Refine autozoom scaling constants and logic

Source/web/tests/WebFrameTest.cpp

Index: Source/web/tests/WebFrameTest.cpp
diff --git a/Source/web/tests/WebFrameTest.cpp b/Source/web/tests/WebFrameTest.cpp
index 5a07739bca5fa37141c2a6de3287e96a0ab60a76..495821d2ba701bfcf4c32573d6da8525c067c090 100644
--- a/Source/web/tests/WebFrameTest.cpp
+++ b/Source/web/tests/WebFrameTest.cpp
@@ -2871,13 +2871,14 @@ TEST_F(WebFrameTest, DivScrollIntoEditableTest)
     int viewportHeight = 300;
     float leftBoxRatio = 0.3f;
     int caretPadding = 10;
-    float minReadableCaretHeight = 18.0f;
+    float minReadableCaretHeight = 16.0f;
     FrameTestHelpers::WebViewHelper webViewHelper;
     webViewHelper.initializeAndLoad(m_baseURL + "get_scale_for_zoom_into_editable_test.html");
+    webViewHelper.webViewImpl()->page()->settings().setTextAutosizingEnabled(false);
     webViewHelper.webView()->resize(WebSize(viewportWidth, viewportHeight));
-    webViewHelper.webView()->setPageScaleFactorLimits(1, 4);
-    webViewHelper.webView()->layout();
+    webViewHelper.webView()->setPageScaleFactorLimits(0.25f, 4);
     webViewHelper.webView()->setDeviceScaleFactor(1.5f);
+    webViewHelper.webView()->layout();
     webViewHelper.webView()->settings()->setAutoZoomFocusedNodeToLegibleScale(true);
 
     webViewHelper.webViewImpl()->enableFakePageScaleAnimationForTesting(true);
@@ -2894,6 +2895,10 @@ TEST_F(WebFrameTest, DivScrollIntoEditableTest)
     WebRect rect, caret;
     webViewHelper.webViewImpl()->selectionBounds(caret, rect);
 
+    // Set the page scale to be smaller than the minimal readable scale.
+    float initialScale = minReadableCaretHeight / caret.height * 0.5f;
+    setScaleAndScrollAndLayout(webViewHelper.webView(), WebPoint(0, 0), initialScale);
+
     float scale;
     IntPoint scroll;
     bool needAnimation;
@@ -2901,43 +2906,44 @@ TEST_F(WebFrameTest, DivScrollIntoEditableTest)
     EXPECT_TRUE(needAnimation);
     // The edit box should be left aligned with a margin for possible label.
     int hScroll = editBoxWithText.x - leftBoxRatio * viewportWidth / scale;
-    EXPECT_NEAR(hScroll, scroll.x(), 5);
+    EXPECT_NEAR(hScroll, scroll.x(), 2);
     int vScroll = editBoxWithText.y - (viewportHeight / scale - editBoxWithText.height) / 2;
-    EXPECT_NEAR(vScroll, scroll.y(), 1);
+    EXPECT_NEAR(vScroll, scroll.y(), 2);
     EXPECT_NEAR(minReadableCaretHeight / caret.height, scale, 0.1);
 
     // The edit box is wider than the viewport when legible.
     viewportWidth = 200;
     viewportHeight = 150;
     webViewHelper.webView()->resize(WebSize(viewportWidth, viewportHeight));
-    setScaleAndScrollAndLayout(webViewHelper.webView(), WebPoint(0, 0), 1);
-    webViewHelper.webViewImpl()->selectionBounds(caret, rect);
+    setScaleAndScrollAndLayout(webViewHelper.webView(), WebPoint(0, 0), initialScale);
     webViewHelper.webViewImpl()->computeScaleAndScrollForFocusedNode(webViewHelper.webViewImpl()->focusedElement(), scale, scroll, needAnimation);
     EXPECT_TRUE(needAnimation);
     // The caret should be right aligned since the caret would be offscreen when the edit box is left aligned.
     hScroll = caret.x + caret.width + caretPadding - viewportWidth / scale;
-    EXPECT_NEAR(hScroll, scroll.x(), 1);
+    EXPECT_NEAR(hScroll, scroll.x(), 2);
     EXPECT_NEAR(minReadableCaretHeight / caret.height, scale, 0.1);
 
