fix: screenshot update

src/sdk/cover/index.js

@@ -305,7 +305,7 @@ export const enter = (dom, isLocal) => {
         
         screenshot: (width, height) => {
             //截图  
-            var {getImagePromise, finishPromise} =  viewer.startScreenshot({ type: 'default' }, width, height) 
+            var {getImagePromise, finishPromise} =  viewer.startScreenshot({ type: 'default', useRenderTarget:true }, width, height) 
             var deferred = $.Deferred();
             finishPromise.done(({dataUrl}) => {
                deferred.resolve(dataUrl)