1 files changed, 53 insertions, 0 deletions
diff --git a/dom/base/nsViewportInfo.cpp b/dom/base/nsViewportInfo.cpp
new file mode 100644
index 0000000000..67ac728330
--- /dev/null
+++ b/dom/base/nsViewportInfo.cpp
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsViewportInfo.h"
+#include "mozilla/Assertions.h"
+#include <algorithm>
+
+using namespace mozilla;
+
+void nsViewportInfo::ConstrainViewportValues() {
+  // Non-positive zoom factors can produce NaN or negative viewport sizes,
+  // so we better be sure our constraints will produce positive zoom factors.
+  MOZ_ASSERT(mMinZoom > CSSToScreenScale(0.0f), "zoom factor must be positive");
+  MOZ_ASSERT(mMaxZoom > CSSToScreenScale(0.0f), "zoom factor must be positive");
+
+  if (mDefaultZoom > mMaxZoom) {
+    mDefaultZoomValid = false;
+    mDefaultZoom = mMaxZoom;
+  }
+  if (mDefaultZoom < mMinZoom) {
+    mDefaultZoomValid = false;
+    mDefaultZoom = mMinZoom;
+  }
+}
+
+static const float& MinOrMax(const float& aA, const float& aB,
+                             const float& (*aMinOrMax)(const float&,
+                                                       const float&)) {
+  MOZ_ASSERT(aA != nsViewportInfo::kExtendToZoom &&
+             aA != nsViewportInfo::kDeviceSize &&
+             aB != nsViewportInfo::kExtendToZoom &&
+             aB != nsViewportInfo::kDeviceSize);
+  if (aA == nsViewportInfo::kAuto) {
+    return aB;
+  }
+  if (aB == nsViewportInfo::kAuto) {
+    return aA;
+  }
+  return aMinOrMax(aA, aB);
+}
+
+// static
+const float& nsViewportInfo::Min(const float& aA, const float& aB) {
+  return MinOrMax(aA, aB, std::min);
+}
+
+// static
+const float& nsViewportInfo::Max(const float& aA, const float& aB) {
+  return MinOrMax(aA, aB, std::max);
+}