//MIT, 2016-present, WinterDev
//MIT, 2015, Michael Popoloski
//FTL, 3-clauses BSD, FreeType project
//-----------------------------------------------------
using System;
using System.Numerics;
namespace Typography.OpenFont
{
//https://en.wikipedia.org/wiki/B%C3%A9zier_curve
//--------------------
//Line, has 2 points..
// (x0,y0) begin point
// (x1,y1) end point
//--------------------
//Curve3 (Quadratic Bézier curves), has 3 points
// (x0,y0) begin point
// (x1,y1) 1st control point
// (x2,y2) end point
//--------------------
//Curve4 (Cubic Bézier curves), has 4 points
// (x0,y0) begin point
// (x1,y1) 1st control point
// (x2,y2) 2nd control point
// (x3,y3) end point
//--------------------
//please note that TrueType font
//compose of Quadractic Bezier Curve ***
//---------------------
public interface IGlyphTranslator
{
///
/// begin read a glyph
///
///
void BeginRead(int contourCount);
///
/// end read a glyph
///
void EndRead();
///
/// set CURRENT pen position to (x0,y0) And set the position as latest MOVETO position
///
///
///
void MoveTo(float x0, float y0);
///
/// add line,begin from CURRENT pen position to (x1,y1) then set (x1,y1) as CURRENT pen position
///
/// end point x
/// end point y
void LineTo(float x1, float y1);
///
/// add Quadratic Bézier curve,begin from CURRENT pen pos, to (x2,y2), then set (x2,y2) as CURRENT pen pos
///
/// x of 1st control point
/// y of 1st control point
/// end point x
/// end point y
void Curve3(float x1, float y1, float x2, float y2);
///
/// add Cubic Bézier curve,begin from CURRENT pen pos, to (x3,y3), then set (x3,y3) as CURRENT pen pos
///
/// x of 1st control point
/// y of 1st control point
/// x of 2nd control point
/// y of 2dn control point
/// end point x
/// end point y
void Curve4(float x1, float y1, float x2, float y2, float x3, float y3);
///
/// close current contour, create line from CURRENT pen position to latest MOVETO position
///
void CloseContour();
}
public static class IGlyphReaderExtensions
{
//for TrueType Font
public static void Read(this IGlyphTranslator tx, GlyphPointF[] glyphPoints, ushort[] contourEndPoints, float scale = 1)
{
if (glyphPoints == null || contourEndPoints == null)
{
return;//?
}
int startContour = 0;
int cpoint_index = 0;//current point index
int todoContourCount = contourEndPoints.Length;
//-----------------------------------
//1. start read data from a glyph
tx.BeginRead(todoContourCount);
//-----------------------------------
float latest_moveto_x = 0;
float latest_moveto_y = 0;
int curveControlPointCount = 0; // 1 curve control point => Quadratic, 2 curve control points => Cubic
while (todoContourCount > 0)
{
//reset
curveControlPointCount = 0;
//foreach contour...
//next contour will begin at...
int nextCntBeginAtIndex = contourEndPoints[startContour] + 1;
//reset ...
bool has_c_begin = false; //see below [A]
Vector2 c_begin = new Vector2(); //special point if the glyph starts with 'off-curve' control point
Vector2 c1 = new Vector2(); //control point of quadratic curve
//-------------------------------------------------------------------
bool offCurveMode = false;
bool foundFirstOnCurvePoint = false;
bool startWithOffCurve = false;
int cnt_point_count = 0;
//-------------------------------------------------------------------
//[A]
//first point may start with 'ON CURVE" or 'OFF-CURVE'
//1. if first point is 'ON-CURVE' => we just set moveto command to it
//
//2. if first point is 'OFF-CURVE' => we store it into c_begin and set has_c_begin= true
// the c_begin will be use when we close the contour
//
//
//eg. glyph '2' in Century font starts with 'OFF-CURVE' point, and ends with 'OFF-CURVE'
//-------------------------------------------------------------------
#if DEBUG
int dbug_cmdcount = 0;
#endif
for (; cpoint_index < nextCntBeginAtIndex; ++cpoint_index)
{
#if DEBUG
dbug_cmdcount++;
#endif
//for each point in this contour
//point p is an on-curve point (on outline). (not curve control point)
//possible ways..
//1. if we are in curve mode, then p is end point
// we must decide which curve to create (Curve3 or Curve4)
// easy, ...
