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#include "cru/ui/render/ScrollRenderObject.hpp"
#include "cru/platform/graphics/Painter.hpp"
#include "cru/platform/graphics/util/Painter.hpp"
#include "cru/ui/Base.hpp"
#include "cru/ui/controls/Control.hpp"
#include "cru/ui/render/ScrollBar.hpp"
#include <algorithm>
#include <memory>
#include <optional>
namespace cru::ui::render {
constexpr float kLineHeight = 16;
namespace {
// This method assumes margin offset is already considered.
// It promises that it won't return negetive value.
Point CoerceScroll(const Point& scroll_offset, const Size& content_size,
const Size& child_size) {
Point result(scroll_offset);
Point max_scroll(child_size - content_size);
max_scroll.x = std::max(max_scroll.x, 0.f);
max_scroll.y = std::max(max_scroll.y, 0.f);
auto coerce = [](float& n, float max) {
if (n < 0)
n = 0;
else if (n > max)
n = max;
};
coerce(result.x, max_scroll.x);
coerce(result.y, max_scroll.y);
return result;
}
} // namespace
ScrollRenderObject::ScrollRenderObject() : RenderObject(ChildMode::Single) {
scroll_bar_delegate_ = std::make_unique<ScrollBarDelegate>(this);
scroll_bar_delegate_->ScrollAttemptEvent()->AddHandler(
[this](const struct Scroll& scroll) { this->Scroll(scroll); });
}
void ScrollRenderObject::Scroll(const struct Scroll& scroll) {
auto direction = scroll.direction;
switch (scroll.kind) {
case ScrollKind::Absolute:
SetScrollOffset(direction, scroll.value);
break;
case ScrollKind::Relative:
SetScrollOffset(direction,
GetScrollOffset(scroll.direction) + scroll.value);
break;
case ScrollKind::Page:
SetScrollOffset(direction, GetScrollOffset(direction) +
(direction == Direction::Horizontal
? GetViewRect().width
: GetViewRect().height) *
scroll.value);
break;
case ScrollKind::Line:
SetScrollOffset(direction,
GetScrollOffset(direction) + kLineHeight * scroll.value);
break;
default:
break;
}
}
RenderObject* ScrollRenderObject::HitTest(const Point& point) {
if (const auto child = GetSingleChild()) {
const auto offset = child->GetOffset();
const auto r = child->HitTest(point - offset);
if (r != nullptr) return r;
}
const auto rect = GetPaddingRect();
return rect.IsPointInside(point) ? this : nullptr;
} // namespace cru::ui::render
void ScrollRenderObject::OnDrawCore(platform::graphics::IPainter* painter) {
DefaultDrawContent(painter);
if (const auto child = GetSingleChild()) {
painter->PushLayer(this->GetContentRect());
const auto offset = child->GetOffset();
platform::graphics::util::WithTransform(
painter, Matrix::Translation(offset.x, offset.y),
[child](platform::graphics::IPainter* p) { child->Draw(p); });
painter->PopLayer();
}
scroll_bar_delegate_->DrawScrollBar(painter);
}
Point ScrollRenderObject::GetScrollOffset() {
if (const auto child = GetSingleChild())
return CoerceScroll(scroll_offset_, GetContentRect().GetSize(),
child->GetSize());
else
return scroll_offset_;
}
void ScrollRenderObject::SetScrollOffset(const Point& offset) {
scroll_offset_ = offset;
InvalidateLayout();
}
void ScrollRenderObject::SetScrollOffset(std::optional<float> x,
std::optional<float> y) {
bool dirty = false;
if (x.has_value()) {
dirty = true;
scroll_offset_.x = *x;
}
if (y.has_value()) {
dirty = true;
scroll_offset_.y = *y;
}
if (dirty) InvalidateLayout();
}
void ScrollRenderObject::ScrollToContain(const Rect& rect,
const Thickness& margin) {
std::optional<float> new_scroll_x;
std::optional<float> new_scroll_y;
Rect real_rect = rect.Expand(margin);
Rect view_rect = GetViewRect();
// horizontal
if (real_rect.left < view_rect.left) {
new_scroll_x = real_rect.left;
} else if (real_rect.GetRight() > view_rect.GetRight()) {
new_scroll_x = real_rect.GetRight() - view_rect.width;
}
// vertical
if (real_rect.top < view_rect.top) {
new_scroll_y = real_rect.top;
} else if (real_rect.GetBottom() > view_rect.GetBottom()) {
new_scroll_y = real_rect.GetBottom() - view_rect.height;
}
SetScrollOffset(new_scroll_x, new_scroll_y);
}
Size ScrollRenderObject::OnMeasureContent(const MeasureRequirement& requirement,
const MeasureSize& preferred_size) {
if (const auto child = GetSingleChild()) {
child->Measure(MeasureRequirement{MeasureSize::NotSpecified(),
MeasureSize::NotSpecified()},
MeasureSize::NotSpecified());
Size result = requirement.Coerce(child->GetSize());
if (preferred_size.width.IsSpecified()) {
result.width = preferred_size.width.GetLengthOrUndefined();
}
if (preferred_size.height.IsSpecified()) {
result.height = preferred_size.height.GetLengthOrUndefined();
}
return result;
} else {
Size result{preferred_size.width.IsSpecified()
? preferred_size.width.GetLengthOrUndefined()
: requirement.min.width.GetLengthOr0(),
preferred_size.height.IsSpecified()
? preferred_size.height.GetLengthOrUndefined()
: requirement.min.height.GetLengthOr0()};
return result;
}
} // namespace cru::ui::render
void ScrollRenderObject::OnLayoutContent(const Rect& content_rect) {
if (const auto child = GetSingleChild()) {
child->Layout(content_rect.GetLeftTop() - GetScrollOffset());
}
}
void ScrollRenderObject::OnAttachedControlChanged(controls::Control* control) {
if (control) {
scroll_bar_delegate_->InstallHandlers(control);
} else {
scroll_bar_delegate_->UninstallHandlers();
}
}
} // namespace cru::ui::render
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