Update touch selection to only modify one selection point at a time.

This is made in preparation for enabling selection auto scroll using touch
handles.

BUG=340658

Review URL: https://codereview.chromium.org/653383002

git-svn-id: svn://svn.chromium.org/blink/trunk@184179 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/web/WebLocalFrameImpl.cpp

@@ -1160,6 +1160,22 @@ void WebLocalFrameImpl::selectRange(const WebRange& webRange)
         frame()->selection().setSelectedRange(range.get(), VP_DEFAULT_AFFINITY, FrameSelection::NonDirectional, NotUserTriggered);
 }
 
+void WebLocalFrameImpl::moveRangeSelectionExtent(const WebPoint& point)
+{
+    VisibleSelection currentSelection = frame()->selection().selection();
+
+    VisiblePosition basePosition = currentSelection.isBaseFirst() ?
+        currentSelection.visibleStart() : currentSelection.visibleEnd();
+    VisiblePosition extentPosition = visiblePositionForWindowPoint(point);
+
+    // Prevent the selection from collapsing.
+    if (comparePositions(basePosition, extentPosition) == 0)
+        return;
+
+    VisibleSelection newSelection = VisibleSelection(basePosition, extentPosition);
+    frame()->selection().setSelection(newSelection, CharacterGranularity);
+}
+
 void WebLocalFrameImpl::moveRangeSelection(const WebPoint& base, const WebPoint& extent)
 {
     VisiblePosition basePosition = visiblePositionForWindowPoint(base);

third_party/WebKit/Source/web/WebLocalFrameImpl.h

@@ -161,6 +161,7 @@ public:
     virtual bool selectWordAroundCaret() override;
     virtual void selectRange(const WebPoint& base, const WebPoint& extent) override;
     virtual void selectRange(const WebRange&) override;
+    virtual void moveRangeSelectionExtent(const WebPoint&) override;
     virtual void moveRangeSelection(const WebPoint& base, const WebPoint& extent) override;
     virtual void moveCaretSelection(const WebPoint&) override;
     virtual bool setEditableSelectionOffsets(int start, int end) override;

third_party/WebKit/Source/web/tests/WebFrameTest.cpp

@@ -4100,6 +4100,65 @@ TEST_F(WebFrameTest, SelectRangeCanMoveSelectionEnd)
     // EXPECT_EQ("Editable 1. Editable 2. ]", selectionAsString(frame));
 }
 
+TEST_F(WebFrameTest, MoveRangeSelectionExtent)
+{
+    WebLocalFrameImpl* frame;
+    WebRect startWebRect;
+    WebRect endWebRect;
+
+    registerMockedHttpURLLoad("move_range_selection_extent.html");
+
+    FrameTestHelpers::WebViewHelper webViewHelper;
+    initializeTextSelectionWebView(m_baseURL + "move_range_selection_extent.html", &webViewHelper);
+    frame = toWebLocalFrameImpl(webViewHelper.webView()->mainFrame());
+    EXPECT_EQ("This text is initially selected.", selectionAsString(frame));
+    webViewHelper.webView()->selectionBounds(startWebRect, endWebRect);
+
+    frame->moveRangeSelectionExtent(WebPoint(640, 480));
+    EXPECT_EQ("This text is initially selected. 16-char footer.", selectionAsString(frame));
+
+    frame->moveRangeSelectionExtent(WebPoint(0, 0));
+    EXPECT_EQ("16-char header. ", selectionAsString(frame));
+
+    // Reset with swapped base and extent.
+    frame->selectRange(topLeft(endWebRect), bottomRightMinusOne(startWebRect));
+    EXPECT_EQ("This text is initially selected.", selectionAsString(frame));
+
+    frame->moveRangeSelectionExtent(WebPoint(640, 480));
+    EXPECT_EQ(" 16-char footer.", selectionAsString(frame));
+
+    frame->moveRangeSelectionExtent(WebPoint(0, 0));
+    EXPECT_EQ("16-char header. This text is initially selected.", selectionAsString(frame));
+
+    frame->executeCommand(WebString::fromUTF8("Unselect"));
+    EXPECT_EQ("", selectionAsString(frame));
+}
+
+TEST_F(WebFrameTest, MoveRangeSelectionExtentCannotCollapse)
+{
+    WebLocalFrameImpl* frame;
+    WebRect startWebRect;
+    WebRect endWebRect;
+
+    registerMockedHttpURLLoad("move_range_selection_extent.html");
+
+    FrameTestHelpers::WebViewHelper webViewHelper;
+    initializeTextSelectionWebView(m_baseURL + "move_range_selection_extent.html", &webViewHelper);
+    frame = toWebLocalFrameImpl(webViewHelper.webView()->mainFrame());
+    EXPECT_EQ("This text is initially selected.", selectionAsString(frame));
+    webViewHelper.webView()->selectionBounds(startWebRect, endWebRect);
+
+    frame->moveRangeSelectionExtent(bottomRightMinusOne(startWebRect));
+    EXPECT_EQ("This text is initially selected.", selectionAsString(frame));
+
+    // Reset with swapped base and extent.
+    frame->selectRange(topLeft(endWebRect), bottomRightMinusOne(startWebRect));
+    EXPECT_EQ("This text is initially selected.", selectionAsString(frame));
+
+    frame->moveRangeSelectionExtent(bottomRightMinusOne(endWebRect));
+    EXPECT_EQ("This text is initially selected.", selectionAsString(frame));
+}
+
 static int computeOffset(RenderObject* renderer, int x, int y)
 {
     return VisiblePosition(renderer->positionForPoint(LayoutPoint(x, y))).deepEquivalent().computeOffsetInContainerNode();

third_party/WebKit/Source/web/tests/data/move_range_selection_extent.html

+<!DOCTYPE html>
+<html id='root'>
+<body>
+<span id='target'>16-char header. This text is initially selected. 16-char footer.</span>
+<script>
+    function select() {
+        var text = document.getElementById('target').firstChild;
+        var range = document.createRange();
+        range.setStart(text, 16);
+        range.setEnd(text, 48);
+        window.getSelection().addRange(range);
+    }
+    window.onload = select;
+</script>
+</body>
+</html>
+

third_party/WebKit/public/web/WebLocalFrame.h

@@ -74,6 +74,14 @@ public:
     // Associates an isolated world with human-readable name which is useful for
     // extension debugging.
     virtual void setIsolatedWorldHumanReadableName(int worldID, const WebString&) = 0;
+
+
+    // Selection --------------------------------------------------------------
+
+    // Moves the selection extent point. This function does not allow the
+    // selection to collapse. If the new extent is set to the same position as
+    // the current base, this function will do nothing.
+    virtual void moveRangeSelectionExtent(const WebPoint&) = 0;
 };
 
 } // namespace blink