WPF学习05：2D绘图 使用Transform进行控件变形

在WPF学习04：2D绘图 使用Shape绘基本图形中，我们了解了如何绘制基本的图形。

这一次，我们进一步，研究如何将图形变形。

例子

一个三角形，经Transform形成组合图形：

XAML代码：

<Window x:Class="Transforms.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" Loaded="Window_Loaded">
    <Canvas Name="MainCanvas">
    </Canvas>
</Window>

C#代码：

for (int i = ; i < ; i++)
{
    var polygon = new Polygon()
    {
        Fill = new SolidColorBrush(Colors.LightBlue),
        Points = new PointCollection() {
            new Point() {X = , Y = },
            new Point(){X = , Y = },
            new Point(){X = , Y = }
        }
    };
    polygon.RenderTransform = new TransformGroup()
    {
        Children = new TransformCollection()
        {
            new RotateTransform(){ Angle = i * }
        }
    };
    Canvas.SetTop(polygon, );
    Canvas.SetLeft(polygon, );
    MainCanvas.Children.Add(polygon);
}

---

Shape简介

WPF提供了Transform类，使我们得以对控件进行变形操作。

Transform提供了TranslateTransform(平移变形) RotateTransform(旋转变形) ScaleTransform(缩放变形) SkewTransform(扭曲变形) MatrixTransform(矩阵变换变形)

回顾一下Shape的继承结构：

UIElement提供了RenderTransform

FrameworkElement提供了LayoutTransform

两者皆为Transform类型的属性，本文将逐个介绍各类变形的使用方法，最后将说明这两种Transform的区别。

---

TranslateTransform:

XAML实现：

<Canvas Name="MainCanvas">
    <Polygon Points="0,0 100,25 0,50" Stroke="Black" StrokeThickness="2" StrokeDashArray="1 1"></Polygon>
    <TextBlock Canvas.Top="15" Canvas.Left="2">我是原图形</TextBlock>
    <Polygon Points="0,0 100,25 0,50" Fill="#019AFF">
        <Polygon.RenderTransform>
            <TransformGroup>
                <TranslateTransform X="50" Y="100"></TranslateTransform>
            </TransformGroup>
        </Polygon.RenderTransform>
    </Polygon>
</Canvas>

后台代码实现：

var polygon = new Polygon()
{
    Fill = new SolidColorBrush(Color.FromRgb(0x01, 0x9A, 0xFF)),
    Points = new PointCollection()
    {
        new Point() {X = , Y = },
        new Point(){X = , Y = },
        new Point(){X = , Y = }
    },
    RenderTransform = new TransformGroup()
    {
        Children = new TransformCollection()
        {
            new TranslateTransform(){X=,Y=}
        }
    }
};
MainCanvas.Children.Add(polygon);

---

RotateTransform

XAML实现:

<Canvas Name="MainCanvas">
    <Polygon Points="0,0 100,25 0,50" Stroke="Black" StrokeThickness="2" StrokeDashArray="1 1"></Polygon>
    <TextBlock Canvas.Top="15" Canvas.Left="2">我是原图形</TextBlock>
    <Polygon Points="0,0 100,25 0,50" Fill="#019AFF">
        <Polygon.RenderTransform>
            <TransformGroup>
                <TranslateTransform X="250" Y="100"></TranslateTransform>
            </TransformGroup>
        </Polygon.RenderTransform>
    </Polygon>
    <Polygon Points="0,0 100,25 0,50" Fill="#019AFF">
        <Polygon.RenderTransform>
            <TransformGroup>
                <TranslateTransform X="50" Y="100"></TranslateTransform>
                <RotateTransform CenterX="50" CenterY="100" Angle="50"></RotateTransform>
            </TransformGroup>
        </Polygon.RenderTransform>
    </Polygon>
</Canvas>

后台代码实现：

var polygon = new Polygon()
{
    Fill = new SolidColorBrush(Color.FromRgb(0x01, 0x9A, 0xFF)),
    Points = new PointCollection()
    {
        new Point() {X = , Y = },
        new Point(){X = , Y = },
        new Point(){X = , Y = }
    },
    RenderTransform = new TransformGroup()
    {
        Children = new TransformCollection()
        {
            new TranslateTransform(){X=,Y=},
            new RotateTransform(){Angle=, CenterX=, CenterY=}
        }
    }
};

注意，这里通过设置CenterX CenterY配置旋转的参考中心点，改点默认为(0, 0)

---

ScaleTransform

XAML实现:

<Canvas Name="MainCanvas">
    <Polygon Points="0,0 100,25 0,50" Stroke="Black" StrokeThickness="2" StrokeDashArray="1 1"></Polygon>
    <TextBlock Canvas.Top="15" Canvas.Left="2">我是原图形</TextBlock>
    <Polygon Points="0,0 100,25 0,50" Fill="#019AFF">
        <Polygon.RenderTransform>
            <TransformGroup>
                <TranslateTransform X="50" Y="100"></TranslateTransform>
                <ScaleTransform ScaleX="0.5" ScaleY="0.5"></ScaleTransform>
            </TransformGroup>
        </Polygon.RenderTransform>
    </Polygon>
    <Polygon Points="0,0 100,25 0,50" Fill="#019AFF">
        <Polygon.RenderTransform>
            <TransformGroup>
                <TranslateTransform X="50" Y="100"></TranslateTransform>
                <ScaleTransform ScaleX="1.5" ScaleY="1.5"></ScaleTransform>
            </TransformGroup>
        </Polygon.RenderTransform>
    </Polygon>
</Canvas>

后台代码实现参考之前的代码，类似。

---

SkewTransform

XAML实现:

<Canvas Name="MainCanvas">
    <Polygon Points="0,0 100,25 0,50" Stroke="Black" StrokeThickness="2" StrokeDashArray="1 1"></Polygon>
    <TextBlock Canvas.Top="15" Canvas.Left="2">我是原图形</TextBlock>
    <Polygon Points="0,0 100,25 0,50" Fill="#019AFF">
        <Polygon.RenderTransform>
            <TransformGroup>
                <SkewTransform AngleY="40" ></SkewTransform>
            </TransformGroup>
        </Polygon.RenderTransform>
    </Polygon>
</Canvas>

后台代码实现参考之前的代码，类似。

---

MatrixTransform

图形变换的本质都是将各个点，映射到一个齐次坐标系，然后乘上一个3X3的矩阵进行变换。

详细的内容这本书介绍的比较全：

这里只实现一个简单的矩阵实现平移：

实现代码：

var polygon = new Polygon()
{
    Fill = new SolidColorBrush(Color.FromRgb(0x01, 0x9A, 0xFF)),
    Points = new PointCollection()
    {
        new Point(){X=, Y = },
        new Point(){X=, Y = },
        new Point(){X=, Y = }
    },
    RenderTransform = new TransformGroup()
    {
        Children = new TransformCollection()
        {
            new MatrixTransform()
            {
                Matrix = new Matrix()
                {
                    M11 = , M12 = ,
                    M21 = , M22 = ,
                    OffsetX = , OffsetY =
                }
            }
        }
    }
};
MainCanvas.Children.Add(polygon);

---

RenderTransform与LayoutTransform

对于Canvas这样使用绝对定位的Layout控件下的变形操作，两者的效果是一致的。

而在其它的布局控件中，LayoutTransform是会影响到布局的。

例子：

XAML代码：

<StackPanel Name="MainCanvas">
    <Polygon Points="0,0 150,25 0,50" Stroke="Black" StrokeThickness="2" StrokeDashArray="1 1">
        <Polygon.LayoutTransform>
            <RotateTransform Angle="50"></RotateTransform>
        </Polygon.LayoutTransform>
    </Polygon>
    <Polygon Points="0,0 150,25 0,50" Stroke="Black" StrokeThickness="2" StrokeDashArray="1 1"></Polygon>
</StackPanel>

我们将LayoutTransform改为RenderTransform，结果如下: