C# CGContext.GetClipBoundingBox方法代码示例

 public override void DrawLayer(CALayer layer, CGContext context)
 {
     context.SaveState ();
     context.SetFillColor (1.0f, 1.0f, 1.0f, 1.0f);
     context.FillRect (context.GetClipBoundingBox ());
     context.TranslateCTM (0.0f, layer.Bounds.Size.Height);
     context.ScaleCTM (1.0f, -1.0f);
     context.ConcatCTM (this.oParentController.currentPDFPage.GetDrawingTransform (CGPDFBox.Crop, layer.Bounds, 0, true));
     context.DrawPDFPage (this.oParentController.currentPDFPage);
     context.RestoreState ();
 }

	public override void DrawInContext (CGContext context)
	{
		var imageRect = new RectangleF (8, 8, 64, 64);
		
		// Note: The images are actually drawn upside down because Quartz image drawing expects
		// the coordinate system to have the origin in the lower-left corner, but a UIView
		// puts the origin in the upper-left corner. For the sake of brevity (and because
		// it likely would go unnoticed for the image used) this is not addressed here.
		// For the demonstration of PDF drawing however, it is addressed, as it would definately
		// be noticed, and one method of addressing it is shown there.
	
		// Draw the image in the upper left corner (0,0) with size 64x64
		context.DrawImage (imageRect, image);
		
		// Tile the same image across the bottom of the view
		// CGContextDrawTiledImage() will fill the entire clipping area with the image, so to avoid
		// filling the entire view, we'll clip the view to the rect below. This rect extends
		// past the region of the view, but since the view's rectangle has already been applied as a clip
		// to our drawing area, it will be intersected with this rect to form the final clipping area
		context.ClipToRect(new RectangleF (0, 80, Bounds.Width, Bounds.Height));
		
		// The origin of the image rect works similarly to the phase parameter for SetLineDash and
		// SetPatternPhase and specifies where in the coordinate system the "first" image is drawn.
		// The size (previously set to 64x64) specifies the size the image is scaled to before being tiled.
		imageRect.X = 32;
		imageRect.Y = 112;
		context.DrawTiledImage (imageRect, image);
		
		// Highlight the "first" image from the DrawTiledImage call.
		context.SetRGBFillColor (1, 0, 0, 0.5f);
		context.FillRect (imageRect);
		
		// And stroke the clipped area
		context.SetLineWidth (3);
		context.SetRGBStrokeColor (1, 0, 0, 1);
		context.StrokeRect (context.GetClipBoundingBox ());
	}

        private void InitializeContext(CGContext context)
        {
            this.context = context;

            modelMatrix = new Matrix();
            viewMatrix = new Matrix();

            ResetTransform();

            boundingBox = context.GetClipBoundingBox().ToRectangleF ();

            // We are going to try this here and it may cause problems down the road.
            // This seems to only happen with Mac and not iOS
            // What is happening is that sub views are offset by their relative location
            // within the window.  That means our drawing locations are also offset by this
            // value as well.  So what we need to do is translate our view by this offset as well.
            subviewClipOffset = context.GetClipBoundingBox().ToRectangleF ();

            PageUnit = GraphicsUnit.Pixel;
            PageScale = 1;

            // Set anti-aliasing
            SmoothingMode = SmoothingMode.Default;

            clipRegion = new Region ();
        }