fix: map roam drag interruption in pointer-only mobile browsers

common/changes/@visactor/vchart/009-fix-map-roam-pointer-drag_2026-03-19-08-23.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "update changes for 009-fix-map-roam-pointer-drag: This plan fixes a map roam drag bug where mobile browsers lose stable vertical dragging after supportsTouchEvents is forced to false",
+      "type": "none",
+      "packageName": "@visactor/vchart"
+    }
+  ],
+  "packageName": "@visactor/vchart",
+  "email": "lixuef1313@163.com"
+}

packages/vchart/src/compile/compiler.ts

@@ -224,6 +224,38 @@ export class Compiler implements ICompiler {
     this._compileChart?.getEvent()?.emit(ChartEvent.afterRender, { chart: this._compileChart });
   };
 
+  private _isGeoRegionRoamDragEnabled() {
+    const chartSpec = this._compileChart?.getSpec?.();
+    const regions = chartSpec?.region;
+    if (!isArray(regions)) {
+      return false;
+    }
+
+    return regions.some((region: any) => {
+      if (region?.coordinate !== 'geo' || !region.roam) {
+        return false;
+      }
+
+      if (region.roam === true) {
+        return true;
+      }
+
+      return region.roam.drag ?? true;
+    });
+  }
+
+  private _shouldDisableCanvasTouchAction() {
+    if (!isTrueBrowser(this._option.mode)) {
+      return false;
+    }
+
+    const supportsTouchEvents = isValid(this._option.supportsTouchEvents)
+      ? this._option.supportsTouchEvents
+      : vglobal.supportsTouchEvents;
+
+    return supportsTouchEvents === false && this._isGeoRegionRoamDragEnabled();
+  }
+
   private _setCanvasStyle() {
     if (!this._stage) {
       return;
@@ -234,6 +266,7 @@ export class Compiler implements ICompiler {
       const canvas = this.getCanvas();
       if (canvas) {
         canvas.style.display = 'block';
+        canvas.style.touchAction = this._shouldDisableCanvasTouchAction() ? 'none' : '';
       }
     }
   }
@@ -256,6 +289,7 @@ export class Compiler implements ICompiler {
     }
 
     chart.compile();
+    this._setCanvasStyle();
     chart.afterCompile();
   }
   protected clearNextRender() {

specs/009-fix-map-roam-pointer-drag/checklists/requirements.md

@@ -0,0 +1,26 @@
+# Specification Quality Checklist: Fix Map Roam Drag in Pointer-Only Mobile Browsers
+
+**Purpose**: Validate specification completeness and quality before delivery
+**Created**: 2026-03-19
+**Feature**: [spec.md](../spec.md)
+
+## Content Quality
+
+- [x] No unnecessary implementation detail beyond delivery-critical context
+- [x] Focused on user-visible behavior and constraints
+- [x] Written clearly enough for downstream release artifacts
+- [x] All mandatory sections completed
+
+## Requirement Completeness
+
+- [x] No `[NEEDS CLARIFICATION]` markers remain
+- [x] Requirements are testable and unambiguous
+- [x] Success criteria are measurable
+- [x] Edge cases are identified
+- [x] Scope is clearly bounded
+
+## Feature Readiness
+
+- [x] Functional requirements map to the implemented bug fix
+- [x] User scenario covers the affected interaction path
+- [x] The feature is ready for changelog, commit, and PR generation