// if curveControlPointCount == 1 , then create Curve3
// else curveControlPointCount ==2 , then create Curve4
//2. if we are NOT in curve mode,
// if p is first point then set this to x0,y0
// else then p is end point of a line.
GlyphPointF p = glyphPoints[cpoint_index];
cnt_point_count++;
float p_x = p.X * scale;
float p_y = p.Y * scale;
//int vtag = (int)flags[cpoint_index] & 0x1;
//bool has_dropout = (((vtag >> 2) & 0x1) != 0);
//int dropoutMode = vtag >> 3;
if (p.onCurve)
{
//-------------------------------------------------------------------
//[B]
//point p is an 'on-curve' point (on outline).
//(not curve control point)***
//the point touch the outline.
//possible ways..
//1. if we are in offCurveMode, then p is a curve end point.
// we must decide which curve to create (Curve3 or Curve4)
// easy, ...
// if curveControlPointCount == 1 , then create Curve3
// else curveControlPointCount ==2 , then create Curve4 (BUT SHOULD NOT BE FOUND IN TRUE TYPEFONT'(
//2. if we are NOT in offCurveMode,
// if p is first point then set this to =>moveto(x0,y0)
// else then p is end point of a line => lineto(x1,y1)
//-------------------------------------------------------------------
if (offCurveMode)
{
//as describe above [B.1] ,...
switch (curveControlPointCount)
{
case 1:
tx.Curve3(
c1.X, c1.Y,
p_x, p_y);
break;
default:
//for TrueType font
//we should not be here?
throw new OpenFontNotSupportedException();
}
//reset curve control point count
curveControlPointCount = 0;
//we touch the curve, set offCurveMode= false
offCurveMode = false;
}
else
{
// p is ON CURVE, but now we are in OFF-CURVE mode.
//
//as describe above [B.2] ,...
if (!foundFirstOnCurvePoint)
{
//special treament for first point
foundFirstOnCurvePoint = true;
switch (curveControlPointCount)
{
case 0:
//describe above, see [A.1]
tx.MoveTo(latest_moveto_x = p_x, latest_moveto_y = p_y);
break;
case 1:
//describe above, see [A.2]
c_begin = c1;
has_c_begin = true;
//since c1 is off curve
//we skip the c1 for and use it when we close the curve
tx.MoveTo(latest_moveto_x = p_x, latest_moveto_y = p_y);
curveControlPointCount--;
break;
default: throw new OpenFontNotSupportedException();
}
}
else
{
tx.LineTo(p_x, p_y);
}
//if (has_dropout)
//{
// //printf("[%d] on,dropoutMode=%d: %d,y:%d \n", mm, dropoutMode, vpoint.x, vpoint.y);
//}
//else
//{
// //printf("[%d] on,x: %d,y:%d \n", mm, vpoint.x, vpoint.y);
//}
}
}
else
{
//p is OFF-CURVE point (this is curve control point)
//
if (cnt_point_count == 1)
{
//1st point
startWithOffCurve = true;
}
switch (curveControlPointCount)
{
case 0:
c1 = new Vector2(p_x, p_y);
if (foundFirstOnCurvePoint)
{
//this point is curve control point***
//so set curve mode = true
//check number if existing curve control
offCurveMode = true;
}
else
{
//describe above, see [A.2]
}
break;
case 1:
{
if (!foundFirstOnCurvePoint)
{
Vector2 mid2 = GetMidPoint(c1, p_x, p_y);
//----------
//2. generate curve3 ***
c_begin = c1;
has_c_begin = true;
tx.MoveTo(latest_moveto_x = mid2.X, latest_moveto_y = mid2.Y);
offCurveMode = true;
foundFirstOnCurvePoint = true;
c1 = new Vector2(p_x, p_y);
continue;
}
//we already have previous 1st control point (c1)
//-------------------------------------
//please note that TrueType font
//compose of Quadractic Bezier Curve (Curve3) ***
//-------------------------------------
//in this case, this is NOT Cubic,
//this is 2 CONNECTED Quadractic Bezier Curves***
//
//we must create 'end point' of the first curve
//and set it as 'begin point of the second curve.
//
//this is done by ...
