Impelemented zooming and slightly better scrolling.

src/components/main/compositing/mod.rs

@@ -126,6 +126,9 @@ fn run_main_loop(port: Port<Msg>,
     let page_size = @mut Size2D(0f32, 0f32);
     let window_size = @mut Size2D(800, 600);
 
+    // Keeps track of the current zoom factor
+    let world_zoom = @mut 1f32;
+
     let check_for_messages: @fn() = || {
         // Periodically check if the script task responded to our last resize event
         resize_rate_limiter.check_resize_response();
@@ -248,16 +251,65 @@ fn run_main_loop(port: Port<Msg>,
         *world_offset = world_offset_copy - delta;
 
         // Clamp the world offset to the screen size.
-        let max_x = (page_size.width - window_size.width as f32).max(&0.0);
+        let max_x = (page_size.width * *world_zoom - window_size.width as f32).max(&0.0);
         world_offset.x = world_offset.x.clamp(&0.0, &max_x);
-        let max_y = (page_size.height - window_size.height as f32).max(&0.0);
+        let max_y = (page_size.height * *world_zoom - window_size.height as f32).max(&0.0);
         world_offset.y = world_offset.y.clamp(&0.0, &max_y);
 
         debug!("compositor: scrolled to %?", *world_offset);
 
-        root_layer.common.set_transform(identity().translate(-world_offset.x,
-                                                             -world_offset.y,
-                                                             0.0));
+        let mut scroll_transform = identity();
+
+        scroll_transform = scroll_transform.translate(window_size.width as f32 / 2f32 * *world_zoom - world_offset.x,
+                                                  window_size.height as f32 / 2f32 * *world_zoom - world_offset.y,
+                                                  0.0);
+        scroll_transform = scroll_transform.scale(*world_zoom, *world_zoom, 1f32);
+        scroll_transform = scroll_transform.translate(window_size.width as f32 / -2f32,
+                                                  window_size.height as f32 / -2f32,
+                                                  0.0);
+
+        root_layer.common.set_transform(scroll_transform);
+
+        window.set_needs_display()
+    }
+
+
+
+    // When the user pinch-zooms, scale the layer
+    do window.set_zoom_callback |delta| {
+        let zoom_const = 0.01;
+        let old_world_zoom = *world_zoom;
+
+        // Determine zoom amount
+        *world_zoom = (*world_zoom + delta.y * zoom_const).max(&1.0);            
+
+        // Update world offset
+        let corner_to_center_x = world_offset.x + window_size.width as f32 / 2f32;
+        let new_corner_to_center_x = corner_to_center_x * *world_zoom / old_world_zoom;
+        world_offset.x = world_offset.x + new_corner_to_center_x - corner_to_center_x;
+
+        let corner_to_center_y = world_offset.y + window_size.height as f32 / 2f32;
+        let new_corner_to_center_y = corner_to_center_y * *world_zoom / old_world_zoom;
+        world_offset.y = world_offset.y + new_corner_to_center_y - corner_to_center_y;        
+
+        // Clamp to page bounds when zooming out
+        let max_x = (page_size.width * *world_zoom - window_size.width as f32).max(&0.0);
+        world_offset.x = world_offset.x.clamp(&0.0, &max_x);
+        let max_y = (page_size.height * *world_zoom - window_size.height as f32).max(&0.0);
+        world_offset.y = world_offset.y.clamp(&0.0, &max_y);
+
+
+        // Apply transformations
+        let mut zoom_transform = identity();
+        zoom_transform = zoom_transform.translate(window_size.width as f32 / 2f32 * *world_zoom - world_offset.x,
+                                                  window_size.height as f32 / 2f32 * *world_zoom - world_offset.y,
+                                                  0.0);
+        zoom_transform = zoom_transform.scale(*world_zoom, *world_zoom, 1f32);
+        zoom_transform = zoom_transform.translate(window_size.width as f32 / -2f32,
+                                                  window_size.height as f32 / -2f32,
+                                                  0.0);
+        root_layer.common.set_transform(zoom_transform);
+
 
         window.set_needs_display()
     }

src/components/main/platform/common/glut_windowing.rs

@@ -8,7 +8,7 @@
 /// least on desktops. It is designed for testing Servo without the need of a UI.
 
