Make thumbnails faster

faststack/app.py

@@ -78,6 +78,7 @@
 from faststack.imaging.mask_engine import inverse_transform
 from faststack.imaging.metadata import get_exif_data
 from faststack.thumbnail_view import (
+    DEFAULT_THUMBNAIL_CACHE_BYTES,
     ThumbnailModel,
     ThumbnailPrefetcher,
     ThumbnailCache,
@@ -351,7 +352,7 @@ def __init__(
         self._grid_model_dirty = True  # Start dirty to ensure initial load
         self._folder_loaded = False  # Track whether the current folder scan is complete
         self._thumbnail_cache = ThumbnailCache(
-            max_bytes=256 * 1024 * 1024,  # 256 MB
+            max_bytes=DEFAULT_THUMBNAIL_CACHE_BYTES,  # cache-ready thumbnail QImages
             max_items=5000,
         )
         self._path_resolver = PathResolver()
@@ -8030,7 +8031,6 @@ def quick_auto_white_balance(self):
 
         t_start = time.perf_counter()
 
-        image_file = self.image_files[self.current_index]
         if self.view_override_path:
             active_path = Path(self.view_override_path)
         else:

faststack/imaging/editor.py

@@ -14,6 +14,9 @@
 import numpy as np
 from PIL import ExifTags, Image, ImageFilter, ImageOps
 
+# Mask subsystem (lazy imports avoided — lightweight dataclasses)
+from faststack.imaging.mask import MaskData
+from faststack.imaging.mask_engine import MaskRasterCache
 from faststack.imaging.math_utils import (
     _analyze_highlight_state,
     _apply_headroom_shoulder,
@@ -27,10 +30,6 @@
 from faststack.imaging.orientation import apply_orientation_to_np, get_exif_orientation
 from faststack.models import DecodedImage
 
-# Mask subsystem (lazy imports avoided — lightweight dataclasses)
-from faststack.imaging.mask import DarkenSettings, MaskData
-from faststack.imaging.mask_engine import MaskRasterCache
-
 try:
     from PySide6.QtGui import QImage
 except ImportError:

faststack/tests/test_editor_reopening.py

@@ -1,5 +1,5 @@
-import unittest
 import sys
+import unittest
 from pathlib import Path
 from unittest.mock import MagicMock, patch
 
@@ -130,7 +130,6 @@ def test_reuse_returns_REUSED_not_True(self):
     def test_prepare_darken_skips_reset_on_reuse(self):
         """_prepare_darken_image_state must NOT call _reset_darken_on_navigation
         when load_image_for_editing returns _REUSED."""
-        target = Path("test.jpg")
         self.controller.image_editor.current_filepath = None  # Force a load
         self.controller.image_editor.float_image = None  # Force needs_load=True
         self.controller.image_editor.current_edits = {}
@@ -184,7 +183,7 @@ def test_save_closes_ui_immediately_but_keeps_memory(self):
         # Mock snapshot
         self.controller.image_editor.snapshot_for_export.return_value = MagicMock()
 
-        with patch.object(self.controller, "_save_executor") as mock_executor:
+        with patch.object(self.controller, "_save_executor"):
             # 2. CALL SAVE
             self.controller.save_edited_image()
 

faststack/tests/test_mask.py

@@ -1,6 +1,5 @@
 """Tests for the reusable mask subsystem and background darkening tool."""
 
-import math
 import unittest
 
 import numpy as np
@@ -427,7 +426,6 @@ def test_apply_edits_with_darken(self):
         # Create a small test image
         img = PILImage.new("RGB", (50, 50), color=(128, 128, 128))
         import tempfile
-        from pathlib import Path
 
         with tempfile.NamedTemporaryFile(suffix=".jpg", delete=False) as f:
             img.save(f.name)
@@ -712,10 +710,11 @@ def test_mask_overlay_returns_transparent_when_no_overlay(self):
         """Verify that requesting mask_overlay with no image returns a
         transparent QImage, not an opaque placeholder."""
         try:
+            from unittest.mock import Mock
+
             from PySide6.QtGui import QImage
-            from PySide6.QtCore import Qt
+
             from faststack.ui.provider import ImageProvider
-            from unittest.mock import Mock
         except ImportError:
             self.skipTest("PySide6 not available")
 

faststack/tests/thumbnail_view/test_folder_stats.py

@@ -272,7 +272,7 @@ def test_single_file_uploaded(self):
         buckets = _compute_coverage_buckets(jpg_files, entries, num_buckets=1)
 
         assert len(buckets) == 1
-        assert buckets[0] == (1.0, 0.0, 0.0)  # uploaded, not stacked, not todo
+        assert buckets[0] == (1.0, 0.0, 0.0, 0.0)
 
     def test_single_file_stacked(self):
         """Test with single stacked file."""
@@ -282,7 +282,7 @@ def test_single_file_stacked(self):
         buckets = _compute_coverage_buckets(jpg_files, entries, num_buckets=1)
 
         assert len(buckets) == 1
-        assert buckets[0] == (0.0, 1.0, 0.0)  # not uploaded, stacked, not todo
+        assert buckets[0] == (0.0, 0.0, 1.0, 0.0)
 
