Feat：新增限制TouchEvent插件双指缩放的最大值和最小值

simple-mind-map/src/constants/defaultOptions.js

@@ -323,6 +323,10 @@ export const defaultOpt = {
   // 禁止双指缩放，你仍旧可以使用api进行缩放
   // 需要注册TouchEvent插件后生效
   disableTouchZoom: false,
+  // 允许最大和最小的缩放值，百分数
+  // 传-1代表不限制
+  minTouchZoomScale: 20,
+  maxTouchZoomScale: -1,
 
   // 【Scrollbar插件】
   // 当注册了滚动条插件（Scrollbar）时，是否将思维导图限制在画布内，isLimitMindMapInCanvas不再起作用

simple-mind-map/src/plugins/TouchEvent.js

@@ -66,7 +66,13 @@ class TouchEvent {
       let touch = e.touches[0]
       this.dispatchMouseEvent('mousemove', touch.target, touch)
     } else if (len === 2) {
-      if (this.mindMap.opt.disableTouchZoom) return
+      let { disableTouchZoom, minTouchZoomScale, maxTouchZoomScale } =
+        this.mindMap.opt
+      if (disableTouchZoom) return
+      minTouchZoomScale =
+        minTouchZoomScale === -1 ? -Infinity : minTouchZoomScale / 100
+      maxTouchZoomScale =
+        maxTouchZoomScale === -1 ? Infinity : maxTouchZoomScale / 100
       let touch1 = e.touches[0]
       let touch2 = e.touches[1]
       let ox = touch1.clientX - touch2.clientX
@@ -101,8 +107,14 @@ class TouchEvent {
       if (Math.abs(distance - viewBefore.distance) <= 10) {
         scale = viewBefore.scale
       }
+      scale =
+        scale < minTouchZoomScale
+          ? minTouchZoomScale
+          : scale > maxTouchZoomScale
+          ? maxTouchZoomScale
+          : scale
       const ratio = 1 - scale / viewBefore.scale
-      view.scale = scale < 0.1 ? 0.1 : scale
+      view.scale = scale
       view.x =
         viewBefore.x +
         (cx - viewBefore.x) * ratio +