windowsphone8.1学习笔记之位图编程

<Image Name="img" Source="可以是网络图片的Uri、应用文件的Uri或者安装包文件的Uri" />
img.Source = new BitmapIamge(new Uri(同上));

    <Grid Background="Black"
          PointerMoved="Grid_PointerMoved">
        <Image Name="ContentPanel" Source="ms-appx:///Assets/Logo.scale-240.png">
            <Image.Clip>
                <RectangleGeometry x:Name="geometry" Rect="0,0,150,150" />
            </Image.Clip>
        </Image>
    </Grid>

        private void Grid_PointerMoved(object sender, PointerRoutedEventArgs e)
        {
            Point p = e.GetCurrentPoint(ContentPanel).Position;
            geometry.Rect = new Rect(p.X, p.Y, 150, 150);
        }

        //PointerReleased可以捕获单击事件
        private async void root_PointerReleased(object sender, PointerRoutedEventArgs e)
        {
            //创建RenderTargetBitmap对象
            RenderTargetBitmap bitmap = new RenderTargetBitmap();
            //root为UIElement的Name
            await bitmap.RenderAsync(root);
            img.Source = bitmap;
        }

    <Grid Name="root">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <StackPanel Name="TitlePanel" Margin="10,35,10,10">
            <TextBlock Text="我的应用程序" FontSize="20" />
            <TextBlock Text="测试" FontSize="60" />
        </StackPanel>
        <Grid Name="ContentPanel" Grid.Row="1" Margin="10,0,10,10">
            <Image Name="img" />
        </Grid>
        <Grid Grid.Row="2">
            <Grid.ColumnDefinitions>
                <ColumnDefinition />
                <ColumnDefinition />
            </Grid.ColumnDefinitions>
            <Button VerticalAlignment="Center" HorizontalAlignment="Center" Content="获取图像" Click="Button_Click_1" />
            <Button VerticalAlignment="Center" HorizontalAlignment="Center" Content="显示图像" Click="Button_Click" Grid.Column="1" />
        </Grid>
    </Grid>

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            img.Source = new BitmapImage(new Uri("ms-appdata:///local/testBitmap.png",UriKind.Absolute));
        }

        private async void Button_Click_1(object sender, RoutedEventArgs e)
        {
            //创建要存储的文件,这个不需多说了。
            var storageFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("testBitmap.png", CreationCollisionOption.OpenIfExists);

            RenderTargetBitmap bitmap = new RenderTargetBitmap();
            await bitmap.RenderAsync(root);

            //获取图像的二进制数据
            var pixelBuffer = await bitmap.GetPixelsAsync();

            using (var fileStream = await storageFile.OpenAsync(FileAccessMode.ReadWrite))
            {
                var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, fileStream);
                encoder.SetPixelData(
                    BitmapPixelFormat.Bgra8,//像素格式
                    BitmapAlphaMode.Ignore,//像素数据的alpha模式，定义透明的
                    (uint)bitmap.PixelWidth,//像素宽
                    (uint)bitmap.PixelHeight,//像素高
                    DisplayInformation.GetForCurrentView().LogicalDpi,//像素水平分辨率，这个就是获取设备的屏幕分辨率的方法
                    DisplayInformation.GetForCurrentView().LogicalDpi,//像素垂直分辨率
                    pixelBuffer.ToArray());//像素数据

                await encoder.FlushAsync();
            }

            await new MessageDialog("获取图像成功并已保存").ShowAsync();
        }