Initial draft - modify ViewportAnchor to know about both inner and outer viewports.

Source/web/tests/PinchViewportTest.cpp

Index: Source/web/tests/PinchViewportTest.cpp
diff --git a/Source/web/tests/PinchViewportTest.cpp b/Source/web/tests/PinchViewportTest.cpp
index 5e34221f8fe38c5d14032894b48dcb345c6c90fe..829ae31e9049118a932eec09250410a85562172f 100644
--- a/Source/web/tests/PinchViewportTest.cpp
+++ b/Source/web/tests/PinchViewportTest.cpp
@@ -155,6 +155,13 @@ public:
         settings->setShrinksViewportContentToFit(true);
     }
 
+    static void resizesAreOrientationChanges(WebSettings* settings)
+    {
+        configureSettings(settings);
+        settings->setViewportEnabled(true);
+        settings->setMainFrameResizesAreOrientationChanges(true);

[bokan, 2014/09/16 19:46:48]

Does anything break if you just add setMainFrameResizesAreOrientationChanges in
configureAndroidSettings and use that? We should use that to get as close to the
Android config as possible.

[timav, 2014/09/16 21:44:51]

Nothing breaks in the existing tests, but for my own ones I had to add a line
 webViewImpl()->setPageScaleFactorLimits(1, 4);

[bokan, 2014/09/16 22:03:19]

Hmm...you shouldn't need that. What was the problem that was happening? The
layout() in resize() should trigger refreshPageScaleFactorAfterLayout() which
calls:

updatePageDefinedViewportConstraints(mainFrameImpl()->frame()->document()->viewportDescription());
m_pageScaleConstraintsSet.computeFinalConstraints();

That should set up the Android default limits.

+    }
+
 protected:
     std::string m_baseURL;
     FrameTestHelpers::TestWebViewClient m_mockWebViewClient;
@@ -193,6 +200,106 @@ TEST_F(PinchViewportTest, TestResize)
     EXPECT_SIZE_EQ(newViewportSize, pinchViewport.size());
 }
 
+// Test that the PinchViewport works as expected in case of a scaled
+// and scrolled viewport - scroll down.
+TEST_F(PinchViewportTest, TestResizeAfterVerticalScroll)
+{
+    /*
+                 200                                 200
+        ---------------------               ---------------------
+        |                   |               |                   |
+        |                   |               |                   |
+        |                   |               |                   |
+        |150                |               |                   |
+        |                   |               |                   |
+        |                   |               |175                |
+        |                   |               |                   |
+        |----------         |300            |                   |300
+        |         |         |   ------->    |                   |
+        |75       |         |               |--------------     |
+        |         |         |               |50           |     |
+        o----     |150      |               o-----        |100  |
+        |   |60   |         |               |    |40      |     |
+        |   |     |         |               |____|        |     |
+        |----     |         |               |--------------     |
+        ---------------------               ---------------------

[bokan, 2014/09/16 19:46:48]

ASCII art is super helpful, nice! The anchor should be at x: 0.5 though right?

[timav, 2014/09/16 21:44:52]

Right, and I keep forgetting about that.

I can move the "o". On the other hand, I was useful for me to mark the inner
origin in the document that we are going to approximately preserve. For
horizontal scroll case I tried to show that we can't do it due to constrains.

+
+     */
+
+    initializeWithDesktopSettings(resizesAreOrientationChanges);

[bokan, 2014/09/16 19:46:48]

use initializeWithAndroidSettings() and move the
mainFrameResizesAreOrientationChanges in there.

[timav, 2014/09/16 21:44:51]

Done.

+
+    registerMockedHttpURLLoad("200-by-300-viewport.html");
+    navigateTo(m_baseURL + "200-by-300-viewport.html");
+
+    webViewImpl()->resize(IntSize(100, 150));
+    webViewImpl()->layout();
+
+    // Scroll main frame to the bottom of the document
+    webViewImpl()->setMainFrameScrollOffset(WebPoint(0, 150));
+
+    webViewImpl()->setPageScaleFactor(2.5);
+
+    PinchViewport& pinchViewport = frame()->page()->frameHost().pinchViewport();
+    pinchViewport.setLocation(FloatPoint(0, 75));
+
+    // Verify the initial size of the pinch viewport in the CSS pixels
+    EXPECT_FLOAT_SIZE_EQ(FloatSize(40, 60), pinchViewport.visibleRect().size());
+
+    webViewImpl()->resize(IntSize(150, 100));
+    webViewImpl()->layout();
+
+    EXPECT_FLOAT_SIZE_EQ(FloatSize(60, 40), pinchViewport.visibleRect().size());
+    EXPECT_POINT_EQ(IntPoint(0, 175), frame()->view()->scrollPosition());
+    EXPECT_FLOAT_POINT_EQ(FloatPoint(0, 50), pinchViewport.location());
+}
+
+// Test that the PinchViewport works as expected in case if a scaled
+// and scrolled viewport - scroll right.
+TEST_F(PinchViewportTest, TestResizeAfterHorizontalScroll)
+{
+    /*
+                 200                                 200
+        ---------------o-----               ---------------o-----
+        |         |    |   ||               |    |        |     |
+        |         | 50 |40 ||               |    |        |_____|
+        |         |    -----|               |    |   90     60  |
+        |         |         |               |    |              |
+        |         |         |               |    ---------------|
+        |   100   |   100   |               | 50        150     |
+        |         |         |               |                   |
+        |         ----------|               |                   |
+        |                   |   ------->    |                   |
+        |                   |               |                   |
+
+     */
+
+    initializeWithDesktopSettings(resizesAreOrientationChanges);
+
+    registerMockedHttpURLLoad("200-by-300-viewport.html");
+    navigateTo(m_baseURL + "200-by-300-viewport.html");
+
+    webViewImpl()->resize(IntSize(100, 150));
+    webViewImpl()->layout();

[bokan, 2014/09/16 19:46:48]

you shouldn't need this layout (there's a layout call inside resize() if
viewport is enabled).

[timav, 2014/09/16 21:44:51]

Done.

+
+    // Scroll main frame to the right of the document
+    webViewImpl()->setMainFrameScrollOffset(WebPoint(100, 0));
+
+    webViewImpl()->setPageScaleFactor(2.5);
+
+    PinchViewport& pinchViewport = frame()->page()->frameHost().pinchViewport();
+    pinchViewport.setLocation(FloatPoint(50, 0));
+
+    // Verify the initial size of the pinch viewport in the CSS pixels
+    EXPECT_FLOAT_SIZE_EQ(FloatSize(40, 60), pinchViewport.visibleRect().size());
+
+    webViewImpl()->resize(IntSize(150, 100));
+    webViewImpl()->layout();
+
+    EXPECT_FLOAT_SIZE_EQ(FloatSize(60, 40), pinchViewport.visibleRect().size());
+    EXPECT_POINT_EQ(IntPoint(50, 0), frame()->view()->scrollPosition());
+    EXPECT_FLOAT_POINT_EQ(FloatPoint(90, 0), pinchViewport.location());
+}
+
 static void disableAcceleratedCompositing(WebSettings* settings)
 {
     PinchViewportTest::configureSettings(settings);