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      1 // Copyright 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CC_LAYERS_DRAW_PROPERTIES_H_
      6 #define CC_LAYERS_DRAW_PROPERTIES_H_
      7 
      8 #include "base/memory/scoped_ptr.h"
      9 #include "ui/gfx/rect.h"
     10 #include "ui/gfx/transform.h"
     11 
     12 namespace cc {
     13 
     14 // Container for properties that layers need to compute before they can be
     15 // drawn.
     16 template <typename LayerType>
     17 struct CC_EXPORT DrawProperties {
     18   DrawProperties()
     19       : opacity(0.f),
     20         opacity_is_animating(false),
     21         screen_space_opacity_is_animating(false),
     22         target_space_transform_is_animating(false),
     23         screen_space_transform_is_animating(false),
     24         can_use_lcd_text(false),
     25         is_clipped(false),
     26         render_target(NULL),
     27         contents_scale_x(1.f),
     28         contents_scale_y(1.f),
     29         num_descendants_that_draw_content(0),
     30         num_unclipped_descendants(0),
     31         layer_or_descendant_has_copy_request(false),
     32         has_child_with_a_scroll_parent(false),
     33         sorted_for_recursion(false),
     34         index_of_first_descendants_addition(0),
     35         num_descendants_added(0),
     36         index_of_first_render_surface_layer_list_addition(0),
     37         num_render_surfaces_added(0) {}
     38 
     39   // Transforms objects from content space to target surface space, where
     40   // this layer would be drawn.
     41   gfx::Transform target_space_transform;
     42 
     43   // Transforms objects from content space to screen space (viewport space).
     44   gfx::Transform screen_space_transform;
     45 
     46   // DrawProperties::opacity may be different than LayerType::opacity,
     47   // particularly in the case when a RenderSurface re-parents the layer's
     48   // opacity, or when opacity is compounded by the hierarchy.
     49   float opacity;
     50 
     51   // xxx_is_animating flags are used to indicate whether the DrawProperties
     52   // are actually meaningful on the main thread. When the properties are
     53   // animating, the main thread may not have the same values that are used
     54   // to draw.
     55   bool opacity_is_animating;
     56   bool screen_space_opacity_is_animating;
     57   bool target_space_transform_is_animating;
     58   bool screen_space_transform_is_animating;
     59 
     60   // True if the layer can use LCD text.
     61   bool can_use_lcd_text;
     62 
     63   // True if the layer needs to be clipped by clip_rect.
     64   bool is_clipped;
     65 
     66   // The layer whose coordinate space this layer draws into. This can be
     67   // either the same layer (draw_properties_.render_target == this) or an
     68   // ancestor of this layer.
     69   LayerType* render_target;
     70 
     71   // The surface that this layer and its subtree would contribute to.
     72   scoped_ptr<typename LayerType::RenderSurfaceType> render_surface;
     73 
     74   // This rect is in the layer's content space.
     75   gfx::Rect visible_content_rect;
     76 
     77   // In target surface space, the rect that encloses the clipped, drawable
     78   // content of the layer.
     79   gfx::Rect drawable_content_rect;
     80 
     81   // In target surface space, the original rect that clipped this layer. This
     82   // value is used to avoid unnecessarily changing GL scissor state.
     83   gfx::Rect clip_rect;
     84 
     85   // The scale used to move between layer space and content space, and bounds
     86   // of the space. One is always a function of the other, but which one
     87   // depends on the layer type. For picture layers, this is an ideal scale,
     88   // and not always the one used.
     89   float contents_scale_x;
     90   float contents_scale_y;
     91   gfx::Size content_bounds;
     92 
     93   // Does not include this layer itself, only its children and descendants.
     94   int num_descendants_that_draw_content;
     95 
     96   // Number of descendants with a clip parent that is our ancestor. NB - this
     97   // does not include our clip children because they are clipped by us.
     98   int num_unclipped_descendants;
     99 
    100   // If true, the layer or some layer in its sub-tree has a CopyOutputRequest
    101   // present on it.
    102   bool layer_or_descendant_has_copy_request;
    103 
    104   // This is true if the layer has any direct child that has a scroll parent.
    105   // This layer will not be the scroll parent in this case. This information
    106   // lets us avoid work in CalculateDrawPropertiesInternal -- if none of our
    107   // children have scroll parents, we will not need to recur out of order.
    108   bool has_child_with_a_scroll_parent;
    109 
    110   // This is true if the order (wrt to its siblings in the tree) in which the
    111   // layer will be visited while computing draw properties has been determined.
    112   bool sorted_for_recursion;
    113 
    114   // If this layer is visited out of order, its contribution to the descendant
    115   // and render surface layer lists will be put aside in a temporary list.
    116   // These values will allow for an efficient reordering of these additions.
    117   size_t index_of_first_descendants_addition;
    118   size_t num_descendants_added;
    119   size_t index_of_first_render_surface_layer_list_addition;
    120   size_t num_render_surfaces_added;
    121 };
    122 
    123 }  // namespace cc
    124 
    125 #endif  // CC_LAYERS_DRAW_PROPERTIES_H_
    126