Refactor viewport initialization logic out of WebViewImpl.

Source/core/page/PageScaleConstraints.cpp

Index: Source/core/page/PageScaleConstraints.cpp
diff --git a/Source/core/page/PageScaleConstraints.cpp b/Source/core/page/PageScaleConstraints.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..9c82650432dbdec821f938d594e8d3fbc967db23
--- /dev/null
+++ b/Source/core/page/PageScaleConstraints.cpp
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "PageScaleConstraints.h"
+
+namespace WebCore {
+
+PageScaleConstraints::PageScaleConstraints()
+    : initialScale(-1), minimumScale(-1), maximumScale(-1) { }
+
+PageScaleConstraints::PageScaleConstraints(float initial, float minimum, float maximum)
+    : initialScale(initial), minimumScale(minimum), maximumScale(maximum) { }
+
+void PageScaleConstraints::overrideWith(const PageScaleConstraints& other)
+{
+    if (other.initialScale != -1) {
+        initialScale = other.initialScale;
+        if (minimumScale != -1)
+            minimumScale = std::min(minimumScale, other.initialScale);
+    }
+    if (other.minimumScale != -1)
+        minimumScale = other.minimumScale;
+    if (other.maximumScale != -1)
+        maximumScale = other.maximumScale;
+    if (!other.layoutSize.isEmpty())
+        layoutSize = other.layoutSize;
+    clampAll();
+}
+
+float PageScaleConstraints::clampToConstraints(float pageScaleFactor) const
+{
+    if (pageScaleFactor == -1)
+        return pageScaleFactor;
+    if (minimumScale != -1)
+        pageScaleFactor = std::max(pageScaleFactor, minimumScale);
+    if (maximumScale != -1)
+        pageScaleFactor = std::min(pageScaleFactor, maximumScale);
+    return pageScaleFactor;
+}
+
+void PageScaleConstraints::clampAll()
+{
+    if (minimumScale != -1 && maximumScale != -1)
+        maximumScale = std::max(minimumScale, maximumScale);
+    initialScale = clampToConstraints(initialScale);
+}
+
+void PageScaleConstraints::fitToContentsWidth(float contentsWidth, int viewWidthNotIncludingScrollbars)
+{
+    if (!contentsWidth || !viewWidthNotIncludingScrollbars)
+        return;
+
+    // Clamp the minimum scale so that the viewport can't exceed the document
+    // width.
+    minimumScale = std::max(minimumScale, viewWidthNotIncludingScrollbars / contentsWidth);
+
+    // If the initial scale wasn't defined, set it to minimum scale now that we
+    // know the real value.
+    if (initialScale == -1)
+        initialScale = minimumScale;
+
+    clampAll();
+}
+
+bool PageScaleConstraints::operator==(const PageScaleConstraints& other) const
+{
+    return layoutSize == other.layoutSize
+        && initialScale == other.initialScale
+        && minimumScale == other.minimumScale
+        && maximumScale == other.maximumScale;
+}
+
+} // namespace WebCore