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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "DoubleTapToZoom.h"
#include <algorithm> // for std::min, std::max
#include "mozilla/PresShell.h"
#include "mozilla/AlreadyAddRefed.h"
#include "mozilla/dom/Element.h"
#include "nsCOMPtr.h"
#include "nsIContent.h"
#include "mozilla/dom/Document.h"
#include "nsIFrame.h"
#include "nsIFrameInlines.h"
#include "nsIScrollableFrame.h"
#include "nsLayoutUtils.h"
#include "nsStyleConsts.h"
namespace mozilla {
namespace layers {
namespace {
using FrameForPointOption = nsLayoutUtils::FrameForPointOption;
// Returns the DOM element found at |aPoint|, interpreted as being relative to
// the root frame of |aPresShell| in visual coordinates. If the point is inside
// a subdocument, returns an element inside the subdocument, rather than the
// subdocument element (and does so recursively). The implementation was adapted
// from DocumentOrShadowRoot::ElementFromPoint(), with the notable exception
// that we don't pass nsLayoutUtils::IGNORE_CROSS_DOC to GetFrameForPoint(), so
// as to get the behaviour described above in the presence of subdocuments.
static already_AddRefed<dom::Element> ElementFromPoint(
const RefPtr<PresShell>& aPresShell, const CSSPoint& aPoint) {
nsIFrame* rootFrame = aPresShell->GetRootFrame();
if (!rootFrame) {
return nullptr;
}
nsIFrame* frame = nsLayoutUtils::GetFrameForPoint(
RelativeTo{rootFrame, ViewportType::Visual}, CSSPoint::ToAppUnits(aPoint),
{{FrameForPointOption::IgnorePaintSuppression}});
while (frame && (!frame->GetContent() ||
frame->GetContent()->IsInNativeAnonymousSubtree())) {
frame = nsLayoutUtils::GetParentOrPlaceholderFor(frame);
}
if (!frame) {
return nullptr;
}
// FIXME(emilio): This should probably use the flattened tree, GetParent() is
// not guaranteed to be an element in presence of shadow DOM.
nsIContent* content = frame->GetContent();
if (!content) {
return nullptr;
}
if (dom::Element* element = content->GetAsElementOrParentElement()) {
return do_AddRef(element);
}
return nullptr;
}
static bool ShouldZoomToElement(const nsCOMPtr<dom::Element>& aElement) {
if (nsIFrame* frame = aElement->GetPrimaryFrame()) {
if (frame->StyleDisplay()->IsInlineFlow()) {
return false;
}
}
if (aElement->IsAnyOfHTMLElements(nsGkAtoms::li, nsGkAtoms::q)) {
return false;
}
return true;
}
static bool IsRectZoomedIn(const CSSRect& aRect,
const CSSRect& aCompositedArea) {
// This functions checks to see if the area of the rect visible in the
// composition bounds (i.e. the overlapArea variable below) is approximately
// the max area of the rect we can show.
CSSRect overlap = aCompositedArea.Intersect(aRect);
float overlapArea = overlap.Width() * overlap.Height();
float availHeight = std::min(
aRect.Width() * aCompositedArea.Height() / aCompositedArea.Width(),
aRect.Height());
float showing = overlapArea / (aRect.Width() * availHeight);
float ratioW = aRect.Width() / aCompositedArea.Width();
float ratioH = aRect.Height() / aCompositedArea.Height();
return showing > 0.9 && (ratioW > 0.9 || ratioH > 0.9);
}
} // namespace
CSSRect CalculateRectToZoomTo(const RefPtr<dom::Document>& 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;
RefPtr<PresShell> presShell = aRootContentDocument->GetPresShell();
if (!presShell) {
return zoomOut;
}
nsIScrollableFrame* rootScrollFrame =
presShell->GetRootScrollFrameAsScrollable();
if (!rootScrollFrame) {
return zoomOut;
}
nsCOMPtr<dom::Element> element = ElementFromPoint(presShell, aPoint);
if (!element) {
return zoomOut;
}
while (element && !ShouldZoomToElement(element)) {
element = element->GetParentElement();
}
if (!element) {
return zoomOut;
}
FrameMetrics metrics =
nsLayoutUtils::CalculateBasicFrameMetrics(rootScrollFrame);
CSSPoint visualScrollOffset = metrics.GetVisualScrollOffset();
CSSRect compositedArea(visualScrollOffset,
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.YMost()) {
rect.MoveByY(rect.Height() - targetHeight);
} else if (newY > rect.Y()) {
rect.MoveToY(newY);
}
rect.SetHeight(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.SetWidth(
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 = visualScrollOffset.y + aPoint.y;
if ((rect.Height() > rounded.Height()) &&
(cssTapY > rounded.Y() + (rounded.Height() * 1.2))) {
rounded.MoveToY(cssTapY - (rounded.Height() / 2));
}
return rounded;
}
} // namespace layers
} // namespace mozilla
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