Auto-prune Empty Chunks in Level Files

* Discovered a bug where if you hit the Undo key to erase pixels and an
  entire chunk became empty by it, the chunk would have rendering errors
  and show as a solid black square instead of the level wallpaper
  showing through.
* Chunks that have no pixels in them are culled from the chunker
  immediately when you call a Delete() operation.
* The level file saver also calls a maintenance function to prune all
  empty chunks upon saving the file. So existing levels with broken
  chunks need only be re-saved to fix them.

dev-assets/doodads/objects/exit-flag.js

@@ -4,6 +4,10 @@ function main() {
 	Self.SetHitbox(22+16, 16, 75-16, 86);
 
 	Events.OnCollide(function(e) {
+		if (!e.Settled) {
+			return;
+		}
+
 		if (e.InHitbox) {
 			EndLevel();
 		}

pkg/doodle.go

@@ -114,12 +114,6 @@ func (d *Doodle) Run() error {
 		// Poll for events.
 		ev, err := d.Engine.Poll()
 		shmem.Cursor = render.NewPoint(ev.CursorX.Now, ev.CursorY.Now)
-		if ev.EnterKey.Now {
-			log.Info("MainLoop sees enter key now")
-		}
-		if ev.KeyName.Now != "" {
-			log.Info("MainLoop sees key %s", ev.KeyName.Now)
-		}
 		if err != nil {
 			log.Error("event poll error: %s", err)
 			d.running = false

pkg/level/chunker.go

@@ -6,6 +6,7 @@ import (
 	"math"
 
 	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/apps/doodle/pkg/log"
 	"github.com/vmihailenco/msgpack"
 )
 
@@ -224,6 +225,8 @@ func (c *Chunker) SetRect(r render.Rect, sw *Swatch) error {
 // Delete a pixel at the given coordinate.
 func (c *Chunker) Delete(p render.Point) error {
 	coord := c.ChunkCoordinate(p)
+	defer c.pruneChunk(coord)
+
 	if chunk, ok := c.Chunks[coord]; ok {
 		return chunk.Delete(p)
 	}
@@ -249,6 +252,17 @@ func (c *Chunker) DeleteRect(r render.Rect) error {
 	return nil
 }
 
+// pruneChunk will remove an empty chunk from the chunk map, called after
+// delete operations.
+func (c *Chunker) pruneChunk(coord render.Point) {
+	if chunk, ok := c.Chunks[coord]; ok {
+		if chunk.Len() == 0 {
+			log.Info("Chunker.pruneChunk: %s has become empty", coord)
+			delete(c.Chunks, coord)
+		}
+	}
+}
+
 // ChunkCoordinate computes a chunk coordinate from an absolute coordinate.
 func (c *Chunker) ChunkCoordinate(abs render.Point) render.Point {
 	if c.Size == 0 {

pkg/level/fmt_maintenance.go

@@ -4,6 +4,19 @@ import "git.kirsle.net/apps/doodle/pkg/log"
 
 // Maintenance functions for the file format on disk.
 
+// PruneChunks cleans up any level chunks that have no pixel data.
+func (m *Level) PruneChunks() int {
+	var count int
+	for coord, chunk := range m.Chunker.Chunks {
+		if chunk.Len() == 0 {
+			log.Info("PruneChunks: %d has no pixels", coord)
+			delete(m.Chunker.Chunks, coord)
+			count++
+		}
+	}
+	return count
+}
+
 // PruneLinks cleans up any Actor Links that can not be resolved in the
 // level data. For example, if actors were linked in Edit Mode and one
 // actor is deleted leaving a broken link.

pkg/level/fmt_readwrite.go

@@ -105,6 +105,7 @@ func (m *Level) WriteFile(filename string) error {
 	m.GameVersion = branding.Version
 
 	// Maintenance functions, clean up cruft before save.
+	m.PruneChunks()
 	m.PruneLinks()
 
 	bin, err := m.ToJSON()