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#include "cru/ui/render/ScrollRenderObject.hpp"
#include "cru/platform/graph/Painter.hpp"
#include "cru/platform/graph/util/Painter.hpp"
#include <algorithm>
namespace cru::ui::render {
namespace {
// This method assumes margin offset is already considered.
// It promises that it won't return negetive value.
Point CalculateChildOffsetOfScroll(const Point& scroll_offset,
const Size& content_area_size,
const Thickness& padding,
const Size& child_size) {
Point result(scroll_offset);
Point max_scroll(child_size - content_area_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, scroll_offset.x);
coerce(result.y, scroll_offset.y);
result.x += padding.left;
result.y += padding.top;
return result;
}
} // namespace
void ScrollRenderObject::Draw(platform::graph::IPainter* painter) {
for (auto child : this->GetChildren()) {
painter->PushLayer(this->GetPaddingRect());
const auto true_offset =
CalculateChildOffsetOfScroll(scroll_offset_, GetContentRect().GetSize(),
GetPadding(), child->GetSize());
platform::graph::util::WithTransform(
painter, Matrix::Translation(true_offset.x, true_offset.y),
[child](platform::graph::IPainter* p) { child->Draw(p); });
painter->PopLayer();
}
}
RenderObject* ScrollRenderObject::HitTest(const Point& point) {
const auto rect = GetPaddingRect();
return rect.IsPointInside(point) ? this : nullptr;
}
void ScrollRenderObject::SetScrollOffset(const Point& offset) {
scroll_offset_ = offset;
InvalidatePaint();
}
Size ScrollRenderObject::OnMeasureContent(
const MeasureRequirement& requirement) {
CRU_UNUSED(requirement);
// TODO!
// const auto& children = GetChildren();
// if (children.empty()) return Size{};
// const auto child = children.front();
// child->Measure(MeasureRequirement::Infinate());
// const auto preferred_size = child->GetMeasuredSize();
return Size{};
} // namespace cru::ui::render
void ScrollRenderObject::OnLayoutContent(const Rect& content_rect) {
CRU_UNUSED(content_rect);
// TODO!
}
} // namespace cru::ui::render
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