Fix：修复导出pdf时异步控制丢失的问题

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

@@ -228,7 +228,7 @@ class Export {
       if (width <= a4Size.width && height && a4Size.height) return false
       return width / height > 1
     })
-    this.mindMap.doExportPDF.pdf(name, img, useMultiPageExport)
+    await this.mindMap.doExportPDF.pdf(name, img, useMultiPageExport)
   }
 
   // 导出为xmind

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

@@ -9,16 +9,17 @@ class ExportPDF {
   }
 
   //  导出为pdf
-  pdf(name, img, useMultiPageExport = false) {
+  async pdf(name, img, useMultiPageExport = false) {
     if (useMultiPageExport) {
-      this.multiPageExport(name, img)
+      await this.multiPageExport(name, img)
     } else {
-      this.onePageExport(name, img)
+      await this.onePageExport(name, img)
     }
   }
 
   // 单页导出
   onePageExport(name, img) {
+    return new Promise((resolve, reject) => {
       let pdf = new JsPDF('', 'pt', 'a4')
       let a4Ratio = a4Size.width / a4Size.height
       let image = new Image()
@@ -49,12 +50,18 @@ class ExportPDF {
           h
         )
         pdf.save(name)
+        resolve()
+      }
+      image.onerror = e => {
+        reject(e)
       }
       image.src = img
+    })
   }
 
   // 多页导出
   multiPageExport(name, img) {
+    return new Promise((resolve, reject) => {
       let image = new Image()
       image.onload = () => {
         let imageWidth = image.width
@@ -93,8 +100,13 @@ class ExportPDF {
           }
         }
         pdf.save(name)
+        resolve()
+      }
+      image.onerror = (e) => {
+        reject(e)
       }
       image.src = img
+    })
   }
 }