Rewrite thumbnail creation

src/main/java/com/replaymod/replay/NoGuiScreenshot.java

@@ -0,0 +1,110 @@
+package com.replaymod.replay;
+
+import com.google.common.io.Files;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.ListenableFutureTask;
+import com.google.common.util.concurrent.SettableFuture;
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.GlStateManager;
+import net.minecraft.util.ScreenShotHelper;
+import org.apache.commons.io.FileUtils;
+
+import javax.imageio.ImageIO;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.util.Queue;
+import java.util.concurrent.FutureTask;
+
+@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
+@Getter
+public class NoGuiScreenshot {
+    private final BufferedImage image;
+    private final int width;
+    private final int height;
+
+    public static ListenableFuture<NoGuiScreenshot> take(final Minecraft mc, final int width, final int height) {
+        final SettableFuture<NoGuiScreenshot> future = SettableFuture.create();
+        Runnable runnable = new Runnable() {
+            @Override
+            public void run() {
+                if (future.isCancelled()) {
+                    return;
+                }
+
+                final boolean guiHidden = mc.gameSettings.hideGUI;
+                try {
+                    mc.gameSettings.hideGUI = true;
+
+                    // Render frame without GUI
+                    GlStateManager.pushMatrix();
+                    GlStateManager.clear(16640);
+                    mc.getFramebuffer().bindFramebuffer(true);
+                    GlStateManager.enableTexture2D();
+
+                    mc.entityRenderer.updateCameraAndRender(mc.timer.renderPartialTicks);
+
+                    mc.getFramebuffer().unbindFramebuffer();
+                    GlStateManager.popMatrix();
+                    GlStateManager.pushMatrix();
+                    mc.getFramebuffer().framebufferRender(mc.displayWidth, mc.displayHeight);
+                    GlStateManager.popMatrix();
+                } catch (Throwable t) {
+                    future.setException(t);
+                    return;
+                } finally {
+                    // Reset GUI settings
+                    mc.gameSettings.hideGUI = guiHidden;
+                }
+
+                // The frame without GUI has been rendered
+                // Read it, create the screenshot and finish the future
+                // We're using Minecraft's ScreenShotHelper even though it writes the screenshot to
+                // disk for better maintainability
+                File tmpFolder = Files.createTempDir();
+                try {
+                    ScreenShotHelper.saveScreenshot(tmpFolder, "tmp", mc.displayWidth, mc.displayHeight, mc.getFramebuffer());
+                    File screenshotFile = new File(tmpFolder, "screenshots/tmp");
+                    BufferedImage image = ImageIO.read(screenshotFile);
+                    int imageWidth = image.getWidth();
+                    int imageHeight = image.getHeight();
+
+                    // First scale
+                    float scaleFactor = Math.max((float) width / imageWidth, (float) height / imageHeight);
+                    int scaledWidth = (int) (imageWidth * scaleFactor);
+                    int scaledHeight = (int) (imageHeight * scaleFactor);
+                    Image scaledImage = image.getScaledInstance(scaledWidth, scaledHeight, Image.SCALE_SMOOTH);
+
+                    // Then crop
+                    int resultX = (scaledWidth - width) / 2;
+                    int resultY = (scaledHeight - height) / 2;
+                    BufferedImage resultImage = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
+                    Graphics2D graphics = resultImage.createGraphics();
+                    graphics.drawImage(scaledImage, 0, 0, width, height,
+                            resultX, resultY, resultX + width, resultY + height, null);
+                    graphics.dispose();
+
+                    // Finish
+                    future.set(new NoGuiScreenshot(resultImage, width, height));
+                } catch (Throwable t) {
+                    future.setException(t);
+                } finally {
+                    FileUtils.deleteQuietly(tmpFolder);
+                }
+            }
+        };
+
+        // Make sure we are not somewhere in the middle of the rendering process but always at the beginning
+        // of the game loop. We cannot use the addScheduledTask method as it'll run the task if called
+        // from the minecraft thread which is exactly what we want to avoid.
+        synchronized (mc.scheduledTasks) {
+            @SuppressWarnings("unchecked")
+            Queue<FutureTask> queue = mc.scheduledTasks;
+            queue.add(ListenableFutureTask.create(runnable, null));
+        }
+        return future;
+    }
+}