Swap tiles when viewport changes slightly, and properly cap prepare bounds

bug:5738336

Viewport changes that overlap previous viewports will result in fast scrolling
mode being activated.

Change-Id: I356df0054caff19519fcf8543f96726e78918922

3 files changed, 11 insertions, 4 deletions

diff --git a/Source/WebCore/platform/graphics/android/GLWebViewState.cpp b/Source/WebCore/platform/graphics/android/GLWebViewState.cpp
index cf49b9e..710ae25 100644
--- a/Source/WebCore/platform/graphics/android/GLWebViewState.cpp
+++ b/Source/WebCore/platform/graphics/android/GLWebViewState.cpp
@@ -87,6 +87,7 @@ GLWebViewState::GLWebViewState()
     , m_frameworkInval(0, 0, 0, 0)
     , m_frameworkLayersInval(0, 0, 0, 0)
     , m_isScrolling(false)
+    , m_isViewportScrolling(false)
     , m_goingDown(true)
     , m_goingLeft(false)
     , m_expandedTileBoundsX(0)
@@ -246,11 +247,16 @@ int GLWebViewState::baseContentHeight()
 void GLWebViewState::setViewport(SkRect& viewport, float scale)
 {
     if ((m_viewport == viewport) &&
-        (zoomManager()->futureScale() == scale))
+        (zoomManager()->futureScale() == scale)) {
+        m_isViewportScrolling = false;
         return;
+    }
 
     m_goingDown = m_viewport.fTop - viewport.fTop <= 0;
     m_goingLeft = m_viewport.fLeft - viewport.fLeft >= 0;
+
+    // detect viewport scrolling from short programmatic scrolls/jumps
+    m_isViewportScrolling = m_viewport != viewport && SkRect::Intersects(m_viewport, viewport);
     m_viewport = viewport;
 
     XLOG("New VIEWPORT %.2f - %.2f %.2f - %.2f (w: %2.f h: %.2f scale: %.2f currentScale: %.2f futureScale: %.2f)",
diff --git a/Source/WebCore/platform/graphics/android/GLWebViewState.h b/Source/WebCore/platform/graphics/android/GLWebViewState.h
index b4c6dff..d195597 100644
--- a/Source/WebCore/platform/graphics/android/GLWebViewState.h
+++ b/Source/WebCore/platform/graphics/android/GLWebViewState.h
@@ -202,7 +202,7 @@ public:
     unsigned int currentPictureCounter() const { return m_currentPictureCounter; }
 
     void setIsScrolling(bool isScrolling) { m_isScrolling = isScrolling; }
-    bool isScrolling() { return m_isScrolling; }
+    bool isScrolling() { return m_isScrolling || m_isViewportScrolling; }
 
     void drawBackground(Color& backgroundColor);
     double setupDrawing(IntRect& viewRect, SkRect& visibleRect,
@@ -283,6 +283,7 @@ private:
     GLExtras m_glExtras;
 
     bool m_isScrolling;
+    bool m_isViewportScrolling;
     bool m_goingDown;
     bool m_goingLeft;
 
diff --git a/Source/WebCore/platform/graphics/android/TiledPage.cpp b/Source/WebCore/platform/graphics/android/TiledPage.cpp
index 31a0593..452a010 100644
--- a/Source/WebCore/platform/graphics/android/TiledPage.cpp
+++ b/Source/WebCore/platform/graphics/android/TiledPage.cpp
@@ -276,8 +276,8 @@ void TiledPage::prepare(bool goingDown, bool goingLeft, const SkIRect& tileBound
         nbTilesHeight += firstTileY;
         firstTileY = 0;
     }
-    nbTilesWidth = std::min(nbTilesWidth, maxX - firstTileX);
-    nbTilesHeight = std::min(nbTilesHeight, maxY - firstTileY);
+    nbTilesWidth = std::min(nbTilesWidth, maxX - firstTileX + 1);
+    nbTilesHeight = std::min(nbTilesHeight, maxY - firstTileY + 1);
 
     // check against corrupted scale values giving bad height/width (use float to avoid overflow)
     float numTiles = static_cast<float>(nbTilesHeight) * static_cast<float>(nbTilesWidth);