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SkiaSharp 之 WPF 自绘 拖曳小球(案例版)
梧桐雨
2022-08-15 11:49:28 2022-08-15
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感谢各位大佬和粉丝的厚爱和关心( 催更),我会再接再厉的,其实这也是督促自己的一种方式,非常感谢。

刚写了一篇万字长文,自己也休养生息(低调发育)了一段时间,接下来来几个小案例。

拖曳小球

WPF的拖曳效果,基本配置一下,就可以了,但是自绘的话,就得自己控制,按键点击,按键移动和按键松开的事件,与其配合达到目的。

这个效果实现了,其实也变相的实现了WPF里的拖动效果,这个效果用着还是很方便的。

但是代码,确十分的简单。

Wpf 和 SkiaSharp

新建一个WPF项目,然后,Nuget包即可

要添加Nuget包

Install-Package SkiaSharp.Views.WPF -Version 2.88.0

其中核心逻辑是这部分,会以我设置的60FPS来刷新当前的画板。

skContainer.PaintSurface += SkContainer_PaintSurface;
_ = Task.Run(() =>
{
while (true)
{
try
{
Dispatcher.Invoke(() =>
{
skContainer.InvalidateVisual();
});
_ = SpinWait.SpinUntil(() => false, 1000 / 60);//每秒60帧
}
catch
{
break;
}
}
});

实现代码的 鼠标按下,移动,鼠标松开

先对SkiaSharp对象,增加相关事件

skContainer.MouseDown += SkContainer_MouseDown;
skContainer.MouseUp += SkContainer_MouseUp;
skContainer.MouseMove += SkContainer_MouseMove;

然后增加相关事件处理代码,我这边都统一处理了.

private void SkContainer_MouseDown(object sender, MouseButtonEventArgs e)
{
var cur = e.GetPosition(sender as IInputElement);
drawClock.MouseDown(new SKPoint((float)cur.X, (float)cur.Y), true);
}
private void SkContainer_MouseUp(object sender, MouseEventArgs e)
{
var cur = e.GetPosition(sender as IInputElement);
drawClock.MouseDown(new SKPoint((float)cur.X, (float)cur.Y), false);
}
private void SkContainer_MouseMove(object sender, MouseEventArgs e)
{
var cur = e.GetPosition(sender as IInputElement);
drawClock.MouseMove(new SKPoint((float)cur.X, (float)cur.Y));
}

拖曳核心类

/// <summary>
/// 拖曳
/// </summary>
public class Drag
{
public SKPoint centerPoint;
public int Radius = 0;
private bool Pressed = false;
private bool CirclePressend = false;
private SKPoint sKPoint = SKPoint.Empty;
private SKPoint CirclePoint = SKPoint.Empty;
private SKCanvas canvas;
private float dx = 0;
private float dy = 0;
/// <summary>
/// 渲染
/// </summary>
public void Render(SKCanvas canvas, SKTypeface Font, int Width, int Height)
{
this.canvas = canvas;
centerPoint = new SKPoint(Width / 2, Height / 2);
this.Radius = 40;
canvas.Clear(SKColors.White);
if (CirclePoint.IsEmpty)
{
CirclePoint = new SKPoint(centerPoint.X, centerPoint.Y);
}
if (CirclePressend)
{
CirclePoint = new SKPoint(sKPoint.X - dx, sKPoint.Y - dy);
DrawCircle(this.canvas, CirclePoint);
}
else
{
DrawCircle(this.canvas, CirclePoint);
}
using var paint = new SKPaint
{
Color = SKColors.Black,
IsAntialias = true,
Typeface = Font,
TextSize = 24
};
var msg = $"X:{ sKPoint.X} Y:{sKPoint.Y} Pressed:{Pressed} CirclePressend:{CirclePressend}";
canvas.DrawText(msg, 0, 30, paint);
}
public void MouseMove(SKPoint sKPoint)
{
this.sKPoint = sKPoint;
if (CirclePressend)//按下,就开始拖动
{
CirclePoint = sKPoint;
}
}
public void MouseDown(SKPoint sKPoint, bool Pressed)
{
this.sKPoint = sKPoint;
this.Pressed = Pressed;
if (this.Pressed)
{
this.CirclePressend = CheckPoint(sKPoint, CirclePoint);
if (this.CirclePressend)
{
dx = sKPoint.X - CirclePoint.X;
dy = sKPoint.Y - CirclePoint.Y;
}
}
else
{
this.CirclePressend = false;
}
}
public bool CheckPoint(SKPoint sKPoint, SKPoint CirclePoint)
{
var d = Math.Sqrt(Math.Pow(sKPoint.X - CirclePoint.X, 2) + Math.Pow(sKPoint.Y - CirclePoint.Y, 2));
return this.Radius >= d;
}
/// <summary>
/// 画一个圆
/// </summary>
public void DrawCircle(SKCanvas canvas, SKPoint sKPoint)
{
using var paint = new SKPaint
{
Color = SKColors.Blue,
Style = SKPaintStyle.Fill,
IsAntialias = true,
StrokeWidth = 2
};
canvas.DrawCircle(sKPoint.X, sKPoint.Y, Radius, paint);
}
}

效果如下:

我可以点的球的边边哦,这也是一个小技巧,点到球哪里,停止的时候,鼠标还在那个位置,是不是有点像拖动窗体的感觉了。

总结

以前对拖曳总是很好奇,一直想是如何实现的,现在自己也自己从头到尾的实现了,那么,它就是已知的,这就是可以写出来的进步,每天都应该有一点这样的进步。

代码地址

https://github.com/kesshei/WPFSkiaDragDemo.git

https://gitee.com/kesshei/WPFSkiaDragDemo.git

一键三连呦!,感谢大佬的支持,您的支持就是我的动力!

版权

蓝创精英团队(公众号同名,CSDN同名,CNBlogs同名)

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