static void PrepareGlyphArcInfo (CTLine line, long glyphCount, GlyphArcInfo[] glyphArcInfo)
{
var runArray = line.GetGlyphRuns ();
// Examine each run in the line, updating glyphOffset to track how far along the run is
// in terms of glyphCount.
long glyphOffset = 0;
float ascent = 0;
float descent = 0;
float leading = 0;
foreach (var run in runArray) {
var runGlyphCount = run.GlyphCount;
// Ask for the width of each glyph in turn.
var runGlyphIndex = 0;
for (; runGlyphIndex < runGlyphCount; runGlyphIndex++) {
glyphArcInfo[runGlyphIndex + glyphOffset].width = (float)run.GetTypographicBounds (new NSRange (runGlyphIndex, 1), out ascent, out descent, out leading);
}
glyphOffset += runGlyphCount;
}
var lineLength = line.GetTypographicBounds (out ascent, out descent, out leading);
var prevHalfWidth = glyphArcInfo[0].width / 2.0;
glyphArcInfo[0].angle = (float)((prevHalfWidth / lineLength) * Math.PI);
var lineGlyphIndex = 1;
for (; lineGlyphIndex < glyphCount; lineGlyphIndex++) {
var halfWidth = glyphArcInfo[lineGlyphIndex].width / 2.0;
var prevCenterToCenter = prevHalfWidth + halfWidth;
glyphArcInfo[lineGlyphIndex].angle = (float)((prevCenterToCenter / lineLength) * Math.PI);
prevHalfWidth = halfWidth;
}
}
public override void DrawRect (RectangleF dirtyRect)
{
// Don't draw if we don't have a font or a title.
if (Font == null || Title == string.Empty)
return;
// Initialize the text matrix to a known value
CGContext context = NSGraphicsContext.CurrentContext.GraphicsPort;
context.TextMatrix = CGAffineTransform.MakeIdentity ();
// Draw a white background
NSColor.White.Set ();
context.FillRect (dirtyRect);
//CTLineRef line = CTLineCreateWithAttributedString((CFAttributedStringRef)self.attributedString);
CTLine line = new CTLine (AttributedString);
int glyphCount = line.GlyphCount;
if (glyphCount == 0)
return;
GlyphArcInfo[] glyphArcInfo = new GlyphArcInfo[glyphCount];
PrepareGlyphArcInfo (line, glyphCount, glyphArcInfo);
// Move the origin from the lower left of the view nearer to its center.
context.SaveState ();
context.TranslateCTM (dirtyRect.GetMidX (), dirtyRect.GetMidY () - Radius / 2);
// Stroke the arc in red for verification.
context.BeginPath ();
context.AddArc (0, 0, Radius, (float)Math.PI, 0, true);
context.SetRGBStrokeColor (1, 0, 0, 1);
context.StrokePath ();
// Rotate the context 90 degrees counterclockwise.
context.RotateCTM ((float)PI_2);
// Now for the actual drawing. The angle offset for each glyph relative to the previous
// glyph has already been calculated; with that information in hand, draw those glyphs
// overstruck and centered over one another, making sure to rotate the context after each
// glyph so the glyphs are spread along a semicircular path.
PointF textPosition = new PointF (0, Radius);
context.TextPosition = textPosition;
var runArray = line.GetGlyphRuns ();
var runCount = runArray.Count ();
var glyphOffset = 0;
var runIndex = 0;
for (; runIndex < runCount; runIndex++) {
var run = runArray[runIndex];
var runGlyphCount = run.GlyphCount;
bool drawSubstitutedGlyphsManually = false;
CTFont runFont = run.GetAttributes ().Font;
// Determine if we need to draw substituted glyphs manually. Do so if the runFont is not
// the same as the overall font.
NSFont rrunFont = new NSFont (runFont.Handle);
// used for comparison
if (DimsSubstitutedGlyphs && Font != rrunFont) {
drawSubstitutedGlyphsManually = true;
}
var runGlyphIndex = 0;
for (; runGlyphIndex < runGlyphCount; runGlyphIndex++) {
var glyphRange = new NSRange (runGlyphIndex, 1);
context.RotateCTM (-(glyphArcInfo[runGlyphIndex + glyphOffset].angle));
// Center this glyph by moving left by half its width.
var glyphWidth = glyphArcInfo[runGlyphIndex + glyphOffset].width;
var halfGlyphWidth = glyphWidth / 2.0;
var positionForThisGlyph = new PointF (textPosition.X - (float)halfGlyphWidth, textPosition.Y);
// Glyphs are positioned relative to the text position for the line, so offset text position leftwards by this glyph's
// width in preparation for the next glyph.
textPosition.X -= glyphWidth;
CGAffineTransform textMatrix = run.TextMatrix;
textMatrix.x0 = positionForThisGlyph.X;
textMatrix.y0 = positionForThisGlyph.Y;
context.TextMatrix = textMatrix;
if (!drawSubstitutedGlyphsManually)
run.Draw (context, glyphRange);
else {
// We need to draw the glyphs manually in this case because we are effectively applying a graphics operation by
// setting the context fill color. Normally we would use kCTForegroundColorAttributeName, but this does not apply
// as we don't know the ranges for the colors in advance, and we wanted demonstrate how to manually draw.
var cgFont = runFont.ToCGFont ();
var glyph = run.GetGlyphs (glyphRange);
var position = run.GetPositions (glyphRange);
context.SetFont (cgFont);
context.SetFontSize (runFont.Size);
context.SetRGBFillColor (0.25f, 0.25f, 0.25f, 1);
context.ShowGlyphsAtPositions (glyph, position, 1);
}
// Draw the glyph bounds
if (ShowsGlyphBounds) {
var glyphBounds = run.GetImageBounds (context, glyphRange);
context.SetRGBStrokeColor (0, 0, 1, 1);
context.StrokeRect (glyphBounds);
}
// Draw the bounding boxes defined by the line metrics
if (ShowsLineMetrics) {
var lineMetrics = new RectangleF ();
float ascent = 0;
float descent = 0;
float leading = 0;
run.GetTypographicBounds (glyphRange, out ascent, out descent, out leading);
// The glyph is centered around the y-axis
lineMetrics.Location = new PointF (-(float)halfGlyphWidth, positionForThisGlyph.Y - descent);
lineMetrics.Size = new SizeF (glyphWidth, ascent + descent);
context.SetRGBStrokeColor (0, 1, 0, 1);
context.StrokeRect (lineMetrics);
}
}
glyphOffset += runGlyphCount;
}
context.RestoreState ();
}
