Question

我想显示一些文字和图片以某种方式显示文字2秒，然后图片将替换它。也是在那个时候不要让UI卡住。

我尝试了以下内容：在WPF UI中：

            <Border x:Name="ComparisonResultImageBox" Visibility="Visible" Grid.Row="2" Grid.Column="2" Background="White" Margin="8,5,8,5">
                <Image x:Name="DiffrenceImage"></Image>
            </Border>

和

            <Border x:Name="LoadingComparisonResultLabel" Visibility="Collapsed" Grid.Row="2" Grid.Column="2" Background="White" Margin="0,5,8,5">
                <Label Content="Loading Comparison Result..." FontFamily="Open Sans" FontSize="13" ></Label>
            </Border>

然后在代码中，当点击页面上的某个按钮时，我调用了以下方法：

private void ClearComparePicture() {
    DiffrenceImage.Source = null;

    LoadingComparisonResultLabel.Visibility = Visibility.Visible;
    ComparisonResultImageBox.Visibility = Visibility.Collapsed;

    Thread.Sleep(2000);
    DiffrenceImage.Source = newBitmapImage;

    LoadingComparisonResultLabel.Visibility = Visibility.Collapsed;
    ComparisonResultImageBox.Visibility = Visibility.Visible;
}

问题是文本在睡眠时间内没有显示....

Answer 1

您不应该在UI线程上使用任何阻塞调用（长时间运行同步）。

可能使这项工作最简单的变化是使用async Task或async void。

private async Task ClearComparePicture() {
    DiffrenceImage.Source = null;    

    LoadingComparisonResultLabel.Visibility = Visibility.Visible;
    ComparisonResultImageBox.Visibility = Visibility.Collapsed;

    await Task.Delay(2000);
    DiffrenceImage.Source = newBitmapImage;

    LoadingComparisonResultLabel.Visibility = Visibility.Collapsed;
    ComparisonResultImageBox.Visibility = Visibility.Visible;
}

更改UI等待2000毫秒并再次更改UI

1 个答案: