feat(ui): add ScrollView widget and dynamic layout on resize

Introduces a ScrollView widget with mouse wheel support and viewport clipping.
Credits and screenshot screens now use it and recompute layout on window resize.
Offset storage switched from ivec2 to vec2 with new accessors.

src/ui/scroll_view.cpp

@@ -0,0 +1,112 @@
+#include "Cubed/ui/scroll_view.hpp"
+
+#include "Cubed/render/renderer.hpp"
+#include "Cubed/tools/log.hpp"
+#include "Cubed/ui/column_layout.hpp"
+
+#include <algorithm>
+#include <glad/glad.h>
+namespace Cubed {
+ScrollView::ScrollView(Widget* parent) : Widget(parent) {}
+ScrollView::~ScrollView() {}
+
+void ScrollView::render(Renderer& renderer) {
+    if (!m_visible)
+        return;
+    auto p = pos();
+    float h = height();
+    float w = width();
+
+    // convert window coords to framebuffer coords for scissor.
+    float sx = renderer.window_width() > 0
+                   ? renderer.frame_width() / renderer.window_width()
+                   : 1.0f;
+    float sy = renderer.window_height() > 0
+                   ? renderer.frame_height() / renderer.window_height()
+                   : 1.0f;
+
+    GLint scissor_x = static_cast<GLint>(p.x * sx);
+    GLint scissor_y = static_cast<GLint>((m_window_height - p.y - h) * sy);
+    GLsizei scissor_w = static_cast<GLsizei>(std::max(0.0f, w * sx));
+    GLsizei scissor_h = static_cast<GLsizei>(std::max(0.0f, h * sy));
+
+    glEnable(GL_SCISSOR_TEST);
+    glScissor(scissor_x, scissor_y, scissor_w, scissor_h);
+
+    Widget::render(renderer);
+
+    glDisable(GL_SCISSOR_TEST);
+}
+
+float ScrollView::width() const {
+    if (Widget::width() > 0) {
+        return Widget::width();
+    }
+    if (m_child) {
+        return m_child->width();
+    }
+    return 0.0f;
+}
+
+float ScrollView::height() const {
+    if (Widget::height() > 0) {
+        return Widget::height();
+    }
+    Logger::warn("You should set Scroll view height!");
+    if (m_parent) {
+        return m_parent->height();
+    }
+    return m_window_height;
+}
+
+ScrollView& ScrollView::set_child(std::unique_ptr<ColumnLayout> children) {
+    Widget::children().clear();
+    m_child = children.get();
+    Widget::children().emplace_back(std::move(children));
+    m_child->set_offset({0, 0});
+    m_child->set_fill_height(false);
+    m_child->set_fill_parent(false);
+    m_child->set_fill_width(false);
+    return *this;
+}
+
+bool ScrollView::handle_mouse_move_event(const MouseMoveEvent& e) {
+    if (Widget::handle_mouse_move_event(e)) {
+        return true;
+    }
+    auto p = pos();
+    if (e.xpos >= p.x && e.xpos <= p.x + width() && e.ypos >= p.y &&
+        e.ypos <= p.y + height()) {
+        m_hovered = true;
+        return true;
+    }
+    m_hovered = false;
+    return false;
+}
+
+bool ScrollView::handle_mouse_wheel_event(const MouseWheelEvent& e) {
+    if (m_hovered && m_child) {
+        float c_height = m_child->height();
+        float offset = m_child->get_offset().y;
+        float viewport = height();
+        float max_offset = std::max(0.0f, c_height - viewport);
+        float new_offset =
+            std::clamp(offset + e.offset * m_scroll_speed, -max_offset, 0.0f);
+        m_child->set_offset({0, new_offset});
+        return true;
+    }
+    return Widget::handle_mouse_wheel_event(e);
+}
+Widget& ScrollView::set_fill_parent(bool) {
+    Logger::warn("You should not use this function in scroll view!");
+    return *this;
+}
+Widget& ScrollView::set_fill_width(bool) {
+    Logger::warn("You should not use this function in scroll view!");
+    return *this;
+}
+Widget& ScrollView::set_fill_height(bool) {
+    Logger::warn("You should not use this function in scroll view!");
+    return *this;
+}
+} // namespace Cubed