 use windowing::{ApplicationMethods, CompositeCallback, LoadUrlCallback, ClickCallback};
-use windowing::{ResizeCallback, ScrollCallback, WindowMethods};
+use windowing::{ResizeCallback, ScrollCallback, ZoomCallback, WindowMethods};
 
 use alert::{Alert, AlertMethods};
 use core::libc::c_int;
@@ -37,8 +37,10 @@ pub struct Window {
     load_url_callback: Option<LoadUrlCallback>,
     click_callback: Option<ClickCallback>,
     scroll_callback: Option<ScrollCallback>,
+    zoom_callback: Option<ZoomCallback>,
 
     drag_origin: Point2D<c_int>,
+    down_button: c_int
 }
 
 impl WindowMethods<Application> for Window {
@@ -57,10 +59,14 @@ impl WindowMethods<Application> for Window {
             load_url_callback: None,
             click_callback: None,
             scroll_callback: None,
+            zoom_callback: None,
 
             drag_origin: Point2D(0, 0),
+            down_button: 0 // FIXME: Hacky solution to 2 button mouse. 
+                           // Replace with tkuehn's code.
         };
 
+
         // Register event handlers.
         do glut::reshape_func(window.glut_window) |width, height| {
             match window.resize_callback {
@@ -78,8 +84,9 @@ impl WindowMethods<Application> for Window {
         do glut::keyboard_func |key, _, _| {
             window.handle_key(key)
         }
-        do glut::mouse_func |_, _, x, y| {
+        do glut::mouse_func |button, _, x, y| {
             window.handle_click(x, y);
+            window.down_button = button;
             window.start_drag(x, y)
         }
         do glut::motion_func |x, y| {
@@ -124,6 +131,11 @@ impl WindowMethods<Application> for Window {
         self.scroll_callback = Some(new_scroll_callback)
     }
 
+    /// Registers a zoom to be run when the user zooms.
+    pub fn set_zoom_callback(&mut self, new_zoom_callback: ZoomCallback) {
+        self.zoom_callback = Some(new_zoom_callback)
+    }
+
     /// Spins the event loop.
     pub fn check_loop(@mut self) {
         glut::check_loop()
@@ -163,9 +175,16 @@ impl Window {
         let delta = new_point - self.drag_origin;
         self.drag_origin = new_point;
 
-        match self.scroll_callback {
-            None => {}
-            Some(callback) => callback(Point2D(delta.x as f32, delta.y as f32)),
+        if self.down_button == 2 { 
+            match self.zoom_callback {
+                None => {}
+                Some(callback) => callback(Point2D(delta.x as f32, delta.y as f32)),
+            }
+        } else {
+            match self.scroll_callback {
+                None => {}
+                Some(callback) => callback(Point2D(delta.x as f32, delta.y as f32)),
+            }
         }
     }
 

src/components/main/windowing.rs

@@ -23,6 +23,9 @@ pub type ClickCallback = @fn(Point2D<f32>);
 /// Type of the function that is called when the user scrolls.
 pub type ScrollCallback = @fn(Point2D<f32>);
 
+///Type of the function that is called when the user zooms.
+pub type ZoomCallback = @fn(Point2D<f32>);
+
 /// Methods for an abstract Application.
 pub trait ApplicationMethods {
     fn new() -> Self;
@@ -46,6 +49,8 @@ pub trait WindowMethods<A> {
     pub fn set_click_callback(&mut self, new_click_callback: ClickCallback);
     /// Registers a callback to run when the user scrolls.
     pub fn set_scroll_callback(&mut self, new_scroll_callback: ScrollCallback);
+    /// Registers a callback to run when the user zooms.
+    pub fn set_zoom_callback(&mut self, new_zoom_callback: ZoomCallback);
 
     /// Spins the event loop.
     pub fn check_loop(@mut self);