WPF使用AForge实现Webcam预览(二)

本文主要介绍如何让摄像头预览界面的宽高比始终在16：9。

首先咱们须要修改一下上一篇随笔实现的UI界面，让Grid变成一个3*3的九宫格，预览界面位于正中间。Xaml示例代码以下：

<Window x:Class="WebcamPreview.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:controls="clr-namespace:AForge.Controls;assembly=AForge.Controls"
        mc:Ignorable="d"
        Title="Webcam" Height="360" Width="320" MinHeight="360" MinWidth="320" ResizeMode="CanResize" SizeChanged="Window_SizeChanged">
    <Grid  Background="Black">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"></ColumnDefinition>
            <ColumnDefinition Width="320" x:Name="col"></ColumnDefinition>
            <ColumnDefinition Width="*"></ColumnDefinition>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="360" x:Name="row"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Grid Grid.Row="1" Grid.Column="1">
            <Grid.RowDefinitions>
                <RowDefinition Height="*"/>
                <RowDefinition Height="*"/>
            </Grid.RowDefinitions>
            <WindowsFormsHost Background="Transparent">
                <controls:VideoSourcePlayer x:Name="VideoSourcePlayer1"/>
            </WindowsFormsHost>
            <WindowsFormsHost Background="Transparent" Grid.Row="1" >
                <controls:VideoSourcePlayer x:Name="VideoSourcePlayer2" />
            </WindowsFormsHost>
        </Grid>
    </Grid>
</Window>

指定Window的ResizeMode为CanResize,这样就咱们能够调整窗口的大小了。

接下来就要实现window的SizeChanged事件。

private double radio = (double)16 / 9;

private void Window_SizeChanged(object sender, SizeChangedEventArgs e)
        {
            int width = Convert.ToInt32(ActualWidth);
            int height = Convert.ToInt32(ActualHeight / 2);
            if (width > height * radio)
            {
                width = Convert.ToInt32(height * radio);
            }
            else
            {
                height = Convert.ToInt32(width / radio);
            }

            row.Height = new GridLength(height * 2);
            col.Width = new GridLength(width);
        }

 

这样就能够在咱们改变窗口大小的时候，使咱们视频预览的宽高比始终保持在16：9了。

最终效果以下：