-    setScaleAndScrollAndLayout(webViewHelper.webView(), WebPoint(0, 0), 1);
+    setScaleAndScrollAndLayout(webViewHelper.webView(), WebPoint(0, 0), initialScale);
     // Move focus to edit box with text.
     webViewHelper.webView()->advanceFocus(false);
-    webViewHelper.webViewImpl()->selectionBounds(caret, rect);
     webViewHelper.webViewImpl()->computeScaleAndScrollForFocusedNode(webViewHelper.webViewImpl()->focusedElement(), scale, scroll, needAnimation);
     EXPECT_TRUE(needAnimation);
     // The edit box should be left aligned.
     hScroll = editBoxWithNoText.x;
-    EXPECT_NEAR(hScroll, scroll.x(), 1);
+    EXPECT_NEAR(hScroll, scroll.x(), 2);
     vScroll = editBoxWithNoText.y - (viewportHeight / scale - editBoxWithNoText.height) / 2;
-    EXPECT_NEAR(vScroll, scroll.y(), 1);
+    EXPECT_NEAR(vScroll, scroll.y(), 2);
     EXPECT_NEAR(minReadableCaretHeight / caret.height, scale, 0.1);
 
-    setScaleAndScrollAndLayout(webViewHelper.webViewImpl(), scroll, scale);
-
     // Move focus back to the first edit box.
     webViewHelper.webView()->advanceFocus(true);
+    // Zoom out slightly.
+    const float withinToleranceScale = scale * 0.9f;
+    setScaleAndScrollAndLayout(webViewHelper.webViewImpl(), scroll, withinToleranceScale);
+    // Move focus back to the second edit box.
+    webViewHelper.webView()->advanceFocus(false);
     webViewHelper.webViewImpl()->computeScaleAndScrollForFocusedNode(webViewHelper.webViewImpl()->focusedElement(), scale, scroll, needAnimation);
-    // The position should have stayed the same since this box was already on screen with the right scale.
+    // The scale should not be adjusted as the zoomed out scale was sufficiently close to the previously focused scale.
     EXPECT_FALSE(needAnimation);
 }
 
@@ -2947,13 +2953,14 @@ TEST_F(WebFrameTest, DivScrollIntoEditablePreservePageScaleTest)
 
     const int viewportWidth = 450;
     const int viewportHeight = 300;
-    const float minReadableCaretHeight = 18.0f;
+    const float minReadableCaretHeight = 16.0f;
     FrameTestHelpers::WebViewHelper webViewHelper;
     webViewHelper.initializeAndLoad(m_baseURL + "get_scale_for_zoom_into_editable_test.html");
+    webViewHelper.webViewImpl()->page()->settings().setTextAutosizingEnabled(false);
     webViewHelper.webView()->resize(WebSize(viewportWidth, viewportHeight));
-    webViewHelper.webView()->setPageScaleFactorLimits(1, 4);
-    webViewHelper.webView()->layout();
+    webViewHelper.webView()->setPageScaleFactorLimits(1.f, 4);
     webViewHelper.webView()->setDeviceScaleFactor(1.5f);
+    webViewHelper.webView()->layout();
     webViewHelper.webView()->settings()->setAutoZoomFocusedNodeToLegibleScale(true);
     webViewHelper.webViewImpl()->enableFakePageScaleAnimationForTesting(true);
 
@@ -2966,7 +2973,7 @@ TEST_F(WebFrameTest, DivScrollIntoEditablePreservePageScaleTest)
     WebRect rect, caret;
     webViewHelper.webViewImpl()->selectionBounds(caret, rect);
 
-    // Set page scale twice larger then minimal readable scale
+    // Set the page scale to be twice as large as the minimal readable scale.
     float newScale = minReadableCaretHeight / caret.height * 2.0;
     setScaleAndScrollAndLayout(webViewHelper.webView(), WebPoint(0, 0), newScale);