Adding Max7219 (#46)

Author: Ellerbach

devices/Max7219/DeviceIdDigit.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace Iot.Device.Max7219
+{
+    public class DeviceIdDigit
+    {
+        public DeviceIdDigit(int deviceId, int digit)
+        {
+            DeviceId = deviceId;
+            Digit = digit;
+        }
+
+        public int DeviceId { get; set; }
+        public int Digit { get; set; }
+    }
+}

devices/Max7219/FixedSizeFont.cs

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+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Iot.Device.Max7219
+{
+    /// <summary>
+    /// Implementation of a <see cref="IFont"/> that uses a common array for all characters.
+    /// The number of bytes per character is constant and zero values between the characters are trimmed.
+    /// </summary>
+    public class FixedSizeFont : IFont
+    {
+        private readonly byte[] _data;
+        private readonly int _bytesPerCharacter;
+        private readonly byte[] _space;
+
+        /// <summary>
+        /// Constructs FixedSizeFont instance
+        /// </summary>
+        /// <param name="bytesPerCharacter">number of bytes per character</param>
+        /// <param name="data">Font data</param>
+        /// <param name="spaceWidth">Space width</param>
+        public FixedSizeFont(int bytesPerCharacter, byte[] data, int spaceWidth = 3)
+        {
+            _data = data;
+            _bytesPerCharacter = bytesPerCharacter;
+            _space = new byte[spaceWidth];
+        }
+
+        /// <summary>
+        /// Get character information
+        /// </summary>
+        public ListByte this[char chr]
+        {
+            get
+            {
+                int start = chr * _bytesPerCharacter;
+                int end = start + _bytesPerCharacter;
+                if (end > _data.Length)
+                {
+                    return new ListByte(_space); // character is not defined
+                }
+
+                if (chr == ' ')
+                {
+                    return new ListByte(_space);
+                }
+
+                // trim the font
+                while (start < end && _data[start] == 0)
+                {
+                    start++;
+                }
+
+                while (end > start && _data[end - 1] == 0)
+                {
+                    end--;
+                }
+
+                return new ListByte(new SpanByte(_data, start, end - start).ToArray());
+            }
+        }
+    }
+}

devices/Max7219/Fonts.cs

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+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Iot.Device.Max7219
+{
+    /// <summary>
+    /// A font contains one list of bytes per character which can be written to the matrix to represent the character.
+    /// </summary>
+    /// <remarks>
+    /// Each character consists of a list of bytes where a single byte represents a column of the display.
+    /// </remarks>
+    ///
+    /// <example>
+    /// This example shows how the 'A' char could by encoded:
+    /// <code>
+    /// var aBytes = new byte[] {
+    ///     0b1111100,
+    ///     0b1111110,
+    ///     0b0010011,
+    ///     0b0010011,
+    ///     0b1111110,
+    ///     0b1111100,
+    ///     0b0000000,
+    ///     0b0000000
+    /// };
+    /// </code>
+    ///
+    /// </example>
+    public interface IFont
+    {
+        /// <summary>
+        /// Returns a list of bytes for a given character to be written to a matrix.
+        /// </summary>
+        ListByte this[char chr]
+        {
+            get;
+        }
+    }
+}