Re-use ComputedStyles in Escalator when possible. (#12186)

2 files changed, 38 insertions, 9 deletions

diff --git a/client/src/main/java/com/vaadin/client/widgets/Escalator.java b/client/src/main/java/com/vaadin/client/widgets/Escalator.java
index a5046ce970..a9f8e0862c 100644
--- a/client/src/main/java/com/vaadin/client/widgets/Escalator.java
+++ b/client/src/main/java/com/vaadin/client/widgets/Escalator.java
@@ -7160,6 +7160,8 @@ public class Escalator extends Widget
 
     private final ElementPositionBookkeeper positions = new ElementPositionBookkeeper();
 
+    private Map<Element, ComputedStyle> computedStyleMap = new HashMap<>();
+
     /**
      * Creates a new Escalator widget instance.
      */
@@ -7249,14 +7251,28 @@ public class Escalator extends Widget
     private double getBoundingWidth(Element element) {
         // Gets the current width, including border and padding, for the element
         // while ignoring any transforms applied to the element (e.g. scale)
-        return new ComputedStyle(element).getWidthIncludingBorderPadding();
+        if (!computedStyleMap.containsKey(element)) {
+            if (computedStyleMap.isEmpty()) {
+                // ensure the next event loop calculates the sizes anew
+                Scheduler.get().scheduleDeferred(() -> clearComputedStyles());
+            }
+            computedStyleMap.put(element, new ComputedStyle(element));
+        }
+        return computedStyleMap.get(element).getWidthIncludingBorderPadding();
     }
 
     private double getBoundingHeight(Element element) {
         // Gets the current height, including border and padding, for the
         // element while ignoring any transforms applied to the element (e.g.
         // scale)
-        return new ComputedStyle(element).getHeightIncludingBorderPadding();
+        if (!computedStyleMap.containsKey(element)) {
+            if (computedStyleMap.isEmpty()) {
+                // ensure the next event loop calculates the sizes anew
+                Scheduler.get().scheduleDeferred(() -> clearComputedStyles());
+            }
+            computedStyleMap.put(element, new ComputedStyle(element));
+        }
+        return computedStyleMap.get(element).getHeightIncludingBorderPadding();
     }
 
     private int getBodyRowCount() {
@@ -8306,6 +8322,25 @@ public class Escalator extends Widget
     }
 
     /**
+     * Gets the escalator's inner height. This is the entire height in pixels,
+     * without the horizontal scrollbar.
+     *
+     * @return escalator's inner height
+     */
+    public double getInnerHeight() {
+        return getBoundingHeight(tableWrapper);
+    }
+
+    /**
+     * FOR INTERNAL USE ONLY, MAY GET REMOVED OR MODIFIED AT ANY TIME!
+     * <p>
+     * Clears the computed styles.
+     */
+    void clearComputedStyles() {
+        computedStyleMap.clear();
+    }
+
+    /**
      * Resets all cached pixel sizes and reads new values from the DOM. This
      * methods should be used e.g. when styles affecting the dimensions of
      * elements in this escalator have been changed.
diff --git a/client/src/main/java/com/vaadin/client/widgets/Grid.java b/client/src/main/java/com/vaadin/client/widgets/Grid.java
index d4c93751ea..99a4a269bd 100755
--- a/client/src/main/java/com/vaadin/client/widgets/Grid.java
+++ b/client/src/main/java/com/vaadin/client/widgets/Grid.java
@@ -77,7 +77,6 @@ import com.google.gwt.user.client.ui.PopupPanel;
 import com.google.gwt.user.client.ui.ResizeComposite;
 import com.google.gwt.user.client.ui.Widget;
 import com.vaadin.client.BrowserInfo;
-import com.vaadin.client.ComputedStyle;
 import com.vaadin.client.DeferredWorker;
 import com.vaadin.client.Focusable;
 import com.vaadin.client.WidgetUtil;
@@ -3456,7 +3455,7 @@ public class Grid<T> extends ResizeComposite implements HasSelectionHandlers<T>,
 
             // Update latest width to prevent recalculate on height change.
             lastCalculatedInnerWidth = escalator.getInnerWidth();
-            lastCalculatedInnerHeight = getEscalatorInnerHeight();
+            lastCalculatedInnerHeight = escalator.getInnerHeight();
         }
 
         private boolean columnsAreGuaranteedToBeWiderThanGrid() {
@@ -9404,11 +9403,6 @@ public class Grid<T> extends ResizeComposite implements HasSelectionHandlers<T>,
         });
     }
 
-    private double getEscalatorInnerHeight() {
-        return new ComputedStyle(getEscalator().getTableWrapper())
-                .getHeightIncludingBorderPadding();
-    }
-
     /**
      * Grid does not support adding Widgets this way.
      * <p>