Make screenshots with F12

src/main/scala/ocelot/desktop/graphics/Graphics.scala

@@ -8,8 +8,10 @@ import ocelot.desktop.graphics.mesh.{Mesh2D, MeshInstance2D, MeshVertex2D}
 import ocelot.desktop.graphics.render.InstanceRenderer
 import ocelot.desktop.ui.UiHandler
 import ocelot.desktop.util.{Font, Logging, Resource, Spritesheet}
+import org.lwjgl.BufferUtils
 import org.lwjgl.opengl.{ARBFramebufferObject, GL11, GL21, GL30}
 
+import java.awt.image.BufferedImage
 import java.nio.ByteBuffer
 import scala.collection.mutable
 import scala.util.control.Breaks._
@@ -392,6 +394,27 @@ class Graphics(private var width: Int, private var height: Int, private var scal
     line(start.x, start.y, end.x, end.y, thickness, color)
   }
 
+  def screenshot(): BufferedImage = {
+    val buffer = BufferUtils.createByteBuffer(width * height * 4)
+    GL11.glReadPixels(0, 0, width, height, GL11.GL_RGBA, GL11.GL_UNSIGNED_BYTE, buffer)
+    val image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB)
+    var y = 0
+    while (y < height) {
+      var x = 0
+      while (x < width) {
+        val i = (x + (height - y - 1) * width) * 4
+        val r = buffer.get(i) & 0xFF
+        val g = buffer.get(i + 1) & 0xFF
+        val b = buffer.get(i + 2) & 0xFF
+        val rgb = (r << 16) | (g << 8) | b
+        image.setRGB(x, y, rgb)
+        x += 1
+      }
+      y += 1
+    }
+    image
+  }
+
   def flush(mainTexture: Texture = Spritesheet.texture, clear: Boolean = false): Unit = {
     if (renderer.isEmpty && !clear) return
 

src/main/scala/ocelot/desktop/ui/UiHandler.scala

@@ -18,6 +18,7 @@ import org.lwjgl.opengl._
 
 import java.awt.Toolkit
 import java.awt.datatransfer.{DataFlavor, StringSelection, UnsupportedFlavorException}
+import java.awt.image.BufferedImage
 import java.io.{File, FileOutputStream}
 import java.nio.ByteBuffer
 import java.nio.channels.Channels
@@ -145,6 +146,8 @@ object UiHandler extends Logging {
     Settings.get.windowFullscreen = value
   }
 
+  def screenshot(): BufferedImage = graphics.screenshot()
+
   private def formatRect(rect: Rect2D): String = {
     val Rect2D(x, y, w, h) = rect
 

src/main/scala/ocelot/desktop/ui/widget/RootWidget.scala

@@ -12,11 +12,16 @@ import ocelot.desktop.ui.widget.itemdrag.DraggedItemPool
 import ocelot.desktop.ui.widget.modal.ModalDialogPool
 import ocelot.desktop.ui.widget.statusbar.StatusBar
 import ocelot.desktop.ui.widget.tooltip.TooltipPool
-import ocelot.desktop.util.{DrawUtils, Orientation}
+import ocelot.desktop.util.{DrawUtils, Logging, Orientation}
 import org.lwjgl.input.Keyboard
 import totoro.ocelot.brain.nbt.NBTTagCompound
 
-class RootWidget(setupDefaultWorkspace: Boolean = true) extends Widget {
+import java.io.File
+import javax.imageio.ImageIO
+import javax.swing.JFileChooser
+import scala.util.Try
+
+class RootWidget(setupDefaultWorkspace: Boolean = true) extends Widget with Logging {
   override protected val layout = new CopyLayout(this)
 
   root = Some(this)
@@ -66,6 +71,18 @@ class RootWidget(setupDefaultWorkspace: Boolean = true) extends Widget {
 
     case KeyEvent(KeyEvent.State.Release, Keyboard.KEY_F11, _) =>
       UiHandler.fullScreen = !UiHandler.fullScreen
+
+    case KeyEvent(KeyEvent.State.Release, Keyboard.KEY_F12, _) =>
+      val image = UiHandler.screenshot()
+      OcelotDesktop.showFileChooserDialog(JFileChooser.SAVE_DIALOG, JFileChooser.DIRECTORIES_ONLY) { dir =>
+        Try {
+          for (dir <- dir) {
+            val file = new File(dir, s"ocelot-${System.currentTimeMillis()}.png")
+            ImageIO.write(image, "PNG", file)
+            logger.debug(s"Saved screenshot to: $file")
+          }
+        }
+      }
   }
 
   override def draw(g: Graphics): Unit = {