e07da7addb
性能优化: - 新建 StrokeRasterCache: 已完成笔画光栅化为 ui.Image 合成位图 - 新建 CachedStrokesPainter: 每帧仅 drawImage，O(1) 开销 - 新建 ActiveStrokePainter: 仅渲染当前笔画，isComplete: false - _currentPoints 改为可变缓冲区 + ValueNotifier 驱动，消除 O(N²) 列表拷贝 - 双层 Stack 架构: 已缓存层(不随指针移动重绘) + 实时层(仅当前笔画) Bug 修复: - 橡皮擦 saveLayer 合成: BlendMode.dstOut 在离屏缓冲区中正确工作 - pointsToOutline 新增 isComplete 参数: 实时绘制传 false，完成笔画传 true - 模式切换不再销毁 HandwritingCanvas: IgnorePointer 替代 if/else 分支 架构改进: - 提取 createPaintForStroke() 为顶层函数，供缓存和 Painter 共用 - 移除旧 StrokePainter 类，由双层 Painter 替代 - LayoutBuilder 跟踪画布尺寸，尺寸变化时缓存自动失效 文件变更: - 新建 stroke_cache.dart (~210 行) - 新建 cached_strokes_painter.dart (~35 行) - 新建 active_stroke_painter.dart (~70 行) - 重写 handwriting_canvas.dart (~300 行) - 重构 stroke_renderer.dart (~185 行, 移除旧 Painter) - 修改 editor_page.dart (IgnorePointer 模式切换) 验证: flutter analyze 0 error
73 lines
2.0 KiB
Dart
73 lines
2.0 KiB
Dart
// 当前笔画实时 Painter — 绘制正在绘制中的笔画
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//
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// 接收可变点缓冲区的直接引用 + 版本号驱动重绘。
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// 每帧仅计算当前笔画的轮廓路径，不影响已完成笔画层。
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// isComplete: false 让 perfect_freehand 对实时笔尖做端点平滑。
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import 'package:flutter/widgets.dart';
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import 'stroke_model.dart';
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import 'stroke_renderer.dart';
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/// 当前笔画实时 Painter
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///
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/// 由 ListenableBuilder 包裹，监听 ValueNotifier<int> _strokeVersion。
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/// 每次 pointer move 递增 version，触发此 Painter 重绘。
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/// 仅渲染当前正在绘制的笔画，已完成笔画由 CachedStrokesPainter 处理。
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class ActiveStrokePainter extends CustomPainter {
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/// 当前笔画的采样点（直接引用可变缓冲区，不拷贝）
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final List<StrokePoint> points;
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/// 画笔类型
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final BrushType brushType;
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/// 画笔颜色（CSS 十六进制）
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final String color;
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/// 画笔宽度
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final double width;
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/// 版本号，每次 pointer move 递增
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final int version;
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ActiveStrokePainter({
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required this.points,
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required this.brushType,
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required this.color,
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required this.width,
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required this.version,
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});
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@override
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void paint(Canvas canvas, Size size) {
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if (points.length < 2) return;
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// isComplete: false — 实时笔尖不做端点封口，视觉更自然
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final outlinePoints = pointsToOutline(
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points,
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brushType,
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width,
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isComplete: false,
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);
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if (outlinePoints.isEmpty) return;
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final path = buildStrokePath(outlinePoints);
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// 构造临时 Stroke 用于获取 Paint
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final stroke = Stroke(
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id: '__active__',
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points: points,
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brushType: brushType,
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color: color,
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width: width,
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);
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final paint = createPaintForStroke(stroke);
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canvas.drawPath(path, paint);
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}
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@override
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bool shouldRepaint(covariant ActiveStrokePainter oldDelegate) {
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return oldDelegate.version != version;
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}
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}
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