Implements CSSPropertyAPI for the touch-action property

third_party/WebKit/Source/core/css/properties/CSSPropertyAPITouchAction.cpp

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/css/properties/CSSPropertyAPITouchAction.h"
+
+#include "core/css/CSSValueList.h"
+#include "core/css/parser/CSSPropertyParserHelpers.h"
+#include "platform/RuntimeEnabledFeatures.h"
+
+namespace blink {
+
+namespace {
+
+static bool consumePan(CSSParserTokenRange& range,
+                       CSSValue*& panX,
+                       CSSValue*& panY,
+                       CSSValue*& pinchZoom) {
+  CSSValueID id = range.peek().id();
+  if ((id == CSSValuePanX || id == CSSValuePanRight || id == CSSValuePanLeft) &&
+      !panX) {
+    if (id != CSSValuePanX &&
+        !RuntimeEnabledFeatures::cssTouchActionPanDirectionsEnabled())
+      return false;
+    panX = CSSPropertyParserHelpers::consumeIdent(range);
+  } else if ((id == CSSValuePanY || id == CSSValuePanDown ||
+              id == CSSValuePanUp) &&
+             !panY) {
+    if (id != CSSValuePanY &&
+        !RuntimeEnabledFeatures::cssTouchActionPanDirectionsEnabled())
+      return false;
+    panY = CSSPropertyParserHelpers::consumeIdent(range);
+  } else if (id == CSSValuePinchZoom && !pinchZoom &&
+             RuntimeEnabledFeatures::cssTouchActionPinchZoomEnabled()) {
+    pinchZoom = CSSPropertyParserHelpers::consumeIdent(range);
+  } else {
+    return false;
+  }
+  return true;
+}
+
+}  // namespace
+
+const CSSValue* CSSPropertyAPITouchAction::parseSingleValue(
+    CSSParserTokenRange& range,
+    const CSSParserContext* context) {
+  CSSValueList* list = CSSValueList::createSpaceSeparated();
+  CSSValueID id = range.peek().id();
+  if (id == CSSValueAuto || id == CSSValueNone || id == CSSValueManipulation) {
+    list->append(*CSSPropertyParserHelpers::consumeIdent(range));
+    return list;
+  }
+
+  CSSValue* panX = nullptr;
+  CSSValue* panY = nullptr;
+  CSSValue* pinchZoom = nullptr;
+  if (!consumePan(range, panX, panY, pinchZoom))
+    return nullptr;
+  if (!range.atEnd() && !consumePan(range, panX, panY, pinchZoom))
+    return nullptr;
+  if (!range.atEnd() && !consumePan(range, panX, panY, pinchZoom))
+    return nullptr;
+
+  if (panX)
+    list->append(*panX);
+  if (panY)
+    list->append(*panY);
+  if (pinchZoom)
+    list->append(*pinchZoom);
+  return list;
+}
+
+}  // namespace blink