C# Path.AddRoundRect方法代码示例

        /// <summary>
        /// Redraws the child.
        /// </summary>
        protected override bool DrawChild(Canvas canvas, global::Android.Views.View child, long drawingTime)
        {
            try
            {
                var radius = (float)((RoundedImage)Element).BorderRadius;
                var stroke = (float)((RoundedImage)Element).BorderThickness;
                var delta = (float)stroke / 2.0f;

                if (radius < 0)
                {
                    radius = Math.Min(Width, Height) / 2.0f;
                }

                radius -= delta;

                // Clip with rounded rect
                var path = new Path();
                path.AddRoundRect(new RectF(delta, delta, Width - stroke, Height - stroke),
                    radius, radius, Path.Direction.Ccw);
                canvas.Save();
                canvas.ClipPath(path);
                path.Dispose();

                var result = base.DrawChild(canvas, child, drawingTime);

                canvas.Restore();

                // Add stroke for smoother border
                path = new Path();
                path.AddRoundRect(new RectF(delta, delta, Width - stroke, Height - stroke),
                    radius, radius, Path.Direction.Ccw);
                var paint = new Paint();
                paint.AntiAlias = true;
                paint.StrokeWidth = stroke;
                paint.SetStyle(Paint.Style.Stroke);
                paint.Color = ((RoundedImage)Element).BorderColor.ToAndroid();
                canvas.DrawPath(path, paint);
                paint.Dispose();

                // Clean up
                path.Dispose();

                return result;
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine("Unable to create circle image: " + ex);
            }

            return base.DrawChild(canvas, child, drawingTime);
        }

		/// <Docs>The Canvas to which the View is rendered.</Docs>
		/// <summary>
		/// Draw the specified canvas.
		/// </summary>
		/// <param name="canvas">Canvas.</param>
		public override void Draw (Canvas canvas)
		{			
			try
			{
				var element = Element as RoundCornerView;
				var cornerRadius = (float)element.CornerRadius*Resources.DisplayMetrics.Density;

				// Paint rounded rect itself
				canvas.Save();
				var paint = new Paint();
				paint.AntiAlias = true;
				var strokeWidth = (((float)element.BorderWidth)*Resources.DisplayMetrics.Density);
				paint.StrokeWidth = strokeWidth;

				if(element.BackgroundColor != Xamarin.Forms.Color.Transparent)
				{
					paint.SetStyle(Paint.Style.Fill);
					paint.Color = element.BackgroundColor.ToAndroid();
					canvas.DrawRoundRect(new RectF(0, 0, Width, Height), cornerRadius, cornerRadius, paint);
				}

				if(element.BorderColor != Xamarin.Forms.Color.Transparent)
				{
					paint.SetStyle(Paint.Style.Stroke);
					paint.Color = element.BorderColor.ToAndroid();
					canvas.DrawRoundRect(new RectF(0, 0, Width, Height), cornerRadius, cornerRadius, paint);
				}

				//Properly dispose
				paint.Dispose();
				canvas.Restore();

				// Create clip path
				var path = new Path();
				path.AddRoundRect(new RectF(0.0f + (strokeWidth/2), 0.0f + (strokeWidth/2), 
					Width - (strokeWidth/2), Height - (strokeWidth/2)), cornerRadius, cornerRadius, Path.Direction.Cw);
				
				canvas.Save();
				canvas.ClipPath(path);

				// Do base drawing
				for(var i=0; i<ChildCount; i++)
					GetChildAt(i).Draw(canvas);

				canvas.Restore();
				path.Dispose();
			}
			catch (Exception)
			{				
			}				
		}

        public static void SetClipPath(this BorderRenderer br, Canvas canvas)
        {
            var clipPath = new Path();
            //float padding = br;// radius / 2;
            float radius = (float)br.Element.CornerRadius - br.Context.ToPixels((float)br.Element.Padding.ThickestSide());// - padding / 2; // + MaxStrokeThickness());

            int w = (int)br.Width;
            int h = (int)br.Height;

