Question

基本上我导航到此页面并将其作为参数传递给我，然后我将其用于从隔离存储中检索该图片。同时我从assets文件夹中检索“frame”。
当我编译代码时没有发生错误，但是一旦我在运行期间到达这个部分，我就得到了frametest的nullexception。我之前尝试在frameImage !=null中构建，以确保值仍然存在错误。两个图像都正确加载到BitMapImage中，我也可以显示它们（测试过这个）

        BitmapImage image = new BitmapImage();
        BitmapImage frameImage = new BitmapImage();

        parameter = string.Empty;

        if (NavigationContext.QueryString.TryGetValue("parameter", out parameter))
        {

            picName = parameter + ".jpg";

            //call function to load image source from isolateStorage
            using (isoStore = IsolatedStorageFile.GetUserStoreForApplication())
            {
                if (isoStore != null)
                {
                    using (isoStream = new IsolatedStorageFileStream(parameter, FileMode.OpenOrCreate, isoStore))
                    {
                        if (isoStream != null)
                        {
                            image.SetSource(isoStream);
                        }
                    }
                    //close the stream object
                    isoStream.Close();
                }
            }
            //close the storage object
            isoStore.Dispose();

            string path = "/Assets/AppGraphics/UserInterface/frame.png";
            Uri uriR = new Uri(path, UriKind.Relative);
            frameImage = new BitmapImage(uriR);

            //error occurs here
            WriteableBitmap frameTest = new WriteableBitmap(frameImage);
            WriteableBitmap imageTest = new WriteableBitmap(image);

            var photo = imageTest;
            var frame = frameTest;
            var merge = new WriteableBitmap(656, 410);

            merge.Blit(new Rect(0, 0, 656, 410), photo, new Rect(0, 0, photo.PixelWidth, photo.PixelHeight)); //draw the photo first
            merge.Blit(new Rect(0, 0, 656, 410), frame, new Rect(0, 0, frame.PixelWidth, frame.PixelHeight)); //draw the frame

            imgCC.Source = merge;

我不明白为什么我得到一个nullexception，当对象显然不是null。任何帮助或想法都表示赞赏。

堆栈跟踪：

   at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
   at MS.Internal.XcpImports.WriteableBitmap_CreateFromSource(WriteableBitmap wb, IntPtr ptrMemory, BitmapSource source, Boolean& bHasProtectedContent)
   at System.Windows.Media.Imaging.WriteableBitmap..ctor(BitmapSource source)
   at PinAppWindowsPhone.confirmPicture.OnNavigatedTo(NavigationEventArgs e)
   at Microsoft.Phone.Controls.PhoneApplicationPage.InternalOnNavigatedTo(NavigationEventArgs e)
   at Microsoft.Phone.Controls.PhoneApplicationPage.Microsoft.Phone.Controls.IPhoneApplicationPage.InternalOnNavigatedToX(NavigationEventArgs e)
   at System.Windows.Navigation.NavigationService.RaiseNavigated(Object content, Uri uri, NavigationMode mode, Boolean isNavigationInitiator, IPhoneApplicationPage existingContentPage, IPhoneApplicationPage newContentPage)
   at System.Windows.Navigation.NavigationService.CompleteNavigation(DependencyObject content, NavigationMode mode)
   at System.Windows.Navigation.NavigationService.ContentLoader_BeginLoad_Callback(IAsyncResult result)

尝试使用WriteableBitMap合并两个图片时出错

0 个答案: