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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "cc/layers/scrollbar_layer_impl_base.h"
#include <algorithm>
#include "cc/layers/layer.h"
#include "ui/gfx/rect_conversions.h"
namespace cc {
ScrollbarLayerImplBase::ScrollbarLayerImplBase(
LayerTreeImpl* tree_impl,
int id,
ScrollbarOrientation orientation,
bool is_left_side_vertical_scrollbar)
: LayerImpl(tree_impl, id),
scroll_layer_id_(Layer::INVALID_ID),
is_overlay_scrollbar_(false),
thumb_thickness_scale_factor_(1.f),
current_pos_(0.f),
maximum_(0),
orientation_(orientation),
is_left_side_vertical_scrollbar_(is_left_side_vertical_scrollbar),
vertical_adjust_(0.f),
visible_to_total_length_ratio_(1.f) {}
void ScrollbarLayerImplBase::PushPropertiesTo(LayerImpl* layer) {
LayerImpl::PushPropertiesTo(layer);
}
ScrollbarLayerImplBase* ScrollbarLayerImplBase::ToScrollbarLayer() {
return this;
}
gfx::Rect ScrollbarLayerImplBase::ScrollbarLayerRectToContentRect(
gfx::RectF layer_rect) const {
// Don't intersect with the bounds as in LayerRectToContentRect() because
// layer_rect here might be in coordinates of the containing layer.
gfx::RectF content_rect = gfx::ScaleRect(layer_rect,
contents_scale_x(),
contents_scale_y());
return gfx::ToEnclosingRect(content_rect);
}
void ScrollbarLayerImplBase::SetCurrentPos(float current_pos) {
if (current_pos_ == current_pos)
return;
current_pos_ = current_pos;
NoteLayerPropertyChanged();
}
void ScrollbarLayerImplBase::SetMaximum(int maximum) {
if (maximum_ == maximum)
return;
maximum_ = maximum;
NoteLayerPropertyChanged();
}
void ScrollbarLayerImplBase::SetVerticalAdjust(float vertical_adjust) {
if (vertical_adjust_ == vertical_adjust)
return;
vertical_adjust_ = vertical_adjust;
NoteLayerPropertyChanged();
}
void ScrollbarLayerImplBase::SetVisibleToTotalLengthRatio(float ratio) {
if (visible_to_total_length_ratio_ == ratio)
return;
visible_to_total_length_ratio_ = ratio;
NoteLayerPropertyChanged();
}
gfx::Rect ScrollbarLayerImplBase::ComputeThumbQuadRect() const {
// Thumb extent is the length of the thumb in the scrolling direction, thumb
// thickness is in the perpendicular direction. Here's an example of a
// horizontal scrollbar - inputs are above the scrollbar, computed values
// below:
//
// |<------------------- track_length_ ------------------->|
//
// |--| <-- start_offset
//
// +--+----------------------------+------------------+-------+--+
// |<|| |##################| ||>|
// +--+----------------------------+------------------+-------+--+
//
// |<- thumb_length ->|
//
// |<------- thumb_offset -------->|
//
// For painted, scrollbars, the length is fixed. For solid color scrollbars we
// have to compute it. The ratio of the thumb's length to the track's length
// is the same as that of the visible viewport to the total viewport, unless
// that would make the thumb's length less than its thickness.
//
// vertical_adjust_ is used when the layer geometry from the main thread is
// not in sync with what the user sees. For instance on Android scrolling the
// top bar controls out of view reveals more of the page content. We want the
// root layer scrollbars to reflect what the user sees even if we haven't
// received new layer geometry from the main thread. If the user has scrolled
// down by 50px and the initial viewport size was 950px the geometry would
// look something like this:
//
// vertical_adjust_ = 50, scroll position 0, visible ratios 99%
// Layer geometry: Desired thumb positions:
// +--------------------+-+ +----------------------+ <-- 0px
// | |v| | #|
// | |e| | #|
// | |r| | #|
// | |t| | #|
// | |i| | #|
// | |c| | #|
// | |a| | #|
// | |l| | #|
// | | | | #|
// | |l| | #|
// | |a| | #|
// | |y| | #|
// | |e| | #|
// | |r| | #|
// +--------------------+-+ | #|
// | horizontal layer | | | #|
// +--------------------+-+ | #| <-- 950px
// | | | #|
// | | |##################### |
// +----------------------+ +----------------------+ <-- 1000px
//
// The layer geometry is set up for a 950px tall viewport, but the user can
// actually see down to 1000px. Thus we have to move the quad for the
// horizontal scrollbar down by the vertical_adjust_ factor and lay the
// vertical thumb out on a track lengthed by the vertical_adjust_ factor. This
// means the quads may extend outside the layer's bounds.
// With the length known, we can compute the thumb's position.
float track_length = TrackLength();
int thumb_length = ThumbLength();
int thumb_thickness = ThumbThickness();
// With the length known, we can compute the thumb's position.
float clamped_current_pos =
std::min(std::max(current_pos_, 0.f), static_cast<float>(maximum_));
float ratio = clamped_current_pos / maximum_;
float max_offset = track_length - thumb_length;
int thumb_offset = static_cast<int>(ratio * max_offset) + TrackStart();
float thumb_thickness_adjustment =
thumb_thickness * (1.f - thumb_thickness_scale_factor_);
gfx::RectF thumb_rect;
if (orientation_ == HORIZONTAL) {
thumb_rect = gfx::RectF(thumb_offset,
vertical_adjust_ + thumb_thickness_adjustment,
thumb_length,
thumb_thickness - thumb_thickness_adjustment);
} else {
thumb_rect = gfx::RectF(
is_left_side_vertical_scrollbar_
? bounds().width() - thumb_thickness
: thumb_thickness_adjustment,
thumb_offset,
thumb_thickness - thumb_thickness_adjustment,
thumb_length);
}
return ScrollbarLayerRectToContentRect(thumb_rect);
}
} // namespace cc
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