

@@ -18,6 +18,11 @@ package dev.patrickgold.florisboard.ime.core
 
 import android.content.Context
 import android.content.res.Configuration
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.Paint
+import android.graphics.Typeface
+import android.text.TextPaint
 import android.util.AttributeSet
 import android.util.DisplayMetrics
 import android.view.ViewGroup
@@ -58,6 +63,13 @@ class InputView : LinearLayout {
     var oneHandedCtrlPanelEnd: ViewGroup? = null
         private set
 
+    private val overlayTextPaint: TextPaint = TextPaint().apply {
+        color = Color.GREEN
+        textAlign = Paint.Align.RIGHT
+        textSize = resources.getDimension(R.dimen.devtools_memory_overlay_textSize)
+        typeface = Typeface.MONOSPACE
+    }
+
     constructor(context: Context) : this(context, null)
     constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, 0)
     constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(
@@ -161,4 +173,34 @@ class InputView : LinearLayout {
             resources.getDimension(R.dimen.inputView_baseHeight)
         )
     }
+
+    override fun dispatchDraw(canvas: Canvas?) {
+        super.dispatchDraw(canvas)
+        canvas ?: return
+
+        if (prefs.devtools.enabled && prefs.devtools.showHeapMemoryStats) {
+            try {
+                // Note: the below code only gets the heap size in MB, the actual RAM usage (native or others) can be
+                //  a lot higher
+                //  Source: https://stackoverflow.com/a/19267315/6801193
+                val runtime = Runtime.getRuntime()
+                val usedMemInMB = (runtime.totalMemory() - runtime.freeMemory()) / 1048576L
+                val maxHeapSizeInMB = runtime.maxMemory() / 1048576L
+                val availHeapSizeInMB = maxHeapSizeInMB - usedMemInMB
+                val output = listOf(
+                    "heap mem:",
+                    String.format("used=%4dMB", usedMemInMB),
+                    String.format("max=%4dMB", maxHeapSizeInMB),
+                    String.format("avail=%4dMB", availHeapSizeInMB),
+                )
+                val x = measuredWidth.toFloat()
+                var y = overlayTextPaint.descent() - overlayTextPaint.ascent()
+                for (line in output) {
+                    canvas.drawText(line, x, y, overlayTextPaint)
+                    y += overlayTextPaint.descent() - overlayTextPaint.ascent()
+                }
+            } catch (_: Throwable) {
+            }
+        }
+    }
 }

app/src/main/java/dev/patrickgold/florisboard/ime/core/PrefHelper.kt

@@ -48,7 +48,9 @@ class PrefHelper(
     private val cacheString: HashMap<String, String> = hashMapOf()
 
     val advanced = Advanced(this)
+    val clipboard = Clipboard(this)
     val correction = Correction(this)
+    val devtools = Devtools(this)
     val gestures = Gestures(this)
     val glide = Glide(this)
     val internal = Internal(this)
@@ -57,7 +59,6 @@ class PrefHelper(
     val smartbar = Smartbar(this)
     val suggestion = Suggestion(this)
     val theme = Theme(this)
-    val clipboard = Clipboard(this)
 
     /**
      * Checks the cache if an entry for [key] exists, else calls [getPrefInternal] to retrieve the
@@ -222,6 +223,23 @@ class PrefHelper(
             set(v) = prefHelper.setPref(REMEMBER_CAPS_LOCK_STATE, v)
     }
 
+    /**
+     * Wrapper class for devtools preferences.
+     */
+    class Devtools(private val prefHelper: PrefHelper) {
+        companion object {
+            const val ENABLED =                     "devtools__enabled"
+            const val SHOW_HEAP_MEMORY_STATS =      "devtools__show_heap_memory_stats"
+        }
+
+        var enabled: Boolean
+            get() =  prefHelper.getPref(ENABLED, false)
+            set(v) = prefHelper.setPref(ENABLED, v)
+        var showHeapMemoryStats: Boolean
+            get() =  prefHelper.getPref(SHOW_HEAP_MEMORY_STATS, false)
+            set(v) = prefHelper.setPref(SHOW_HEAP_MEMORY_STATS, v)
+    }
+
     /**
      * Wrapper class for gestures preferences.
      */

app/src/main/res/values/dimens.xml

@@ -26,6 +26,7 @@
     <dimen name="key_numeric_textSize">12sp</dimen>
     <dimen name="key_popup_textSize">21sp</dimen>
     <dimen name="emoji_key_textSize">22sp</dimen>
+    <dimen name="devtools_memory_overlay_textSize">8sp</dimen>
 
     <dimen name="landscapeInputUi_padding">8dp</dimen>
     <dimen name="landscapeInputUi_actionButton_cornerRadius">6dp</dimen>

app/src/main/res/values/strings.xml

@@ -310,6 +310,10 @@
     <string name="pref__advanced__show_app_icon__label" comment="Label of Show app icon preference in Advanced">Show app icon in launcher</string>
     <string name="pref__advanced__force_private_mode__label" comment="Label of Force private mode preference in Advanced">Force private mode</string>
     <string name="pref__advanced__force_private_mode__summary" comment="Summary of Force private mode preference in Advanced">Will disable any features which have to temporarily work with your input data</string>
+    <string name="pref__devtools__enabled__label" comment="Label of Enable developer tools in Advanced">Enable developer tools</string>
+    <string name="pref__devtools__enabled__summary" comment="Summary of Enable developer tools in Advanced">Tools specifically designed for debugging and troubleshooting</string>
+    <string name="pref__devtools__show_heap_memory_stats__label" comment="Label of Show heap memory stats in Advanced">Show heap memory stats</string>
+    <string name="pref__devtools__show_heap_memory_stats__summary" comment="Summary of Show heap memory stats in Advanced">Overlays the heap memory usage and max size in the top-right corner</string>
 
     <!-- About UI strings -->
     <string name="about__title" comment="Title of About activity">About</string>

app/src/main/res/xml/prefs_advanced.xml

@@ -26,4 +26,21 @@
         app:summary="@string/pref__advanced__force_private_mode__summary"
         app:useSimpleSummaryProvider="true"/>
 
+    <SwitchPreferenceCompat
+        android:defaultValue="false"
+        app:key="devtools__enabled"
+        app:iconSpaceReserved="false"
+        app:title="@string/pref__devtools__enabled__label"
+        app:summary="@string/pref__devtools__enabled__summary"
+        app:useSimpleSummaryProvider="true"/>
+
+    <SwitchPreferenceCompat
+        android:defaultValue="false"
+        app:dependency="devtools__enabled"
+        app:key="devtools__show_heap_memory_stats"
+        app:iconSpaceReserved="false"
+        app:title="@string/pref__devtools__show_heap_memory_stats__label"
+        app:summary="@string/pref__devtools__show_heap_memory_stats__summary"
+        app:useSimpleSummaryProvider="true"/>
+
 </PreferenceScreen>