core.fmt.targa¶

TGA (Truevision TARGA) image file parser.

Overview¶

core.fmt.targa parses a 32-bit uncompressed TGA image from a raw byte buffer and produces a TTexture pixel array in BGRA order. Only type-2 (uncompressed true-colour) images with a 32-bit pixel depth are supported. The parser handles both top-to-bottom and bottom-to-top vertical orientation, determined by bit 5 of the TGA image descriptor byte.

The primary consumer of this unit is core.panic, which uses it to decode the embedded teapot image displayed on the kernel panic screen.

Dependencies¶

memory.heap — kalloc (via core.gfx.texture)
core.gfx.texture — newTexture, PTexture

Types¶

TTARGAColor / PTARGAColor¶

TTARGAColor = packed record
    b, g, r, a: uint8;
end;

A single 32-bit pixel in the TGA source format (BGRA byte order).

TTARGAHeader / PTARGAHeader¶

TTARGAHeader = packed record
    IDLength        : uint8;
    ColorMapType    : uint8;
    ImageType       : uint8;
    ColorMapOrigin  : uint16;
    ColorMapLength  : uint16;
    ColorMapDepth   : uint8;
    XOrigin         : uint16;
    YOrigin         : uint16;
    Width           : uint16;
    Height          : uint16;
    PixelDepth      : uint8;
    ImageDescriptor : uint8;
end;

The 18-byte TGA file header. ImageType must be 2 (uncompressed true-colour). PixelDepth must be 32. Pixel data begins immediately after the header plus any optional ID field (IDLength bytes).

Functions and Procedures¶

Parse¶

function Parse(buffer : puint8; len : uint32) : PTexture;

Parses a TGA image from len bytes at buffer. Returns a heap-allocated TTexture containing the decoded pixel data in BGRA order, or nil if: - len is smaller than the header size, - ImageType is not 2, or - PixelDepth is not 32.

Vertical orientation is determined by bit 5 of ImageDescriptor: 1 = top-to-bottom (stored as-is); 0 = bottom-to-top (rows are flipped during copy).

Notes¶

Only 32-bit uncompressed TGA files are supported. Run-length encoded (type 10), colour-mapped (type 1), or other image types are rejected.

The output texture pixel layout mirrors the TGA source: BGRA byte order matching TRGB32 (B at the lowest address, then G, R, A). Callers consuming the texture for LVGL display must ensure the LVGL colour format matches this layout, or convert appropriately.