Improve window handling in overview mode

* For small window counts, lay the windows out according to a
  predefined scheme. For larger window counts, continue putting
  the windows along the diagonal as before, but do it a bit better.
* Special case the desktop window and use it as the background
  of the window area.
* Add a little translucency to windows
* Use tweener to animate everything into place
* Clean up - add constants and break things into multiple methods

svn path=/trunk/; revision=32

js/ui/overlay.js

@@ -1,16 +1,40 @@
 /* -*- mode: js2; js2-basic-offset: 4; -*- */
 
-const Shell = imports.gi.Shell;
 const Clutter = imports.gi.Clutter;
+const Meta = imports.gi.Meta;
+const Shell = imports.gi.Shell;
+const Tweener = imports.tweener.tweener;
 
 const Panel = imports.ui.panel;
 
 const OVERLAY_BACKGROUND_COLOR = new Clutter.Color();
 OVERLAY_BACKGROUND_COLOR.from_pixel(0x000000ff);
 
+// Time for initial animation going into overlay mode
+const ANIMATION_TIME = 0.3;
+
+// How much to scale the desktop down by in overlay mode
+const DESKTOP_SCALE = 0.75;
+
+// Windows are slightly translucent in the overlay mode
+const WINDOW_OPACITY = 0.9 * 255;
+
+// Define a layout scheme for small window counts. For larger
+// counts we fall back to an algorithm. We need more schemes here
+// unless we have a really good algorithm.
+//
+// Each triplet is [x_center, y_center, scale] where the scale
+// is relative to the width of the desktop.
+const POSITIONS = {
+    1: [[0.5, 0.5, 0.8]],
+    2: [[0.25, 0.5, 0.4], [0.75, 0.5, 0.4]],
+    3: [[0.2, 0.33, 0.3],  [0.5, 0.67, 0.3],  [0.8, 0.33, 0.3]],
+    4: [[0.25, 0.25, 0.3],   [0.75, 0.25, 0.3], [0.75, 0.75, 0.3], [0.25, 0.75, 0.3]]
+};
+
 function Overlay() {
     this._init();
-}
+};
 
 Overlay.prototype = {
     _init : function() {
@@ -37,50 +61,48 @@ Overlay.prototype = {
 	if (!this.visible) {
 	    this.visible = true;
 
-	    // Very simple version of a window overview ... when we show the
-	    // overlay, display all the user's windows in the overlay scaled
-	    // down.
-	    //
-	    // We show the window using "clones" of the texture .. separate
-	    // actors that mirror the original actors for the window. For
-	    // animation purposes, it may be better to actually move the
-	    // original actors about instead.
-
 	    let global = Shell.global_get();
 	    let windows = global.get_windows();
-	
+	    let desktop_window = null;
+
 	    let screen_width = global.screen_width
 	    let screen_height = global.screen_height
 
-	    let x = screen_width / 4
-	    let y = screen_height / 4
-    
 	    for (let i = 0; i < windows.length; i++)
-		if (!windows[i].is_override_redirect()) {
-		    let clone = new Clutter.CloneTexture({ parent_texture: windows[i].get_texture(),
-							   x: x,
-							   y: y });
+		if (windows[i].get_window_type() == Meta.WindowType.DESKTOP)
+		    desktop_window = windows[i];
 
-		    // We scale each window down so that it is at most 300x300, but we 
-		    // never want to scale a window up.
-		    let size = clone.width;
-		    if (clone.height > size)
-			size = clone.height;
+	    // The desktop windows are shown on top of a scaled down version of the
+	    // desktop. This is positioned at the right side of the screen
+	    this._desktop_width = screen_width * DESKTOP_SCALE;
+	    this._desktop_height = screen_height * DESKTOP_SCALE;
+	    this._desktop_x = screen_width - this._desktop_width - 10;
+	    this._desktop_y = Panel.PANEL_HEIGHT + (screen_height - this._desktop_height - Panel.PANEL_HEIGHT) / 2;
 
