Function avifDecoderDataAllocateImagePlanes

src/read.c:1733–1819

Allocates the dstImage. Also verifies some spec compliance rules for grids, if relevant.

// Allocates the dstImage. Also verifies some spec compliance rules for grids, if relevant.
static avifResult avifDecoderDataAllocateImagePlanes(const avifDecoderData * data, const avifTileInfo * info, avifImage * dstImage, avifBool * cicpSet)
{
    const avifTile * tile = &data->tiles.tile[info->firstTileIndex];
    uint32_t dstWidth;
    uint32_t dstHeight;

    if (info->grid.rows > 0 && info->grid.columns > 0) {
        const avifImageGrid * grid = &info->grid;
        // Validate grid image size and tile size.
        //
        // HEIF (ISO/IEC 23008-12:2017), Section 6.6.2.3.1:
        //   The tiled input images shall completely "cover" the reconstructed image grid canvas, ...
        if ((((uint64_t)tile->image->width * grid->columns) < grid->outputWidth) ||
            (((uint64_t)tile->image->height * grid->rows) < grid->outputHeight)) {
            avifDiagnosticsPrintf(data->diag,
                                  "Grid image tiles do not completely cover the image (HEIF (ISO/IEC 23008-12:2017), Section 6.6.2.3.1)");
            return AVIF_RESULT_INVALID_IMAGE_GRID;
        }
        // Tiles in the rightmost column and bottommost row must overlap the reconstructed image grid canvas. See MIAF (ISO/IEC 23000-22:2019), Section 7.3.11.4.2, Figure 2.
        if ((((uint64_t)tile->image->width * (grid->columns - 1)) >= grid->outputWidth) ||
            (((uint64_t)tile->image->height * (grid->rows - 1)) >= grid->outputHeight)) {
            avifDiagnosticsPrintf(data->diag,
                                  "Grid image tiles in the rightmost column and bottommost row do not overlap the reconstructed image grid canvas. See MIAF (ISO/IEC 23000-22:2019), Section 7.3.11.4.2, Figure 2");
            return AVIF_RESULT_INVALID_IMAGE_GRID;
        }
        if (!avifAreGridDimensionsValid(tile->image->yuvFormat,
                                        grid->outputWidth,
                                        grid->outputHeight,
                                        tile->image->width,
                                        tile->image->height,
                                        data->diag)) {
            return AVIF_RESULT_INVALID_IMAGE_GRID;
        }
        dstWidth = grid->outputWidth;
        dstHeight = grid->outputHeight;
    } else {
        // Only one tile. Width and height are inherited from the 'ispe' property of the corresponding avifDecoderItem.
        dstWidth = tile->width;
        dstHeight = tile->height;
    }

    const avifBool alpha = avifIsAlpha(tile->input->itemCategory);
    if (alpha) {
        // An alpha tile does not contain any YUV pixels.
        AVIF_ASSERT_OR_RETURN(tile->image->yuvFormat == AVIF_PIXEL_FORMAT_NONE);
    }

    const uint32_t dstDepth = tile->image->depth;

    // Lazily populate dstImage with the new frame's properties.
    const avifBool dimsOrDepthIsDifferent = (dstImage->width != dstWidth) || (dstImage->height != dstHeight) ||
                                            (dstImage->depth != dstDepth);
    const avifBool yuvFormatIsDifferent = !alpha && (dstImage->yuvFormat != tile->image->yuvFormat);
    if (dimsOrDepthIsDifferent || yuvFormatIsDifferent) {
        if (alpha) {
            // Alpha doesn't match size, just bail out
            avifDiagnosticsPrintf(data->diag, "Alpha plane dimensions do not match color plane dimensions");
            return AVIF_RESULT_INVALID_IMAGE_GRID;