Disable transform layer for images where it is not needed (to speed-u…

…p image processing) (#7449)

src/engine/h2d_file.cpp

@@ -191,6 +191,7 @@ namespace fheroes2
         const size_t size = static_cast<size_t>( width * height );
         image.resize( width, height );
         memcpy( image.image(), data.data() + 4 + 4 + 4 + 4, size );
+        // TODO: Store in h2d images the 'isSingleLayer' state to disable and skip transform layer for such images.
         memcpy( image.transform(), data.data() + 4 + 4 + 4 + 4 + size, size );
 
         image.setPosition( x, y );

src/engine/image_tool.cpp

@@ -339,6 +339,9 @@ namespace fheroes2
 
         const uint8_t * dataEnd = data + sizeData;
 
+        // The need for a transform layer can only be determined during ICN decoding.
+        bool noTransformLayer = true;
+
         while ( true ) {
             if ( 0 == *data ) { // 0x00 - end of row
                 imageData += width;
@@ -347,6 +350,8 @@ namespace fheroes2
                 ++data;
             }
             else if ( 0x80 > *data ) { // 0x01-0x7F - repeat a pixel N times
+                noTransformLayer = noTransformLayer && ( static_cast<int32_t>( posX ) >= width );
+
                 const uint8_t pixelCount = *data;
                 ++data;
 
@@ -362,13 +367,19 @@ namespace fheroes2
                 posX += pixelCount;
             }
             else if ( 0x80 == *data ) { // 0x80 - end of image
+                noTransformLayer = noTransformLayer && ( static_cast<int32_t>( posX ) >= width );
+
                 break;
             }
             else if ( 0xC0 > *data ) { // 0xBF - empty (transparent) pixels
+                noTransformLayer = false;
+
                 posX += *data - 0x80;
                 ++data;
             }
             else if ( 0xC0 == *data ) { // 0xC0 - transform layer
+                noTransformLayer = false;
+
                 ++data;
 
                 const uint8_t transformValue = *data;
@@ -414,6 +425,10 @@ namespace fheroes2
             }
         }
 
+        if ( noTransformLayer ) {
+            sprite._disableTransformLayer();
+        }
+
         return sprite;
     }