Fix up problems with float placement

src/components/main/layout/block.rs

@@ -249,11 +249,13 @@ impl BlockFlowData {
     pub fn assign_height_block(@mut self, ctx: &mut LayoutContext) {
         let mut cur_y = Au(0);
         let mut top_offset = Au(0);
+        let mut left_offset = Au(0);
 
         for self.box.each |&box| {
             do box.with_model |model| {
                 top_offset = model.margin.top + model.border.top + model.padding.top;
                 cur_y += top_offset;
+                left_offset = model.offset();
             }
         }
 
@@ -268,7 +270,7 @@ impl BlockFlowData {
         // visit child[i]
         // repeat until all children are visited.
         // last_child.floats_out -> self.floats_out (done at the end of this method)
-        let mut float_ctx = self.common.floats_in.clone();
+        let mut float_ctx = self.common.floats_in.translate(Point2D(-left_offset, -top_offset));
         for BlockFlow(self).each_child |kid| {
             do kid.with_mut_base |child_node| {
                 child_node.floats_in = float_ctx.clone();
@@ -310,7 +312,7 @@ impl BlockFlowData {
         self.common.position.size.height = height + noncontent_height;
 
     
-        self.common.floats_out = float_ctx.translate(Point2D(Au(0), self.common.position.size.height));
+        self.common.floats_out = float_ctx.translate(Point2D(left_offset, self.common.position.size.height));
     }
 
     pub fn build_display_list_block<E:ExtraDisplayListData>(@mut self,

src/components/main/layout/float.rs

@@ -27,6 +27,8 @@ pub struct FloatFlowData {
 
     containing_width: Au,
 
+    /// Parent clobbers our position, so store it separately
+    rel_pos: Point2D<Au>,
 
     /// Index into the box list for inline floats
     index: Option<uint>,
@@ -40,6 +42,7 @@ impl FloatFlowData {
             containing_width: Au(0),
             box: None,
             index: None,
+            rel_pos: Point2D(Au(0), Au(0)),
         }
     }
 
@@ -210,10 +213,10 @@ impl FloatFlowData {
             f_type: FloatLeft,
         };
 
+        // Place the float and return the FloatContext back to the parent flow.
+        // After, grab the position and use that to set our position.
         self.common.floats_out = self.common.floats_in.add_float(&info);
-
-
-
+        self.rel_pos = self.common.floats_out.last_float_pos();
     }
 
     pub fn build_display_list_float<E:ExtraDisplayListData>(@mut self,
@@ -221,15 +224,17 @@ impl FloatFlowData {
                                                             dirty: &Rect<Au>, 
                                                             offset: &Point2D<Au>,
                                                             list: &Cell<DisplayList<E>>) {
+
+        let offset = *offset + self.rel_pos;
         self.box.map(|&box| {
-            box.build_display_list(builder, dirty, offset, list)
+            box.build_display_list(builder, dirty, &offset, list)
         });
 
 
         // go deeper into the flow tree
         let flow = FloatFlow(self);
         for flow.each_child |child| {
-            flow.build_display_list_for_child(builder, child, dirty, offset, list)
+            flow.build_display_list_for_child(builder, child, dirty, &offset, list)
         }
     }
 }

src/components/main/layout/float_context.rs

@@ -122,7 +122,10 @@ impl FloatContextBase{
 
         match self.float_data[self.floats_used - 1] {
             None => fail!("FloatContext error: floats should never be None here"),
-            Some(float) => float.bounds.origin
+            Some(float) => {
+                debug!("Returning float position: %?", float.bounds.origin + self.offset);
+                float.bounds.origin + self.offset
+            }
         }
     }
 
@@ -135,6 +138,10 @@ impl FloatContextBase{
             (max(top_1, top_2), min(bottom_1, bottom_2))
         }
 
+        debug!("available_rect: trying to find space at %?", top);
+
+        let top = top - self.offset.y;
+
         // Relevant dimensions for the right-most left float
         let mut (max_left, l_top, l_bottom) = (Au(0) - self.offset.x, None, None);
         // Relevant dimensions for the left-most right float
@@ -183,7 +190,15 @@ impl FloatContextBase{
             (None, None, None, None) => return None,
             _ => fail!("Reached unreachable state when computing float area")
         };
-        assert!(max_left < min_right, "Float position error");
+
+        // When the window is smaller than the float, we will return a rect
+        // with negative width.
+        assert!(max_left < min_right 
+                || max_left > max_x - self.offset.x
+                || min_right < Au(0) - self.offset.x
+                ,"Float position error");
+
+        //TODO(eatkinson): do we need to do something similar for heights?
         assert!(top < bottom, "Float position error");
 
         Some(Rect{
@@ -212,11 +227,13 @@ impl FloatContextBase{
     /// LOCAL COORDINATES. i.e. must be translated before placed
     /// in the float list
     fn place_float(&self, info: &PlacementInfo) -> Point2D<Au>{
+        debug!("place_float: Placing float with width %? and height %?", info.width, info.height);
         // Can't go any higher than previous floats or
         // previous elements in the document.
-        let mut float_y = max(info.ceiling, self.max_y);
+        let mut float_y = max(info.ceiling, self.max_y + self.offset.y);
         loop {
             let maybe_location = self.available_rect(float_y, info.height, info.max_width);
+            debug!("place_float: Got available rect: %? for y-pos: %?", maybe_location, float_y);
             match maybe_location {
                 // If there are no floats blocking us, return the current location
                 // TODO(eatknson): integrate with overflow