improve:实时笔锋

2026-04-25 17:27:28 +08:00
parent 004364c3a9
commit 77dff81217
2 changed files with 203 additions and 21 deletions
@@ -48,6 +48,198 @@ namespace Ink_Canvas
        private bool isPalmEraserActive;
        private bool palmEraserWasEnabledBeforeMultiTouch;
        private InkCanvasEditingMode palmEraserPreviousEditingMode = InkCanvasEditingMode.Ink;
+        private readonly Dictionary<int, RealtimeBrushTipState> _realtimeBrushTipStates = new Dictionary<int, RealtimeBrushTipState>();
+        private readonly Guid RealtimeVelocityBrushTipAppliedGuid = new Guid("74E57D95-945F-4A8C-B52A-7D3EF2D4FD5B");
+
+        private sealed class OneEuroFilter
+        {
+            private readonly float _minCutoff;
+            private readonly float _beta;
+            private readonly float _dCutoff;
+            private bool _initialized;
+            private float _xPrev;
+            private float _dxPrev;
+
+            public OneEuroFilter(float minCutoff, float beta, float dCutoff)
+            {
+                _minCutoff = minCutoff;
+                _beta = beta;
+                _dCutoff = dCutoff;
+            }
+
+            public float Filter(float value, float dt, float speed)
+            {
+                if (!_initialized)
+                {
+                    _initialized = true;
+                    _xPrev = value;
+                    _dxPrev = 0f;
+                    return value;
+                }
+
+                var dx = (value - _xPrev) / Math.Max(1e-6f, dt);
+                var aD = Alpha(_dCutoff, dt);
+                var dxHat = Lerp(_dxPrev, dx, aD);
+                var a = Alpha(_minCutoff + _beta * speed, dt);
+                var xHat = Lerp(_xPrev, value, a);
+                _xPrev = xHat;
+                _dxPrev = dxHat;
+                return xHat;
+            }
+
+            private static float Alpha(float cutoff, float dt)
+            {
+                var tau = 1f / (2f * (float)Math.PI * Math.Max(1e-3f, cutoff));
+                return 1f / (1f + tau / Math.Max(1e-6f, dt));
+            }
+
+            private static float Lerp(float a, float b, float t) => a + (b - a) * t;
+        }
+
+        private sealed class RealtimeBrushTipState
+        {
+            public float LastRawX { get; set; }
+            public float LastRawY { get; set; }
+            public long LastTimestampMs { get; set; }
+            public float SmoothedSampleRateHz { get; set; } = 120f;
+            public bool HasSeed { get; set; }
+            public float LastSmoothX { get; set; }
+            public float LastSmoothY { get; set; }
+            public float LastSmoothPressure { get; set; } = 0.5f;
+            public OneEuroFilter FilterX { get; } = new OneEuroFilter(1.2f, 0.015f, 1f);
+            public OneEuroFilter FilterY { get; } = new OneEuroFilter(1.2f, 0.015f, 1f);
+            public OneEuroFilter FilterPressure { get; } = new OneEuroFilter(1f, 0.02f, 1f);
+        }
+
+        private static long RealtimeNowMs() => Environment.TickCount64;
+
+        private static float RealtimeClamp(float x, float min, float max)
+        {
+            if (x < min) return min;
+            if (x > max) return max;
+            return x;
+        }
+
+        private bool ShouldUseRealtimeVelocityBrushTip()
+        {
+            return Settings.Canvas.InkStyle == 3
+                && Settings.Canvas.VelocityBrushTipMix > 0
+                && !Settings.Canvas.DisablePressure
+                && penType == 0;
+        }
+
+        private void InitializeRealtimeBrushTipState(int stylusId, StylusDownEventArgs e)
+        {
+            if (!ShouldUseRealtimeVelocityBrushTip())
+            {
+                _realtimeBrushTipStates.Remove(stylusId);
+                return;
+            }
+
+            var startPoint = e.GetPosition(this);
+            _realtimeBrushTipStates[stylusId] = new RealtimeBrushTipState
+            {
+                LastRawX = (float)startPoint.X,
+                LastRawY = (float)startPoint.Y,
+                LastTimestampMs = RealtimeNowMs()
+            };
+        }
+
+        private void CleanupRealtimeBrushTipState(int stylusId)
+        {
