code clean up - DrawCanvas

[Ethran]

CanvasEventBus - Extract the companion object from DrawCanvas.kt

[Copilot]

Pull request overview

This PR refactors the editor canvas signaling/observer plumbing by extracting DrawCanvas’s former companion-object event flows into a dedicated CanvasEventBus, and moving the observer wiring into a standalone registry. This reduces the responsibilities of DrawCanvas and updates the rest of the app to use the new event bus.

Changes:

• Introduces CanvasEventBus to host shared flows/state previously on DrawCanvas.Companion.
• Extracts DrawCanvas.registerObservers() implementation into CanvasObserverRegistry.
• Updates multiple UI/editor components to emit/collect via CanvasEventBus (including page change events formerly on EditorControlTower).

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
app/src/main/java/com/ethran/notable/ui/dialogs/BackgroundSelector.kt	Switches refresh signaling from DrawCanvas to CanvasEventBus.
app/src/main/java/com/ethran/notable/ui/components/QuickNav.kt	Uses CanvasEventBus for save/preview/restore and page-change signaling.
app/src/main/java/com/ethran/notable/ui/Router.kt	Uses CanvasEventBus.isDrawing to toggle drawing state around QuickNav.
app/src/main/java/com/ethran/notable/editor/utils/Select.kt	Uses CanvasEventBus.refreshUi after selection updates.
app/src/main/java/com/ethran/notable/editor/ui/toolbar/ToolbarMenu.kt	Routes clear-page action through CanvasEventBus.clearPageSignal.
app/src/main/java/com/ethran/notable/editor/ui/toolbar/Toolbar.kt	Routes image insert + refresh through CanvasEventBus.
app/src/main/java/com/ethran/notable/editor/ui/EditorGestureReceiver.kt	Emits gesture selection/force update via CanvasEventBus.
app/src/main/java/com/ethran/notable/editor/state/history.kt	Moves history commit coordination to CanvasEventBus flows/deferred.
app/src/main/java/com/ethran/notable/editor/drawing/pageDrawing.kt	Clears inserted-image state via CanvasEventBus.addImageByUri.
app/src/main/java/com/ethran/notable/editor/PageView.kt	Triggers redraws via CanvasEventBus instead of DrawCanvas flows.
app/src/main/java/com/ethran/notable/editor/EditorControlTower.kt	Collects page-change events from CanvasEventBus.changePage.
app/src/main/java/com/ethran/notable/editor/DrawCanvas.kt	Removes companion event bus + inlines observer hookup via new registry.
app/src/main/java/com/ethran/notable/editor/CanvasObserverRegistry.kt	New: encapsulates all canvas-related flow observers/handlers.
app/src/main/java/com/ethran/notable/editor/CanvasEventBus.kt	New: centralized shared flows/state for canvas/editor events.
app/src/main/java/com/ethran/notable/data/PageDataManager.kt	Emits canvas redraw on background-file invalidation via CanvasEventBus.
app/src/main/java/com/ethran/notable/MainActivity.kt	Uses CanvasEventBus for restart/focus/refresh signaling.

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[Copilot]

CanvasObserverRegistry is constructed with touchHelper, which forces evaluation of the touchHelper lazy during DrawCanvas construction. That changes the lifecycle/initialization timing of TouchHelper.create(...) (it now happens before init()/surface callbacks). Consider making observers lazy as well, or passing a getter (or TouchHelper? provider) so touchHelper stays lazily initialized when first needed.

[Copilot]

Pull request overview

Copilot reviewed 24 out of 24 changed files in this pull request and generated 5 comments.

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[Copilot]

CanvasRefreshManager.drawCanvasToView(...) duplicates drawing logic that also exists in DrawCanvas.drawCanvasToView(...) (and similarly for restoreCanvas). Keeping two copies increases the chance they drift. Consider delegating to a single implementation (either have DrawCanvas delegate to CanvasRefreshManager or remove the duplicate methods from the manager).

Suggested change

	val zoneToRedraw = dirtyRect ?: Rect(0, 0, page.viewWidth, page.viewHeight)
	var canvas: Canvas? = null
	try {
	// Lock the canvas only for the dirtyRect region
	canvas = drawCanvas.holder.lockCanvas(zoneToRedraw) ?: return
	canvas.drawBitmap(page.windowedBitmap, zoneToRedraw, zoneToRedraw, Paint())
	if (drawCanvas.getActualState().mode == Mode.Select) {
	// render selection, but only within dirtyRect
	drawCanvas.getActualState().selectionState.firstPageCut?.let { cutPoints ->
	log.i("render cut")
	val path = pointsToPath(cutPoints.map {
	SimplePointF(
	it.x - page.scroll.x, it.y - page.scroll.y
	)
	})
	canvas.drawPath(path, selectPaint)
	}
	}
	} catch (e: IllegalStateException) {
	log.w("Surface released during draw", e)
	// ignore — surface is gone
	} finally {
	try {
	if (canvas != null) {
	drawCanvas.holder.unlockCanvasAndPost(canvas)
	}
	} catch (e: IllegalStateException) {
	log.w("Surface released during unlock", e)
	}
	}
	}
	fun restoreCanvas(dirtyRect: Rect, bitmap: Bitmap = page.windowedBitmap) {
	drawCanvas.post {
	val holder = drawCanvas.holder
	var surfaceCanvas: Canvas? = null
	try {
	surfaceCanvas = holder.lockCanvas(dirtyRect)
	// Draw the preview bitmap scaled to fit the dirty rect
	surfaceCanvas.drawBitmap(bitmap, dirtyRect, dirtyRect, null)
	} catch (e: Exception) {
	Log.e("DrawCanvas", "Canvas lock failed: ${e.message}")
	} finally {
	if (surfaceCanvas != null) {
	holder.unlockCanvasAndPost(surfaceCanvas)
	}
	// Trigger partial refresh
	refreshScreenRegion(drawCanvas, dirtyRect)
	}
	}
	// Delegate drawing logic to DrawCanvas to avoid duplication.
	drawCanvas.drawCanvasToView(dirtyRect)
	}
	fun restoreCanvas(dirtyRect: Rect, bitmap: Bitmap = page.windowedBitmap) {
	// Delegate restore logic to DrawCanvas to avoid duplication.
	drawCanvas.restoreCanvas(dirtyRect, bitmap)