| // Copyright 2019 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/base/math_util.h" |
| #include "cc/input/scrollbar.h" |
| #include "cc/input/scrollbar_controller.h" |
| #include "cc/trees/layer_tree_impl.h" |
| |
| namespace cc { |
| ScrollbarController::ScrollbarController( |
| LayerTreeHostImpl* layer_tree_host_impl) |
| : layer_tree_host_impl_(layer_tree_host_impl), |
| scrollbar_scroll_is_active_(false), |
| thumb_drag_in_progress_(false), |
| currently_captured_scrollbar_(nullptr), |
| previous_pointer_position_(gfx::PointF(0, 0)) {} |
| |
| // Performs hit test and prepares scroll deltas that will be used by GSB and |
| // GSU. |
| InputHandlerPointerResult ScrollbarController::HandleMouseDown( |
| const gfx::PointF position_in_widget) { |
| InputHandlerPointerResult scroll_result; |
| LayerImpl* layer_impl = GetLayerHitByPoint(position_in_widget); |
| |
| // If a non-custom scrollbar layer was not found, we return early as there is |
| // no point in setting additional state in the ScrollbarController. |
| if (!(layer_impl && layer_impl->ToScrollbarLayer())) |
| return scroll_result; |
| |
| currently_captured_scrollbar_ = layer_impl->ToScrollbarLayer(); |
| scroll_result.type = PointerResultType::kScrollbarScroll; |
| layer_tree_host_impl_->active_tree()->UpdateScrollbarGeometries(); |
| scroll_result.scroll_offset = |
| GetScrollDeltaFromPointerDown(position_in_widget); |
| previous_pointer_position_ = position_in_widget; |
| scrollbar_scroll_is_active_ = true; |
| if (thumb_drag_in_progress_) { |
| scroll_result.scroll_units = ScrollUnitType::kPrecisePixel; |
| } else { |
| // TODO(arakeri): This needs to be updated to kLine once cc implements |
| // handling it. crbug.com/959441 |
| scroll_result.scroll_units = ScrollUnitType::kPixel; |
| } |
| |
| return scroll_result; |
| } |
| |
| // Performs hit test and prepares scroll deltas that will be used by GSU. |
| InputHandlerPointerResult ScrollbarController::HandleMouseMove( |
| const gfx::PointF position_in_widget) { |
| InputHandlerPointerResult scroll_result; |
| if (!thumb_drag_in_progress_) |
| return scroll_result; |
| |
| scroll_result.type = PointerResultType::kScrollbarScroll; |
| const ScrollbarOrientation orientation = |
| currently_captured_scrollbar_->orientation(); |
| if (orientation == ScrollbarOrientation::VERTICAL) |
| scroll_result.scroll_offset.set_y(position_in_widget.y() - |
| previous_pointer_position_.y()); |
| else |
| scroll_result.scroll_offset.set_x(position_in_widget.x() - |
| previous_pointer_position_.x()); |
| |
| LayerImpl* owner_scroll_layer = |
| layer_tree_host_impl_->active_tree()->ScrollableLayerByElementId( |
| currently_captured_scrollbar_->scroll_element_id()); |
| |
| // Calculating the delta by which the scroller layer should move when |
| // dragging the thumb depends on the following factors: |
| // - scrollbar_track_length |
| // - scrollbar_thumb_length |
| // - scroll_layer_length |
| // - viewport_length |
| // - device_scale_factor |
| // - position_in_widget |
| // |
| // When a thumb drag is in progress, for every pixel that the pointer moves, |
| // the delta for the corresponding scroll_layer needs to be scaled by the |
| // following ratio: |
| // scaled_scroller_to_scrollbar_ratio = |
| // (scroll_layer_length - viewport_length) / |
| // (scrollbar_track_length - scrollbar_thumb_length) |
| // |
| // |<--------------------- scroll_layer_length -------------------------->| |
| // |
| // +------------------------------------------------+...................... |
| // | | . |
| // |<-------------- viewport_length --------------->| . |
| // | | . |
| // | | . |
| // | | . |
| // | | . |
| // | | . |
| // | | . |
| // | | . |
| // | | . |
| // | | . |
| // | |<------- scrollbar_track_length --------->| | . |
| // | | . |
| // +--+-----+----------------------------+-------+--+...................... |
| // |<|| |############################| ||>| |
| // +--+-----+----------------------------+-------+--+ |
| // |
| // |<- scrollbar_thumb_length ->| |
| // |
| layer_tree_host_impl_->active_tree()->UpdateScrollbarGeometries(); |
| float scroll_layer_length = |
| currently_captured_scrollbar_->scroll_layer_length(); |
| float scrollbar_track_length = currently_captured_scrollbar_->TrackLength(); |
| gfx::Rect thumb_rect(currently_captured_scrollbar_->ComputeThumbQuadRect()); |
| float scrollbar_thumb_length = orientation == ScrollbarOrientation::VERTICAL |
| ? thumb_rect.height() |
| : thumb_rect.width(); |
| |
| float viewport_length = |
| orientation == ScrollbarOrientation::VERTICAL |
| ? owner_scroll_layer->scroll_container_bounds().height() |
| : (owner_scroll_layer->scroll_container_bounds().width()); |
| float scaled_scroller_to_scrollbar_ratio = |
| ((scroll_layer_length - viewport_length) / |
| (scrollbar_track_length - scrollbar_thumb_length)) * |
| layer_tree_host_impl_->active_tree()->device_scale_factor(); |
