From c75adb067140893690382b465b4ac728f897c343 Mon Sep 17 00:00:00 2001
From: Tomer Shalev <tomer.shalev@gmail.com>
Date: Tue, 13 Mar 2018 03:06:42 -0700
Subject: [PATCH] solves the Android pixel bug

Summary:
emilsjolander hi,
this PR solves the following common and probable layout pixel scenario:
the older code is presented for reference:

```java
view.measure(
    View.MeasureSpec.makeMeasureSpec(
        Math.round(node.getLayoutWidth()),
        View.MeasureSpec.EXACTLY),
    View.MeasureSpec.makeMeasureSpec(
        Math.round(node.getLayoutHeight()),
        View.MeasureSpec.EXACTLY));
view.layout(
    Math.round(xOffset + node.getLayoutX()),
    Math.round(yOffset + node.getLayoutY()),
    Math.round(xOffset + node.getLayoutX() + node.getLayoutWidth()),
    Math.round(yOffset + node.getLayoutY() + node.getLayoutHeight()));

```

suppose now the following:
- `xOffset + node.getLayoutX() = 2.2`
- `node.getLayoutWidth() = 0.4` ==> `Math.round(node.getLayoutWidth()) = 0`
- `Math.round(xOffset + node.getLayoutX() + node.getLayoutWidth()) = Math.round(2.2 + 0.4) = 3`

this induces, the following measurements:
```java
view.measure(
    View.MeasureSpec.makeMeasureSpec(
        0,
        View.MeasureSpec.EXACTLY),
    View.MeasureSpec.makeMeasureSpec(
        Math.round(node.getLayoutHeight()),
        View.MeasureSpec.EXACTLY));
view.layout(
    2,
    Math.round(yOffset + node.getLayoutY()),
    3,
    Math.round(yOffset + node.getLayoutY() + node.getLayoutHeight()));

```

the width measurement of the view is 0, while the layout is `(3 - 2 = 1)`.
my proposed solution is to measure the view the way it is now, but when layouting
I use the `#getMeasuredWidth/Height()` methods, this will stop this problem
from happening.

I also want to note that this bug happens with high probability.
Closes https://github.com/facebook/yoga/pull/712

Reviewed By: emilsjolander

Differential Revision: D7231798

Pulled By: priteshrnandgaonkar

fbshipit-source-id: 171da519639dbecd75416a574bccc4456aa22f31
---
 .../com/facebook/yoga/android/YogaLayout.java   | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/android/src/main/java/com/facebook/yoga/android/YogaLayout.java b/android/src/main/java/com/facebook/yoga/android/YogaLayout.java
index 5801fbad..90d61af8 100644
--- a/android/src/main/java/com/facebook/yoga/android/YogaLayout.java
+++ b/android/src/main/java/com/facebook/yoga/android/YogaLayout.java
@@ -7,9 +7,6 @@
 
 package com.facebook.yoga.android;
 
-import java.util.HashMap;
-import java.util.Map;
-
 import android.content.Context;
 import android.content.res.Configuration;
 import android.content.res.TypedArray;
@@ -21,9 +18,6 @@ import android.util.SparseArray;
 import android.util.TypedValue;
 import android.view.View;
 import android.view.ViewGroup;
-import android.util.Log;
-
-import com.facebook.yoga.android.R;
 import com.facebook.yoga.YogaAlign;
 import com.facebook.yoga.YogaConstants;
 import com.facebook.yoga.YogaDirection;
@@ -35,10 +29,11 @@ import com.facebook.yoga.YogaMeasureFunction;
 import com.facebook.yoga.YogaMeasureMode;
 import com.facebook.yoga.YogaMeasureOutput;
 import com.facebook.yoga.YogaNode;
-import com.facebook.yoga.YogaNode;
 import com.facebook.yoga.YogaOverflow;
 import com.facebook.yoga.YogaPositionType;
 import com.facebook.yoga.YogaWrap;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
  * A {@code ViewGroup} based on the Yoga layout engine.
@@ -291,6 +286,8 @@ public class YogaLayout extends ViewGroup {
       if (view.getVisibility() == GONE) {
         return;
       }
+      int left = Math.round(xOffset + node.getLayoutX());
+      int top = Math.round(yOffset + node.getLayoutY());
       view.measure(
           View.MeasureSpec.makeMeasureSpec(
               Math.round(node.getLayoutWidth()),
@@ -298,11 +295,7 @@ public class YogaLayout extends ViewGroup {
           View.MeasureSpec.makeMeasureSpec(
               Math.round(node.getLayoutHeight()),
               View.MeasureSpec.EXACTLY));
-      view.layout(
-          Math.round(xOffset + node.getLayoutX()),
-          Math.round(yOffset + node.getLayoutY()),
-          Math.round(xOffset + node.getLayoutX() + node.getLayoutWidth()),
-          Math.round(yOffset + node.getLayoutY() + node.getLayoutHeight()));
+      view.layout(left, top, left + view.getMeasuredWidth(), top + view.getMeasuredHeight());
     }
 
     final int childrenCount = node.getChildCount();