feat(editor): support connector dom renderer (#12505)

### TL;DR

Added DOM-based renderer for connector elements in the AFFiNE editor.

### What changed?

- Created a new DOM-based renderer for connector elements that uses SVG
for rendering
- Implemented `ConnectorDomRendererExtension` to register the DOM
renderer for connector elements
- Added support for rendering connector paths, endpoints (arrows,
triangles, circles, diamonds), stroke styles, and labels
- Registered the new DOM renderer extension in the connector view setup
- Added comprehensive tests to verify DOM rendering functionality

### How to test?

1. Enable the DOM renderer flag in the editor
2. Create connector elements between shapes or with fixed positions
3. Verify that connectors render correctly with different styles:
   - Try different stroke styles (solid, dashed)
   - Test various endpoint styles (Arrow, Triangle, Circle, Diamond)
   - Add text labels to connectors
4. Check that connectors update properly when connected elements move
5. Verify that connectors are removed when deleted

### Why make this change?

The DOM-based renderer provides an alternative to the Canvas-based
renderer, offering better accessibility and potentially improved
performance for certain use cases. This implementation allows connectors
to be rendered as SVG elements within the DOM, which can be more easily
inspected, styled with CSS, and interacted with by assistive
technologies.

blocksuite/affine/gfx/connector/src/element-renderer/connector-dom.ts

@@ -0,0 +1,11 @@
+import { DomElementRendererExtension } from '@blocksuite/affine-block-surface';
+
+import { connectorDomRenderer } from './connector-dom/index.js';
+
+/**
+ * Extension to register the DOM-based renderer for 'connector' elements.
+ */
+export const ConnectorDomRendererExtension = DomElementRendererExtension(
+  'connector',
+  connectorDomRenderer
+);

