WPF学习05：2D绘图使用Transform进行控件变形

2019-11-14 16:05:00

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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：

image_thumb3 image_thumb2[1]

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 = 0; i < 36; i++){    var polygon = new Polygon()    {        Fill = new SolidColorBrush(Colors.LightBlue),        Points = new PointCollection() {             new Point() {X = 0, Y = 0},            new Point(){X = 100, Y = 5},            new Point(){X = 0, Y = 10}        }    };    polygon.RenderTransform = new TransformGroup()    {        Children = new TransformCollection()         {             new RotateTransform(){ Angle = i * 10}        }    };    Canvas.SetTop(polygon, 100);    Canvas.SetLeft(polygon, 200);    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：

image_thumb31

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:

image_thumb1

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 = 0, Y = 0},        new Point(){X = 100, Y = 25},        new Point(){X = 0, Y = 50}    },    RenderTransform = new TransformGroup()    {        Children = new TransformCollection()         {            new TranslateTransform(){X=50,Y=100}        }    }};MainCanvas.Children.Add(polygon);

RotateTransform

image_thumb2

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 = 0, Y = 0},        new Point(){X = 100, Y = 25},        new Point(){X = 0, Y = 50}    },    RenderTransform = new TransformGroup()    {        Children = new TransformCollection()         {            new TranslateTransform(){X=50,Y=100},            new RotateTransform(){Angle=50, CenterX=50, CenterY=100}        }    }};

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

image_thumb4

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

image_thumb5

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： image_thumb6

这里只实现一个简单的矩阵实现平移：

image_thumb7

实现代码：

var polygon = new Polygon(){    Fill = new SolidColorBrush(Color.FromRgb(0x01, 0x9A, 0xFF)),    Points = new PointCollection()    {        new Point(){X=0, Y = 0},        new Point(){X=0, Y = 50},        new Point(){X=100, Y = 25}    },    RenderTransform = new TransformGroup()    {        Children = new TransformCollection()         {            new MatrixTransform()            {                Matrix = new Matrix()                {                    M11 = 1, M12 = 0,                    M21 = 0, M22 = 1,                    OffsetX = 150, OffsetY = 100                }            }        }    }};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： image_thumb8

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>