/// <summary>
/// Determines whether this instance can draw the specified character.
/// </summary>
/// <param name="character">The character.</param>
/// <param name="drawingBoard">The drawing board.</param>
/// <param name="columnOffset">The column offset.</param>
/// <param name="rowOffset">The row offset.</param>
/// <param name="blender">The blender.</param>
/// <param name="hasNonBlanks">if set to <c>true</c> [has non spaces].</param>
/// <returns>
/// <c>true</c> if this instance can draw the specified character; otherwise, <c>false</c>.
/// </returns>
private bool CanDraw(FIGcharacter character, DrawingBoard drawingBoard, int columnOffset, int rowOffset, IDrawingElementBlender blender, out bool hasNonBlanks)
{
hasNonBlanks = false;
foreach (var element in GetCharacterDrawingElements(character))
{
var column = element.Column + columnOffset;
var row = element.Row + rowOffset;
if (column < 0 || row < 0)
{
return(false);
}
// this relies on the fact that element.DrawingElement is never null
var under = drawingBoard[column, row];
if (blender.TryBlend(under, element.DrawingElement) is null)
{
return(false);
}
if (!(under is null) && !under.IsBlank && !element.DrawingElement.IsBlank)
{
hasNonBlanks = true;
}
}
return(true);
}
private void AddCharacter(FIGcharacter character)
{
if (!(character is null) && character.Code > 0)
{
Characters[character.Code] = character;
}
}
/// <summary>
/// Creates a drawing element.
/// This may be overriden in inherited classes, in order to add your own metadata.
/// This method is not invoked if a delegate is given to <see cref="FIGdriver"/> constructor.
/// </summary>
/// <param name="glyph">The glyph to be displayed.</param>
/// <param name="character">The related <see cref="FIGcharacter"/> that generated this glyph</param>
/// <returns></returns>
protected virtual DrawingElement CreateDrawingElement(char glyph, FIGcharacter character)
{
if (glyph == '\0')
{
return(null);
}
return(new DrawingElement(glyph));
}
private DrawingElement InvokeCreateDrawingElement(FIGcharacter character, char glyph)
{
if (!(_createDrawingElement is null))
{
return(_createDrawingElement(character, glyph));
}
return(CreateDrawingElement(glyph, character));
}
/// <summary>
/// Draws the specified <see cref="FIGcharacter" /> to <see cref="DrawingBoard" />.
/// </summary>
/// <param name="character">The character.</param>
/// <param name="drawingBoard">The drawing board.</param>
/// <param name="columnOffset">The column offset.</param>
/// <param name="rowOffset">The row offset.</param>
/// <param name="blender">The blender.</param>
private void Draw(FIGcharacter character, DrawingBoard drawingBoard, int columnOffset, int rowOffset, IDrawingElementBlender blender)
{
foreach (var element in GetCharacterDrawingElements(character))
{
var column = element.Column + columnOffset;
var row = element.Row + rowOffset;
drawingBoard[column, row] = blender.TryBlend(drawingBoard[column, row], element.DrawingElement) ?? element.DrawingElement;
}
}
private IEnumerable <CharacterDrawingElement> GetCharacterDrawingElements(FIGcharacter character)
{
for (int row = 0; row < character.Height; row++)
{
for (int column = 0; column < character.Width; column++)
{
var glyph = character[column, row];
if (glyph == Font.HardBlank)
{
glyph = HardBlank;
}
var drawingElement = InvokeCreateDrawingElement(character, glyph);
if (drawingElement is null)
{
continue;
}
yield return(new CharacterDrawingElement(column, row, drawingElement));
}
}
}
private int AdjustCaret(FIGcharacter character, DrawingBoard drawingBoard, int columnOffset, int rowOffset, IDrawingElementBlender blender)
{
// this is the poor man's fix (again)
// character does not have a visual, so we ignore it
if (character.Width == 0)
{
return(columnOffset);
}
var previousHasNonBlanks = false;
for (; ; columnOffset--)
{
if (!CanDraw(character, drawingBoard, columnOffset - 1, rowOffset, blender, out var hasNonBlanks) || previousHasNonBlanks)
{
return(columnOffset);
}
previousHasNonBlanks = hasNonBlanks;
}
}
