【fix】 修复ol webmap 新增固定比例尺后报错 review by songym

Author: xilanhuaweidapao

src/openlayers/mapping/WebMap.js

@@ -29,6 +29,7 @@ import MVT from 'ol/format/MVT';
 import Observable from 'ol/Observable';
 import olMap from 'ol/Map';
 import View from 'ol/View';
+import MouseWheelZoom from 'ol/interaction/MouseWheelZoom';
 import * as olProj from 'ol/proj';
 import * as olProj4 from 'ol/proj/proj4';
 import Units from 'ol/proj/Units';
@@ -673,7 +674,83 @@ export class WebMap extends Observable {
             // 挂载带baseLayer上，便于删除
             baseLayer.labelLayer = labelLayer;
         }
-    }
+        this.limitScale(mapInfo, baseLayer);
+    }
+
+    validScale(scale) {
+      if (!scale) {
+          return false;
+      }
+      const scaleNum = scale.split(':')[1];
+      if (!scaleNum) {
+          return false;
+      }
+      const res = 1 / +scaleNum;
+      if (res === Infinity || res >= 1) {
+          return false;
+      }
+      return true;
+  }
+
+  limitScale(mapInfo, baseLayer) {
+      if (this.validScale(mapInfo.minScale) && this.validScale(mapInfo.maxScale)) {
+          let visibleScales, minScale, maxScale;
+          if (baseLayer.layerType === 'WMTS') {
+              visibleScales = baseLayer.scales;
+              minScale = mapInfo.minScale.split(':')[1];
+              maxScale = mapInfo.maxScale.split(':')[1];
+          } else {
+              const scales = this.scales.map((scale) => {
+                  return 1 / scale.split(':')[1];
+              });
+              visibleScales = baseLayer.visibleScales || scales;
+              minScale = 1 / mapInfo.minScale.split(':')[1];
+              maxScale = 1 / mapInfo.maxScale.split(':')[1];
+          }
+        
+          const minVisibleScale = this.findNearest(visibleScales, minScale);
+          const maxVisibleScale = this.findNearest(visibleScales, maxScale);
+          const minZoom = visibleScales.indexOf(minVisibleScale);
+          const maxZoom = visibleScales.indexOf(maxVisibleScale);
+          if (minZoom !== 0 && maxZoom !== visibleScales.length - 1) {
+              this.map.setView(
+                  new View(
+                      Object.assign({}, this.map.getView().options_, {
+                          maxResolution: undefined,
+                          minResolution: undefined,
+                          minZoom,
+                          maxZoom,
+                          constrainResolution: false
+                      })
+                  )
+              );
+              this.map.addInteraction(
+                  new MouseWheelZoom({
+                      constrainResolution: true
+                  })
+              );
+          }
+      }
+  }
+
+  parseNumber(scaleStr) {
+    return Number(scaleStr.split(":")[1])
+  }
+
+  findNearest(scales, target) {
+    let resultIndex = 0
+    let targetScaleD = target;
+    for (let i = 1, len = scales.length; i < len; i++) {
+      if (
+        Math.abs(scales[i] - targetScaleD) <
+        Math.abs(scales[resultIndex] - targetScaleD)
+      ) {
+        resultIndex = i
+      }
+    }
+    return scales[resultIndex]
+  }
+
     /**
      * @private
      * @function ol.supermap.WebMap.prototype.addMVTMapLayer
@@ -752,6 +829,7 @@ export class WebMap extends Observable {
         // if(options.baseLayer.visibleScales && options.baseLayer.visibleScales.length > 0){
         //     maxZoom = options.baseLayer.visibleScales.length;
         // }
+        this.map.setView(new View({ zoom, center, projection, maxZoom }));
         let viewOptions = {};
 
         if (baseLayer.scales && baseLayer.scales.length > 0 && baseLayer.layerType === "WMTS" ||