Separate FlexLine functionality

Differential Revision: D49133837

fbshipit-source-id: 77e501ff7319e31d9b45c20c3d39c905c28fe8bb

yoga/algorithm/BoundAxis.h

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <yoga/algorithm/FlexDirection.h>
+#include <yoga/algorithm/ResolveValue.h>
+#include <yoga/node/Node.h>
+#include <yoga/numeric/Comparison.h>
+#include <yoga/numeric/FloatOptional.h>
+
+namespace facebook::yoga {
+
+inline float paddingAndBorderForAxis(
+    const yoga::Node* const node,
+    const YGFlexDirection axis,
+    const float widthSize) {
+  return (node->getLeadingPaddingAndBorder(axis, widthSize) +
+          node->getTrailingPaddingAndBorder(axis, widthSize))
+      .unwrap();
+}
+
+inline FloatOptional boundAxisWithinMinAndMax(
+    const yoga::Node* const node,
+    const YGFlexDirection axis,
+    const FloatOptional value,
+    const float axisSize) {
+  FloatOptional min;
+  FloatOptional max;
+
+  if (isColumn(axis)) {
+    min = yoga::resolveValue(
+        node->getStyle().minDimensions()[YGDimensionHeight], axisSize);
+    max = yoga::resolveValue(
+        node->getStyle().maxDimensions()[YGDimensionHeight], axisSize);
+  } else if (isRow(axis)) {
+    min = yoga::resolveValue(
+        node->getStyle().minDimensions()[YGDimensionWidth], axisSize);
+    max = yoga::resolveValue(
+        node->getStyle().maxDimensions()[YGDimensionWidth], axisSize);
+  }
+
+  if (max >= FloatOptional{0} && value > max) {
+    return max;
+  }
+
+  if (min >= FloatOptional{0} && value < min) {
+    return min;
+  }
+
+  return value;
+}
+
+// Like boundAxisWithinMinAndMax but also ensures that the value doesn't
+// go below the padding and border amount.
+inline float boundAxis(
+    const yoga::Node* const node,
+    const YGFlexDirection axis,
+    const float value,
+    const float axisSize,
+    const float widthSize) {
+  return yoga::maxOrDefined(
+      boundAxisWithinMinAndMax(node, axis, FloatOptional{value}, axisSize)
+          .unwrap(),
+      paddingAndBorderForAxis(node, axis, widthSize));
+}
+
+} // namespace facebook::yoga