Блог

Как вы можете видеть, когда я пытаюсь нарисовать путь с SkiaSharp помощью, путь находится под линией. Как я могу перенести его через линию?

 using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;

using SkiaSharp;
using SkiaSharp.Views.Forms;
using TouchTracking;

namespace SenzorApp
{
    public partial class MainPage : ContentPage
    {
        Dictionary<long, SKPath> inProgressPaths = new Dictionary<long, SKPath>();
        List<SKPath> completedPaths = new List<SKPath>();
        SKBitmap saveBitmap;

        SKPaint paint = new SKPaint
        {
            Style = SKPaintStyle.Stroke,
            StrokeWidth = 80,
            StrokeCap = SKStrokeCap.Round,
            StrokeJoin = SKStrokeJoin.Round,

        };

        public MainPage()
        {
            InitializeComponent();
        }

        float scale;            // ranges from 0 to 1 to 0
        void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs args)
        {
            SKImageInfo info = args.Info;
            SKSurface surface = args.Surface;
            SKCanvas canvas = surface.Canvas;

            // Create bitmap the size of the display surface
            if (saveBitmap == null)
            {
                saveBitmap = new SKBitmap(info.Width, info.Height);
            }
            // Or create new bitmap for a new size of display surface
            else if (saveBitmap.Width < info.Width || saveBitmap.Height < info.Height)
            {
                SKBitmap newBitmap = new SKBitmap(Math.Max(saveBitmap.Width, info.Width),
                                                  Math.Max(saveBitmap.Height, info.Height));

                using (SKCanvas newCanvas = new SKCanvas(newBitmap))
                {
                    newCanvas.Clear();
                    newCanvas.DrawBitmap(saveBitmap, 0, 0);
                }

                saveBitmap = newBitmap;
                
            }

            // Render the bitmap
            canvas.Clear();
            canvas.DrawBitmap(saveBitmap, 0, 0);

            using (SKPaint paint = new SKPaint())
            {
                paint.Style = SKPaintStyle.Fill;
                paint.Color = SKColors.Red;
                paint.StrokeWidth = 50;
                canvas.DrawLine(-info.Width, info.Height / 2, info.Width, info.Height / 2, paint);
            }
        }

        void OnTouchEffectAction(object sender, TouchActionEventArgs args)
        {
            switch (args.Type)
            {
                case TouchActionType.Pressed:
                    if (!inProgressPaths.ContainsKey(args.Id))
                    {
                        SKPath path = new SKPath();
                        
                        path.MoveTo(ConvertToPixel(args.Location));
                        inProgressPaths.Add(args.Id, path);
                        UpdateBitmap();
                    }
                    break;

                case TouchActionType.Moved:
                    if (inProgressPaths.ContainsKey(args.Id))
                    {
                        SKPath path = inProgressPaths[args.Id];
                        path.LineTo(ConvertToPixel(args.Location));
                        UpdateBitmap();
                    }
                    break;

                case TouchActionType.Released:
                    if (inProgressPaths.ContainsKey(args.Id))
                    {
                        completedPaths.Add(inProgressPaths[args.Id]);
                        inProgressPaths.Remove(args.Id);
                        UpdateBitmap();
                    }
                    break;

                case TouchActionType.Cancelled:
                    if (inProgressPaths.ContainsKey(args.Id))
                    {
                        inProgressPaths.Remove(args.Id);
                        UpdateBitmap();
                    }
                    break;
            }
        }

        void UpdateBitmap()
        {
            using (SKCanvas saveBitmapCanvas = new SKCanvas(saveBitmap))
            {
                saveBitmapCanvas.Clear();

                foreach (SKPath path in completedPaths)
                {
                    saveBitmapCanvas.DrawPath(path, paint);
                }

                foreach (SKPath path in inProgressPaths.Values)
                {
                    saveBitmapCanvas.DrawPath(path, paint);
                }
            }

            canvasView.InvalidateSurface();
        }

        SKPoint ConvertToPixel(Point pt)
        {
            return new SKPoint((float)(canvasView.CanvasSize.Width * pt.X / canvasView.Width),
                               (float)(canvasView.CanvasSize.Height * pt.Y / canvasView.Height));
        }
    }
}