Allow decimal measurements on java

Summary: Preserve floating point values when passing them across the JNI bridge.

Differential Revision: D4366605

fbshipit-source-id: 0b94ee87a03a6ed918360dd9998930e780fc865d

java/com/facebook/yoga/YogaMeasureOutput.java

@@ -15,18 +15,20 @@ package com.facebook.yoga;
 public class YogaMeasureOutput {
 
   public static long make(float width, float height) {
-    return make((int) width, (int) height);
+    final int wBits = Float.floatToRawIntBits(width);
+    final int hBits = Float.floatToRawIntBits(height);
+    return ((long) wBits) << 32 | ((long) hBits);
   }
 
   public static long make(int width, int height) {
-    return ((long) width) << 32 | ((long) height);
+    return make((float) width, (float) height);
   }
 
-  public static int getWidth(long measureOutput) {
-    return (int) (0xFFFFFFFF & (measureOutput >> 32));
+  public static float getWidth(long measureOutput) {
+    return Float.intBitsToFloat((int) (0xFFFFFFFF & (measureOutput >> 32)));
   }
 
-  public static int getHeight(long measureOutput) {
-    return (int) (0xFFFFFFFF & measureOutput);
+  public static float getHeight(long measureOutput) {
+    return Float.intBitsToFloat((int) (0xFFFFFFFF & measureOutput));
   }
 }

java/jni/YGJNI.cpp

@@ -67,10 +67,13 @@ static YGSize YGJNIMeasureFunc(YGNodeRef node,
     static_assert(sizeof(measureResult) == 8,
                   "Expected measureResult to be 8 bytes, or two 32 bit ints");
 
-    const float measuredWidth = static_cast<float>(0xFFFFFFFF & (measureResult >> 32));
-    const float measuredHeight = static_cast<float>(0xFFFFFFFF & measureResult);
+    int32_t wBits = 0xFFFFFFFF & (measureResult >> 32);
+    int32_t hBits = 0xFFFFFFFF & measureResult;
 
-    return YGSize{measuredWidth, measuredHeight};
+    const float *measuredWidth = reinterpret_cast<float*>(&wBits);
+    const float *measuredHeight = reinterpret_cast<float*>(&hBits);
+
+    return YGSize{*measuredWidth, *measuredHeight};
   } else {
     YGLog(YGLogLevelError, "Java YGNode was GCed during layout calculation\n");
     return YGSize{

java/tests/com/facebook/yoga/YogaNodeTest.java

@@ -41,6 +41,60 @@ public class YogaNodeTest {
     assertEquals(100, (int) node.getLayoutHeight());
   }
 
+  @Test
+  public void testMeasureFloat() {
+    final YogaNode node = new YogaNode();
+    node.setMeasureFunction(new YogaMeasureFunction() {
+        public long measure(
+            YogaNodeAPI node,
+            float width,
+            YogaMeasureMode widthMode,
+            float height,
+            YogaMeasureMode heightMode) {
+          return YogaMeasureOutput.make(100.5f, 100.5f);
+        }
+    });
+    node.calculateLayout();
+    assertEquals(100.5f, node.getLayoutWidth(), 0.0f);
+    assertEquals(100.5f, node.getLayoutHeight(), 0.0f);
+  }
+
+  @Test
+  public void testMeasureFloatMin() {
+    final YogaNode node = new YogaNode();
+    node.setMeasureFunction(new YogaMeasureFunction() {
+        public long measure(
+            YogaNodeAPI node,
+            float width,
+            YogaMeasureMode widthMode,
+            float height,
+            YogaMeasureMode heightMode) {
+          return YogaMeasureOutput.make(Float.MIN_VALUE, Float.MIN_VALUE);
+        }
+    });
+    node.calculateLayout();
+    assertEquals(Float.MIN_VALUE, node.getLayoutWidth(), 0.0f);
+    assertEquals(Float.MIN_VALUE, node.getLayoutHeight(), 0.0f);
+  }
+
+  @Test
+  public void testMeasureFloatMax() {
+    final YogaNode node = new YogaNode();
+    node.setMeasureFunction(new YogaMeasureFunction() {
+        public long measure(
+            YogaNodeAPI node,
+            float width,
+            YogaMeasureMode widthMode,
+            float height,
+            YogaMeasureMode heightMode) {
+          return YogaMeasureOutput.make(Float.MAX_VALUE, Float.MAX_VALUE);
+        }
+    });
+    node.calculateLayout();
+    assertEquals(Float.MAX_VALUE, node.getLayoutWidth(), 0.0f);
+    assertEquals(Float.MAX_VALUE, node.getLayoutHeight(), 0.0f);
+  }
+
   private YogaLogLevel mLogLevel;
   private String mLogMessage;