/// <summary>
/// Draws text with a border.
/// </summary>
/// <param name="gfx">The source graphics object</param>
/// <param name="text">The text to render</param>
/// <param name="font">The font to render</param>
/// <param name="brush">The brush to use for the rendered text</param>
/// <param name="x">The x location to render the text at</param>
/// <param name="y">The y location to render the text at</param>
/// <param name="border">The width of the border to render in pixels</param>
/// <param name="borderColors">A collection of colors to border should cycle through</param>
/// <param name="colorOffsets">An index-matching collection of offsets to render the border colors at</param>
public static void DrawString(this Graphics gfx, string text, Font font, Brush brush, int x, int y, int border, Color[] borderColors, float[] colorOffsets)
{
if (string.IsNullOrWhiteSpace(text))
return;
if (gfx == null)
throw new ArgumentNullException("gfx");
if (font == null)
throw new ArgumentNullException("font");
if (brush == null)
throw new ArgumentNullException("brush");
if (border <= 0)
throw new ArgumentException("Border must be greater than 0", "border");
if (borderColors.Length == 0)
throw new ArgumentException("Border requires at least 1 color", "borderColors");
if (borderColors.Length > 1 && borderColors.Length != colorOffsets.Length)
throw new ArgumentException("A border with more than 1 color requires a matching number of offsets", "colorOffsets");
if (colorOffsets == null || colorOffsets.Length == 0)
colorOffsets = new[] {(float)0};
// Organize color fades from inner to outer
var colors = borderColors
.Select((c, i) => new KeyValuePair<float, Color>(colorOffsets[i], c))
.OrderBy(c => c.Key)
.ToArray();
// Get bordered boundaries
var offset = gfx.MeasureStringBoundaries(text, font).Location;
var measure = gfx.MeasureStringBoundaries(text, font, border);
using (var workImage = new Bitmap((int)measure.Width, (int)measure.Height))
using (var gfxWork = Graphics.FromImage(workImage))
{
gfxWork.PageUnit = GraphicsUnit.Point;
gfxWork.SmoothingMode = gfx.SmoothingMode;
var path = new GraphicsPath();
path.AddString(text, font.FontFamily, (int) font.Style, font.Size, new PointF((border-offset.X)*(float).75, (border-offset.Y)*(float).75), StringFormat.GenericDefault);
// Fade the border from outer to inner.
for (var b = border; b > 0; b--)
{
var colorIndex = (float) 1/border*b;
var colorStart = colors.Length > 1 ? colors.Last(c => c.Key <= colorIndex) : colors.First();
var colorEnd = colors.Length > 1 ? colors.First(c => c.Key >= colorIndex) : colors.First();
var colorOffset = 1/Math.Max((float).0000001, colorEnd.Key - colorStart.Key)*(colorIndex - colorStart.Key);
var color = colorStart.Value.FadeTo(colorEnd.Value, colorOffset);
const float lineWidthOffset = (float) .65; // This is approximate
using (var pen = new Pen(color, b/lineWidthOffset) { LineJoin = LineJoin.Round })
gfxWork.DrawPath(pen, path);
}
// Draw the text
gfxWork.FillPath(brush, path);
var bounds = workImage.DetectPadding();
var offsetX = ((measure.Width - bounds.Right) - bounds.X)/2;
// Apply the generated image
gfx.DrawImage(workImage, x + offsetX, y);
}
}
private void button1_Click(object sender, EventArgs e)
{
var dlg = new OpenFileDialog { Title = "Please select an image to open:", Filter = "Jpeg|*.jpg|Jpeg|*.jpeg|Png|*.png|Bitmap|*.bmp" };
if (dlg.ShowDialog() != DialogResult.OK)
return;
var img = Image.FromFile(dlg.FileName);
// Scale to fit
_scaleToFit.BackgroundImage = img.ScaleToFit(_scaleToFit.Size, false);
// Scale to fit (overflow)
_scaleToOverflow.BackgroundImage = img.ScaleToFit(_scaleToOverflow.Size, false, ScalingMode.Overflow);
// Stretch to fit
_stretch.BackgroundImage = img.Stretch(_stretch.Size, false);
// Rotate and fit
_rotateFit.BackgroundImage = img.ScaleToFit(_rotateFit.Size, false).Rotate(45, ScalingMode.FitContent).ScaleToFit(_rotateOverflow.Size);
// Rotate and overflow
_rotateOverflow.BackgroundImage = img.ScaleToFit(_rotateOverflow.Size, false).Rotate(45);
// Fast pixel manipulation (UnsafeContext)
_pixelManipulation.BackgroundImage = img.ScaleToFit(_pixelManipulation.Size, false);
using (var context = _pixelManipulation.BackgroundImage.CreateUnsafeContext())
{
for (var y = 0; y < context.Height; y++)
for (var x = 0; x < context.Width; x++)
{
var pixel = context.GetRawPixel(x, y);
var level = Math.Max(pixel.Red, Math.Max(pixel.Green, pixel.Blue));
context.SetPixel(x, y, pixel.Alpha, level, level, level);
}
}
_pixelManipulation.Refresh();
// Detect Edges
var edge = new Bitmap(_edgeDetection.Width, _edgeDetection.Height);
using (var gfx = Graphics.FromImage(edge))
{
gfx.DrawEllipse(Pens.Black, 25, 25, 50, 50);
var bounds = edge.DetectPadding();
gfx.DrawLine(Pens.Red, bounds.Left, 0, bounds.Left, edge.Height);
gfx.DrawLine(Pens.Red, bounds.Right, 0, bounds.Right, edge.Height);
gfx.DrawLine(Pens.Red, 0, bounds.Top, edge.Width, bounds.Top);
gfx.DrawLine(Pens.Red, 0, bounds.Bottom, edge.Width, bounds.Bottom);
}
_edgeDetection.BackgroundImage = edge;
// Create animated Gif
var gifImage = img.ScaleToFit(_gifGeneration.Size, false);
var gifStream = new MemoryStream(); // NOTE: Disposing this stream will break this demo - I don't know why.
using (var encoder = new GifEncoder(gifStream))
for (var angle = 0; angle < 360; angle += 10)
using (var frame = gifImage.Rotate(angle, false))
{
encoder.AddFrame(frame, 0, 0, TimeSpan.FromSeconds(0));
}
gifStream.Position = 0;
_gifGeneration.Image = Image.FromStream(gifStream);
// Draw text with effects
_textGen.BackgroundImage = img.ScaleToFit(_textGen.Size, false, ScalingMode.Overflow);
using (var gfx = Graphics.FromImage(_textGen.BackgroundImage))
{
gfx.DrawString("A B C 1 2 3", new Font(FontFamily.Families.First(f => f.Name.Contains("Times")), 15), Brushes.Green, 15, 25, 10,
new[] {Color.Yellow, Color.Blue, Color.Red, Color.Green, Color.Purple, Color.Black},
new[] { 0, (float).20, (float).40, (float).60, (float).80, 1 });
}
}
