Fix unnecessary measure calls

Summary:
Fix #334
Closes https://github.com/facebook/yoga/pull/347

Reviewed By: dshahidehpour

Differential Revision: D4455438

Pulled By: emilsjolander

fbshipit-source-id: 013c89e71757d9048708ec85cbb6af9f33ac1ea6

tests/YGMeasureCacheTest.cpp

@@ -39,6 +39,22 @@ static YGSize _measureMin(YGNodeRef node,
   };
 }
 
+static YGSize _measure_84_49(YGNodeRef node,
+                        float width,
+                        YGMeasureMode widthMode,
+                        float height,
+                        YGMeasureMode heightMode) {
+  int *measureCount = (int*) YGNodeGetContext(node);
+  if (measureCount) {
+    (*measureCount)++;
+  }
+
+  return YGSize {
+      .width = 84.f,
+      .height = 49.f,
+  };
+}
+
 TEST(YogaTest, measure_once_single_flexible_child) {
   const YGNodeRef root = YGNodeNew();
   YGNodeStyleSetFlexDirection(root, YGFlexDirectionRow);
@@ -131,3 +147,28 @@ TEST(YogaTest, remeasure_with_atmost_computed_width_undefined_height) {
 
   YGNodeFreeRecursive(root);
 }
+
+TEST(YogaTest, remeasure_with_already_measured_value_smaller_but_still_float_equal) {
+  int measureCount = 0;
+
+  const YGNodeRef root = YGNodeNew();
+  YGNodeStyleSetWidth(root, 288.f);
+  YGNodeStyleSetHeight(root, 288.f);
+  YGNodeStyleSetFlexDirection(root, YGFlexDirectionRow);
+  
+  const YGNodeRef root_child0 = YGNodeNew();
+  YGNodeStyleSetPadding(root_child0, YGEdgeAll, 2.88f);
+  YGNodeStyleSetFlexDirection(root_child0, YGFlexDirectionRow);
+  YGNodeInsertChild(root, root_child0, 0);
+  
+  const YGNodeRef root_child0_child0 = YGNodeNew();
+  YGNodeSetContext(root_child0_child0, &measureCount);
+  YGNodeSetMeasureFunc(root_child0_child0, _measure_84_49);
+  YGNodeInsertChild(root_child0, root_child0_child0, 0);
+  
+  YGNodeCalculateLayout(root, YGUndefined, YGUndefined, YGDirectionLTR);
+  
+  YGNodeFreeRecursive(root);
+
+  ASSERT_EQ(1, measureCount);
+}

yoga/Yoga.c

@@ -2785,7 +2785,7 @@ static inline bool YGMeasureModeOldSizeIsUnspecifiedAndStillFits(YGMeasureMode s
                                                                  YGMeasureMode lastSizeMode,
                                                                  float lastComputedSize) {
   return sizeMode == YGMeasureModeAtMost && lastSizeMode == YGMeasureModeUndefined &&
-         size >= lastComputedSize;
+         (size >= lastComputedSize || YGFloatsEqual(size, lastComputedSize));
 }
 
 static inline bool YGMeasureModeNewMeasureSizeIsStricterAndStillValid(YGMeasureMode sizeMode,
@@ -2794,7 +2794,7 @@ static inline bool YGMeasureModeNewMeasureSizeIsStricterAndStillValid(YGMeasureM
                                                                       float lastSize,
                                                                       float lastComputedSize) {
   return lastSizeMode == YGMeasureModeAtMost && sizeMode == YGMeasureModeAtMost &&
-         lastSize > size && lastComputedSize <= size;
+         lastSize > size && (lastComputedSize <= size || YGFloatsEqual(size, lastComputedSize));
 }
 
 bool YGNodeCanUseCachedMeasurement(const YGMeasureMode widthMode,