LlamaCasty/ViewModels/MainViewModel.Zoom.cs

using System;
using System.Linq;
using System.Windows;
using ytLive.Models;

namespace ytLive.ViewModels;

/// <summary>
/// The zoom box (creator-corrected model, 2026-10-08): right-clicking the live
/// preview anchors a CAPTURE window — the box/2 region centred on the click — and
/// parks a movable 2x magnifier box on screen. The box shows a live, always-on,
/// magnified view of that anchored capture region (the CLICKED area, never re-follows
/// the box); dragging it only repositions the box. The content is composited LAST
/// (layer n+1) by <see cref="Services.Compositor.SceneCompositor"/> from the already-
/// composed frame, so it captures every layer — prove it with the ZoomMagnifierTests
/// banded-buffer "box over blue shows green" proof. The transient
/// <see cref="ZoomSceneElement"/> carries the box placement + capture anchor; the
/// output crop stays the normal tier (the box is NEVER the crop source).
/// </summary>
public partial class MainViewModel
{
    public void ActivateZoom(double clickX, double clickY)
    {
        var maxW = MasterFrameWidth * 0.7;
        var maxH = MasterFrameHeight * 0.7;
        double w, h;
        switch (_zoomShape)
        {
            case ZoomShape.Circle:
                var size = Math.Min(maxW, maxH);
                w = size; h = size;
                break;
            case ZoomShape.VerticalRectangle:
                h = maxH;
                w = h * 9.0 / 16.0;
                break;
            default:
                // HorizontalRectangle: 4:3 per creator ("more of a 640x480 aspect
                // ratio") — NOT the 16:9 of the first cut, which read as a square.
                h = maxH;
                w = h * 4.0 / 3.0;
                break;
        }

        // The box AND the capture are both centred on the click; the capture window
        // is the box/2 interior and is FIXED after this call. Each is clamped to the
        // master 1920x1080 frame independently (an edge click can push the capture
        // toward centre while the box still sits right at the edge).
        var x = Math.Clamp(clickX - w / 2, 0, MasterFrameWidth - w);
        var y = Math.Clamp(clickY - h / 2, 0, MasterFrameHeight - h);
        var capX = Math.Clamp(clickX - w / 4, 0, MasterFrameWidth - w / 2);
        var capY = Math.Clamp(clickY - h / 4, 0, MasterFrameHeight - h / 2);
        _zoomState.X = x;
        _zoomState.Y = y;
        _zoomState.Width = w;
        _zoomState.Height = h;
        _zoomState.CaptureX = capX;
        _zoomState.CaptureY = capY;
        _zoomState.IsActive = true;
        _zoomState.IsMoving = false;

        var zoomTarget = EnsureZoomLayer(StagedScene);
        zoomTarget.X = x;
        zoomTarget.Y = y;
        zoomTarget.Width = w;
        zoomTarget.Height = h;
        zoomTarget.CaptureX = capX;
        zoomTarget.CaptureY = capY;
        zoomTarget.ClipShape = _zoomShape == ZoomShape.Circle ? ClipShape.Round : ClipShape.Traditional;
        zoomTarget.IsZoomActive = true;
        zoomTarget.IsVisible = true;
        ScheduleSave();
        RefreshZoomUi();
    }

    /// <summary>
    /// The gesture behind the zoom box: activate it centred on the click, or dismiss it if it is
    /// already open. Both halves live here because the old split (activate while live, dismiss
    /// only otherwise) made the gesture do nothing at all when idle — the box could be turned off
    /// but never on (creator, 2026-11-01).
    /// </summary>
    public void ToggleZoom(double clickX, double clickY)
    {
        if (_zoomState.IsActive) DismissZoom();
        else ActivateZoom(clickX, clickY);
    }

    public void DismissZoom()
    {
        if (!_zoomState.IsActive) return;
        _zoomState.IsActive = false;
        _zoomState.IsMoving = false;
        var zoomTarget = StagedScene?.Elements.OfType<ZoomSceneElement>().FirstOrDefault();
        if (zoomTarget != null)
        {
            zoomTarget.IsZoomActive = false;
            zoomTarget.IsVisible = false;
            zoomTarget.CaptureX = 0;
            zoomTarget.CaptureY = 0;
        }
        if (StagedScene != null) _sceneGraph.InvalidateBake(StagedScene);
        RefreshZoomUi();
    }

    public void StartZoomMove(double x, double y)
    {
        if (!_zoomState.IsActive) return;
        _zoomState.IsMoving = true;
        _zoomState.GrabOffsetX = x - _zoomState.X;
        _zoomState.GrabOffsetY = y - _zoomState.Y;
        OnPropertyChanged(nameof(ZoomState));
    }

    public void UpdateZoomMove(double x, double y)
    {
        if (!_zoomState.IsActive || !_zoomState.IsMoving) return;
        var nx = x - _zoomState.GrabOffsetX;
        var ny = y - _zoomState.GrabOffsetY;
        _zoomState.X = Math.Clamp(nx, 0, MasterFrameWidth - _zoomState.Width);
        _zoomState.Y = Math.Clamp(ny, 0, MasterFrameHeight - _zoomState.Height);
        var zoomTarget = StagedScene?.Elements.OfType<ZoomSceneElement>().FirstOrDefault(e => e.IsZoomActive);
        if (zoomTarget != null)
        {
            zoomTarget.X = _zoomState.X;
            zoomTarget.Y = _zoomState.Y;
            // CaptureX/Y are deliberately NOT touched: dragging relocates the box,
            // never the anchored captured area (creator ruling 2026-10-08).
        }
        OnPropertyChanged(nameof(ZoomState));
        RebuildDimRectsForZoom();
    }

    public void EndZoomMove()
    {
        if (_zoomState.IsMoving)
        {
            _zoomState.IsMoving = false;
            OnPropertyChanged(nameof(ZoomState));
        }
    }

    private void RefreshZoomUi()
    {
        OnPropertyChanged(nameof(ZoomState));
        OnPropertyChanged(nameof(IsZoomActive));
        OnPropertyChanged(nameof(ShowZoomOverlay));
        RebuildDimRectsForZoom();
    }

    private void RebuildDimRectsForZoom()
    {
        if (_zoomState.IsActive)
        {
            var zx = _zoomState.X;
            var zy = _zoomState.Y;
            var zw = _zoomState.Width;
            var zh = _zoomState.Height;
            DimRects.Clear();
            if (zx > 0) DimRects.Add(new Rect(0, 0, zx, MasterFrameHeight));
            var rx = zx + zw;
            if (rx < MasterFrameWidth) DimRects.Add(new Rect(rx, 0, MasterFrameWidth - rx, MasterFrameHeight));
            if (zy > 0) DimRects.Add(new Rect(0, 0, MasterFrameWidth, zy));
            var ry = zy + zh;
            if (ry < MasterFrameHeight) DimRects.Add(new Rect(0, ry, MasterFrameWidth, MasterFrameHeight - ry));
            return;
        }
        RebuildQualityDimRects();
    }

    /// <summary>Heals a missing zoom placeholder on every scene after a layout
    /// load: the invisible 0x0 row mirrored by the healed backgrounds. The zoom box
    /// itself is transient — the placeholder survives so the layer has a seat. The
    /// compositor ranks the ACTIVE box last regardless of this index.</summary>
    private void HealZoomLayers()
    {
        foreach (var scene in Scenes)
            EnsureZoomLayer(scene);
    }

    /// <summary>Gets or inserts the scene's zoom placeholder at z-index 1.</summary>
    private ZoomSceneElement EnsureZoomLayer(Scene? scene)
    {
        var existing = scene?.Elements.OfType<ZoomSceneElement>().FirstOrDefault();
        if (existing != null) return existing;
        var zoom = new ZoomSceneElement();
        _sceneGraph.InsertElement(scene!, Math.Min(1, scene!.Elements.Count), zoom);
        return zoom;
    }
}