Add a hook to allow continuously using items through stack changes (#4834)

src/main/java/net/minecraftforge/common/ForgeHooks.java

@@ -183,6 +183,15 @@ public class ForgeHooks
         return entry.getStack(rand, fortune);
     }
 
+    public static boolean canContinueUsing(@Nonnull ItemStack from, @Nonnull ItemStack to)
+    {
+        if (!from.isEmpty() && !to.isEmpty())
+        {
+            return from.getItem().canContinueUsing(from, to);
+        }
+        return false;
+    }
+
     public static boolean canHarvestBlock(@Nonnull IBlockState state, @Nonnull EntityPlayer player, @Nonnull IBlockReader world, @Nonnull BlockPos pos)
     {
         //state = state.getActualState(world, pos);

src/main/java/net/minecraftforge/common/extensions/IForgeItem.java

@@ -647,6 +647,20 @@ public interface IForgeItem
                 && (newStack.isDamageable() || newStack.getDamage() == oldStack.getDamage()));
     }
 
+    /**
+     * Called while an item is in 'active' use to determine if usage should
+     * continue. Allows items to continue being used while sustaining damage, for
+     * example.
+     *
+     * @param oldStack the previous 'active' stack
+     * @param newStack the stack currently in the active hand
+     * @return true to set the new stack to active and continue using it
+     */
+    default boolean canContinueUsing(ItemStack oldStack, ItemStack newStack)
+    {
+        return oldStack.equals(newStack);
+    }
+
     /**
      * Called to get the Mod ID of the mod that *created* the ItemStack, instead of
      * the real Mod ID that *registered* it.