            clipPath.AddRoundRect(new RectF(
                br.ViewGroup.PaddingLeft,
                br.ViewGroup.PaddingTop,
                w - br.ViewGroup.PaddingRight,
                h - br.ViewGroup.PaddingBottom),
                radius,
                radius,
                Path.Direction.Cw);

            canvas.ClipPath(clipPath);
        }

		protected override bool DrawChild(Canvas canvas, global::Android.Views.View child, long drawingTime)
		{
			try
			{
				var path = new Path ();
				path.AddRoundRect (new RectF (0, 0, Width, Height), 15f, 15f, Path.Direction.Ccw);
				canvas.Save ();
				canvas.ClipPath (path);

				var result = base.DrawChild(canvas, child, drawingTime);

				canvas.Restore();
				path.Dispose();
				return result;
			}
			catch (Exception ex)
			{
				System.Diagnostics.Debug.WriteLine("Unable to create rounded rectangle image: " + ex);
			}

			return base.DrawChild(canvas, child, drawingTime);
		}

        protected override void OnDraw(Shape shape, Android.Graphics.Canvas canvas, Paint paint)
        {
            var height = canvas.ClipBounds.Bottom;
            var width = canvas.ClipBounds.Right;
            if (noChild)
            {
                var borderHeight = (int)(this.borderThickness.Top + this.borderThickness.Bottom);
                var borderWidth = (int)(this.borderThickness.Left + this.borderThickness.Right);
                height = borderHeight > 0 ? borderHeight : canvas.ClipBounds.Bottom;
                width = borderWidth > 0 ? borderWidth : canvas.ClipBounds.Right;
            }
            shape.Resize(width, height);
            shape.Draw(canvas, strokepaint);

            var pathInner = new Path();
            var rect = new RectF(
                (float)(borderThickness.Left),
                (float)(borderThickness.Top),
                (float)(canvas.ClipBounds.Right - borderThickness.Right),
                (float)(canvas.ClipBounds.Bottom - borderThickness.Bottom));
            pathInner.AddRoundRect(rect, cornerRadiusArray, Path.Direction.Cw);
            if (!noChild)
            {
                var clearPaint = new Paint();
                clearPaint.SetXfermode(new PorterDuffXfermode(PorterDuff.Mode.Clear));
                canvas.DrawPath(pathInner, clearPaint);
            }
            canvas.DrawPath(pathInner, fillpaint);
        }

		void DrawOutline(Canvas canvas, int width, int height)
		{
			if (Button.BorderWidth <= 0)
				return;

			using (var paint = new Paint { AntiAlias = true })
			using (var path = new Path())
			{
				float borderWidth = Forms.Context.ToPixels(Button.BorderWidth);
				float inset = borderWidth / 2;

				// adjust border radius so outer edge of stroke is same radius as border radius of background
				float borderRadius = Forms.Context.ToPixels(Button.BorderRadius) - inset;

				path.AddRoundRect(new RectF(inset, inset, width - inset, height - inset), borderRadius, borderRadius, Path.Direction.Cw);
				paint.StrokeWidth = borderWidth;
				paint.SetStyle(Paint.Style.Stroke);
				paint.Color = Button.BorderColor.ToAndroid();

				canvas.DrawPath(path, paint);
			}
		}

		void DrawBackground(Canvas canvas, int width, int height, bool pressed)
		{
			var paint = new Paint { AntiAlias = true };
			var path = new Path();

			float borderRadius = Forms.Context.ToPixels(Button.BorderRadius);

			path.AddRoundRect(new RectF(0, 0, width, height), borderRadius, borderRadius, Path.Direction.Cw);

			paint.Color = pressed ? Button.BackgroundColor.AddLuminosity(-0.1).ToAndroid() : Button.BackgroundColor.ToAndroid();
			paint.SetStyle(Paint.Style.Fill);
			canvas.DrawPath(path, paint);
		}

 protected override void OnLayout(bool changed, int left, int top, int right, int bottom)
 {
     base.OnLayout (changed, left, top, right, bottom);
     clipMask = new Path ();
     var rect = new RectF (0, 0, Width, Height);
     clipMask.AddRoundRect (rect, cornerRadius, cornerRadius, Path.Direction.Cw);
 }