Fixed preview state file updating too early, and reuse file handle for writing state changes

src/main/java/me/voidxwalker/worldpreview/StateOutputHelper.java

@@ -3,8 +3,8 @@
 import org.apache.logging.log4j.Level;
 
 import java.io.IOException;
+import java.io.RandomAccessFile;
 import java.nio.charset.StandardCharsets;
-import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.concurrent.ExecutorService;
@@ -21,6 +21,8 @@ public final class StateOutputHelper {
     public static boolean titleHasEverLoaded = false;
     private static String lastOutput = "";
 
+    private static RandomAccessFile stateFile;
+
 
     private StateOutputHelper() {
     }
@@ -44,8 +46,12 @@ public static void outputState(String string) {
 
     private static void outputStateInternal(String string) {
         try {
-            // Java 11+ method
-            Files.write(OUT_PATH, string.getBytes(StandardCharsets.UTF_8));
+            if(stateFile == null){ // opening file only once is better for performance
+                stateFile = new RandomAccessFile(OUT_PATH.toString(), "rw");
+            }
+            stateFile.setLength(0); // clear existing file contents
+            stateFile.seek(0); // move pointer back to start of file
+            stateFile.write(string.getBytes(StandardCharsets.UTF_8));
             WorldPreview.log(Level.INFO, "WorldPreview State: " + string);
         } catch (IOException ignored) {
             WorldPreview.log(Level.ERROR, "Failed to write state output!");

src/main/java/me/voidxwalker/worldpreview/WorldPreview.java

@@ -22,6 +22,7 @@ public class WorldPreview  implements ClientModInitializer {
    public static ClientPlayerEntity player;
    public static ClientWorld clientWord;
    public static boolean inPreview;
+   public static boolean renderingPreview;
    public static BlockPos spawnPos;
    public static int kill=0;
    public static int playerSpawn;

src/main/java/me/voidxwalker/worldpreview/mixin/client/MinecraftClientMixin.java

@@ -144,4 +144,14 @@ private void worldpreview_outputInWorldState(CallbackInfo info) {
             StateOutputHelper.outputState("inworld,gamescreenopen");
         }
     }
+
+    @Inject(method = "render", at = @At(value = "INVOKE", target="Lnet/minecraft/client/util/Window;swapBuffers()V", shift = At.Shift.AFTER))
+    private void worldpreview_actuallyInPreview(boolean tick, CallbackInfo ci) {
+        if (WorldPreview.inPreview && !WorldPreview.renderingPreview) {
+            WorldPreview.renderingPreview = true;
+            StateOutputHelper.outputState("previewing," + StateOutputHelper.loadingProgress);
+            WorldPreview.log(Level.INFO, "Starting Preview at (" + WorldPreview.player.getX() + ", " + (double) Math.floor(WorldPreview.player.getY()) + ", " + WorldPreview.player.getZ() + ")");
+        }
+    }
+
 }

src/main/java/me/voidxwalker/worldpreview/mixin/client/WorldGenerationProgressLoggerMixin.java

@@ -18,7 +18,7 @@ public abstract class WorldGenerationProgressLoggerMixin {
     private void worldpreview_outputGenerationState(ChunkPos pos, ChunkStatus status, CallbackInfo info) {
         // Using the getProgressPercentage to recalculate is slightly unoptimized but prevents needing to do locals capture, making it easier to port this mixin.
         StateOutputHelper.loadingProgress = MathHelper.clamp(getProgressPercentage(), 0, 100);
-        StateOutputHelper.outputState((WorldPreview.inPreview ? "previewing," : "generating,") + StateOutputHelper.loadingProgress);
+        StateOutputHelper.outputState((WorldPreview.renderingPreview ? "previewing," : "generating,") + StateOutputHelper.loadingProgress);
     }
 
     @Shadow

src/main/java/me/voidxwalker/worldpreview/mixin/client/render/LevelLoadingScreenMixin.java

@@ -89,8 +89,6 @@ public void worldpreview_render(MatrixStack matrices, int mouseX, int mouseY, fl
                     WorldPreview.camera.update(WorldPreview.world, WorldPreview.player, this.client.options.perspective > 0, this.client.options.perspective == 2, 0.2F);
                     WorldPreview.player.refreshPositionAndAngles(WorldPreview.player.getX(), WorldPreview.player.getY() - 1.5, WorldPreview.player.getZ(), 0.0F, 0.0F);
                     WorldPreview.inPreview=true;
-                    StateOutputHelper.outputState("previewing," + StateOutputHelper.loadingProgress);
-                    WorldPreview.log(Level.INFO,"Starting Preview at ("+ WorldPreview.player.getX() + ", "+(double)Math.floor(WorldPreview.player.getY())+ ", "+ WorldPreview.player.getZ()+")");
                 }
                 MatrixStack matrixStack = new MatrixStack();
                 matrixStack.peek().getModel().multiply(this.worldpreview_getBasicProjectionMatrix());

src/main/java/me/voidxwalker/worldpreview/mixin/server/MinecraftServerMixin.java

@@ -137,6 +137,7 @@ public void worldpreview_kill(CallbackInfo ci){
     @Inject(method="runServer",at=@At(value="INVOKE",target="Lnet/minecraft/server/MinecraftServer;setupServer()Z",shift = At.Shift.AFTER), cancellable = true)
     public void worldpreview_kill2(CallbackInfo ci){
         WorldPreview.inPreview=false;
+        WorldPreview.renderingPreview=false;
         LockSupport.unpark(((MinecraftClientMixin)MinecraftClient.getInstance()).invokeGetThread());
         if(WorldPreview.kill==1){
             ci.cancel();