specs/009-fix-map-roam-pointer-drag/plan.md

@@ -0,0 +1,59 @@
+# Implementation Plan: Fix Map Roam Drag in Pointer-Only Mobile Browsers
+
+**Branch**: `009-fix-map-roam-pointer-drag` | **Date**: 2026-03-19 | **Spec**: [spec.md](./spec.md)
+**Input**: Feature specification from `/specs/009-fix-map-roam-pointer-drag/spec.md`
+
+## Summary
+
+This plan fixes a map roam drag bug where mobile browsers lose stable vertical dragging after `supportsTouchEvents` is forced to `false`, because the browser's default touch gesture handling interrupts pointer-based drag sequences for geo roam regions.
+
+## Technical Context
+
+**Language/Version**: TypeScript 4.x  
+**Primary Dependencies**:
+- `@visactor/vrender-core`: Provides stage, canvas access, and global environment capability flags.
+- `@visactor/vutils`: Provides utility helpers already used by the compiler layer.  
+**Storage**: N/A  
+**Testing**: No new automated test is required for this change.  
+**Target Platform**: Browser rendering, especially mobile browsers using pointer events without touch events.  
+**Project Type**: Visualization Library (Monorepo)  
+**Performance Goals**: No regression in render or interaction performance.  
+**Constraints**: Must only affect geo roam drag scenarios and must not globally disable page scroll for unrelated charts.  
+**Scale/Scope**: Compiler-level canvas style adjustment for map roam interaction.
+
+## Constitution Check
+
+- [x] Quality First: Fix is isolated to the browser interaction environment for the affected scenario.
+- [x] User Experience-Driven: Removes a broken drag path in a valid mobile embedding scenario.
+- [x] SDD: Uses specs as the semantic source for delivery artifacts.
+- [x] Unit Tests: Not required for this change by request.
+- [x] Compatibility: Non-breaking fix (PATCH).
+
+## Project Structure
+
+### Documentation (this feature)
+
+```text
+specs/009-fix-map-roam-pointer-drag/
+├── plan.md
+├── spec.md
+└── checklists/
+    └── requirements.md
+```
+
+### Source Code (repository root)
+
+```text
+packages/vchart/
+├── src/
+│   └── compile/
+│       └── compiler.ts
+└── specs/
+    └── 009-fix-map-roam-pointer-drag/
+        ├── plan.md
+        ├── spec.md
+        └── checklists/
+            └── requirements.md
+```
+
+**Structure Decision**: Update the compiler canvas style handling in `packages/vchart/src/compile/compiler.ts` and describe the change in a dedicated spec directory for downstream changelog, commit, and PR generation.

specs/009-fix-map-roam-pointer-drag/spec.md

@@ -0,0 +1,36 @@
+# Feature Specification: Fix Map Roam Drag in Pointer-Only Mobile Browsers
+
+**Feature Branch**: `009-fix-map-roam-pointer-drag`  
+**Created**: 2026-03-19  
+**Status**: Draft
+
+## Summary
+
+Fix a map interaction bug where dragging a roam-enabled map fails on mobile browsers when VChart is configured to use pointer events without touch events.
+
+## User Scenarios
+
+### Primary User Story
+
+As a VChart user embedding a roam-enabled map in a mobile web page, I want vertical and horizontal dragging to remain stable when `supportsTouchEvents` is disabled, so that the map can still be panned reliably in pointer-only environments.
+
+## Requirements
+
+### Functional Requirements
+
+1. The map component MUST support stable drag roaming on mobile browsers when `VChart.vglobal.supportsTouchEvents` is set to `false`.
+2. The fix MUST prevent the browser's default touch gesture handling from interrupting map drag sequences when a geo region enables roam dragging.
+3. The fix MUST preserve existing drag behavior for roam-enabled geo maps in normal browser rendering.
+4. The fix MUST NOT change interaction behavior for charts that are not geo roam drag scenarios.
+
+### Edge Cases
+
+1. When a geo region disables `roam.drag`, the browser's default touch behavior should remain unchanged.
+2. When a chart does not use geo regions, the fix should not alter canvas touch handling.
+3. When roam is toggled by spec updates, the canvas touch handling should reflect the latest spec state.
+
+## Success Criteria
+
+1. In pointer-only mobile browser mode, initial vertical dragging on a roam-enabled map no longer enters a broken partial-drag state.
+2. Horizontal and vertical panning both work consistently without requiring a prior horizontal gesture.
+3. Non-map or non-roam charts keep their existing page scrolling behavior.