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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/AlreadyAddRefed.h"
#include "mozilla/dom/Element.h"
#include "nsCOMPtr.h"
#include "nsIContent.h"
#include "nsIDocument.h"
#include "nsIDOMHTMLLIElement.h"
#include "nsIDOMHTMLQuoteElement.h"
#include "nsIDOMWindow.h"
#include "nsIFrame.h"
#include "nsIFrameInlines.h"
#include "nsIPresShell.h"
#include "nsLayoutUtils.h"
#include "nsStyleConsts.h"
namespace mozilla {
namespace layers {
// Returns the DOM element found at |aPoint|, interpreted as being relative to
// the root frame of |aShell|. 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 nsDocument::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 nsCOMPtr<nsIPresShell>& aShell,
const CSSPoint& aPoint)
{
if (nsIFrame* rootFrame = aShell->GetRootFrame()) {
if (nsIFrame* frame = nsLayoutUtils::GetFrameForPoint(rootFrame,
CSSPoint::ToAppUnits(aPoint),
nsLayoutUtils::IGNORE_PAINT_SUPPRESSION |
nsLayoutUtils::IGNORE_ROOT_SCROLL_FRAME)) {
while (frame && (!frame->GetContent() || frame->GetContent()->IsInAnonymousSubtree())) {
frame = nsLayoutUtils::GetParentOrPlaceholderFor(frame);
}
nsIContent* content = frame->GetContent();
if (content && !content->IsElement()) {
content = content->GetParent();
}
if (content) {
nsCOMPtr<dom::Element> result = content->AsElement();
return result.forget();
}
}
}
return nullptr;
}
static bool
ShouldZoomToElement(const nsCOMPtr<dom::Element>& aElement) {
if (nsIFrame* frame = aElement->GetPrimaryFrame()) {
if (frame->GetDisplay() == StyleDisplay::Inline) {
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);
}
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 = 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;
}
}
}
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