(BmpFormat): recognize non-standard bitmaps with embedded alpha channel.

This commit is contained in:
morkt 2016-04-25 18:02:01 +04:00
parent 2c82b05afa
commit 78d7d693d6

View File

@ -2,7 +2,7 @@
//! \date Wed Jul 16 18:06:47 2014
//! \brief BMP image implementation.
//
// Copyright (C) 2014 by morkt
// Copyright (C) 2014-2016 by morkt
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
@ -33,6 +33,12 @@ using System.Windows.Media;
namespace GameRes
{
public class BmpMetaData : ImageMetaData
{
public uint ImageLength;
public uint HeaderLength;
}
[Export(typeof(ImageFormat))]
public class BmpFormat : ImageFormat
{
@ -42,6 +48,20 @@ namespace GameRes
public override ImageData Read (Stream file, ImageMetaData info)
{
var bmp_info = info as BmpMetaData;
if (bmp_info != null && file.CanSeek
&& info.Width * info.Height * (uint)info.BPP/8 + bmp_info.HeaderLength == bmp_info.ImageLength)
{
if (0x20 == info.BPP)
{
return ReadBitmapBGRA (file, bmp_info);
}
else if (0x18 == info.BPP
&& (bmp_info.ImageLength + info.Width * info.Height) == file.Length)
{
return ReadBitmapWithAlpha (file, bmp_info);
}
}
var decoder = new BmpBitmapDecoder (file,
BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
BitmapSource frame = decoder.Frames.First();
@ -56,6 +76,46 @@ namespace GameRes
encoder.Save (file);
}
private ImageData ReadBitmapWithAlpha (Stream file, BmpMetaData info)
{
file.Position = info.ImageLength;
var alpha = new byte[info.Width*info.Height];
if (alpha.Length != file.Read (alpha, 0, alpha.Length))
throw new EndOfStreamException();
file.Position = info.HeaderLength;
int dst_stride = (int)info.Width * 4;
var pixels = new byte[(int)info.Height * dst_stride];
int a_src = 0;
for (int y = (int)info.Height-1; y >= 0; --y)
{
int dst = dst_stride * y;
for (int x = 0; x < dst_stride; x += 4)
{
file.Read (pixels, dst+x, 3);
pixels[dst+x+3] = alpha[a_src++];
}
}
return ImageData.Create (info, PixelFormats.Bgra32, null, pixels, dst_stride);
}
private ImageData ReadBitmapBGRA (Stream file, BmpMetaData info)
{
file.Position = info.HeaderLength;
int stride = (int)info.Width * 4;
var pixels = new byte[(int)info.Height * stride];
bool has_alpha = false;
for (int y = (int)info.Height-1; y >= 0; --y)
{
int dst = stride * y;
file.Read (pixels, dst, stride);
for (int x = 3; !has_alpha && x < stride; x += 4)
has_alpha = pixels[dst+x] != 0;
}
PixelFormat format = has_alpha ? PixelFormats.Bgra32 : PixelFormats.Bgr32;
return ImageData.Create (info, format, null, pixels, stride);
}
void SkipBytes (BinaryReader file, uint num)
{
if (file.BaseStream.CanSeek)
@ -88,12 +148,14 @@ namespace GameRes
uint height = file.ReadUInt32();
file.ReadInt16();
int bpp = file.ReadInt16();
return new ImageMetaData {
return new BmpMetaData {
Width = width,
Height = height,
OffsetX = 0,
OffsetY = 0,
BPP = bpp
BPP = bpp,
ImageLength = size,
HeaderLength = header_size + 14,
};
}
}