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Add basic tga encoder for SKBitmap

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This commit is contained in:
cinder
2025-04-27 17:34:22 -05:00
parent b73c614174
commit a4e2ed0853
1 changed files with 61 additions and 5 deletions
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66
LibreMetaverse/Imaging/Targa.cs
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2024, Sjofn LLC.
* Copyright (c) 2024-2025, Sjofn LLC.
* All rights reserved.
*
* - Redistribution and use in source and binary forms, with or without
@@ -34,7 +34,7 @@ namespace OpenMetaverse.Imaging
{
public static class Targa
{
/// <summary>Decode Truvision TGA file to <see cref="SKBitmap" /></summary>
/// <summary>Decode Truevision TGA file to <see cref="SKBitmap" /></summary>
public static SKBitmap Decode(string fileName)
{
using (var image = Pfimage.FromFile(fileName))
@@ -43,7 +43,7 @@ namespace OpenMetaverse.Imaging
}
}
/// <summary>Decode Truvision TGA stream to <see cref="SKBitmap" /></summary>
/// <summary>Decode Truevision TGA stream to <see cref="SKBitmap" /></summary>
public static SKBitmap Decode(Stream stream)
{
using (var image = Pfimage.FromStream(stream))
@@ -100,8 +100,64 @@ namespace OpenMetaverse.Imaging
}
}
}
/// <summary>Encode <see cref="ManagedImage"/> to Truvision TGA byte array</summary>
public static byte[] Encode(SKBitmap image)
{
if (image == null) { return null; }
var imageType = (byte)(image.ColorType == SKColorType.Gray8 || image.ColorType == SKColorType.Alpha8
? 0x03 : 0x02);
var imageDescriptor = (byte)(image.AlphaType <= SKAlphaType.Opaque ? 0 : 0x8);
var tga = new byte[image.Width * image.Height * image.BytesPerPixel + 18];
var di = 0;
tga[di++] = 0x00; // id length
tga[di++] = 0x00; // colormap type = 0: no colormap
tga[di++] = imageType; // image type
tga[di++] = 0x00; // color map spec is five zeroes for no color map
tga[di++] = 0x00; // color map spec is five zeroes for no color map
tga[di++] = 0x00; // color map spec is five zeroes for no color map
tga[di++] = 0x00; // color map spec is five zeroes for no color map
tga[di++] = 0x00; // color map spec is five zeroes for no color map
tga[di++] = 0; // x origin = two bytes
tga[di++] = 0; // x origin = two bytes
tga[di++] = 0; // y origin = two bytes
tga[di++] = 0; // y origin = two bytes
tga[di++] = (byte)(image.Width & 0xFF); // width - low byte
tga[di++] = (byte)(image.Width >> 8); // width - hi byte
tga[di++] = (byte)(image.Height & 0xFF); // height - low byte
tga[di++] = (byte)(image.Height >> 8); // height - hi byte
tga[di++] = (byte)(image.BytesPerPixel*8); // pixel depth, includes attribute bits
tga[di++] = imageDescriptor; // image descriptor byte
for (var y = image.Height - 1; y >= 0; --y) // takes lines from bottom lines to top (mirrored horizontally)
{
for (var x = 0; x < image.Width; ++x)
{
var c = image.GetPixel(x, y);
if (image.ColorType == SKColorType.Gray8)
{
tga[di++] = c.Red;
} else if (image.ColorType == SKColorType.Alpha8)
{
tga[di++] = c.Alpha;
}
else
{
tga[di++] = c.Blue;
tga[di++] = c.Green;
tga[di++] = c.Red;
tga[di++] = (byte)(image.AlphaType > SKAlphaType.Opaque ? 0x0 : c.Alpha);
}
}
}
return tga;
}
/// <summary>Encode <see cref="ManagedImage"/> to Truevision TGA byte array</summary>
public static byte[] Encode(ManagedImage image)
{
var tga = new byte[image.Width * image.Height * ((image.Channels & ManagedImage.ImageChannels.Alpha) == 0 ? 3 : 4) + 32];