blocksuite/affine/gfx/connector/src/element-renderer/connector-dom/index.ts

@@ -0,0 +1,367 @@
+import type { DomRenderer } from '@blocksuite/affine-block-surface';
+import {
+  type ConnectorElementModel,
+  ConnectorMode,
+  DefaultTheme,
+  type PointStyle,
+} from '@blocksuite/affine-model';
+import { PointLocation, SVGPathBuilder } from '@blocksuite/global/gfx';
+
+import { isConnectorWithLabel } from '../../connector-manager.js';
+import { DEFAULT_ARROW_SIZE } from '../utils.js';
+
+interface PathBounds {
+  minX: number;
+  minY: number;
+  maxX: number;
+  maxY: number;
+}
+
+function calculatePathBounds(path: PointLocation[]): PathBounds {
+  if (path.length === 0) {
+    return { minX: 0, minY: 0, maxX: 0, maxY: 0 };
+  }
+
+  let minX = path[0][0];
+  let minY = path[0][1];
+  let maxX = path[0][0];
+  let maxY = path[0][1];
+
+  for (const point of path) {
+    minX = Math.min(minX, point[0]);
+    minY = Math.min(minY, point[1]);
+    maxX = Math.max(maxX, point[0]);
+    maxY = Math.max(maxY, point[1]);
+  }
+
+  return { minX, minY, maxX, maxY };
+}
+
+function createConnectorPath(
+  points: PointLocation[],
+  mode: ConnectorMode
+): string {
+  if (points.length < 2) return '';
+
+  const pathBuilder = new SVGPathBuilder();
+  pathBuilder.moveTo(points[0][0], points[0][1]);
+
+  if (mode === ConnectorMode.Curve) {
+    // Use bezier curves
+    for (let i = 1; i < points.length; i++) {
+      const prev = points[i - 1];
+      const curr = points[i];
+      pathBuilder.curveTo(
+        prev.absOut[0],
+        prev.absOut[1],
+        curr.absIn[0],
+        curr.absIn[1],
+        curr[0],
+        curr[1]
+      );
+    }
+  } else {
+    // Use straight lines
+    for (let i = 1; i < points.length; i++) {
+      pathBuilder.lineTo(points[i][0], points[i][1]);
+    }
+  }
+
+  return pathBuilder.build();
+}
+
+function createArrowMarker(
+  id: string,
+  style: PointStyle,
+  color: string,
+  strokeWidth: number,
+  isStart: boolean = false
+): SVGMarkerElement {
+  const marker = document.createElementNS(
+    'http://www.w3.org/2000/svg',
+    'marker'
+  );
+  const size = DEFAULT_ARROW_SIZE * (strokeWidth / 2);
+
+  marker.id = id;
+  marker.setAttribute('viewBox', '0 0 20 20');
+  marker.setAttribute('refX', isStart ? '20' : '0');
+  marker.setAttribute('refY', '10');
+  marker.setAttribute('markerWidth', String(size));
+  marker.setAttribute('markerHeight', String(size));
+  marker.setAttribute('orient', 'auto');
+  marker.setAttribute('markerUnits', 'strokeWidth');
+
+  switch (style) {
+    case 'Arrow': {
+      const path = document.createElementNS(
+        'http://www.w3.org/2000/svg',
+        'path'
+      );
+      path.setAttribute(
+        'd',
+        isStart ? 'M 20 5 L 10 10 L 20 15 Z' : 'M 0 5 L 10 10 L 0 15 Z'
+      );
+      path.setAttribute('fill', color);
+      path.setAttribute('stroke', color);
+      marker.append(path);
+      break;
+    }
+    case 'Triangle': {
+      const path = document.createElementNS(
+        'http://www.w3.org/2000/svg',
+        'path'
+      );
+      path.setAttribute(
+        'd',
+        isStart ? 'M 20 7 L 12 10 L 20 13 Z' : 'M 0 7 L 8 10 L 0 13 Z'
+      );
+      path.setAttribute('fill', color);
+      path.setAttribute('stroke', color);
+      marker.append(path);
+      break;
+    }
+    case 'Circle': {
+      const circle = document.createElementNS(
+        'http://www.w3.org/2000/svg',
+        'circle'
+      );
+      circle.setAttribute('cx', '10');
+      circle.setAttribute('cy', '10');
+      circle.setAttribute('r', '4');
+      circle.setAttribute('fill', color);
+      circle.setAttribute('stroke', color);
+      marker.append(circle);
+      break;
+    }
+    case 'Diamond': {
+      const path = document.createElementNS(
+        'http://www.w3.org/2000/svg',
+        'path'
+      );
+      path.setAttribute('d', 'M 10 6 L 14 10 L 10 14 L 6 10 Z');
+      path.setAttribute('fill', color);
+      path.setAttribute('stroke', color);
+      marker.append(path);
+      break;
+    }
+  }
+
+  return marker;
+}
+
+function renderConnectorLabel(
+  model: ConnectorElementModel,
+  container: HTMLElement,
+  renderer: DomRenderer,
+  zoom: number
+) {
+  if (!isConnectorWithLabel(model) || !model.labelXYWH) {
+    return;
+  }
+
+  const [lx, ly, lw, lh] = model.labelXYWH;
+  const {
+    labelStyle: {
+      color,
+      fontSize,
+      fontWeight,
+      fontStyle,
+      fontFamily,
+      textAlign,
+    },
+  } = model;
+
+  // Create label element
+  const labelElement = document.createElement('div');
+  labelElement.style.position = 'absolute';
+  labelElement.style.left = `${lx * zoom}px`;
+  labelElement.style.top = `${ly * zoom}px`;
+  labelElement.style.width = `${lw * zoom}px`;
+  labelElement.style.height = `${lh * zoom}px`;
+  labelElement.style.pointerEvents = 'none';
+  labelElement.style.overflow = 'hidden';
+  labelElement.style.display = 'flex';
+  labelElement.style.alignItems = 'center';
+  labelElement.style.justifyContent =
+    textAlign === 'center'
+      ? 'center'
+      : textAlign === 'right'
+        ? 'flex-end'
+        : 'flex-start';
+
+  // Style the text
+  labelElement.style.color = renderer.getColorValue(
+    color,
+    DefaultTheme.black,
+    true
+  );
+  labelElement.style.fontSize = `${fontSize * zoom}px`;
+  labelElement.style.fontWeight = fontWeight;
+  labelElement.style.fontStyle = fontStyle;
+  labelElement.style.fontFamily = fontFamily;
+  labelElement.style.textAlign = textAlign;
+  labelElement.style.lineHeight = '1.2';
+  labelElement.style.whiteSpace = 'pre-wrap';
+  labelElement.style.wordWrap = 'break-word';
+
+  // Add text content
+  if (model.text) {
+    labelElement.textContent = model.text.toString();
+  }
+
+  container.append(labelElement);
+}
+
+/**
+ * Renders a ConnectorElementModel to a given HTMLElement using DOM/SVG.
+ * This function is intended to be registered via the DomElementRendererExtension.
+ *
+ * @param model - The connector element model containing rendering properties.
+ * @param element - The HTMLElement to apply the connector's styles to.
+ * @param renderer - The main DOMRenderer instance, providing access to viewport and color utilities.
+ */
+export const connectorDomRenderer = (
+  model: ConnectorElementModel,
+  element: HTMLElement,
+  renderer: DomRenderer
+): void => {
+  const { zoom } = renderer.viewport;
+  const {
+    mode,
+    path: points,
+    strokeStyle,
+    frontEndpointStyle,
+    rearEndpointStyle,
+    strokeWidth,
+    stroke,
+  } = model;
+
+  // Clear previous content
+  element.innerHTML = '';
+
+  // Early return if no path points
+  if (!points || points.length < 2) {
+    return;
+  }
+
+  // Calculate bounds for the SVG viewBox
+  const pathBounds = calculatePathBounds(points);
+  const padding = Math.max(strokeWidth * 2, 20); // Add padding for arrows
+  const svgWidth = (pathBounds.maxX - pathBounds.minX + padding * 2) * zoom;
+  const svgHeight = (pathBounds.maxY - pathBounds.minY + padding * 2) * zoom;
+  const offsetX = pathBounds.minX - padding;
+  const offsetY = pathBounds.minY - padding;
+
+  // Create SVG element
+  const svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
+  svg.style.position = 'absolute';
+  svg.style.left = `${offsetX * zoom}px`;
+  svg.style.top = `${offsetY * zoom}px`;
+  svg.style.width = `${svgWidth}px`;
+  svg.style.height = `${svgHeight}px`;
+  svg.style.overflow = 'visible';
+  svg.style.pointerEvents = 'none';
+  svg.setAttribute('viewBox', `0 0 ${svgWidth / zoom} ${svgHeight / zoom}`);
+
+  // Create defs for markers
+  const defs = document.createElementNS('http://www.w3.org/2000/svg', 'defs');
+  svg.append(defs);
+
+  const strokeColor = renderer.getColorValue(
+    stroke,
+    DefaultTheme.connectorColor,
+    true
+  );
+
+  // Create markers for endpoints
+  let startMarkerId = '';
+  let endMarkerId = '';
+
+  if (frontEndpointStyle !== 'None') {
+    startMarkerId = `start-marker-${model.id}`;
+    const startMarker = createArrowMarker(
+      startMarkerId,
+      frontEndpointStyle,
+      strokeColor,
+      strokeWidth,
+      true
+    );
+    defs.append(startMarker);
+  }
+
+  if (rearEndpointStyle !== 'None') {
+    endMarkerId = `end-marker-${model.id}`;
+    const endMarker = createArrowMarker(
+      endMarkerId,
+      rearEndpointStyle,
+      strokeColor,
+      strokeWidth,
+      false
+    );
+    defs.append(endMarker);
+  }
+
+  // Create path element
+  const pathElement = document.createElementNS(
+    'http://www.w3.org/2000/svg',
+    'path'
+  );
+
+  // Adjust points relative to the SVG coordinate system
+  const adjustedPoints = points.map(point => {
+    const adjustedPoint = new PointLocation([
+      point[0] - offsetX,
+      point[1] - offsetY,
+    ]);
+    if (point.absIn) {
+      adjustedPoint.in = [
+        point.absIn[0] - offsetX - adjustedPoint[0],
+        point.absIn[1] - offsetY - adjustedPoint[1],
+      ];
+    }
+    if (point.absOut) {
+      adjustedPoint.out = [
+        point.absOut[0] - offsetX - adjustedPoint[0],
+        point.absOut[1] - offsetY - adjustedPoint[1],
+      ];
+    }
+    return adjustedPoint;
+  });
+
+  const pathData = createConnectorPath(adjustedPoints, mode);
+  pathElement.setAttribute('d', pathData);
+  pathElement.setAttribute('stroke', strokeColor);
+  pathElement.setAttribute('stroke-width', String(strokeWidth));
+  pathElement.setAttribute('fill', 'none');
+  pathElement.setAttribute('stroke-linecap', 'round');
+  pathElement.setAttribute('stroke-linejoin', 'round');
+
+  // Apply stroke style
+  if (strokeStyle === 'dash') {
+    pathElement.setAttribute('stroke-dasharray', '12,12');
+  }
+
+  // Apply markers
+  if (startMarkerId) {
+    pathElement.setAttribute('marker-start', `url(#${startMarkerId})`);
+  }
+  if (endMarkerId) {
+    pathElement.setAttribute('marker-end', `url(#${endMarkerId})`);
+  }
+
+  svg.append(pathElement);
+  element.append(svg);
+
+  // Set element size and position
+  element.style.width = `${model.w * zoom}px`;
+  element.style.height = `${model.h * zoom}px`;
+  element.style.overflow = 'visible';
+  element.style.pointerEvents = 'none';
+
+  // Set z-index for layering
+  element.style.zIndex = renderer.layerManager.getZIndex(model).toString();
+
+  // Render label if present
+  renderConnectorLabel(model, element, renderer, zoom);
+};

