🎨: refactor layout-policy resizing and prevent feedbackloop via meta flag

Replaces old and not very well working control flows with a more sophisticated approach to determining sizing behavior of a styled morph within the context of various layouts.
According to the identified sizing behavior, the extent is applied in varying fashions. Also previously accidental re-execution of layouts would happen due to policies applying themselves, which lead to inefficient layout applications overall. This is now prevented with a meta flag.

Author: merryman

lively.morphic/components/policy.js

@@ -1295,7 +1295,7 @@ export class StylePolicy {
    * @returns { boolean | object } Wether or not size is controlled via layout and if so, the concrete policy.
    */
   isResizedByLayout (aSubmorph) {
-    const layout = aSubmorph.owner && aSubmorph.owner.layout;
+    let layout = aSubmorph.owner && aSubmorph.owner.layout;
     let heightPolicy = 'fixed'; let widthPolicy = 'fixed';
     if (aSubmorph.isText) {
       if (!aSubmorph.fixedHeight) heightPolicy = 'hug';
@@ -1306,6 +1306,19 @@ export class StylePolicy {
       if (widthPolicy !== 'hug') widthPolicy = layout.getResizeWidthPolicyFor(aSubmorph);
       if (heightPolicy === 'fill' || widthPolicy === 'fill') return { widthPolicy, heightPolicy };
     }
+
+    layout = aSubmorph.layout;
+
+    if (layout?.hugContentsVertically ||
+        layout?.hugContentsHorizontally ||
+        widthPolicy === 'hug' ||
+        heightPolicy === 'hug') {
+      return {
+        widthPolicy: layout?.hugContentsHorizontally ? 'hug' : widthPolicy,
+        heightPolicy: layout?.hugContentsVertically ? 'hug' : heightPolicy
+      };
+    }
+
     return false;
   }
 
@@ -1498,8 +1511,17 @@ export class PolicyApplicator extends StylePolicy {
       if (propName === 'position' && this.isPositionedByLayout(morphToBeStyled)) continue;
       let resizePolicy;
       if (propName === 'extent' && (resizePolicy = this.isResizedByLayout(morphToBeStyled))) {
-        if (resizePolicy.widthPolicy === 'fixed' && morphToBeStyled.width !== propValue.x) morphToBeStyled.width = propValue.x;
-        if (resizePolicy.heightPolicy === 'fixed' && morphToBeStyled.height !== propValue.y) morphToBeStyled.height = propValue.y;
+        morphToBeStyled.withMetaDo({ deferLayoutApplication: true }, () => {
+          if (resizePolicy.widthPolicy === 'fixed' && morphToBeStyled.width !== propValue.x) {
+            morphToBeStyled.width = propValue.x;
+          }
+          if (resizePolicy.heightPolicy === 'fixed' && morphToBeStyled.height !== propValue.y) {
+            morphToBeStyled.height = propValue.y;
+          }
+          if (morphToBeStyled.isText && (resizePolicy.widthPolicy === 'hug' || resizePolicy.heightPolicy === 'hug')) {
+            morphToBeStyled.withMetaDo({ doNotFit: false }, () => morphToBeStyled.fit());
+          }
+        });
         continue;
       }
 
@@ -1514,32 +1536,11 @@ export class PolicyApplicator extends StylePolicy {
         if (propName === 'position') continue;
       }
 
-      // FIXME: other special cases??
-      if (morphToBeStyled.isText && propName === 'extent') {
-        if (!morphToBeStyled.fixedWidth && !morphToBeStyled.fixedHeight) continue;
-        if (!morphToBeStyled.fixedWidth) propValue = propValue.withX(morphToBeStyled.width);
-        if (!morphToBeStyled.fixedHeight) propValue = propValue.withY(morphToBeStyled.height);
-      }
-
-      if (morphToBeStyled.isText && propName === 'width' && morphToBeStyled.lineWrapping !== 'no-wrap') {
-        if (!morphToBeStyled.fixedWidth) continue;
-        morphToBeStyled.width = propValue;
-        morphToBeStyled.withMetaDo({ doNotFit: false }, () => morphToBeStyled.fit());
-      }
-
       if (['border', 'borderTop', 'borderBottom', 'borderRight', 'borderLeft'].includes(propName)) continue; // handled by sub props;
 
       if (!obj.equals(morphToBeStyled[propName], propValue)) {
         morphToBeStyled[propName] = propValue;
       }
-
-      // we may be late for the game when setting these props
-      // se we need to make sure, we restore the morphs "intended extent"
-      // for this purpose we enforce the masterSubmorph extent
-      if (['fixedHeight', 'fixedWidth'].includes(propName) &&
-          morphToBeStyled._parametrizedProps?.extent) {
-        morphToBeStyled.extent = morphToBeStyled._parametrizedProps.extent;
-      }
     }
   }
 

lively.morphic/layout.js

@@ -419,6 +419,10 @@ export class TilingLayout extends Layout {
   }
 
   scheduleApply (submorph, animation, change = {}) {
+    if (change.meta?.deferLayoutApplication) {
+      return;
+    }
+
     if (!change.meta?.isLayoutAction || !this.container?._yogaNode?.getParent()) {
       this._alreadyComputed = false;
     }