-		    let scale = 300 / size;
-		    if (scale > 1)
-			scale = 1;
-		    
-		    clone.set_scale(scale, scale);
-		    this._group.add_actor(clone);
-		    this._window_clones.push(clone);
+	    if (desktop_window)
+		this._createDesktopClone(desktop_window);
+
+	    // Count the total number of windows so we know what layout scheme to use
+	    let n_windows = 0;
+	    for (let i = 0; i < windows.length; i++) {
+		let w = windows[i];
+		if (w == desktop_window || w.is_override_redirect())
+		    continue;
+
+		n_windows++;
+	    }
+
+	    // Now create actors for all the desktop windows
+	    let window_index = 0;
+	    for (let i = 0; i < windows.length; i++) {
+		let w = windows[i];
+		if (w == desktop_window || w.is_override_redirect())
+		    continue;
+		this._createWindowClone(w, window_index, n_windows);
+
+		window_index++;
+	    }
 
-		    // Windows are overlapped diagonally. If there are too many, they'll
-		    // end up off the screen
-		    x += 50;
-		    y += 50;
-		}
-	    
 	    this._group.show();
 	}
     },
@@ -96,5 +118,100 @@ Overlay.prototype = {
 
 	    this._window_clones = [];
 	}
+    },
+
+    _createDesktopClone : function(w) {
+	let clone = new Clutter.CloneTexture({ parent_texture: w.get_texture(),
+					       reactive: true,
+					       x: 0,
+					       y: 0 });
+	this._window_clones.push(clone);
+	this._group.add_actor(clone);
+
+	Tweener.addTween(clone,
+			 { x: this._desktop_x,
+			   y: this._desktop_y,
+			   scale_x: DESKTOP_SCALE,
+			   scale_y: DESKTOP_SCALE,
+			   time: ANIMATION_TIME,
+			   transition: "linear"
+			 });
+
+	let me = this;
+	clone.connect("button-press-event",
+		      function() {
+			  me._deactivate();
+		      });
+    },
+
+    _computeWindowPosition : function(window_index, n_windows) {
+	if (n_windows in POSITIONS)
+	    return POSITIONS[n_windows][window_index];
+
+	// If we don't have a predefined scheme for this window count, overlap the windows
+	// along the diagonal of the desktop (improve this!)
+	let fraction = Math.sqrt(1/n_windows);
+	let x_center = (fraction / 2) + (1 - fraction) * window_index / (n_windows - 1);
+	let y_center = x_center;
+
+	log(x_center + "," + y_center + "," + fraction);
+	return [x_center, y_center, fraction];
+    },
+
+    _createWindowClone : function(w, window_index, n_windows) {
+	// We show the window using "clones" of the texture .. separate
+	// actors that mirror the original actors for the window. For
+	// animation purposes, it may be better to actually move the
+	// original actors about instead.
+
+	let clone = new Clutter.CloneTexture({ parent_texture: w.get_texture(),
+					       reactive: true,
+					       x: w.x,
+					       y: w.y });
+
+	let [x_center, y_center, fraction] = this._computeWindowPosition(window_index, n_windows);
+
+	let desired_size = this._desktop_width * fraction;
+
+	x_center = this._desktop_x + x_center * this._desktop_width;
+	y_center = this._desktop_y + y_center * this._desktop_height;
+
+	let size = clone.width;
+	if (clone.height > size)
+	    size = clone.height;
+
+	// Never scale up
+	let scale = desired_size / size;
+	if (scale > 1)
+	    scale = 1;
+
+	this._group.add_actor(clone);
+	this._window_clones.push(clone);
+
+	Tweener.addTween(clone,
+			 { x: x_center - 0.5 * scale * w.width,
+			   y: y_center - 0.5 * scale * w.height,
+			   scale_x: scale,
+			   scale_y: scale,
+			   time: ANIMATION_TIME,
+			   opacity: WINDOW_OPACITY,
+			   transition: "linear"
+			  });
+
+	let me = this;
+	clone.connect("button-press-event",
+		      function() {
+			  me._activateWindow(w);
+		      });
+    },
+
+    _activateWindow : function(w) {
+	this._deactivate();
+	log("Activate "+ w.get_description());
+    },
+
+    _deactivate : function() {
+	let Main = imports.ui.main;
+	Main.hide_overlay();
     }
 };