blocksuite/affine/gfx/connector/src/index.ts

@@ -2,6 +2,7 @@ export * from './adapter';
 export * from './connector-manager';
 export * from './connector-tool';
 export * from './element-renderer';
+export { ConnectorDomRendererExtension } from './element-renderer/connector-dom';
 export * from './element-transform';
 export * from './text';
 export * from './toolbar/config';

blocksuite/affine/gfx/connector/src/view.ts

@@ -7,6 +7,7 @@ import { ConnectionOverlay } from './connector-manager';
 import { ConnectorTool } from './connector-tool';
 import { effects } from './effects';
 import { ConnectorElementRendererExtension } from './element-renderer';
+import { ConnectorDomRendererExtension } from './element-renderer/connector-dom';
 import { ConnectorFilter } from './element-transform';
 import { connectorToolbarExtension } from './toolbar/config';
 import { connectorQuickTool } from './toolbar/quick-tool';
@@ -24,6 +25,7 @@ export class ConnectorViewExtension extends ViewExtensionProvider {
     super.setup(context);
     context.register(ConnectorElementView);
     context.register(ConnectorElementRendererExtension);
+    context.register(ConnectorDomRendererExtension);
     if (this.isEdgeless(context.scope)) {
       context.register(ConnectorTool);
       context.register(ConnectorFilter);