WinForms FAQ - Brushes

The Brushes Sample shows you how to use four different brushes in several shapes. Below is a code snippet showing how to use hatched and gradient brushes.

Rectangle rect = new Rectangle(35, 190, 100, 100);       
 LinearGradientBrush brush2 = new LinearGradientBrush(rect, 
                           Color.DarkOrange, Color.Aquamarine, 
                          LinearGradientMode.ForwardDiagonal); 
 g.FillEllipse(brush2, 35, 190, 100, 100); 
 
 HatchBrush brush1 = new HatchBrush(HatchStyle.DiagonalCross, 
                          Color.DarkOrange, Color.Aquamarine); 
 g.FillEllipse(brush1, 35, 190, 100, 100);

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GDI+ features a TextureBrush that lets you draw repeating patterns. You can specify any bitmap to be drawn repeatedly. In this example we create bitmaps using code and attach them to a TextureBrush.

		static object[] patternSpecs = new object[] 
		{
			new short[] { 0xff, 0xff, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00 },  // horizontal
			new short[] { 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc },  // vertical
			new short[] { 0x77, 0xbb, 0xdd, 0xee, 0x77, 0xbb, 0xdd, 0xee },   // \\\ Down
			new short[] { 0xee, 0xdd, 0xbb, 0x77, 0xee, 0xdd, 0xbb, 0x77 },   // /// Up
			new short[] { 0xee, 0x00, 0xee, 0xee, 0xee, 0x00, 0xee, 0xee },   // +++ 
		}

		public static Bitmap CreateBitmapFromPattern(int pattern)
		{
			Bitmap patternBitmap;
			IntPtr hBitmap = NativeMethods.CreateBitmap(8, 8, 1, 1, (short[]) patternSpecs[pattern]);
			if (hBitmap != IntPtr.Zero)
				patternBitmap = Image.FromHbitmap(hBitmap);
			NativeMethods.DeleteObject(hBitmap);
			return patternBitmap;
		}

		public static void FillRectangle(Graphics g, Rectangle r, int pattern, Color foreColor, Color backColor) 
		{
			Bitmap bm = CreateBitmapFromPattern(pattern);
			FillRectangle(g, r, bm, foreColor, backColor);
		}
		public static void FillRectangle(Graphics g, Rectangle r, Bitmap bm, Color foreColor, Color backColor) 
		{
			if (bm != null)
			{
				Size size = bm.PhysicalDimension.ToSize();
				TextureBrush br = new TextureBrush(bm, new Rectangle(new Point(0, 0), size), ia);
				br.WrapMode = WrapMode.Tile;
                
				g.FillRectangle(br, r);
				br.Dispose();
			}             
		}

	public class NativeMethods
	{
		[DllImport('gdi32', CharSet=CharSet.Auto, ExactSpelling=true)]
		extern public static IntPtr CreateBitmap(int nWidth, int nHeight, int nPlanes, int nBitsPerPixel, 
			[MarshalAs(UnmanagedType.LPArray)] short[] lpvBits);

		[DllImport('gdi32')]
		extern public static bool DeleteObject(IntPtr hObject)  ;

	}

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The Graphics.RenderingOrigin property lets you specify a Point structure that represents the dither origin for 8-bits-per-pixel and 16-bits-per-pixel dithering and is also used to set the origin for hatch brushes.

The following example shows how to use RenderingOrigin:

namespace Scrollable1
{
    using System;
    using System.Collections;
    using System.ComponentModel;
    using System.Drawing;
    using System.Drawing.Drawing2D;
    using System.Windows.Forms;

    /// <summary>
    ///    Summary description for ScrollableControl1.
    /// </summary>
    public class ScrollableControl1 : System.Windows.Forms.ScrollableControl
    {
        private void InitializeComponent ()
        {
        }
    
        public ScrollableControl1()
        {
            InitializeComponent ();

            this.AutoScrollMinSize = new Size(500, 500);
        }

        protected override void OnPaint(PaintEventArgs pe)
        {
	pe.Graphics.RenderingOrigin = AutoScrollPosition;
            HatchBrush br = new HatchBrush(HatchStyle.ForwardDiagonal, Color.Blue, Color.White);
            pe.Graphics.FillRectangle(br, ClientRectangle /*or pe.ClipRectangle*/);
            br.Dispose();
        }
    }
}

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