112 lines
4.1 KiB
C#
112 lines
4.1 KiB
C#
using System.Text;
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using Age.Engine.Model;
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namespace Age.Engine.Text;
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public readonly record struct ImmediateSurfaceTextResult(
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int GlyphCount,
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int CursorX,
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int CursorY);
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/// <summary>
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/// Converts one string into backend-policy glyph requests and composites it directly into an AGE
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/// RGBA surface. Request construction completes before any pixels change, so an unsupported
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/// character cannot leave a partially drawn string behind.
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/// </summary>
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public sealed class ImmediateSurfaceTextRenderer
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{
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public const string DefaultFontFace = "ＭＳ 明朝";
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private static readonly Encoding Cp932 = CreateCp932();
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private readonly IGlyphMaskRasterizer _rasterizer;
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private readonly GlyphRasterPolicy _policy;
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public ImmediateSurfaceTextRenderer(
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IGlyphMaskRasterizer rasterizer,
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GlyphRasterPolicy policy = GlyphRasterPolicy.NativeCp932Gray4)
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{
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_rasterizer = rasterizer ?? throw new ArgumentNullException(nameof(rasterizer));
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_policy = policy;
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}
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public ImmediateSurfaceTextResult Render(
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RgbaImage destination,
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int x,
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int y,
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string text,
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AdvTextStyle style)
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{
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ArgumentNullException.ThrowIfNull(destination);
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ArgumentNullException.ThrowIfNull(text);
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IReadOnlyList<GlyphRasterRequest> requests = CreateRequests(text, style, _policy);
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int cursorX = x;
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int cursorY = y;
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foreach (GlyphRasterRequest request in requests)
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{
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GlyphMask mask = _rasterizer.Rasterize(request);
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AgeGlyphMaskCompositor.DrawGlyph(
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destination, mask, cursorX, cursorY, request.PixelHeight, style);
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cursorX = checked(cursorX + mask.CellAdvanceX);
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cursorY = checked(cursorY + mask.CellAdvanceY);
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}
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return new ImmediateSurfaceTextResult(requests.Count, cursorX, cursorY);
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}
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public static IReadOnlyList<GlyphRasterRequest> CreateRequests(
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string text,
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AdvTextStyle style,
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GlyphRasterPolicy policy = GlyphRasterPolicy.NativeCp932Gray4)
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{
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ArgumentNullException.ThrowIfNull(text);
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int requestedHeight = style.PrimaryFontSize > 0 ? style.PrimaryFontSize : 24;
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int pixelHeight = NativePixelHeight(requestedHeight);
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int requestedWidth = -(pixelHeight / 2);
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int weight = style.Bold ? 700 : 0;
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string fontFace = string.IsNullOrWhiteSpace(style.FontFace)
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? DefaultFontFace
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: style.FontFace;
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var requests = new List<GlyphRasterRequest>(text.Length);
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foreach (Rune rune in text.EnumerateRunes())
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{
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ushort? cp932Code = null;
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try
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{
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byte[] encoded = Cp932.GetBytes(rune.ToString());
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if (encoded.Length is < 1 or > 2)
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throw new ArgumentException(
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$"U+{rune.Value:X4} encoded to unsupported CP932 length {encoded.Length}.",
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nameof(text));
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cp932Code = encoded.Length == 1
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? encoded[0]
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: (ushort)((encoded[0] << 8) | encoded[1]);
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}
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catch (EncoderFallbackException error)
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{
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if (policy == GlyphRasterPolicy.NativeCp932Gray4)
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throw new ArgumentException(
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$"U+{rune.Value:X4} is not representable in native CP932 text.",
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nameof(text), error);
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}
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requests.Add(new GlyphRasterRequest(
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fontFace, pixelHeight, requestedWidth, weight,
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rune.Value, cp932Code, policy));
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}
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return requests;
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}
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public static int NativePixelHeight(int requestedHeight)
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{
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if (requestedHeight <= 0) return 24;
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if (requestedHeight is 32 or 33) return 31;
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return (requestedHeight & 1) != 0 ? requestedHeight - 1 : requestedHeight;
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}
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private static Encoding CreateCp932()
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{
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Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
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return Encoding.GetEncoding(
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932, EncoderFallback.ExceptionFallback, DecoderFallback.ExceptionFallback);
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}
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}
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