Question

我使用Xam.Plugins.Forms.Svg来支持svg图像。我需要更改图像，所以我尝试了：

xaml中

绑定：

private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",         /* suffix */
            storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentPhotoPath = "file:" + image.getAbsolutePath();
    return image;
}

private void dispatchTakePictureIntent() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    // Ensure that there's a camera activity to handle the intent
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        // Create the File where the photo should go
        File photoFile = null;
        try {
            photoFile = createImageFile();
        } catch (IOException ex) {
            // Error occurred while creating the File
        }
        // Continue only if the File was successfully created
        if (photoFile != null) {
            fileUri = FileProvider.getUriForFile(this,
                    "com.example.android.fileprovider",
                    photoFile);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
        }
    }
}
private void previewSavedImage() {
    try {
        // hide video preview
        videoPreview.setVisibility(View.GONE);

        imgPreview.setVisibility(View.VISIBLE);

        // bimatp factory
        BitmapFactory.Options options = new BitmapFactory.Options();

        // downsizing image as it throws OutOfMemory Exception for larger
        // images
        options.inSampleSize = 2;

        String path = fileUri.getPath();

        //File img_file = new  File(getFilesDir(), path);



        final Bitmap bitmap = BitmapFactory.decodeFile(path, options);

        imgPreview.setImageBitmap(bitmap);
    } catch (NullPointerException e) {
        e.printStackTrace();
    }
}

直接从C＃更改它：

<abstractions:SvgImage
    SvgPath="{Binding CurrentWeather.IconSource, StringFormat='Umbrella.Images.{0:F0}.svg'}"
    ....
    />

SvgPath属性确实发生了变化，但图像没有重新渲染。

有没有解决方案？

Answer 1

渲染渲染器的方式是问题，您需要创建新 SvgImage对象并替换页面中的当前内容渲染器的工作方式，以便从新的SVG文件更新静态Image。

您可以通过覆盖OnElementPropertyChanged事件来修补渲染器并回复SvgPath PropertyName更改：

iOS示例：

protected override void OnElementPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
    base.OnElementPropertyChanged(sender, e);
    if (e.PropertyName == "SvgPath")
    {
        var svgStream = _formsControl.SvgAssembly.GetManifestResourceStream(_formsControl.SvgPath);
        var reader = new SvgReader(new StreamReader(svgStream), new StylesParser(new ValuesParser()), new ValuesParser());
        var graphics = reader.Graphic;
        var canvas = new ApplePlatform().CreateImageCanvas(graphics.Size);
        graphics.Draw(canvas);
        var image = canvas.GetImage();
        var uiImage = image.GetUIImage();
        Control.Image = uiImage;
    }
}

参考：https://github.com/paulpatarinski/Xamarin.Forms.Plugins/blob/eab230fcf4158a288387727c15903a954e01cdaa/SVG/SVG/SVG.Forms.Plugin.Android/SvgImageRenderer.cs

参考：https://github.com/paulpatarinski/Xamarin.Forms.Plugins/blob/eab230fcf4158a288387727c15903a954e01cdaa/SVG/SVG/SVG.Forms.Plugin.iOS/SvgImageRenderer.cs

Xamarin Xam.Plugins.Forms.Svg更改SvgPath以重新渲染图像

1 个答案: