CSSRect
CalculateRectToZoomTo(const nsCOMPtr<nsIDocument>& aRootContentDocument,
const CSSPoint& aPoint)
{
// Ensure the layout information we get is up-to-date.
aRootContentDocument->FlushPendingNotifications(FlushType::Layout);
// An empty rect as return value is interpreted as "zoom out".
const CSSRect zoomOut;
nsCOMPtr<nsIPresShell> shell = aRootContentDocument->GetShell();
if (!shell) {
return zoomOut;
}
nsIScrollableFrame* rootScrollFrame = shell->GetRootScrollFrameAsScrollable();
if (!rootScrollFrame) {
return zoomOut;
}
nsCOMPtr<dom::Element> element = ElementFromPoint(shell, aPoint);
if (!element) {
return zoomOut;
}
while (element && !ShouldZoomToElement(element)) {
element = element->GetParentElement();
}
if (!element) {
return zoomOut;
}
FrameMetrics metrics = nsLayoutUtils::CalculateBasicFrameMetrics(rootScrollFrame);
CSSRect compositedArea(metrics.GetScrollOffset(), metrics.CalculateCompositedSizeInCssPixels());
const CSSCoord margin = 15;
CSSRect rect = nsLayoutUtils::GetBoundingContentRect(element, rootScrollFrame);
// If the element is taller than the visible area of the page scale
// the height of the |rect| so that it has the same aspect ratio as
// the root frame. The clipped |rect| is centered on the y value of
// the touch point. This allows tall narrow elements to be zoomed.
if (!rect.IsEmpty() && compositedArea.width > 0.0f) {
const float widthRatio = rect.width / compositedArea.width;
float targetHeight = compositedArea.height * widthRatio;
if (widthRatio < 0.9 && targetHeight < rect.height) {
const CSSPoint scrollPoint = CSSPoint::FromAppUnits(rootScrollFrame->GetScrollPosition());
float newY = aPoint.y + scrollPoint.y - (targetHeight * 0.5f);
if ((newY + targetHeight) > (rect.y + rect.height)) {
rect.y += rect.height - targetHeight;
} else if (newY > rect.y) {
rect.y = newY;
}
rect.height = targetHeight;
}
}
rect = CSSRect(std::max(metrics.GetScrollableRect().x, rect.x - margin),
rect.y,
rect.width + 2 * margin,
rect.height);
// Constrict the rect to the screen's right edge
rect.width = std::min(rect.width, metrics.GetScrollableRect().XMost() - rect.x);
// If the rect is already taking up most of the visible area and is
// stretching the width of the page, then we want to zoom out instead.
if (IsRectZoomedIn(rect, compositedArea)) {
return zoomOut;
}
CSSRect rounded(rect);
rounded.Round();
// If the block we're zooming to is really tall, and the user double-tapped
// more than a screenful of height from the top of it, then adjust the
// y-coordinate so that we center the actual point the user double-tapped
// upon. This prevents flying to the top of the page when double-tapping
// to zoom in (bug 761721). The 1.2 multiplier is just a little fuzz to
// compensate for 'rect' including horizontal margins but not vertical ones.
CSSCoord cssTapY = metrics.GetScrollOffset().y + aPoint.y;
if ((rect.height > rounded.height) && (cssTapY > rounded.y + (rounded.height * 1.2))) {
rounded.y = cssTapY - (rounded.height / 2);
}
return rounded;
}
CSSRect
CalculateRectToZoomTo(const nsCOMPtr<nsIDocument>& aRootContentDocument,
const CSSPoint& aPoint)
{
// Ensure the layout information we get is up-to-date.
aRootContentDocument->FlushPendingNotifications(Flush_Layout);
// An empty rect as return value is interpreted as "zoom out".
const CSSRect zoomOut;
nsCOMPtr<nsIPresShell> shell = aRootContentDocument->GetShell();
if (!shell) {
return zoomOut;
}
nsIScrollableFrame* rootScrollFrame = shell->GetRootScrollFrameAsScrollable();
if (!rootScrollFrame) {
return zoomOut;
}
nsCOMPtr<dom::Element> element = ElementFromPoint(shell, aPoint);
if (!element) {
return zoomOut;
}
while (element && !ShouldZoomToElement(element)) {
element = element->GetParentElement();
}
if (!element) {
return zoomOut;
}
FrameMetrics metrics = nsLayoutUtils::CalculateBasicFrameMetrics(rootScrollFrame);
CSSRect compositedArea(metrics.GetScrollOffset(), metrics.CalculateCompositedSizeInCssPixels());
const CSSCoord margin = 15;
CSSRect rect = GetBoundingContentRect(shell, element, rootScrollFrame);
rect = CSSRect(std::max(metrics.GetScrollableRect().x, rect.x - margin),
rect.y,
rect.width + 2 * margin,
rect.height);
// Constrict the rect to the screen's right edge
rect.width = std::min(rect.width, metrics.GetScrollableRect().XMost() - rect.x);
// If the rect is already taking up most of the visible area and is
// stretching the width of the page, then we want to zoom out instead.
if (IsRectZoomedIn(rect, compositedArea)) {
return zoomOut;
}
CSSRect rounded(rect);
rounded.Round();
// If the block we're zooming to is really tall, and the user double-tapped
// more than a screenful of height from the top of it, then adjust the
// y-coordinate so that we center the actual point the user double-tapped
// upon. This prevents flying to the top of the page when double-tapping
// to zoom in (bug 761721). The 1.2 multiplier is just a little fuzz to
// compensate for 'rect' including horizontal margins but not vertical ones.
CSSCoord cssTapY = metrics.GetScrollOffset().y + aPoint.y;
if ((rect.height > rounded.height) && (cssTapY > rounded.y + (rounded.height * 1.2))) {
rounded.y = cssTapY - (rounded.height / 2);
}
return rounded;
}