+            _realtimeBrushTipStates.Remove(stylusId);
+        }
+
+        private bool TryAppendRealtimeVelocityBrushTipPoints(StrokeVisual strokeVisual, StylusEventArgs e)
+        {
+            if (!ShouldUseRealtimeVelocityBrushTip() || strokeVisual == null || e?.StylusDevice == null)
+                return false;
+
+            if (!_realtimeBrushTipStates.TryGetValue(e.StylusDevice.Id, out var state))
+                return false;
+
+            var stylusPointCollection = e.GetStylusPoints(this);
+            if (stylusPointCollection == null || stylusPointCollection.Count == 0)
+                return true;
+
+            var mix = RealtimeClamp((float)Settings.Canvas.VelocityBrushTipMix, 0f, 1f);
+            var appended = false;
+
+            foreach (StylusPoint rawPoint in stylusPointCollection)
+            {
+                var nowMs = RealtimeNowMs();
+                var dtMs = Math.Max(1L, nowMs - state.LastTimestampMs);
+                var dt = dtMs / 1000f;
+                var sampleRate = 1f / Math.Max(1e-4f, dt);
+                state.SmoothedSampleRateHz = state.SmoothedSampleRateHz * 0.85f + sampleRate * 0.15f;
+
+                var rawX = (float)rawPoint.X;
+                var rawY = (float)rawPoint.Y;
+                var dx = rawX - state.LastRawX;
+                var dy = rawY - state.LastRawY;
+                var dist = (float)Math.Sqrt(dx * dx + dy * dy);
+                var speed = dist / dt;
+
+                var filteredX = state.FilterX.Filter(rawX, dt, speed);
+                var filteredY = state.FilterY.Filter(rawY, dt, speed);
+
+                var speedPressure = RealtimeBrushTipMixRatePressureFromSpeed(GetPointSpeed(
+                    new Point(state.LastRawX, state.LastRawY),
+                    new Point(rawX, rawY),
+                    new Point(filteredX, filteredY)));
+                var pressure = (1f - mix) * (float)rawPoint.PressureFactor + mix * speedPressure;
+                pressure = RealtimeClamp(pressure, 0.08f, 1f);
+                pressure = state.FilterPressure.Filter(pressure, dt, speed);
+
+                // 高频采样时做最小距离门限，避免点爆炸导致实时重绘卡顿
+                var minDist = state.SmoothedSampleRateHz > 160f ? 0.55f
+                    : state.SmoothedSampleRateHz > 90f ? 0.4f
+                    : 0.25f;
+                if (dist < minDist && state.HasSeed)
+                {
+                    state.LastRawX = rawX;
+                    state.LastRawY = rawY;
+                    state.LastTimestampMs = nowMs;
+                    continue;
+                }
+
+                if (!state.HasSeed)
+                {
+                    state.HasSeed = true;
+                    state.LastSmoothX = filteredX;
+                    state.LastSmoothY = filteredY;
+                    state.LastSmoothPressure = pressure;
+                    strokeVisual.Add(new StylusPoint(filteredX, filteredY, pressure));
+                }
+                else
+                {
+                    // 采用中点链减抖：保持实时笔锋同时降低折线锯齿
+                    var midX = (state.LastSmoothX + filteredX) * 0.5f;
+                    var midY = (state.LastSmoothY + filteredY) * 0.5f;
+                    var midPressure = (state.LastSmoothPressure + pressure) * 0.5f;
+                    strokeVisual.Add(new StylusPoint(midX, midY, midPressure));
+                    state.LastSmoothX = filteredX;
+                    state.LastSmoothY = filteredY;
+                    state.LastSmoothPressure = pressure;
+                }
+
+                state.LastRawX = rawX;
+                state.LastRawY = rawY;
+                state.LastTimestampMs = nowMs;
+                appended = true;
+            }
+
+            var committedStroke = strokeVisual.Stroke;
+            if (appended && committedStroke != null)
+            {
+                if (committedStroke.DrawingAttributes != null)
+                    committedStroke.DrawingAttributes.IgnorePressure = false;
+                if (!committedStroke.ContainsPropertyData(RealtimeVelocityBrushTipAppliedGuid))
+                    committedStroke.AddPropertyData(RealtimeVelocityBrushTipAppliedGuid, true);
+            }
+
+            return true;
+        }

