added sources for Slick

Former-commit-id: 1647fa32ef6894bd7db44f741f07c2f4dcdf9054
Former-commit-id: 0e5810dcfbe1fd59b13e7cabe9f1e93c5542da2d

lib/slick-source/org/newdawn/slick/opengl/SlickCallable.java

@@ -0,0 +1,122 @@
+package org.newdawn.slick.opengl;
+
+import org.lwjgl.opengl.GL11;
+import org.newdawn.slick.SlickException;
+import org.newdawn.slick.opengl.renderer.Renderer;
+
+/**
+ * A utility to allow performing GL operations without contaminating the
+ * Slick OpenGL state. Note this will not protect you from OpenGL programming errors
+ * like a glBegin() without a glEnd(), or glPush() without glPop() etc.
+ * 
+ * Expected usage:
+ * 
+ * <code>
+ * SlickCallable callable = new SlickCallable() {
+ * 	   public performGLOperations() throws SlickException {
+ * 			GL.glTranslate(0,0,1);
+ * 			glBegin(GL.GL_POLYGONS);
+ *  			glVertex(..);
+ *              ...
+ *          glEnd();
+ *     }
+ * }
+ * callable.call();
+ * </code>
+ * 
+ * Alternatively you can use the static methods directly
+ * 
+ * <code>
+ * SlickCallable.enterSafeBlock();
+ * 
+ * GL.glTranslate(0,0,1);
+ * glBegin(GL.GL_POLYGONS);
+ *     glVertex(..);
+ *     ...
+ * glEnd();
+ * 
+ * SlickCallable.leaveSafeBlock();
+ * </code>
+ * 
+ * @author kevin
+ */
+public abstract class SlickCallable {
+	/** The last texture used */
+	private static Texture lastUsed;
+	/** True if we're in a safe block */
+	private static boolean inSafe = false;
+	
+	
+	/**
+	 * Enter a safe block ensuring that all the OpenGL state that slick 
+	 * uses is safe before touching the GL state directly.
+	 */
+	public static void enterSafeBlock() 
+	{
+		if (inSafe) {
+			return;
+		}
+		
+		Renderer.get().flush();
+		lastUsed = TextureImpl.getLastBind();
+		TextureImpl.bindNone();
+		GL11.glPushAttrib(GL11.GL_ALL_ATTRIB_BITS);
+		GL11.glPushClientAttrib(GL11.GL_ALL_CLIENT_ATTRIB_BITS);
+		GL11.glMatrixMode(GL11.GL_MODELVIEW);
+		GL11.glPushMatrix();
+		GL11.glMatrixMode(GL11.GL_PROJECTION);
+		GL11.glPushMatrix();
+		GL11.glMatrixMode(GL11.GL_MODELVIEW);
+		
+		inSafe = true;
+	}
+
+	/**
+	 * Leave a safe block ensuring that all of Slick's OpenGL state is
+	 * restored since the last enter.
+	 */
+	public static void leaveSafeBlock() 
+	{
+		if (!inSafe) {
+			return;
+		}
+
+		GL11.glMatrixMode(GL11.GL_PROJECTION);
+		GL11.glPopMatrix();
+		GL11.glMatrixMode(GL11.GL_MODELVIEW);
+		GL11.glPopMatrix();
+		GL11.glPopClientAttrib();
+		GL11.glPopAttrib();
+		
+		if (lastUsed != null) {
+			lastUsed.bind();
+		} else {
+			TextureImpl.bindNone();
+		}
+		
+		inSafe = false;
+	}
+	
+	/**
+	 * Cause this callable to perform it's GL operations (@see performGLOperations()). This
+	 * method will block until the GL operations have been performed.
+	 *
+	 * @throws SlickException Indicates a failure while performing the GL operations or 
+	 * maintaing SlickState
+	 */
+	public final void call() throws SlickException {
+		enterSafeBlock();
+		
+		performGLOperations();
+		
+		leaveSafeBlock();
+	}
+	
+	/**
+	 * Perform the GL operations that this callable is intended to. This operations should
+	 * not effect the slick OpenGL state.
+	 * 
+	 * @throws SlickException Indicates a failure of some sort. This is user exception
+	 */
+	protected abstract void performGLOperations() throws SlickException;
+}