LibGfx: Add TGA Loader :^)

This patch adds a basic TGA Loader. Currently it can only handle
uncompressed files with a bit depth of 24 or 32 bits per pixel.

1 files changed, 263 insertions, 0 deletions

diff --git a/Userland/Libraries/LibGfx/TGALoader.cpp b/Userland/Libraries/LibGfx/TGALoader.cpp
new file mode 100644
index 0000000000..db6b1851b8
--- /dev/null
+++ b/Userland/Libraries/LibGfx/TGALoader.cpp
@@ -0,0 +1,263 @@
+/*
+ * Copyright (c) 2022, Tom Needham <06needhamt@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Span.h>
+#include <AK/StdLibExtraDetails.h>
+#include <AK/String.h>
+#include <LibGfx/TGALoader.h>
+
+namespace Gfx {
+
+enum TGADataType : u8 {
+    None = 0,
+    UncompressedColorMapped = 1,
+    UncompressedRGB = 2,
+    UncompressedBlackAndWhite = 3,
+    RunLengthEncodedColorMapped = 9,
+    RunLengthEncodedRGB = 10,
+    CompressedBlackAndWhite = 11,
+    CompressedColorMapped = 32,
+    CompressedColorMappedFourPass = 33
+};
+
+struct [[gnu::packed]] TGAHeader {
+    u8 id_length;
+    u8 color_map_type;
+    TGADataType data_type_code;
+    i16 color_map_origin;
+    i16 color_map_length;
+    u8 color_map_depth;
+    i16 x_origin;
+    i16 y_origin;
+    u16 width;
+    u16 height;
+    u8 bits_per_pixel;
+    u8 image_descriptor;
+};
+
+static_assert(sizeof(TGAHeader) == 18);
+
+union [[gnu::packed]] TGAPixel {
+    struct TGAColor {
+        u8 blue;
+        u8 green;
+        u8 red;
+        u8 alpha;
+    } components;
+
+    u32 data;
+};
+
+static_assert(AssertSize<TGAPixel, 4>());
+
+class TGAReader {
+public:
+    TGAReader(ReadonlyBytes data)
+        : m_data(move(data))
+    {
+    }
+
+    ALWAYS_INLINE u8 read_u8()
+    {
+        u8 value = m_data[m_index];
+        m_index++;
+        return value;
+    }
+
+    ALWAYS_INLINE i8 read_i8()
+    {
+        return static_cast<i8>(read_u8());
+    }
+
+    ALWAYS_INLINE u16 read_u16()
+    {
+        return read_u8() | read_u8() << 8;
+    }
+
+    ALWAYS_INLINE i16 read_i16()
+    {
+        return read_i8() | read_i8() << 8;
+    }
+
+    ALWAYS_INLINE u32 read_u32()
+    {
+        return read_u16() | read_u16() << 16;
+    }
+
+    ALWAYS_INLINE i32 read_i32()
+    {
+        return read_i16() | read_i16() << 16;
+    }
+
+    ALWAYS_INLINE TGAPixel read_pixel(u8 bits_per_pixel)
+    {
+        auto pixel = TGAPixel();
+
+        switch (bits_per_pixel) {
+        case 24:
+            pixel.components.blue = read_u8();
+            pixel.components.green = read_u8();
+            pixel.components.red = read_u8();
+            pixel.components.alpha = 0xFF;
+            return pixel;
+
+        case 32:
+            pixel.components.blue = read_u8();
+            pixel.components.green = read_u8();
+            pixel.components.red = read_u8();
+            pixel.components.alpha = read_u8();
+            return pixel;
+
+        default:
+            VERIFY_NOT_REACHED();
+        }
+    }
+
+    size_t index() const
+    {
+        return m_index;
+    }
+
+    ReadonlyBytes data() const
+    {
+        return m_data;
+    }
+
+private:
+    ReadonlyBytes m_data;
+    size_t m_index { 0 };
+};
+
+struct TGALoadingContext {
+    TGAHeader header;
+    ReadonlyBytes bytes;
+    size_t file_size;
+    OwnPtr<TGAReader> reader = { nullptr };
+    RefPtr<Gfx::Bitmap> bitmap;
+};
+
+TGAImageDecoderPlugin::TGAImageDecoderPlugin(u8 const* file_data, size_t file_size)
+{
+    m_context = make<TGALoadingContext>();
+    m_context->bytes = ReadonlyBytes(file_data, file_size);
+    m_context->file_size = move(file_size);
+    m_context->reader = make<TGAReader>(m_context->bytes);
+}
+
+TGAImageDecoderPlugin::~TGAImageDecoderPlugin() = default;
