mpv/libvo/bitmap_packer.h

#ifndef MPLAYER_PACK_RECTANGLES_H
#define MPLAYER_PACK_RECTANGLES_H

struct pos {
    int x;
    int y;
};

struct bitmap_packer {
    int w;
    int h;
    int w_max;
    int h_max;
    int padding;
    int count;
    struct pos *in;
    struct pos *result;
    int used_width;
    int used_height;

    // internal
    int *scratch;
    int asize;
};

struct ass_image;
struct sub_bitmaps;

// Clear all internal state. Leave the following fields: w_max, h_max
void packer_reset(struct bitmap_packer *packer);

// Get the bounding box used for bitmap data (including padding).
// The bounding box doesn't exceed (0,0)-(packer->w,packer->h).
void packer_get_bb(struct bitmap_packer *packer, struct pos out_bb[2]);

/* Reallocate packer->in for at least to desired number of items.
 * Also sets packer->count to the same value.
 */
void packer_set_size(struct bitmap_packer *packer, int size);

/* To use this, set packer->count to number of rectangles, w_max and h_max
 * to maximum output rectangle size, and w and h to start size (may be 0).
 * Write input sizes in packer->in.
 * Resulting packing will be written in packer->result.
 * w and h will be increased if necessary for successful packing.
 * There is a strong guarantee that w and h will be powers of 2 (or set to 0).
 * Return value is -1 if packing failed because w and h were set to max
 * values but that wasn't enough, 1 if w or h was increased, and 0 otherwise.
 */
int packer_pack(struct bitmap_packer *packer);

/* Like above, but packer->count will be automatically set and
 * packer->in will be reallocated if needed and filled from the
 * given image list.
 */
int packer_pack_from_subbitmaps(struct bitmap_packer *packer,
                                struct sub_bitmaps *b);

// Copy the (already packed) sub-bitmaps from b to the image in data.
// data must point to an image that is at least (packer->w, packer->h) big.
// The image has the given stride (bytes between (x, y) to (x, y + 1)), and the
// pixel format used by both the sub-bitmaps and the image uses pixel_stride
// bytes per pixel (bytes between (x, y) to (x + 1, y)).
// If packer->padding is set, the padding borders are cleared with 0.
void packer_copy_subbitmaps(struct bitmap_packer *packer, struct sub_bitmaps *b,
                            void *data, int pixel_stride, int stride);

#endif