nsgif__parse_image_descriptor()

static nsgif_error fl::third_party::nsgif__parse_image_descriptor ( struct nsgif * gif, struct nsgif_frame * frame, const fl::u8 ** pos, bool decode )

static

Parse a GIF Image Descriptor.

The format is:

+0 CHAR Image Separator (0x2c) +1 SHORT Image Left Position +3 SHORT Image Top Position +5 SHORT Width +7 SHORT Height +9 CHAR Packed Fields 1BIT Local Colour Table Flag 1BIT Interlace Flag 1BIT Sort Flag 2BITS Reserved 3BITS Size of Local Colour Table

Parameters

[in]	gif	The gif object we're decoding.
[in]	frame	The frame to parse an image descriptor for.
[in]	pos	Current position in data, updated on exit.
[in]	decode	Whether to decode the image descriptor.

Returns

NSGIF_OK on success, appropriate error otherwise.

Definition at line 1015 of file gif.cpp.hpp.

{
    const fl::u8 *data = *pos;
    fl::size len = gif->buf + gif->buf_len - data;
    enum {
        NSGIF_IMAGE_DESCRIPTOR_LEN = 10u,
        NSGIF_IMAGE_SEPARATOR      = 0x2Cu,
        NSGIF_MASK_INTERLACE       = 0x40u,
    };
 
    FL_ASSERT(gif != nullptr, "GIF object required");
    FL_ASSERT(frame != nullptr, "Frame object required");
 
    if (len < NSGIF_IMAGE_DESCRIPTOR_LEN) {
        return NSGIF_ERR_END_OF_DATA;
    }
 
    if (decode) {
        fl::u32 x, y, w, h;
 
        if (data[0] != NSGIF_IMAGE_SEPARATOR) {
            return NSGIF_ERR_DATA_FRAME;
        }
 
        x = data[1] | (data[2] << 8);
        y = data[3] | (data[4] << 8);
        w = data[5] | (data[6] << 8);
        h = data[7] | (data[8] << 8);
        frame->flags = data[9];
 
        frame->info.rect.x0 = x;
        frame->info.rect.y0 = y;
        frame->info.rect.x1 = x + w;
        frame->info.rect.y1 = y + h;
 
        frame->info.interlaced = frame->flags & NSGIF_MASK_INTERLACE;
 
        /* Allow first frame to grow image dimensions. */
        if (gif->info.frame_count == 0) {
            if (x + w > gif->info.width) {
                gif->info.width = x + w;
            }
            if (y + h > gif->info.height) {
                gif->info.height = y + h;
            }
        }
    }
 
    *pos += NSGIF_IMAGE_DESCRIPTOR_LEN;
    return NSGIF_OK;
}

References FL_ASSERT, FL_NOEXCEPT, NSGIF_ERR_DATA_FRAME, NSGIF_ERR_END_OF_DATA, NSGIF_OK, pos, fl::x, and fl::y.

Referenced by nsgif__process_frame().

Here is the caller graph for this function: