使用C#編寫兩個(gè)漂亮?xí)r鐘的示例代碼
谷歌在2021年5月份推出的Android 12給我們帶來了新的UI設(shè)計(jì)規(guī)范Material You,你是否已經(jīng)體驗(yàn)到了Material You設(shè)計(jì)的魅力了呢?
在原生主屏幕啟動(dòng)器中,有一個(gè)時(shí)鐘小部件。這個(gè)小部件可以選擇表盤風(fēng)格。

圖:Android 12的時(shí)鐘小部件
今天挑戰(zhàn)在.NET MAU中實(shí)現(xiàn)這個(gè)Material You風(fēng)格時(shí)鐘。
最終效果如下:

時(shí)鐘1
繪制鋸齒表盤
鋸齒表盤是正玄波曲線閉合成一個(gè)圓形。
創(chuàng)建Clock1,打開Xaml文件
在頁面布局中創(chuàng)建一個(gè)Path對(duì)象,設(shè)置Stroke和Fill屬性。
<Path Grid.Row="0"
Grid.Column="1"
Stroke="white"
Fill="#FFEED9"
IsVisible="true"
x:Name="ModulatedPath">
<Path.Data>
<PathGeometry>
<PathGeometry.Figures>
<PathFigureCollection>
<PathFigure IsClosed="True" x:Name="MainPathFigure">
<PathFigure.Segments>
<PathSegmentCollection x:Name="MainPathSegmentCollection">
</PathSegmentCollection>
</PathFigure.Segments>
</PathFigure>
</PathFigureCollection>
</PathGeometry.Figures>
</PathGeometry>
</Path.Data>
</Path>在codebehind中,訂閱SizeChanged事件,當(dāng)控件大小發(fā)生變化時(shí),重新繪制表盤。
public Clock1()
{
InitializeComponent();
this.SizeChanged+=ContentView_SizeChanged;
}正弦曲線繪制原理
單位圓中的正弦函數(shù)在平面直角坐標(biāo)系中可以映射為一個(gè)波形曲線,下圖所示在0-2π范圍中y=sin(x)的圖像。

其中最低點(diǎn)和最高點(diǎn)決定了波形的振幅,他們與平衡點(diǎn)的距離即單位圓的半徑
設(shè)置變量 r為平衡點(diǎn),r2為最高點(diǎn),r3為最低點(diǎn)。
centerX和centerY為圓心坐標(biāo)。
segemts為繪制的線段數(shù),越大鋸齒越密集。
private void ContentView_SizeChanged(object sender, EventArgs e)
{
var length = (float)Math.Min(this.Width, this.Height) * 0.95;
var centerX = (float)this.Width / 2;
var centerY = (float)this.Height / 2;
var points = new List<Point>();
var r = length / 2;
var r2 = r * 1.1;
var r3 = r * 0.9;
var index = 0;
var segments = 40;
}首先計(jì)算各平衡點(diǎn)在圓周上的離散分布坐標(biāo)(x,y)
根據(jù)index的奇偶性,給與當(dāng)前點(diǎn)最高點(diǎn)或最低點(diǎn)的半徑。
根據(jù)各分配的半徑計(jì)算調(diào)整后的離散點(diǎn)坐標(biāo)

代碼如下:
...
for (var i = 0; i < segments; i += 2)
{
var x = r * Math.Cos(i * 2 * Math.PI / segments) + centerX;
var y = r * Math.Sin(i * 2 * Math.PI / segments) + centerY;
points.Add(new Point((float)x, (float)y));
var currentR = index++ % 2 == 0 ? r2 : r3;
x = currentR * Math.Cos((i + 1) * 2 * Math.PI / segments) + centerX;
y = currentR * Math.Sin((i + 1) * 2 * Math.PI / segments) + centerY;
points.Add(new Point((float)x, (float)y));
}如此,我們得到一個(gè)閉合的鋸齒圓形表盤

繪制指針
在表盤上繪制時(shí)鐘指針,需要計(jì)算時(shí)針、分針、秒針的角度,然后根據(jù)角度旋轉(zhuǎn)畫布,繪制指針。
秒針每秒鐘轉(zhuǎn)動(dòng)6度,
分針每分鐘轉(zhuǎn)動(dòng)6度,并疊加每秒0.1度。
時(shí)針每小時(shí)轉(zhuǎn)動(dòng)30度。并疊加每分鐘0.5度。
其中時(shí)針和分針由寬度為15的實(shí)心填充圓角線條構(gòu)成
DateTime dateTime = DateTime.Now;
// Hour hand
strokePaint.Color = SKColor.Parse("#5E4000");
strokePaint.StrokeWidth = 15;
canvas.Save();
canvas.RotateDegrees(30 * dateTime.Hour + dateTime.Minute / 2f);
canvas.DrawLine(0, 0, 0, -r*(float)0.4, strokePaint);
canvas.Restore();
// Minute hand
strokePaint.Color = SKColor.Parse("#9C6D00");
canvas.Save();
canvas.RotateDegrees(6 * dateTime.Minute + dateTime.Second / 10f);
canvas.DrawLine(0, 0, 0, -r*(float)0.8, strokePaint);
canvas.Restore();
// Second hand
strokePaint.Color = SKColor.Parse("#657E3F");
canvas.Save();
canvas.RotateDegrees(6 * dateTime.Second);
strokePaint.StrokeWidth *=(float)0.5;
strokePaint.Style=SKPaintStyle.Fill;
canvas.DrawCircle(0, -r*(float)0.8, strokePaint.StrokeWidth, strokePaint);
canvas.Restore();指針效果如下:

其中秒針需要繪制一個(gè)點(diǎn),在其以圓心為中心的對(duì)側(cè)繪制一個(gè)帶有日期的文本
繪制沿路徑文本
首先繪制文本路徑,它是一個(gè)圓弧,在初始狀態(tài)圓弧的角度為20度,圓弧的起始角度為70度,終止角度為110度。
var pathAngle = 20; var startAngle = 90-pathAngle; var sweepAngle = pathAngle*2; var rect = new SKRect(-r*(float)0.8, -r*(float)0.8, r*(float)0.8, r*(float)0.8);
使用SkiaSharp的DrawTextOnPath方法繪制沿路徑的文本,詳情請(qǐng)查看官方文檔
using (SKPath path = new SKPath())
{
path.AddArc(rect, startAngle, sweepAngle);
canvas.DrawTextOnPath(dateStr, path, new SKPoint(), strokePaint);
}指針效果如下:

時(shí)鐘1的完整代碼如下:
void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs args)
{
SKImageInfo info = args.Info;
SKSurface surface = args.Surface;
SKCanvas canvas = surface.Canvas;
canvas.Clear();
using (SKPaint strokePaint = new SKPaint())
using (SKPaint fillPaint = new SKPaint())
{
strokePaint.Style = SKPaintStyle.Stroke;
strokePaint.StrokeCap = SKStrokeCap.Round;
fillPaint.Style = SKPaintStyle.Fill;
fillPaint.Color = SKColors.Transparent;
// Transform for 100-radius circle centered at origin
var r = 100f;
canvas.Translate(info.Width / 2f, info.Height / 2f);
canvas.Scale(Math.Min(info.Width / 200f, info.Height / 200f));
DateTime dateTime = DateTime.Now;
// Hour hand
strokePaint.Color = SKColor.Parse("#5E4000");
strokePaint.StrokeWidth = 15;
canvas.Save();
canvas.RotateDegrees(30 * dateTime.Hour + dateTime.Minute / 2f);
canvas.DrawLine(0, 0, 0, -r*(float)0.4, strokePaint);
canvas.Restore();
// Minute hand
strokePaint.Color = SKColor.Parse("#9C6D00");
canvas.Save();
canvas.RotateDegrees(6 * dateTime.Minute + dateTime.Second / 10f);
canvas.DrawLine(0, 0, 0, -r*(float)0.62, strokePaint);
canvas.Restore();
// Second hand
strokePaint.Color = SKColor.Parse("#657E3F");
canvas.Save();
canvas.RotateDegrees(6 * dateTime.Second);
strokePaint.StrokeWidth *=(float)0.5;
strokePaint.Style=SKPaintStyle.Fill;
canvas.DrawCircle(0, -r*(float)0.8, strokePaint.StrokeWidth, strokePaint);
strokePaint.Color = SKColors.Black;
strokePaint.StrokeWidth = 1;
var dateStr = dateTime.ToString("M");
var pathAngle = 20;
var startAngle = 90-pathAngle;
var sweepAngle = pathAngle*2;
var rect = new SKRect(-r*(float)0.8, -r*(float)0.8, r*(float)0.8, r*(float)0.8);
using (SKPath path = new SKPath())
{
path.AddArc(rect, startAngle, sweepAngle);
//canvas.DrawPath(path, strokePaint);
canvas.DrawTextOnPath(dateStr, path, new SKPoint(), strokePaint);
}
canvas.Restore();
}
}配置一個(gè)定時(shí)器,每秒刷新各指針位置
IDispatcherTimer _timer;
public Clock1()
{
...
this.SizeChanged+=ContentView_SizeChanged;
_timer= Dispatcher.CreateTimer();
_timer.Interval=TimeSpan.FromSeconds(1);
_timer.Tick+=_timer_Tick;
_timer.Start();
}
private void _timer_Tick(object sender, EventArgs e)
{
this.canvasView?.InvalidateSurface();
}時(shí)鐘1 效果如下:

時(shí)鐘2
將URWGeometricBlack字體文件放到Fonts目錄下

在MauiProgram.cs中注冊(cè)字體
.ConfigureFonts(fonts =>
{
...
fonts.AddFont("URWGeometricBlack.otf", "URWGeometricBlack");
});繪制表盤
時(shí)鐘2的表盤相對(duì)簡(jiǎn)單,是一個(gè)簡(jiǎn)單的圓配簡(jiǎn)潔抽象的數(shù)字刻度組成
創(chuàng)建Clock2,打開Xaml文件,代碼如下:
<Grid>
<Ellipse Grid.Row="0"
Grid.Column="1"
Stroke="white"
Fill="#FFEED9"
IsVisible="true"
HeightRequest="200"
WidthRequest="200"
x:Name="ModulatedPath">
</Ellipse>
<Grid TranslationY="-15">
<Grid.RowDefinitions>
<RowDefinition></RowDefinition>
<RowDefinition></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition></ColumnDefinition>
<ColumnDefinition></ColumnDefinition>
</Grid.ColumnDefinitions>
<Label Grid.Row="0"
Grid.ColumnSpan="2"
Text="12"
Style="{StaticResource ClockPlateNumberLabelStyle}"></Label>
<Label Grid.RowSpan="2"
Grid.Column="1"
Text="3"
Style="{StaticResource ClockPlateNumberLabelStyle}"></Label>
<Label Grid.Row="1"
Grid.ColumnSpan="2"
Text="6"
Style="{StaticResource ClockPlateNumberLabelStyle}"></Label>
<Label Grid.RowSpan="2"
Grid.Column="0"
Text="9"
Style="{StaticResource ClockPlateNumberLabelStyle}"></Label>
</Grid>
<forms:SKCanvasView x:Name="canvasView"
PaintSurface="OnCanvasViewPaintSurface" />
<Label FontSize="28"
HorizontalOptions="Center"
VerticalOptions="Center"
x:Name="labelView"></Label>
</Grid>同樣我們需要放置SKCanvasView對(duì)象用于繪制指針
其中ClockPlateNumberLabelStyle定義如下:
<Style TargetType="Label"
x:Key="ClockPlateNumberLabelStyle">
<Setter Property="HorizontalTextAlignment"
Value="Center"></Setter>
<Setter Property="VerticalTextAlignment"
Value="Center"></Setter>
<Setter Property="VerticalOptions"
Value="Center"></Setter>
<Setter Property="FontAttributes"
Value="Bold"></Setter>
<Setter Property="FontSize"
Value="120"></Setter>
<Setter Property="TextColor"
Value="#F9BC49"></Setter>
<Setter Property="FontFamily"
Value="URWGeometricBlack"></Setter>
</Style>效果如下:

繪制指針
時(shí)鐘2的指針繪制原理與時(shí)鐘1類似,此處將不贅述,完整代碼如下:
void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs args)
{
SKImageInfo info = args.Info;
SKSurface surface = args.Surface;
SKCanvas canvas = surface.Canvas;
canvas.Clear();
using (SKPaint strokePaint = new SKPaint())
using (SKPaint fillPaint = new SKPaint())
{
strokePaint.Style = SKPaintStyle.Stroke;
strokePaint.StrokeCap = SKStrokeCap.Round;
fillPaint.Style = SKPaintStyle.Fill;
fillPaint.Color = SKColors.Transparent;
// Transform for 100-radius circle centered at origin
var r = 100f;
canvas.Translate(info.Width / 2f, info.Height / 2f);
canvas.Scale(Math.Min(info.Width / 200f, info.Height / 200f));
DateTime dateTime = DateTime.Now;
// Hour hand
strokePaint.Color = SKColor.Parse("#5E4000");
strokePaint.StrokeWidth = 15;
canvas.Save();
canvas.RotateDegrees(30 * dateTime.Hour + dateTime.Minute / 2f);
canvas.DrawLine(0, 0, 0, -r*(float)0.4, strokePaint);
canvas.Restore();
// Minute hand
strokePaint.Color = SKColor.Parse("#9C6D00");
strokePaint.StrokeWidth = 5;
canvas.Save();
canvas.RotateDegrees(6 * dateTime.Minute + dateTime.Second / 10f);
canvas.DrawLine(0, 0, 0, -r*(float)0.8, strokePaint);
canvas.Restore();
// Second hand
strokePaint.Color = SKColor.Parse("#657E3F");
strokePaint.StrokeWidth = 2;
canvas.Save();
canvas.RotateDegrees(6 * dateTime.Second);
canvas.DrawLine(0, r*(float)0.1, 0, -r*(float)0.8, strokePaint);
strokePaint.Style=SKPaintStyle.Fill;
canvas.DrawCircle(0, 0, 5, strokePaint);
canvas.Restore();
}
}時(shí)鐘2 效果如下

以上就是使用C#編寫兩個(gè)漂亮?xí)r鐘的示例代碼的詳細(xì)內(nèi)容,更多關(guān)于C#時(shí)鐘的資料請(qǐng)關(guān)注腳本之家其它相關(guān)文章!
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