     def test_even_distribution(self):
         """Test even distribution across buckets."""
@@ -356,7 +356,7 @@ def test_coverage_buckets_support_path_keys(self, temp_folder):
         stats = read_folder_stats(temp_folder)
 
         assert stats is not None
-        assert stats.coverage_buckets == [(1.0, 0.0, 0.0)]
+        assert stats.coverage_buckets == [(1.0, 0.0, 0.0, 0.0)]
 
 
 class TestCountImagesInFolder:

faststack/tests/thumbnail_view/test_prefetcher.py

@@ -5,6 +5,7 @@
 
 import pytest
 from PIL import Image
+from PySide6.QtGui import QImage
 
 from faststack.io.utils import compute_path_hash
 from faststack.thumbnail_view.prefetcher import ThumbnailCache, ThumbnailPrefetcher
@@ -185,6 +186,16 @@ def test_size_and_bytes_used(self, cache):
         assert cache.size == 2
         assert cache.bytes_used == 10
 
+    def test_qimage_size_accounting(self):
+        """QImage entries should count their in-memory pixel footprint."""
+        cache = ThumbnailCache(max_bytes=1024 * 1024, max_items=10)
+        image = QImage(10, 10, QImage.Format.Format_RGB888)
+
+        cache.put("img", image)
+
+        assert cache.get("img") is image
+        assert cache.bytes_used == image.bytesPerLine() * image.height()
+
     def test_update_existing_key(self, cache):
         """Test updating an existing key."""
         cache.put("key1", b"old")
@@ -216,7 +227,9 @@ def test_submit_schedules_job(self, prefetcher, test_image, cache, qt_app):
             lambda: cache.get(cache_key) is not None, timeout_s=2.0, qt_app=qt_app
         )
 
-        assert cache.get(cache_key) is not None
+        cached_image = cache.get(cache_key)
+        assert isinstance(cached_image, QImage)
+        assert not cached_image.isNull()
 
     def test_submit_skips_if_cached(self, prefetcher, test_image, cache):
         """Test that submit skips if already cached."""
@@ -328,9 +341,10 @@ def test_decode_applies_exif_orientation(self, cache, temp_folder, qt_app):
                 lambda: cache.get(cache_key) is not None, timeout_s=2.0, qt_app=qt_app
             )
 
-            cached_bytes = cache.get(cache_key)
-            assert cached_bytes is not None
-            assert len(cached_bytes) > 0
+            cached_image = cache.get(cache_key)
+            assert isinstance(cached_image, QImage)
+            assert not cached_image.isNull()
+            assert cached_image.height() >= cached_image.width()
         finally:
             prefetcher.shutdown()
 
@@ -357,7 +371,9 @@ def test_decode_handles_png(self, cache, temp_folder, qt_app):
             assert _wait_until(
                 lambda: cache.get(cache_key) is not None, timeout_s=2.0, qt_app=qt_app
             )
-            assert cache.get(cache_key) is not None
+            cached_image = cache.get(cache_key)
+            assert isinstance(cached_image, QImage)
+            assert not cached_image.isNull()
         finally:
             prefetcher.shutdown()
 

faststack/tests/thumbnail_view/test_provider_logic.py

@@ -5,6 +5,7 @@
 
 import pytest
 from PySide6.QtCore import QSize
+from PySide6.QtGui import QColor, QImage
 
 from faststack.thumbnail_view.prefetcher import ThumbnailCache
 from faststack.thumbnail_view.provider import (
@@ -155,3 +156,20 @@ def test_bad_cached_bytes_evicts_and_submits(self, wired_provider):
         assert args[1] == 999  # mtime_ns
         assert args[2] == 200  # thumb_size
         assert kwargs["priority"] == prefetcher.PRIO_HIGH
+
+    def test_qimage_cache_hit_returns_cached_image_without_submit(self, wired_provider):
+        provider, cache, prefetcher = wired_provider
+
+        cache_key = "200/abc123/999"
+        cached = QImage(20, 12, QImage.Format.Format_RGB888)
+        cached.fill(QColor(12, 34, 56))
+        cache.put(cache_key, cached)
+
+        out_size = QSize()
+        result = provider.requestImage(f"{cache_key}?r=1", out_size, QSize())
+
+        assert result is cached
+        pixel = result.pixelColor(0, 0)
+        assert (pixel.red(), pixel.green(), pixel.blue()) == (12, 34, 56)
+        assert (out_size.width(), out_size.height()) == (20, 12)
+        prefetcher.submit.assert_not_called()

faststack/thumbnail_view/__init__.py

@@ -2,11 +2,16 @@
 
 from .folder_stats import FolderStats, read_folder_stats
 from .model import ThumbnailEntry, ThumbnailModel
-from .prefetcher import ThumbnailCache, ThumbnailPrefetcher
+from .prefetcher import (
+    DEFAULT_THUMBNAIL_CACHE_BYTES,
+    ThumbnailCache,
+    ThumbnailPrefetcher,
+)
 from .provider import PathResolver, ThumbnailProvider
 
 __all__ = [
     "FolderStats",
+    "DEFAULT_THUMBNAIL_CACHE_BYTES",
     "PathResolver",
     "read_folder_stats",
     "ThumbnailCache",