feat: Throttle InteractiveViewer update events (#4704)

* initial commit * update pubspec.lock * rename to interaction_update_interval * reformat --------- Co-authored-by: Feodor Fitsner <[email protected]>
flet-dev · Jan 16, 2025 · b98e0a0 · b98e0a0
1 parent 5ac5753
commit b98e0a0
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Showing 2 changed files with 36 additions and 16 deletions.
diff --git a/packages/flet/lib/src/controls/interactive_viewer.dart b/packages/flet/lib/src/controls/interactive_viewer.dart
@@ -41,6 +41,7 @@ class _InteractiveViewerControlState extends State<InteractiveViewerControl>
   late AnimationController _animationController;
   Animation<Matrix4>? _animation;
   Matrix4? _savedMatrix;
+  int _interactionUpdateTimestamp = DateTime.now().millisecondsSinceEpoch;
 
   @override
   void initState() {
@@ -158,22 +159,30 @@ class _InteractiveViewerControlState extends State<InteractiveViewerControl>
           : null,
       onInteractionUpdate: !disabled
           ? (ScaleUpdateDetails details) {
-              debugPrint(
-                  "InteractiveViewer ${widget.control.id} onInteractionUpdate");
-              widget.backend.triggerControlEvent(
-                  widget.control.id,
-                  "interaction_update",
-                  jsonEncode({
-                    "pc": details.pointerCount,
-                    "fp_x": details.focalPoint.dx,
-                    "fp_y": details.focalPoint.dy,
-                    "lfp_x": details.localFocalPoint.dx,
-                    "lfp_y": details.localFocalPoint.dy,
-                    "s": details.scale,
-                    "hs": details.horizontalScale,
-                    "vs": details.verticalScale,
-                    "rot": details.rotation,
-                  }));
+              var interactionUpdateInterval =
+                  widget.control.attrInt("interactionUpdateInterval", 0)!;
+              var now = DateTime.now().millisecondsSinceEpoch;
+              if (now - _interactionUpdateTimestamp >
+                  interactionUpdateInterval) {
+                debugPrint(
+                    "InteractiveViewer ${widget.control.id} onInteractionUpdate");
+                _interactionUpdateTimestamp = now;
+                widget.backend.triggerControlEvent(
+                    widget.control.id,
+                    "interaction_update",
+                    jsonEncode({
+                      "pc": details.pointerCount,
+                      "fp_x": details.focalPoint.dx,
+                      "fp_y": details.focalPoint.dy,
+                      "lfp_x": details.localFocalPoint.dx,
+                      "lfp_y": details.localFocalPoint.dy,
+                      "s": details.scale,
+                      "hs": details.horizontalScale,
+                      "vs": details.verticalScale,
+                      "rot": details.rotation,
+                    }));
+                ;
+              }
             }
           : null,
       child: contentCtrls.isNotEmpty

diff --git a/sdk/python/packages/flet/src/flet/core/interactive_viewer.py b/sdk/python/packages/flet/src/flet/core/interactive_viewer.py
@@ -79,6 +79,7 @@ def __init__(
         clip_behavior: Optional[ClipBehavior] = None,
         alignment: Optional[Alignment] = None,
         boundary_margin: Optional[MarginValue] = None,
+        interaction_update_interval: Optional[int] = None,
         on_interaction_start: Optional[
             Callable[[InteractiveViewerInteractionStartEvent], None]
         ] = None,
@@ -189,6 +190,7 @@ def __init__(
         self.on_interaction_start = on_interaction_start
         self.on_interaction_end = on_interaction_end
         self.on_interaction_update = on_interaction_update
+        self.interaction_update_interval = interaction_update_interval
 
     def _get_control_name(self):
         return "interactiveviewer"
@@ -228,6 +230,15 @@ def min_scale(self) -> float:
     def min_scale(self, value: OptionalNumber):
         self._set_attr("minScale", value)
 
+    # interaction_update_interval
+    @property
+    def interaction_update_interval(self) -> int:
+        return self._get_attr("interactionUpdateInterval", data_type="int", def_value=0)
+
+    @interaction_update_interval.setter
+    def interaction_update_interval(self, value: Optional[int]):
+        self._set_attr("interactionUpdateInterval", value)
+
     # max_scale
     @property
     def max_scale(self) -> float: