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feat(D.2b): window resize (UiRoot edge-grip resize-drag mode)

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Add parallel resize mode to the UiRoot retained-mode input state machine.
A left-drag starting within ResizeGrip=5px of a Resizable window's edge or
corner resizes it (min-size clamped); interior drags on a Draggable window
still reposition it.

Changes:
- UiElement: Resizable, MinWidth, MinHeight properties
- UiRoot: ResizeEdges flags enum; _resizeTarget state fields; FindWindow
  (replaces FindDraggable, matches Draggable||Resizable); HitEdges (static,
  internal, testable); ResizeRect (static, public, testable); OnMouseDown
  checks edge-grip before move; OnMouseMove resize branch precedes move;
  OnMouseUp clears _resizeTarget
- UiNineSlicePanel: Resizable = true (retail windows are resizable)
- UiRootInputTests: 4 new tests — ResizeRect_RightBottom, ResizeRect_LeftTop
  (min-clamp + origin shift), HitEdges_DetectsCornerAndInteriorNone,
  EdgeDrag_ResizesPanel_InteriorDragMoves (full integration path)

Note on test coordinate: right-edge grab uses x=298 (2px inside the panel's
hit-test boundary) rather than x=300 (exactly at edge, misses OnHitTest's
strict `<` check). This is intentional — the grip zone extends inward from
the edge boundary, so a click 2px inside correctly lands in both the
hit-test rect AND the resize-grip zone.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik 2026-06-14 18:27:57 +02:00
parent 4acecffcd6
commit de4f0167ef
4 changed files with 145 additions and 10 deletions
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93
src/AcDream.App/UI/UiRoot.cs
View file

@ -4,6 +4,10 @@ using System.Numerics;
namespace AcDream.App.UI;
/// <summary>Which edges of a window a resize-drag is affecting (corners combine two).</summary>
[System.Flags]
public enum ResizeEdges { None = 0, Left = 1, Right = 2, Top = 4, Bottom = 8 }
/// <summary>
/// Top-level UI container. Implements the retail "Device" responsibilities
/// (mouse cursor tracking, keyboard focus, modal overlay, mouse capture,
@ -68,6 +72,11 @@ public sealed class UiRoot : UiElement
private bool _dragCandidate;
private UiElement? _windowDragTarget;
private int _windowDragOffX, _windowDragOffY;
private UiElement? _resizeTarget;
private ResizeEdges _resizeEdges;
private float _resizeStartX, _resizeStartY, _resizeStartW, _resizeStartH;
private int _resizeMouseX, _resizeMouseY;
private const int ResizeGrip = 5; // px proximity to an edge to start a resize
private const int DragDistanceThreshold = 3; // pixels, retail-observed
// Hover / tooltip tracking.
@ -133,6 +142,18 @@ public sealed class UiRoot : UiElement
MouseX = x;
MouseY = y;
// Window resize takes precedence over move / drag-drop / hover.
if (_resizeTarget is not null)
{
var (nx, ny, nw, nh) = ResizeRect(
_resizeStartX, _resizeStartY, _resizeStartW, _resizeStartH,
_resizeEdges, x - _resizeMouseX, y - _resizeMouseY,
_resizeTarget.MinWidth, _resizeTarget.MinHeight);
_resizeTarget.Left = nx; _resizeTarget.Top = ny;
_resizeTarget.Width = nw; _resizeTarget.Height = nh;
return;
}
// Window-move drag takes precedence over drag-drop / hover / fall-through.
if (_windowDragTarget is not null)
{
@ -188,15 +209,30 @@ public sealed class UiRoot : UiElement
SetCapture(target);
// Window-move: if the target or an ancestor is Draggable, a left-drag
// repositions that window instead of starting a drag-drop.
var draggable = FindDraggable(target);
if (btn == UiMouseButton.Left && draggable is not null)
// Window resize / move: find the window (Draggable or Resizable ancestor).
// A left-drag starting near an edge resizes; interior drag repositions;
// otherwise it's a normal drag-drop candidate.
var window = FindWindow(target);
if (btn == UiMouseButton.Left && window is not null)
{
_windowDragTarget = draggable;
_windowDragOffX = x - (int)draggable.Left;
_windowDragOffY = y - (int)draggable.Top;
_dragCandidate = false;
var edges = window.Resizable ? HitEdges(window, x, y, ResizeGrip) : ResizeEdges.None;
if (edges != ResizeEdges.None)
{
_resizeTarget = window;
_resizeEdges = edges;
_resizeStartX = window.Left; _resizeStartY = window.Top;
_resizeStartW = window.Width; _resizeStartH = window.Height;
_resizeMouseX = x; _resizeMouseY = y;
_dragCandidate = false;
}
else if (window.Draggable)
{
_windowDragTarget = window;
_windowDragOffX = x - (int)window.Left;
_windowDragOffY = y - (int)window.Top;
_dragCandidate = false;
}
else { _dragCandidate = true; }
}
else
{
@ -221,6 +257,13 @@ public sealed class UiRoot : UiElement
MouseX = x; MouseY = y;
UpdateButtonFlag(btn, down: false);
if (_resizeTarget is not null)
{
_resizeTarget = null;
ReleaseCapture();
return;
}
if (_windowDragTarget is not null)
{
_windowDragTarget = null;
@ -477,16 +520,46 @@ public sealed class UiRoot : UiElement
return (null, 0, 0);
}
private static UiElement? FindDraggable(UiElement? e)
private static UiElement? FindWindow(UiElement? e)
{
while (e is not null)
{
if (e.Draggable) return e;
if (e.Draggable || e.Resizable) return e;
e = e.Parent;
}
return null;
}
/// <summary>Which edges of <paramref name="w"/>'s screen rect the point
/// (<paramref name="x"/>,<paramref name="y"/>) is within <paramref name="grip"/> px of.
/// None if the point is outside the grip-expanded box entirely.</summary>
internal static ResizeEdges HitEdges(UiElement w, int x, int y, int grip)
{
float l = w.Left, t = w.Top, r = w.Left + w.Width, b = w.Top + w.Height;
if (x < l - grip || x > r + grip || y < t - grip || y > b + grip) return ResizeEdges.None;
var e = ResizeEdges.None;
if (System.Math.Abs(x - l) <= grip) e |= ResizeEdges.Left;
if (System.Math.Abs(x - r) <= grip) e |= ResizeEdges.Right;
if (System.Math.Abs(y - t) <= grip) e |= ResizeEdges.Top;
if (System.Math.Abs(y - b) <= grip) e |= ResizeEdges.Bottom;
return e;
}
/// <summary>Compute a resized rect from a start rect + drag delta + which edges,
/// clamping to (<paramref name="minW"/>,<paramref name="minH"/>). Left/Top edges
/// move the origin so the opposite edge stays put.</summary>
public static (float x, float y, float w, float h) ResizeRect(
float startX, float startY, float startW, float startH,
ResizeEdges edges, float dx, float dy, float minW, float minH)
{
float x = startX, y = startY, w = startW, h = startH;
if ((edges & ResizeEdges.Right) != 0) w = System.Math.Max(minW, startW + dx);
if ((edges & ResizeEdges.Bottom) != 0) h = System.Math.Max(minH, startH + dy);
if ((edges & ResizeEdges.Left) != 0) { float nw = System.Math.Max(minW, startW - dx); x = startX + (startW - nw); w = nw; }
if ((edges & ResizeEdges.Top) != 0) { float nh = System.Math.Max(minH, startH - dy); y = startY + (startH - nh); h = nh; }
return (x, y, w, h);
}
private static bool ContainsAbsolute(UiElement e, int x, int y)
{
var sp = e.ScreenPosition;