+
+IntSize TGAImageDecoderPlugin::size()
+{
+    return IntSize { m_context->header.width, m_context->header.height };
+}
+
+void TGAImageDecoderPlugin::set_volatile()
+{
+    if (m_context->bitmap)
+        m_context->bitmap->set_volatile();
+}
+
+bool TGAImageDecoderPlugin::set_nonvolatile(bool& was_purged)
+{
+    if (!m_context->bitmap)
+        return false;
+    return m_context->bitmap->set_nonvolatile(was_purged);
+}
+
+bool TGAImageDecoderPlugin::decode_tga_header()
+{
+    auto& reader = m_context->reader;
+    m_context->header = TGAHeader();
+    m_context->header.id_length = reader->read_u8();
+    m_context->header.color_map_type = reader->read_u8();
+    m_context->header.data_type_code = static_cast<TGADataType>(reader->read_u8());
+    m_context->header.color_map_origin = reader->read_i16();
+    m_context->header.color_map_length = reader->read_i16();
+    m_context->header.color_map_depth = reader->read_u8();
+    m_context->header.x_origin = reader->read_i16();
+    m_context->header.y_origin = reader->read_i16();
+    m_context->header.width = reader->read_u16();
+    m_context->header.height = reader->read_u16();
+    m_context->header.bits_per_pixel = reader->read_u8();
+    m_context->header.image_descriptor = reader->read_u8();
+
+    auto bytes_remaining = reader->data().size() - reader->index();
+
+    if (bytes_remaining < (m_context->header.width * m_context->header.height * (m_context->header.bits_per_pixel / 8)))
+        return false;
+
+    if (m_context->header.bits_per_pixel < 8 || m_context->header.bits_per_pixel > 32)
+        return false;
+
+    return true;
+}
+
+bool TGAImageDecoderPlugin::sniff()
+{
+    return decode_tga_header();
+}
+
+bool TGAImageDecoderPlugin::is_animated()
+{
+    return false;
+}
+
+size_t TGAImageDecoderPlugin::loop_count()
+{
+    return 0;
+}
+
+size_t TGAImageDecoderPlugin::frame_count()
+{
+    return 1;
+}
+
+ErrorOr<ImageFrameDescriptor> TGAImageDecoderPlugin::frame(size_t index)
+{
+    auto bits_per_pixel = m_context->header.bits_per_pixel;
+    auto color_map = m_context->header.color_map_type;
+    auto data_type = m_context->header.data_type_code;
+    auto width = m_context->header.width;
+    auto height = m_context->header.height;
+
+    if (index != 0)
+        return Error::from_string_literal("TGAImageDecoderPlugin: frame index must be 0");
+
+    if (color_map > 1)
+        return Error::from_string_literal("TGAImageDecoderPlugin: Invalid color map type");
+
+    switch (bits_per_pixel) {
+    case 24:
+        m_context->bitmap = TRY(Bitmap::try_create(BitmapFormat::BGRx8888, { m_context->header.width, m_context->header.height }));
+        break;
+
+    case 32:
+        m_context->bitmap = TRY(Bitmap::try_create(BitmapFormat::BGRA8888, { m_context->header.width, m_context->header.height }));
+        break;
+
+    default:
+        // FIXME: Implement other TGA bit depths
+        return Error::from_string_literal("TGAImageDecoderPlugin: Can only handle 24 and 32 bits per pixel");
+    }
+    switch (data_type) {
+    case TGADataType::UncompressedRGB: {
+        for (int row = 0; row < height; ++row) {
+            for (int col = 0; col < width; ++col) {
+                auto pixel = m_context->reader->read_pixel(bits_per_pixel);
+                m_context->bitmap->scanline(row)[col] = pixel.data;
+            }
+        }
+        break;
+    }
+    default:
+        // FIXME: Implement other TGA data types
+        return Error::from_string_literal("TGAImageDecoderPlugin: Can currently only handle the UncompressedRGB data type");
+    }
+
+    VERIFY(m_context->bitmap);
+    return ImageFrameDescriptor { m_context->bitmap, 0 };
+}
+}