| scroll_result.scroll_offset.Scale(scaled_scroller_to_scrollbar_ratio); |
| previous_pointer_position_ = position_in_widget; |
| // Thumb drags have more granularity and are purely dependent on the pointer |
| // movement. Hence we use kPrecisePixel when dragging the thumb. |
| scroll_result.scroll_units = ScrollUnitType::kPrecisePixel; |
| |
| return scroll_result; |
| } |
| |
| // Performs hit test and prepares scroll deltas that will be used by GSE. |
| InputHandlerPointerResult ScrollbarController::HandleMouseUp( |
| const gfx::PointF position_in_widget) { |
| InputHandlerPointerResult scroll_result; |
| if (scrollbar_scroll_is_active_) { |
| scrollbar_scroll_is_active_ = false; |
| scroll_result.type = PointerResultType::kScrollbarScroll; |
| } |
| thumb_drag_in_progress_ = false; |
| return scroll_result; |
| } |
| |
| // Returns the layer that is hit by the position_in_widget. |
| LayerImpl* ScrollbarController::GetLayerHitByPoint( |
| const gfx::PointF position_in_widget) { |
| LayerTreeImpl* active_tree = layer_tree_host_impl_->active_tree(); |
| gfx::Point viewport_point(position_in_widget.x(), position_in_widget.y()); |
| |
| gfx::PointF device_viewport_point = gfx::ScalePoint( |
| gfx::PointF(viewport_point), active_tree->device_scale_factor()); |
| LayerImpl* layer_impl = |
| active_tree->FindFirstScrollingLayerOrScrollbarThatIsHitByPoint( |
| device_viewport_point); |
| |
| return layer_impl; |
| } |
| |
| int ScrollbarController::GetScrollDeltaForScrollbarPart( |
| ScrollbarPart scrollbar_part) { |
| int scroll_delta = 0; |
| int viewport_length = 0; |
| LayerImpl* owner_scroll_layer = nullptr; |
| |
| switch (scrollbar_part) { |
| case ScrollbarPart::BACK_BUTTON: |
| case ScrollbarPart::FORWARD_BUTTON: |
| scroll_delta = kPixelsPerLineStep; |
| break; |
| case ScrollbarPart::BACK_TRACK: |
| case ScrollbarPart::FORWARD_TRACK: |
| owner_scroll_layer = |
| layer_tree_host_impl_->active_tree()->ScrollableLayerByElementId( |
| currently_captured_scrollbar_->scroll_element_id()); |
| viewport_length = |
| currently_captured_scrollbar_->orientation() == |
| ScrollbarOrientation::VERTICAL |
| ? owner_scroll_layer->scroll_container_bounds().height() |
| : (owner_scroll_layer->scroll_container_bounds().width()); |
| scroll_delta = viewport_length * kMinFractionToStepWhenPaging; |
| break; |
| default: |
| scroll_delta = 0; |
| } |
| return scroll_delta * |
| layer_tree_host_impl_->active_tree()->device_scale_factor(); |
| } |
| |
| // Determines the scroll offsets based on hit test results. |
| gfx::ScrollOffset ScrollbarController::GetScrollDeltaFromPointerDown( |
| const gfx::PointF position_in_widget) { |
| const ScrollbarOrientation orientation = |
| currently_captured_scrollbar_->orientation(); |
| |
| // position_in_widget needs to be transformed and made relative to the |
| // scrollbar layer because hit testing assumes layer relative coordinates. |
| ScrollbarPart scrollbar_part = ScrollbarPart::NO_PART; |
| gfx::Transform inverse_screen_space_transform( |
| gfx::Transform::kSkipInitialization); |
| if (!currently_captured_scrollbar_->ScreenSpaceTransform().GetInverse( |
| &inverse_screen_space_transform)) |
| return gfx::ScrollOffset(0, 0); |
| |
| bool clipped; |
| gfx::PointF scroller_relative_position(MathUtil::ProjectPoint( |
| inverse_screen_space_transform, position_in_widget, &clipped)); |
| |
| if (clipped) |
| return gfx::ScrollOffset(0, 0); |
| |
| scrollbar_part = currently_captured_scrollbar_->IdentifyScrollbarPart( |
| scroller_relative_position); |
| |
| float scroll_delta = GetScrollDeltaForScrollbarPart(scrollbar_part); |
| |
| // See CreateScrollStateForGesture for more information on how these values |
| // will be interpreted. |
| if (scrollbar_part == ScrollbarPart::BACK_BUTTON) { |
| return orientation == ScrollbarOrientation::VERTICAL |
| ? gfx::ScrollOffset(0, -scroll_delta) // Up arrow |
| : gfx::ScrollOffset(-scroll_delta, 0); // Left arrow |
| } else if (scrollbar_part == ScrollbarPart::FORWARD_BUTTON) { |
| return orientation == ScrollbarOrientation::VERTICAL |
| ? gfx::ScrollOffset(0, scroll_delta) // Down arrow |
| : gfx::ScrollOffset(scroll_delta, 0); // Right arrow |
| } else if (scrollbar_part == ScrollbarPart::THUMB) { |
| // Offsets are calculated in HandleMouseMove. |
| thumb_drag_in_progress_ = true; |
| } else if (scrollbar_part == ScrollbarPart::BACK_TRACK) { |
| return orientation == ScrollbarOrientation::VERTICAL |
| ? gfx::ScrollOffset(0, -scroll_delta) // Track click up |
| : gfx::ScrollOffset(-scroll_delta, 0); // Track click left |
| } else if (scrollbar_part == ScrollbarPart::FORWARD_TRACK) { |
| return orientation == ScrollbarOrientation::VERTICAL |
| ? gfx::ScrollOffset(0, scroll_delta) // Track click down |
| : gfx::ScrollOffset(scroll_delta, 0); // Track click right |
| } |
| |
| return gfx::ScrollOffset(0, 0); |
| } |
| |
| } // namespace cc |