//1. calculate mid point between c1 and the latest point (p_x,p_y)
Vector2 mid = GetMidPoint(c1, p_x, p_y);
//----------
//2. generate curve3 ***
tx.Curve3(
c1.X, c1.Y,
mid.X, mid.Y);
//------------------------
//3. so curve control point number is reduce by 1***
curveControlPointCount--;
//------------------------
//4. and set (p_x,p_y) as 1st control point for the new curve
c1 = new Vector2(p_x, p_y);
offCurveMode = true;
//
//printf("[%d] bzc2nd, x: %d,y:%d \n", mm, vpoint.x, vpoint.y);
}
break;
default:
throw new OpenFontNotSupportedException();
}
//count
curveControlPointCount++;
}
}
//--------
//when finish,
//ensure that the contour is closed.
if (offCurveMode)
{
switch (curveControlPointCount)
{
case 0: break;
case 1:
{
if (has_c_begin)
{
Vector2 mid = GetMidPoint(c1, c_begin.X, c_begin.Y);
//----------
//2. generate curve3 ***
tx.Curve3(
c1.X, c1.Y,
mid.X, mid.Y);
//------------------------
//3. so curve control point number is reduce by 1***
curveControlPointCount--;
//------------------------
tx.Curve3(
c_begin.X, c_begin.Y,
latest_moveto_x, latest_moveto_y);
}
else
{
tx.Curve3(
c1.X, c1.Y,
latest_moveto_x, latest_moveto_y);
}
}
break;
default:
//for TrueType font
//we should not be here?
throw new OpenFontNotSupportedException();
}
}
else
{
//end with touch curve
//but if this start with off curve
//then we must close it properly
if (startWithOffCurve)
{
//start with off-curve and end with touch curve
tx.Curve3(
c_begin.X, c_begin.Y,
latest_moveto_x, latest_moveto_y);
}
}
//--------
tx.CloseContour(); //***
startContour++;
//--------
todoContourCount--;
//--------
}
//finish
tx.EndRead();
}
static Vector2 GetMidPoint(Vector2 v0, float x1, float y1)
{
//mid point between v0 and (x1,y1)
return new Vector2(
((v0.X + x1) / 2f),
((v0.Y + y1) / 2f));
}
//-----------
//for CFF1
public static void Read(this IGlyphTranslator tx, CFF.Cff1Font cff1Font, CFF.Cff1GlyphData glyphData, float scale = 1)
{
CFF.CffEvaluationEngine evalEngine = new CFF.CffEvaluationEngine();
evalEngine.Run(tx, glyphData.GlyphInstructions, scale);
}
}
//static int s_POINTS_PER_INCH = 72; //default value,
//static int s_PIXELS_PER_INCH = 96; //default value
//public static float ConvEmSizeInPointsToPixels(float emsizeInPoint)
//{
// return (int)(((float)emsizeInPoint / (float)s_POINTS_PER_INCH) * (float)s_PIXELS_PER_INCH);
//}
////from http://www.w3schools.com/tags/ref_pxtoemconversion.asp
////set default
//// 16px = 1 em
////-------------------
////1. conv font design unit to em
//// em = designUnit / unit_per_Em
////2. conv font design unit to pixels
//// float scale = (float)(size * resolution) / (pointsPerInch * _typeface.UnitsPerEm);
////-------------------
////https://www.microsoft.com/typography/otspec/TTCH01.htm
////Converting FUnits to pixels
////Values in the em square are converted to values in the pixel coordinate system by multiplying them by a scale. This scale is:
////pointSize * resolution / ( 72 points per inch * units_per_em )
////where pointSize is the size at which the glyph is to be displayed, and resolution is the resolution of the output device.
////The 72 in the denominator reflects the number of points per inch.
////For example, assume that a glyph feature is 550 FUnits in length on a 72 dpi screen at 18 point.
////There are 2048 units per em. The following calculation reveals that the feature is 4.83 pixels long.
////550 * 18 * 72 / ( 72 * 2048 ) = 4.83
////-------------------
//public static float ConvFUnitToPixels(ushort reqFUnit, float fontSizeInPoint, ushort unitPerEm)
//{
// //reqFUnit * scale
// return reqFUnit * GetFUnitToPixelsScale(fontSizeInPoint, unitPerEm);
//}
//public static float GetFUnitToPixelsScale(float fontSizeInPoint, ushort unitPerEm)
//{
// //reqFUnit * scale
// return ((fontSizeInPoint * s_PIXELS_PER_INCH) / (s_POINTS_PER_INCH * unitPerEm));
//}
}