WPF学习之路（十一）布局（续）

布局实际上是一个Slot模型，其中每个父对象分配给子对象一个Slot，子对象可以自由占用Slot中的空间，通过MarginVerticalAlignmentHorizontalAlignment控制

实例

<Border Background="LightBlue" BorderBrush="Black" BorderThickness="2" CornerRadius="45" Padding="25">
    <StackPanel Name="SP1" Background="White">
        <TextBlock FontSize="15" HorizontalAlignment="Center" Margin="0,0,0,15" Text="StackPanel1"></TextBlock>
        <Border BorderThickness="1" BorderBrush="Black">
            <Button Margin="5,10,15,20">Normal</Button>
        </Border>
        <Border BorderThickness="1" BorderBrush="Black">
            <Button Margin="5,10,15,20" HorizontalAlignment="Left">
                <Button.LayoutTransform>
                    <RotateTransform Angle="15" />
                </Button.LayoutTransform>
                Left</Button>
        </Border>
        <Border BorderThickness="1" BorderBrush="Black">
            <Button Margin="5,10,15,20" HorizontalAlignment="Right">
                <Button.LayoutTransform>
                    <RotateTransform Angle="45" />
                </Button.LayoutTransform>
                Right</Button>
        </Border>
        <Border BorderThickness="1" BorderBrush="Black">
            <Button Margin="5,10,15,20" HorizontalAlignment="Center">
                <Button.LayoutTransform>
                    <RotateTransform Angle="75" />
                </Button.LayoutTransform>
                Center</Button>
        </Border>
        <Border BorderThickness="1" BorderBrush="Black">
            <Button Margin="5,10,15,20" >
                <Button.LayoutTransform>
                    <RotateTransform Angle="15" />
                </Button.LayoutTransform>
                LayoutTransform
            </Button>
        </Border>
        <Border BorderThickness="1" BorderBrush="Black">
            <Button Margin="5,10,15,20" >
                <Button.RenderTransform>
                    <RotateTransform Angle="15" />
                </Button.RenderTransform>
                RenderTransform
            </Button>
        </Border>
    </StackPanel>
</Border>

注意LayoutTransform和RenderTransform的区别

自定义布局

确定空间最佳尺寸经历两个阶段，1.测量，父元素询问子元素期望的尺寸，来确定自身尺寸 2.布置，父元素告知子元素的位置

具体实现为以下两个重载函数

protected override Size ArrangeOverride(Size arrangeBounds);
protected override Size MeasureOverride(Size constraint);

自定义CustomPanel

public class CustomPanel : Panel
{
    public CustomPanel()
        : base()
    {
    }

    protected override Size MeasureOverride(Size availableSize)
    {
        double maxChildWidth = 0.0;
        double maxChildHeight = 0.0;
        foreach (UIElement child in InternalChildren)
        {
            child.Measure(availableSize);
            maxChildWidth = Math.Max(child.DesiredSize.Width, maxChildWidth);
            maxChildHeight = Math.Max(child.DesiredSize.Height, maxChildHeight);
        }

        double idealCircumference = maxChildWidth * InternalChildren.Count;
        double idealRadius = idealCircumference / (Math.PI * 2) + maxChildHeight;

        Size desired = new Size(idealRadius * 2, idealRadius * 2);

        if (!double.IsInfinity(availableSize.Width))
        {
            if (availableSize.Width < desired.Width)
                desired.Width = availableSize.Width;
        }
        if (!double.IsInfinity(availableSize.Height))
        {
            if (availableSize.Height < desired.Height)
                desired.Height = availableSize.Height;
        }

        return desired;
    }

    protected override Size ArrangeOverride(Size finalSize)
    {
        Rect layoutRect;
        if (finalSize.Width > finalSize.Height)
        {
            layoutRect = new Rect((finalSize.Width - finalSize.Height) / 2, 0, finalSize.Height, finalSize.Height);
        }
        else
        {
            layoutRect = new Rect((finalSize.Height - finalSize.Width) / 2, 0, finalSize.Width, finalSize.Width);
        }

        double angleInc = 360 / InternalChildren.Count;
        double angle = 0;
        foreach (UIElement child in InternalChildren)
        {
            Point childLocation = new Point(layoutRect.Left + (layoutRect.Width - child.DesiredSize.Width) / 2, layoutRect.Top);
            child.RenderTransform = new RotateTransform(angle, child.DesiredSize.Width / 2, finalSize.Height / 2 - layoutRect.Top);
            angle += angleInc;
            child.Arrange(new Rect(childLocation, child.DesiredSize));
        }

        return finalSize;
    }
}

<Page x:Class="Alex_WPFAPPDemo09.DemoPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:local="clr-namespace:Alex_WPFAPPDemo09"
      mc:Ignorable="d" 
      d:DesignHeight="300" d:DesignWidth="300"
    Title="DemoPage">

    <Grid Margin="5">
        <local:CustomPanel>
            <Button Content="1" MinWidth="100" />
            <Button Content="2" MinWidth="100" />
            <Button Content="3" MinWidth="100" />
            <Button Content="4" MinWidth="100" />
            <Button Content="5" MinWidth="100" />
            <Button Content="6" MinWidth="100" />
            <Button Content="7" MinWidth="100" />
        </local:CustomPanel>
    </Grid>
</Page>

To be continue...