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b193fe658d
We use instances of `Gfx::Bitmap` to move pixel data all the way from raw image bytes up to the Skia renderer. A vital piece of information for correct blending of bitmaps is the alpha type, i.e. are we dealing with premultiplied or unpremultiplied color values? Premultiplied means that the RGB colors have been multiplied with the associated alpha value, i.e. RGB(255, 255, 255) with an alpha of 2% is stored as RGBA(5, 5, 5, 2%). Unpremultiplied means that the original RGB colors are stored, regardless of the alpha value. I.e. RGB(255, 255, 255) with an alpha of 2% is stored as RGBA(255, 255, 255, 2%). It is important to know how the color data is stored in a `Gfx::Bitmap`, because correct blending depends on knowing the alpha type: premultiplied blending uses `S + (1 - A) * D`, while unpremultiplied blending uses `A * S + (1 - A) * D`. This adds the alpha type information to `Gfx::Bitmap` across the board. It isn't used anywhere yet.
65 lines
2.1 KiB
C++
65 lines
2.1 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibGfx/Bitmap.h>
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#include <LibGfx/ShareableBitmap.h>
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#include <LibGfx/Size.h>
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#include <LibIPC/Decoder.h>
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#include <LibIPC/Encoder.h>
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#include <LibIPC/File.h>
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namespace Gfx {
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ShareableBitmap::ShareableBitmap(NonnullRefPtr<Bitmap> bitmap, Tag)
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: m_bitmap(move(bitmap))
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{
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}
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}
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namespace IPC {
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template<>
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ErrorOr<void> encode(Encoder& encoder, Gfx::ShareableBitmap const& shareable_bitmap)
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{
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TRY(encoder.encode(shareable_bitmap.is_valid()));
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if (!shareable_bitmap.is_valid())
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return {};
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auto& bitmap = *shareable_bitmap.bitmap();
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TRY(encoder.encode(TRY(IPC::File::clone_fd(bitmap.anonymous_buffer().fd()))));
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TRY(encoder.encode(bitmap.size()));
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TRY(encoder.encode(static_cast<u32>(bitmap.format())));
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TRY(encoder.encode(static_cast<u32>(bitmap.alpha_type())));
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return {};
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}
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template<>
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ErrorOr<Gfx::ShareableBitmap> decode(Decoder& decoder)
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{
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if (auto valid = TRY(decoder.decode<bool>()); !valid)
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return Gfx::ShareableBitmap {};
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auto anon_file = TRY(decoder.decode<IPC::File>());
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auto size = TRY(decoder.decode<Gfx::IntSize>());
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auto raw_bitmap_format = TRY(decoder.decode<u32>());
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if (!Gfx::is_valid_bitmap_format(raw_bitmap_format))
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return Error::from_string_literal("IPC: Invalid Gfx::ShareableBitmap format");
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auto bitmap_format = static_cast<Gfx::BitmapFormat>(raw_bitmap_format);
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auto raw_alpha_type = TRY(decoder.decode<u32>());
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if (!Gfx::is_valid_alpha_type(raw_alpha_type))
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return Error::from_string_literal("IPC: Invalid Gfx::ShareableBitmap alpha type");
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auto alpha_type = static_cast<Gfx::AlphaType>(raw_alpha_type);
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auto buffer = TRY(Core::AnonymousBuffer::create_from_anon_fd(anon_file.take_fd(), Gfx::Bitmap::size_in_bytes(Gfx::Bitmap::minimum_pitch(size.width(), bitmap_format), size.height())));
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auto bitmap = TRY(Gfx::Bitmap::create_with_anonymous_buffer(bitmap_format, alpha_type, move(buffer), size));
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return Gfx::ShareableBitmap { move(bitmap), Gfx::ShareableBitmap::ConstructWithKnownGoodBitmap };
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}
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}
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