sx/library/modules/ui/stacks.sx

#import "modules/std.sx";
#import "modules/math";
#import "modules/ui/types.sx";
#import "modules/ui/render.sx";
#import "modules/ui/events.sx";
#import "modules/ui/view.sx";
#import "modules/ui/layout.sx";

VStack :: struct {
    children: List(ViewChild);
    spacing: f32;
    alignment: HAlignment;

    add :: (self: *VStack, view: View) {
        self.children.append(.{ view = view });
    }
}

impl View for VStack {
    size_that_fits :: (self: *VStack, proposal: ProposedSize) -> Size {
        measure_vstack(@self.children, proposal, self.spacing)
    }

    layout :: (self: *VStack, bounds: Frame) {
        layout_vstack(@self.children, bounds, self.spacing, self.alignment);
    }

    render :: (self: *VStack, ctx: *RenderContext, frame: Frame) {
        i := 0;
        while i < self.children.len {
            child := @self.children.items[i];
            child.view.render(ctx, child.computed_frame);
            i += 1;
        }
    }

    handle_event :: (self: *VStack, event: *Event, frame: Frame) -> bool {
        // Iterate children in reverse (front-to-back for overlapping)
        i := self.children.len - 1;
        while i >= 0 {
            child := @self.children.items[i];
            if child.view.handle_event(event, child.computed_frame) {
                return true;
            }
            i -= 1;
        }
        false
    }
}

HStack :: struct {
    children: List(ViewChild);
    spacing: f32;
    alignment: VAlignment;

    add :: (self: *HStack, view: View) {
        self.children.append(.{ view = view });
    }
}

impl View for HStack {
    size_that_fits :: (self: *HStack, proposal: ProposedSize) -> Size {
        measure_hstack(@self.children, proposal, self.spacing)
    }

    layout :: (self: *HStack, bounds: Frame) {
        layout_hstack(@self.children, bounds, self.spacing, self.alignment);
    }

    render :: (self: *HStack, ctx: *RenderContext, frame: Frame) {
        i := 0;
        while i < self.children.len {
            child := @self.children.items[i];
            child.view.render(ctx, child.computed_frame);
            i += 1;
        }
    }

    handle_event :: (self: *HStack, event: *Event, frame: Frame) -> bool {
        i := self.children.len - 1;
        while i >= 0 {
            child := @self.children.items[i];
            if child.view.handle_event(event, child.computed_frame) {
                return true;
            }
            i -= 1;
        }
        false
    }
}

ZStack :: struct {
    children: List(ViewChild);
    alignment: Alignment;

    add :: (self: *ZStack, view: View) {
        self.children.append(.{ view = view });
    }
}

impl View for ZStack {
    size_that_fits :: (self: *ZStack, proposal: ProposedSize) -> Size {
        measure_zstack(@self.children, proposal)
    }

    layout :: (self: *ZStack, bounds: Frame) {
        layout_zstack(@self.children, bounds, self.alignment);
    }

    render :: (self: *ZStack, ctx: *RenderContext, frame: Frame) {
        // Render back-to-front (first child is bottommost)
        i := 0;
        while i < self.children.len {
            child := @self.children.items[i];
            child.view.render(ctx, child.computed_frame);
            i += 1;
        }
    }

    handle_event :: (self: *ZStack, event: *Event, frame: Frame) -> bool {
        // Handle front-to-back (last child is topmost)
        i := self.children.len - 1;
        while i >= 0 {
            child := @self.children.items[i];
            if child.view.handle_event(event, child.computed_frame) {
                return true;
            }
            i -= 1;
        }
        false
    }
}

// Spacer — fills available space

Spacer :: struct {
    min_length: f32;

}

impl View for Spacer {
    size_that_fits :: (self: *Spacer, proposal: ProposedSize) -> Size {
        w := proposal.width ?? self.min_length;
        h := proposal.height ?? self.min_length;
        Size.{ width = max(w, self.min_length), height = max(h, self.min_length) }
    }

    layout :: (self: *Spacer, bounds: Frame) {}
    render :: (self: *Spacer, ctx: *RenderContext, frame: Frame) {}
    handle_event :: (self: *Spacer, event: *Event, frame: Frame) -> bool { false }
}

// Rect — simple colored rectangle view

RectView :: struct {
    color: Color;
    corner_radius: f32;
    preferred_width: f32;
    preferred_height: f32;

}

impl View for RectView {
    size_that_fits :: (self: *RectView, proposal: ProposedSize) -> Size {
        w := proposal.width ?? self.preferred_width;
        h := proposal.height ?? self.preferred_height;
        Size.{ width = w, height = h }
    }

    layout :: (self: *RectView, bounds: Frame) {}

    render :: (self: *RectView, ctx: *RenderContext, frame: Frame) {
        if self.corner_radius > 0.0 {
            ctx.add_rounded_rect(frame, self.color, self.corner_radius);
        } else {
            ctx.add_rect(frame, self.color);
        }
    }

    handle_event :: (self: *RectView, event: *Event, frame: Frame) -> bool { false }
}