[Android WebView] Update viewport size and scale calculation to match WebView Classic

Source/WebKit/chromium/src/ChromeClientImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * 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.
@@ skipping 638 matching lines @@
     if (!viewportSize.width() || !viewportSize.height())
         return;
 
     ViewportAttributes computed = arguments.resolve(viewportSize, viewportSize, m_webView->page()->settings()->layoutFallbackWidth());
     restrictScaleFactorToInitialScaleIfNotUserScalable(computed);
 
     if (m_webView->ignoreViewportTagMaximumScale()) {
         computed.maximumScale = max(computed.maximumScale, m_webView->maxPageScaleFactor);
         computed.userScalable = true;
     }
-    if (arguments.zoom == ViewportArguments::ValueAuto && !m_webView->settingsImpl()->initializeAtMinimumPageScale())
-        computed.initialScale = 1.0f;
-
+    float initialScale = computed.initialScale;
+    if (arguments.zoom == ViewportArguments::ValueAuto && !m_webView->settingsImpl()->initializeAtMinimumPageScale()) {
+        if (arguments.width == ViewportArguments::ValueAuto
+            || (m_webView->settingsImpl()->useWideViewport()
+                && arguments.width != ViewportArguments::ValueAuto && arguments.width != ViewportArguments::ValueDeviceWidth))
+            computed.initialScale = 1.0f;
+    }
     if (m_webView->settingsImpl()->supportDeprecatedTargetDensityDPI()) {
+        bool applyTargetDensityDpiToLayoutSize = true;

[abarth-chromium, 2013/04/15 23:33:57]

Dpi -> DPI

[mnaganov (inactive), 2013/04/16 14:41:26]

Done.

+        if (!m_webView->settingsImpl()->useWideViewport()) {
+            if (arguments.zoom == ViewportArguments::ValueAuto)
+                computed.layoutSize.setWidth(viewportSize.width());
+            else
+                computed.layoutSize.setWidth(viewportSize.width() / initialScale);
+        } else {
+            if (arguments.width == ViewportArguments::ValueAuto && arguments.zoom != 1.0f) {
+                computed.layoutSize.setWidth(m_webView->page()->settings()->layoutFallbackWidth());
+                applyTargetDensityDpiToLayoutSize = false;
+            }
+            if (arguments.width != ViewportArguments::ValueAuto && arguments.width != ViewportArguments::ValueDeviceWidth)
+                applyTargetDensityDpiToLayoutSize = false;
+        }

[abarth-chromium, 2013/04/15 23:33:57]

Why does this need to be so complicated?  Can we structure this code a bit more
(maybe using inline helper functions) to make it more clear what's going on?

[mnaganov (inactive), 2013/04/16 14:41:26]

I compared the resulting scales and widths of old and new WebViews in different
combinations of settings and meta viewport arguments, and this was required to
align them.

I brushed this logic a bit, getting rid of this boolean var, and extracting one
case into an inline function. The result is shorter and looks a bit simpler.

I would like to somehow bring this logic on WebView implementation side, but I
have no idea how to do this yet.

         float targetDensityDPIFactor = calculateTargetDensityDPIFactor(arguments, deviceScaleFactor);
         computed.initialScale *= targetDensityDPIFactor;
         computed.minimumScale *= targetDensityDPIFactor;
         computed.maximumScale *= targetDensityDPIFactor;
-        computed.layoutSize.scale(1.0f / targetDensityDPIFactor);
+        if (applyTargetDensityDpiToLayoutSize)
+            computed.layoutSize.scale(1.0f / targetDensityDPIFactor);
     }
 
     m_webView->setInitialPageScaleFactor(computed.initialScale);
     m_webView->setFixedLayoutSize(flooredIntSize(computed.layoutSize));
     m_webView->setDeviceScaleFactor(deviceScaleFactor);
     m_webView->setPageScaleFactorLimits(computed.minimumScale, computed.maximumScale);
 #endif
 }
 
 void ChromeClientImpl::print(Frame* frame)
@@ skipping 505 matching lines @@
 {
 }
 
 void NavigatorContentUtilsClientImpl::registerProtocolHandler(const String& scheme, const String& baseURL, const String& url, const String& title)
 { 
     m_webView->client()->registerProtocolHandler(scheme, baseURL, url, title);
 } 
 #endif
 
 } // namespace WebKit