fix: 解决首次绘制可能出现的canvas尺寸问题

painter.js

@@ -662,12 +662,10 @@ Component({
 
     startPaint() {
       this.initScreenK();
-
-      this.downloadImages(this.properties.palette).then(async (palette) => {
       const {
         width,
         height
-        } = palette;
+      } = this.properties.palette;
 
       if (!width || !height) {
         console.error(`You should set width and height correctly for painter, width: ${width}, height: ${height}`);
@@ -691,7 +689,8 @@ Component({
       }
       this.setData({
         photoStyle: `width:${this.canvasWidthInPx}px;height:${this.canvasHeightInPx}px;`,
-        });
+      }, function () {
+        this.downloadImages(this.properties.palette).then(async palette => {
           if (!this.photoContext) {
             this.photoContext = await this.getCanvasContext(this.properties.use2D, 'photo');
           }
@@ -706,6 +705,7 @@ Component({
           });
           setStringPrototype(this.screenK, this.properties.scaleRatio);
         });
+      });
     },
 
     downloadImages(palette) {