Add preview window padding config and run on window activation (#251)

Resolves #249

Author: facelessuser

CHANGES.md

@@ -8,6 +8,9 @@
   likely what people expect even if it is not an ideal approach. Use  
   `gamut_map` in settings option to manually control the approach.
 - **NEW**: Upgrade ColorAide to 2.4.
+- **NEW**: Previews now run immediately on view activation.
+- **NEW**: The sliding preview window has configurable padding to scan  
+  a larger region.
 - **FIX**: Fix regression where contrast logic could not adjust to a  
   given contrast due to a property access.
 

ch_preview.py

@@ -336,7 +336,20 @@ def do_search(self, force=False):
             force = True
 
         # Get viewable bounds so we can constrain both vertically and horizontally.
+        padding = ch_settings.get('preview_window_padding', [0, 0])
+        row_pad = int(padding[0])
+        col_pad = int(padding[1])
+        last_row = self.view.rowcol(self.view.size())[0]
         visible_region = self.view.visible_region()
+        if row_pad or col_pad:
+            row1, col1 = self.view.rowcol(visible_region.begin())
+            row2, col2 = self.view.rowcol(visible_region.end())
+            row1 = max(0, row1 - int(row_pad))
+            row2 = min(last_row, row2 + int(row_pad))
+            col1 = max(0, col1 - col_pad)
+            col2 = col2 + col_pad
+            visible_region = sublime.Region(self.view.text_point(row1, col1), self.view.text_point(row2, col2))
+
         position = self.view.viewport_position()
         dimensions = self.view.viewport_extent()
         bounds = Dimensions(
@@ -665,9 +678,8 @@ def on_activated(self, view):
             return
 
         if self.should_update(view):
-            ch_preview_thread.modified = True
-            ch_preview_thread.time = time()
             self.set_file_scan_rules(view)
+            view.window().run_command('color_helper_preview', {"clear": False, "force": True})
 
     def set_file_scan_rules(self, view):
         """Set the scan rules for the current view."""

color_helper.sublime-settings

@@ -101,6 +101,14 @@
     // color by using gamut mapping.
     "show_out_of_gamut_preview": true,
 
+    // Define padding around sliding preview window
+    // Extend the range previews processed by ColorHelper.
+    // Value should be positive integers and represent the rows and columns
+    // to extend the range by. Padding is applied on both sides. So padding
+    // by 20 rows pads by 20 on the top and 20 on the bottom. Large padding
+    // could cause lag with typing or scrolling.
+    "preview_window_padding": [20, 20],
+
     // The gamut space to render previews in.
     // Supported spaces are: `srgb`, `display-p3`, `rec2020`,
     //                       `a98-rgb`, and `prophoto-rgb`.

docs/src/markdown/settings/previews.md

@@ -15,6 +15,22 @@ Previews can be positioned to the left or right of a color. Set this value to "l
     "inline_preview_position": "left",
 ```
 
+## 
+
+Color previews are processed in a sliding window. Without any padding it exactly matches the visible region. This allows
+you to extend the window and process content just out of visible range. It should be noted though that large padding
+could cause typing or scrolling lag.
+
+```js
+    // Define padding around sliding preview window
+    // Extend the range previews processed by ColorHelper.
+    // Value should be positive integers and represent the rows and columns
+    // to extend the range by. Padding is applied on both sides. So padding
+    // by 20 rows pads by 20 on the top and 20 on the bottom. Large padding
+    // could cause lag with typing or scrolling.
+    "preview_window_padding": [20, 20],
+````
+
 ## `preview_on_select`
 
 Enables/disables previews only showing when they are selected.

messages/recent.md

@@ -18,5 +18,8 @@ related to the upgrade to stable `coloraide`.
   likely what people expect even if it is not an ideal approach. Use  
   `gamut_map` in settings option to manually control the approach.
 - **NEW**: Upgrade ColorAide to 2.4.
+- **NEW**: Previews now run immediately on view activation.
+- **NEW**: The sliding preview window has configurable padding to scan  
+  a larger region.
 - **FIX**: Fix regression where contrast logic could not adjust to a  
   given contrast due to a property access.