diff options
| -rw-r--r-- | WebKit/android/WebCoreSupport/ChromeClientAndroid.cpp | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/WebKit/android/WebCoreSupport/ChromeClientAndroid.cpp b/WebKit/android/WebCoreSupport/ChromeClientAndroid.cpp index dd608b6..015f9a0 100644 --- a/WebKit/android/WebCoreSupport/ChromeClientAndroid.cpp +++ b/WebKit/android/WebCoreSupport/ChromeClientAndroid.cpp @@ -81,8 +81,28 @@ FloatRect ChromeClientAndroid::pageRect() { notImplemented(); return FloatRect() float ChromeClientAndroid::scaleFactor() { - ASSERT(m_webFrame); - return m_webFrame->density(); + /* Conceptually, we should return the density of the device's screen, + except that we don't really model webkit's notion of drawing. Webkit + expects the drawing context's matrix (plus scale-factor) to reflect the + actually transformation to the pixels, and thus it uses scaleFactor to + perform some pre-rounding in a few places (e.g. HTMLCanvasElement). + + ASSERT(m_webFrame); + return m_webFrame->density(); + + However, in Android we capture the drawing into a displayList, and then + replay that list at various scale factors (sometimes zoomed out, other + times zoomed in for "normal" reading, yet other times at arbitrary + zoom values based on the user's choice). In all of these cases, we do + not re-record the displayList, hence it is usually harmful to perform + any pre-rounding, since we just don't know the actual drawing resolution + at record time. + + Given Android's device-independent drawing model, we always return 1.0 + for this function, and we implement roundToDevicePixels() to be a no-op + so that we don't introduce pre-rounding artifacts during record. + */ + return 1.0f; } void ChromeClientAndroid::focus() { |