WPF利用DrawingContext实现绘制温度计

第WPF利用DrawingContext实现绘制温度计项目使用MIT开源许可协议；

定义Interval步长、MaxValue最大温度值、MinValue最小温度值。

CurrentGeometry重新绘制当前刻度的Path值。

CurrentValue当前值如果发生变化时则去重新CurrentGeometry。

OnRender绘制如下

RoundedRectangle温度计的外边框。使用方法DrawText单字绘制华氏温度文本Y轴变化。使用方法DrawText单字绘制摄氏温度文本Y轴变化。使用方法DrawText绘制温度计两侧的刻度数值。使用方法DrawLine绘制温度计两侧的刻度线。

实现代码

1）准备Thermometer.cs如下：

using

System;

using

System.Windows;

using

System.Windows.Controls;

using

System.Windows.Media;

namespace

WPFDevelopers.Controls

public

class

Thermometer

:

Control

{

public

static

readonly

DependencyProperty

MaxValueProperty

=

DependencyProperty.Register("MaxValue",

typeof(double),

typeof(Thermometer),

new

UIPropertyMetadata(40.0));

public

static

readonly

DependencyProperty

MinValueProperty

=

DependencyProperty.Register("MinValue",

typeof(double),

typeof(Thermometer),

new

UIPropertyMetadata(-10.0));

///

summary

///

当前值

///

/summary

public

static

readonly

DependencyProperty

CurrentValueProperty

=

DependencyProperty.Register("CurrentValue",

typeof(double),

typeof(Thermometer),

new

UIPropertyMetadata(OnCurrentValueChanged));

///

summary

///

步长

///

/summary

public

static

readonly

DependencyProperty

IntervalProperty

=

DependencyProperty.Register("Interval",

typeof(double),

typeof(Thermometer),

new

UIPropertyMetadata(10.0));

///

summary

///

当前值的图形坐标点

///

/summary

public

static

readonly

DependencyProperty

CurrentGeometryProperty

=

DependencyProperty.Register("CurrentGeometry",

typeof(Geometry),

typeof(Thermometer),

new

PropertyMetadata(

Geometry.Parse(@"M

2

132.8

a

4

4

0

0

1

4

-4

h

18

a

4

4

0

0

1

4

4

v

32.2

a

4

4

0

0

1

-4

4

h

-18

a

4

4

0

0

1

-4

-4

z")));

///

summary

///

构造函数

///

/summary

static

Thermometer()

{

DefaultStyleKeyProperty.OverrideMetadata(typeof(Thermometer),

new

FrameworkPropertyMetadata(typeof(Thermometer)));

}

public

double

MaxValue

{

get

=

(double)GetValue(MaxValueProperty);

set

=

SetValue(MaxValueProperty,

value);

}

public

double

MinValue

{

get

=

(double)GetValue(MinValueProperty);

set

=

SetValue(MinValueProperty,

value);

}

public

double

CurrentValue

{

get

=

(double)GetValue(CurrentValueProperty);

set

{

SetValue(CurrentValueProperty,

value);

PaintPath();

}

}

public

double

Interval

{

get

=

(double)GetValue(IntervalProperty);

set

=

SetValue(IntervalProperty,

value);

}

public

Geometry

CurrentGeometry

{

get

=

(Geometry)GetValue(CurrentGeometryProperty);

set

=

SetValue(CurrentGeometryProperty,

value);

}

private

static

void

OnCurrentValueChanged(DependencyObject

d,

DependencyPropertyChangedEventArgs

e)

{

var

thermometer

=

d

as

Thermometer;

thermometer.CurrentValue

=

Convert.ToDouble(e.NewValue);

}

public

override

void

OnApplyTemplate()

{

base.OnApplyTemplate();

PaintPath();

}

protected

override

void

OnRender(DrawingContext

drawingContext)

{

var

brush

=

new

SolidColorBrush((Color)ColorConverter.ConvertFromString("#82848A"));

var

rect

=

new

Rect();

rect.Width

=

30;

rect.Height

=

169;

drawingContext.DrawRoundedRectangle(Brushes.Transparent,

new

Pen(brush,

2d),

rect,

8d,

8d);

#region

华氏温度

drawingContext.D