        /// <summary>
        /// 保存画布上的非笔画元素（如图片、媒体元素等）
@@ -391,6 +583,7 @@ namespace Ink_Canvas
                || inkCanvas.EditingMode == InkCanvasEditingMode.EraseByStroke
                || inkCanvas.EditingMode == InkCanvasEditingMode.Select) return;

+            InitializeRealtimeBrushTipState(e.StylusDevice.Id, e);
            TouchDownPointsList[e.StylusDevice.Id] = InkCanvasEditingMode.None;
        }

@@ -490,6 +683,7 @@ namespace Ink_Canvas
                StrokeVisualList.Remove(e.StylusDevice.Id);
                VisualCanvasList.Remove(e.StylusDevice.Id);
                TouchDownPointsList.Remove(e.StylusDevice.Id);
+                CleanupRealtimeBrushTipState(e.StylusDevice.Id);
                if (StrokeVisualList.Count == 0 || VisualCanvasList.Count == 0 || TouchDownPointsList.Count == 0)
                {
                    // 只清除手写笔预览相关的Canvas，不清除所有子元素
@@ -552,28 +746,15 @@ namespace Ink_Canvas


                var strokeVisual = GetStrokeVisual(e.StylusDevice.Id);
-                var stylusPointCollection = e.GetStylusPoints(this);
-                foreach (var stylusPoint in stylusPointCollection)
-                    strokeVisual.Add(new StylusPoint(stylusPoint.X, stylusPoint.Y, stylusPoint.PressureFactor));
+                var isHandledByRealtime = TryAppendRealtimeVelocityBrushTipPoints(strokeVisual, e);
+                if (!isHandledByRealtime)
+                {
+                    var stylusPointCollection = e.GetStylusPoints(this);
+                    foreach (var stylusPoint in stylusPointCollection)
+                        strokeVisual.Add(new StylusPoint(stylusPoint.X, stylusPoint.Y, stylusPoint.PressureFactor));
+                }

-                // 实时笔锋：混合度 > 0 时在绘制过程中更新压感并整笔重绘预览；混合为 0 时与普通过程一致用增量 Redraw，避免每点 ForceRedraw 整笔清空（长笔画卡顿）。
-                var committedStroke = strokeVisual.Stroke;
-                if (committedStroke != null
-                    && Settings.Canvas.InkStyle == 3
-                    && Settings.Canvas.VelocityBrushTipMix > 0
-                    && !Settings.Canvas.DisablePressure
-                    && penType == 0
-                    && committedStroke.DrawingAttributes != null
-                    && !committedStroke.DrawingAttributes.IsHighlighter
-                    && committedStroke.StylusPoints.Count >= 3)
-                {
-                    ApplyVelocityBrushTipFromSpeed(committedStroke);
-                    strokeVisual.ForceRedraw();
-                }
-                else
-                {
-                    strokeVisual.Redraw();
-                }
+                strokeVisual.Redraw();
            }
            catch (Exception ex) { System.Diagnostics.Debug.WriteLine(ex); }
        }