C# CGContext.DrawLayer方法代码示例

		protected void DrawFlag (CGContext context)
		{
			// declare vars
			int i, j;
			
			// general sizes
			float flagWidth = imageView.Frame.Width * .8f;
			float flagHeight = (float)(flagWidth / 1.9);
			PointF flagOrigin = new PointF (imageView.Frame.Width * .1f, imageView.Frame.Height / 3);
			
			// stripe
			float stripeHeight = flagHeight / 13;
			float stripeSpacing = stripeHeight * 2;
			RectangleF stripeRect = new RectangleF (0, 0, flagWidth, stripeHeight);
			
			// star field
			float starFieldHeight = 7 * stripeHeight;
			float starFieldWidth = flagWidth * (2f / 5f);
			RectangleF starField = new RectangleF (flagOrigin.X, flagOrigin.Y + (6 * stripeHeight), starFieldWidth, starFieldHeight);
			
			// stars
			float starDiameter = flagHeight * 0.0616f;
			float starHorizontalCenterSpacing = (starFieldWidth / 6);
			float starHorizontalPadding = (starHorizontalCenterSpacing / 4);
			float starVerticalCenterSpacing = (starFieldHeight / 5);
			float starVerticalPadding = (starVerticalCenterSpacing / 4);
			PointF firstStarOrigin = new PointF (flagOrigin.X + starHorizontalPadding, flagOrigin.Y + flagHeight - starVerticalPadding - (starVerticalCenterSpacing / 2));
			PointF secondRowFirstStarOrigin = new PointF (firstStarOrigin.X + (starHorizontalCenterSpacing / 2), firstStarOrigin.Y - (starVerticalCenterSpacing / 2));
			
			// white background + shadow
			context.SaveState ();
			context.SetShadow (new SizeF (15, -15), 7);
			context.SetFillColor (1, 1, 1, 1);
			context.FillRect (new RectangleF (flagOrigin.X, flagOrigin.Y, flagWidth, flagHeight));
			context.RestoreState ();
			
			// create a stripe layer
			using (CGLayer stripeLayer = CGLayer.Create (context, stripeRect.Size)) {
				
				// set red as the fill color
				// this works
				stripeLayer.Context.SetFillColor (1f, 0f, 0f, 1f);
				// but this doesn't ????
				//stripeLayer.Context.SetFillColor (new float[] { 1f, 0f, 0f, 1f });
				// fill the stripe
				stripeLayer.Context.FillRect (stripeRect);
				
				// loop through the stripes and draw the layer
				context.SaveState ();
				for (i = 0; i < 7; i++) {
					Console.WriteLine ("drawing stripe layer");
					// draw the layer
					context.DrawLayer (stripeLayer, flagOrigin);
					// move the origin
					context.TranslateCTM (0, stripeSpacing);
				}
				context.RestoreState ();
			}
			
			// draw the star field
			//BUGBUG: apple bug - this only works on on-screen CGContext and CGLayer
			//context.SetFillColor (new float[] { 0f, 0f, 0.329f, 1.0f });
			context.SetFillColor (0f, 0f, 0.329f, 1.0f);
			context.FillRect (starField);
			
			// create the star layer
			using (CGLayer starLayer = CGLayer.Create (context, starField.Size)) {
				
				// draw the stars
				DrawStar (starLayer.Context, starDiameter);
				
				// 6-star rows
				// save state so that as we translate (move the origin around, 
				// it goes back to normal when we restore)
				context.SaveState ();
				context.TranslateCTM (firstStarOrigin.X, firstStarOrigin.Y);
				// loop through each row
				for (j = 0; j < 5; j++) {
					
					// each star in the row
					for (i = 0; i < 6; i++) {
						
						// draw the star, then move the origin to the right
						context.DrawLayer (starLayer, new PointF (0f, 0f));
						context.TranslateCTM (starHorizontalCenterSpacing, 0f);
					}
					// move the row down, and then back left
					context.TranslateCTM ( (-i * starHorizontalCenterSpacing), -starVerticalCenterSpacing);
				}
				context.RestoreState ();
				
				// 5-star rows			
				context.SaveState ();
				context.TranslateCTM (secondRowFirstStarOrigin.X, secondRowFirstStarOrigin.Y);
				// loop through each row
				for (j = 0; j < 4; j++) {
					
					// each star in the row
					for (i = 0; i < 5; i++) {
						
//.........这里部分代码省略.........

		/// <summary>
		/// Draws our coordinate grid
		/// </summary>
		protected void DrawCoordinateSpace (CGContext context)
		{
			// declare vars
			int remainder;
			int textHeight = 20;
			
			#region -= vertical ticks =-
			
			// create our vertical tick lines
			using (CGLayer verticalTickLayer = CGLayer.Create (context, new SizeF (20, 3))) {
				
				// draw a single tick
				verticalTickLayer.Context.FillRect (new RectangleF (0, 1, 20, 2));
				
				// draw a vertical tick every 20 pixels
				float yPos = 20;
				int numberOfVerticalTicks = ((int)(Frame.Height / 20) - 1);
				for (int i = 0; i < numberOfVerticalTicks; i++) {
					
					// draw the layer
					context.DrawLayer (verticalTickLayer, new PointF (0, yPos));
					
					// starting at 40, draw the coordinate text nearly to the top
					if (yPos > 40 && i < (numberOfVerticalTicks - 2)) {
						
						// draw it every 80 points
						Math.DivRem ((int)yPos, (int)80, out remainder);
						if (remainder == 0)
							DrawTextAtPoint (context, 30, (yPos - (textHeight / 2)), yPos.ToString (), textHeight);
					}
					
					// increment the position of the next tick
					yPos += 20;
				}
			}
			
			#endregion
			
			#region -= horizontal ticks =-
			
			// create our horizontal tick lines
			using (CGLayer horizontalTickLayer = CGLayer.Create (context, new SizeF (3, 20))) {
				
				horizontalTickLayer.Context.FillRect (new RectangleF (1, 0, 2, 20));
				
				// draw a horizontal tick every 20 pixels
				float xPos = 20;
				int numberOfHorizontalTicks = ((int)(Frame.Width / 20) - 1);
				for (int i = 0; i < numberOfHorizontalTicks; i++) {
					
					context.DrawLayer (horizontalTickLayer, new PointF (xPos, 0));
					
					// starting at 100, draw the coordinate text nearly to the top
					if (xPos > 100 && i < (numberOfHorizontalTicks - 1)) {
						
						// draw it every 80 points
						Math.DivRem ((int)xPos, (int)80, out remainder);
						if (remainder == 0)
							DrawCenteredTextAtPoint (context, xPos, 30, xPos.ToString (), textHeight);
					}
					
					// increment the position of the next tick
					xPos += 20;
				}
			}
			
			#endregion
			
			// draw our "origin" text
			DrawTextAtPoint (context, 20, (20 + (textHeight / 2)), "Origin (0,0)", textHeight);
		}