skiasharp test

SkiaForm.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using SkiaSharp;

namespace TestPreview
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            
        }

        private void skControl_Click(object sender, EventArgs e)
        {

        }

        private void skControl_PaintSurface(object sender, SkiaSharp.Views.Desktop.SKPaintSurfaceEventArgs e)
        {
            var surface = e.Surface;
            var surfaceWidth = e.Info.Width;
            var surfaceHeight = e.Info.Height;

            var bounds = new SKRect ( 0, 0, surfaceWidth, surfaceHeight );
            int offset1;
            int offset2;
            var canvas = surface.Canvas;
            var label = CreateLabel("Hello World", SKColors.DarkOliveGreen);
            var panel = CreatePanel(new SKRect(0, 0, 200, 100), SKColors.White);
            var shadow = CreateShadow(panel, 2, 4, out offset1 );
            var shadow2 = CreateShadow(panel, 6, 3, out offset2);

            canvas.DrawBitmap(shadow, 
                bounds.MidX - label.Width / 2 + offset1, 
                bounds.MidY + offset1 + 1, 
                new SKPaint { Color = new SKColor(0xff, 0xff, 0xff, 0x28) });
            canvas.DrawBitmap(shadow2, 
                bounds.MidX - label.Width / 2 + offset2, 
                bounds.MidY + offset2 + 2, 
                new SKPaint { Color = new SKColor(0xff, 0xff, 0xff, 0x3D) });

            canvas.DrawBitmap(panel, bounds.MidX - label.Width / 2 , bounds.MidY,
                new SKPaint { Color = new SKColor(0xff, 0xff, 0xff, 0xFF) });
            canvas.DrawBitmap(label, bounds.MidX - label.Width/2 + 20, bounds.MidY + 20);

            canvas.Flush();
        }

        private SKBitmap CreateLabel(string text, SKColor color)
        {
            var paint = new SKPaint(){
                Color = color,
                Typeface = SKTypeface.FromFamilyName("Roboto"),
                TextSize = 24,
                IsAntialias = true
            };

            var bounds = new SKRect();
            var width = paint.MeasureText(text, ref bounds);

            var output = new SKBitmap(            
                (int)Math.Ceiling(bounds.Width), 
                (int)Math.Ceiling(bounds.Height));

            var canvas = new SKCanvas(output);
            canvas.Clear();
            canvas.DrawText(text, -bounds.Left, -bounds.Top, paint);
            canvas.Flush();
            return output;
        }

        private SKBitmap CreatePanel(SKRect rect, SKColor color)
        {
            var paint = new SKPaint()
            {
                Color = color,
                IsAntialias = true
            };

            var output = new SKBitmap(
                (int)Math.Ceiling(rect.Width),
                (int)Math.Ceiling(rect.Height));

            var canvas = new SKCanvas(output);
            canvas.Clear();
            canvas.DrawRoundRect(rect, 1, 1, paint);

            canvas.Flush();
            return output;
        }

        private SKBitmap CreateShadow(SKBitmap src, int spread, float radius, out int offset)
        {
            var output = new SKBitmap(
                (int)Math.Ceiling(src.Width + (spread * 2) + (2*radius)),
                (int)Math.Ceiling(src.Height + (spread * 2) + (2*radius)));

            var resized = src.Resize(
                new SKImageInfo(src.Width + (spread * 2), src.Height + (spread * 2)), 
                SKBitmapResizeMethod.Lanczos3);

            var canvas = new SKCanvas(output);

            canvas.Clear();
            canvas.DrawBitmap(resized, 0 + radius, 0 + radius, new SKPaint
            {
                MaskFilter = SKMaskFilter.CreateBlur(SKBlurStyle.Normal, 
                    SKMaskFilter.ConvertRadiusToSigma(radius),
                    SKBlurMaskFilterFlags.All),
            });

            canvas.DrawRect(new SKRect(0, 0, output.Width, output.Height), new SKPaint 
            { 
                Color = SKColors.Black, 
                BlendMode = SKBlendMode.SrcATop, 
                IsAntialias = true
            });
            canvas.Flush();

            offset = -(int)Math.Ceiling(spread + radius);
            return output;
        }
    }
}