For Loop and SkiaSharp

Yusuf 731 Reputation points
2022-04-11T11:40:35.067+00:00

Hi,
How can I use for in SkiaSharp,
Let's say I want to show every word for 10 seconds (600 frames).

It sounds simple, but I haven't figured it out today.

for code

string[] numbers = { "one", "two", "three", "four",  "five"};
foreach (string i in numbers)
{
    text = i;
}

SkiaSharp code

using SkiaSharp;
using System;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace MyApp1
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class Page1 : ContentPage
    {
        string text = "";

        public Page1()
        {
            InitializeComponent();

             Device.StartTimer(TimeSpan.FromSeconds(1f / 60), () =>
            {
                canvasView.InvalidateSurface();
                return true;
            });

         }

        private void canvas_PaintSurface(object sender, SkiaSharp.Views.Forms.SKPaintSurfaceEventArgs e)
        {

            SKSurface surface = e.Surface;
            SKCanvas canvas = surface.Canvas;

            int width = e.Info.Width;
            int height = e.Info.Height;

            canvas.Clear();  

            SKPaint textPaint = new SKPaint();
            textPaint.Color = SKColors.MidnightBlue;
            textPaint.TextSize = 30;
            canvas.DrawText(text, width / 2, height / 2, textPaint);
        }
    }
}

Thank you in advance.

Xamarin
Xamarin
A Microsoft open-source app platform for building Android and iOS apps with .NET and C#.
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C#
C#
An object-oriented and type-safe programming language that has its roots in the C family of languages and includes support for component-oriented programming.
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2 answers

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  1. Bruce (SqlWork.com) 59,306 Reputation points
    2022-04-11T16:58:51.643+00:00

    use the timer:

    Action doLoop<int> = (count) =>
    {            
       if (count >= numbers.Length)
            return;
       text = numbers[count];
       Device.StartTimer(TimeSpan.FromSeconds(1f / 60), () =>
       {
              canvasView.InvalidateSurface();
              doLoop(--count); 
             return true;
       });
    }
    doLoop();
    

  2. JessieZhang-MSFT 7,706 Reputation points Microsoft Vendor
    2022-04-19T09:25:28.673+00:00

    Hello,

    For this problem, you can use nested function to achieve this .

    I used a Label to simulate this functionality and loop through the array.

    You can refer to my code:

    public partial class MainPage : ContentPage  
    {  
        string[] numbers = { "one", "two", "three", "four", "five" };  
      
        string text = "one";  
      
      
        public MainPage()  
        {  
            InitializeComponent();  
        }  
      
        private void Button_Clicked(object sender, EventArgs e)  
        {  
            MyLoop(0);  
        }  
      
      
        public void MyLoop(int count)   
        {  
            if (count >= numbers.Length) {  
                count = 0;  
            }  
      
            text = numbers[count];  
      
            Device.StartTimer(TimeSpan.FromMilliseconds(10000), () =>  
            {  
      
                mLabel.Text = text;  
      
                MyLoop(++count);  
                return false;  
            });  
        }  
    }  
    

    Note:

    When the last element of the data is traversed, the first element is traversed again.

     if (count >= numbers.Length) {  
                    count = 0;  
                }  
    

    Best Regards,
    Jessie Zhang


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