Dragging (d3-drag)
Drag and drop SVG, HTML or Canvas using mouse or touch input.使用鼠标或者手势，拖拽SVG,HTML,CANVAS
- d3.drag - create a drag behavior创建一个行为.
- drag - apply the drag behavior to a selection.将一个拖拽行为应用到一个拖拽对象上
- drag.container - set the coordinate system.设置坐标系统
- drag.filter - ignore some initiating input events.忽略一些初始化的输入事件
- drag.touchable - set the touch support detector.设置触碰支持检测
- drag.subject - set the thing being dragged.设置可拖拽对象
- drag.clickDistance - set the click distance threshold.设置点击距离阈值
- drag.on - listen for drag events.监听拖拽事件
- d3.dragDisable - prevent native drag-and-drop and text selection.阻住原生拖放和文本选择事件
- d3.dragEnable - enable native drag-and-drop and text selection.启用原生拖放和文本选择事件
- event.on - listen for drag events on the current gesture.在现有手势上监听拖动事件
