ADFA-4419: Remote peer editor decoration API

app/src/main/java/com/itsaky/androidide/activities/editor/PeerCursorOverlayManager.kt

@@ -0,0 +1,139 @@
+package com.itsaky.androidide.activities.editor
+
+import android.graphics.Color
+import android.graphics.drawable.GradientDrawable
+import android.view.Gravity
+import android.view.View
+import android.widget.TextView
+import io.github.rosemoe.sora.widget.CodeEditor
+import io.github.rosemoe.sora.widget.base.EditorPopupWindow
+import java.io.File
+
+/**
+ * Renders remote-collaborator presence as small named caret badges floating in the editor,
+ * one per (file, peerId). Markers are positioned in content coordinates and track scrolling
+ * via [EditorPopupWindow.FEATURE_SCROLL_AS_CONTENT]; the plugin repositions a marker by
+ * calling [addMarker] again with a new line/column on each cursor move.
+ *
+ * All methods must be called on the main thread (the editor view is touched directly).
+ */
+class PeerCursorOverlayManager(
+	private val editorForFile: (File) -> CodeEditor?,
+) {
+	private val markers: HashMap<String, HashMap<String, PeerCursorWindow>> = HashMap()
+
+	fun addMarker(
+		file: File,
+		line: Int,
+		column: Int,
+		peerId: String,
+		peerName: String,
+		peerColor: Int,
+	): Boolean {
+		val editor = editorForFile(file) ?: return false
+		val content = editor.text
+		if (line !in 0 until content.lineCount) return false
+		val safeColumn = column.coerceIn(0, content.getColumnCount(line))
+		val byPeer = markers.getOrPut(file.absolutePath) { HashMap() }
+		val existing = byPeer[peerId]
+		val window =
+			if (existing != null && existing.boundEditor === editor) {
+				existing
+			} else {
+				existing?.dismiss()
+				PeerCursorWindow(editor).also { byPeer[peerId] = it }
+			}
+		window.update(peerName, peerColor, line, safeColumn)
+		return true
+	}
+
+	fun removeMarker(
+		file: File,
+		peerId: String,
+	): Boolean {
+		val removed = markers[file.absolutePath]?.remove(peerId) ?: return false
+		removed.dismiss()
+		return true
+	}
+
+	fun clear(file: File) {
+		markers.remove(file.absolutePath)?.values?.forEach { it.dismiss() }
+	}
+
+	fun clearAll() {
+		markers.values.forEach { byPeer -> byPeer.values.forEach { it.dismiss() } }
+		markers.clear()
+	}
+}
+
+class PeerCursorWindow(
+	val boundEditor: CodeEditor,
+) : EditorPopupWindow(
+		boundEditor,
+		FEATURE_SCROLL_AS_CONTENT or FEATURE_SHOW_OUTSIDE_VIEW_ALLOWED,
+	) {
+	private val density = boundEditor.context.resources.displayMetrics.density
+
+	private val label =
+		TextView(boundEditor.context).apply {
+			textSize = 11f
+			gravity = Gravity.CENTER
+			maxLines = 1
+			includeFontPadding = false
+			val padH = (8 * density).toInt()
+			val padV = (3 * density).toInt()
+			setPadding(padH, padV, padH, padV)
+		}
+
+	init {
+		popup.isClippingEnabled = false
+		setContentView(label)
+	}
+
+	fun update(
+		peerName: String,
+		peerColor: Int,
+		line: Int,
+		column: Int,
+	) {
+		// getOffset returns the on-screen x. If the caret is past the visible width, add a
+		// direction arrow so the badge (clamped to the edge below) signals where the peer is.
+		val rawX = boundEditor.getOffset(line, column).toInt()
+		label.text =
+			when {
+				rawX > boundEditor.width -> "$peerName  →"
+				rawX < 0 -> "←  $peerName"
+				else -> peerName
+			}
+		label.setTextColor(contrastingTextColor(peerColor))
+		label.background =
+			GradientDrawable().apply {
+				setColor(peerColor)
+				cornerRadius = 4 * density
+			}
+
+		label.measure(
+			View.MeasureSpec.makeMeasureSpec(boundEditor.width, View.MeasureSpec.AT_MOST),
+			View.MeasureSpec.makeMeasureSpec(boundEditor.height, View.MeasureSpec.AT_MOST),
+		)
+		val width = label.measuredWidth
+		val height = label.measuredHeight
+		setSize(width, height)
+
+		// Clamp into the visible width so a caret scrolled off to the right pins at the edge
+		// instead of vanishing. Only clamp when the editor has a known width.
+		val maxX = boundEditor.width - width
+		val x = if (maxX >= 0) rawX.coerceIn(0, maxX) else rawX
+		val y = (boundEditor.rowHeight * line) - boundEditor.offsetY - height
+		setLocationAbsolutely(x, y)
+		if (!isShowing) show()
+	}
+
+	private fun contrastingTextColor(background: Int): Int {
+		val r = Color.red(background) / 255.0
+		val g = Color.green(background) / 255.0
+		val b = Color.blue(background) / 255.0
+		val luminance = 0.2126 * r + 0.7152 * g + 0.0722 * b
+		return if (luminance > 0.6) Color.parseColor("#0A0A0A") else Color.WHITE
+	}
+}