Commit b575ecf8 for libheif

commit b575ecf8b8e4422d0ba8d0b0bbc6f35d778b3a5d
Author: Dirk Farin <dirk.farin@gmail.com>
Date:   Tue Feb 24 16:01:48 2026 +0100

    fix encoding single-tile grids and decoding individual tiles with new size check

diff --git a/examples/heif_enc.cc b/examples/heif_enc.cc
index 533540d0..16ff8d6b 100644
--- a/examples/heif_enc.cc
+++ b/examples/heif_enc.cc
@@ -1170,22 +1170,13 @@ heif_image_handle* encode_tiled(heif_context* ctx, heif_encoder* encoder, heif_e
   std::cout << "encoding tiled image, tile size: " << tiling.tile_width << "x" << tiling.tile_height
             << " image size: " << tiling.image_width << "x" << tiling.image_height << "\n";

-  int tile_width = 0, tile_height = 0;
+  int tile_width = tiling.tile_width;
+  int tile_height = tiling.tile_height;

   for (uint32_t ty = 0; ty < tile_generator->nRows(); ty++)
     for (uint32_t tx = 0; tx < tile_generator->nColumns(); tx++) {
       InputImage input_image = tile_generator->get_image(tx,ty, output_bit_depth);

-      if (tile_width == 0) {
-        tile_width = heif_image_get_primary_width(input_image.image.get());
-        tile_height = heif_image_get_primary_height(input_image.image.get());
-
-        if (tile_width <= 0 || tile_height <= 0) {
-          std::cerr << "Could not read input image size correctly\n";
-          return nullptr;
-        }
-      }
-
       heif_error error;
       error = heif_image_extend_to_size_fill_with_zero(input_image.image.get(), tile_width, tile_height);
       if (error.code) {
diff --git a/libheif/context.cc b/libheif/context.cc
index e12c43be..fdc7fe7b 100644
--- a/libheif/context.cc
+++ b/libheif/context.cc
@@ -1342,7 +1342,7 @@ Result<std::shared_ptr<HeifPixelImage>> HeifContext::decode_image(heif_item_id I

   // --- check that the decoded image has the claimed size (only check if transformations are applied)

-  if (!options.ignore_transformations) {
+  if (!options.ignore_transformations && !decode_only_tile) {
     uint32_t primary_component = img->get_primary_component();

     if (imgitem->get_width() != img->get_width(primary_component) ||