Home | History | Annotate | Download | only in layers
      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         layer_or_descendant_has_input_handler(false),
     33         has_child_with_a_scroll_parent(false),
     34         sorted_for_recursion(false),
     35         index_of_first_descendants_addition(0),
     36         num_descendants_added(0),
     37         index_of_first_render_surface_layer_list_addition(0),
     38         num_render_surfaces_added(0),
     39         last_drawn_render_surface_layer_list_id(0),
     40         ideal_contents_scale(0.f),
     41         maximum_animation_contents_scale(0.f),
     42         page_scale_factor(0.f),
     43         device_scale_factor(0.f) {}
     44 
     45   // Transforms objects from content space to target surface space, where
     46   // this layer would be drawn.
     47   gfx::Transform target_space_transform;
     48 
     49   // Transforms objects from content space to screen space (viewport space).
     50   gfx::Transform screen_space_transform;
     51 
     52   // DrawProperties::opacity may be different than LayerType::opacity,
     53   // particularly in the case when a RenderSurface re-parents the layer's
     54   // opacity, or when opacity is compounded by the hierarchy.
     55   float opacity;
     56 
     57   // xxx_is_animating flags are used to indicate whether the DrawProperties
     58   // are actually meaningful on the main thread. When the properties are
     59   // animating, the main thread may not have the same values that are used
     60   // to draw.
     61   bool opacity_is_animating;
     62   bool screen_space_opacity_is_animating;
     63   bool target_space_transform_is_animating;
     64   bool screen_space_transform_is_animating;
     65 
     66   // True if the layer can use LCD text.
     67   bool can_use_lcd_text;
     68 
     69   // True if the layer needs to be clipped by clip_rect.
     70   bool is_clipped;
     71 
     72   // The layer whose coordinate space this layer draws into. This can be
     73   // either the same layer (draw_properties_.render_target == this) or an
     74   // ancestor of this layer.
     75   LayerType* render_target;
     76 
     77   // The surface that this layer and its subtree would contribute to.
     78   scoped_ptr<typename LayerType::RenderSurfaceType> render_surface;
     79 
     80   // This rect is in the layer's content space.
     81   gfx::Rect visible_content_rect;
     82 
     83   // In target surface space, the rect that encloses the clipped, drawable
     84   // content of the layer.
     85   gfx::Rect drawable_content_rect;
     86 
     87   // In target surface space, the original rect that clipped this layer. This
     88   // value is used to avoid unnecessarily changing GL scissor state.
     89   gfx::Rect clip_rect;
     90 
     91   // The scale used to move between layer space and content space, and bounds
     92   // of the space. One is always a function of the other, but which one
     93   // depends on the layer type. For picture layers, this is an ideal scale,
     94   // and not always the one used.
     95   float contents_scale_x;
     96   float contents_scale_y;
     97   gfx::Size content_bounds;
     98 
     99   // Does not include this layer itself, only its children and descendants.
    100   int num_descendants_that_draw_content;
    101 
    102   // Number of descendants with a clip parent that is our ancestor. NB - this
    103   // does not include our clip children because they are clipped by us.
    104   int num_unclipped_descendants;
    105 
    106   // If true, the layer or some layer in its sub-tree has a CopyOutputRequest
    107   // present on it.
    108   bool layer_or_descendant_has_copy_request;
    109 
    110   // If true, the layer or one of its descendants has a wheel or touch handler.
    111   bool layer_or_descendant_has_input_handler;
    112 
    113   // This is true if the layer has any direct child that has a scroll parent.
    114   // This layer will not be the scroll parent in this case. This information
    115   // lets us avoid work in CalculateDrawPropertiesInternal -- if none of our
    116   // children have scroll parents, we will not need to recur out of order.
    117   bool has_child_with_a_scroll_parent;
    118 
    119   // This is true if the order (wrt to its siblings in the tree) in which the
    120   // layer will be visited while computing draw properties has been determined.
    121   bool sorted_for_recursion;
    122 
    123   // If this layer is visited out of order, its contribution to the descendant
    124   // and render surface layer lists will be put aside in a temporary list.
    125   // These values will allow for an efficient reordering of these additions.
    126   size_t index_of_first_descendants_addition;
    127   size_t num_descendants_added;
    128   size_t index_of_first_render_surface_layer_list_addition;
    129   size_t num_render_surfaces_added;
    130 
    131   // Each time we generate a new render surface layer list, an ID is used to
    132   // identify it. |last_drawn_render_surface_layer_list_id| is set to the ID
    133   // that marked the render surface layer list generation which last updated
    134   // these draw properties and determined that this layer will draw itself.
    135   // If these draw properties are not a part of the render surface layer list,
    136   // or the layer doesn't contribute anything, then this ID will be either out
    137   // of date or 0.
    138   int last_drawn_render_surface_layer_list_id;
    139 
    140   // The scale at which content for the layer should be rastered in order to be
    141   // perfectly crisp.
    142   float ideal_contents_scale;
    143 
    144   // The maximum scale during the layers current animation at which content
    145   // should be rastered at to be crisp.
    146   float maximum_animation_contents_scale;
    147 
    148   // The page scale factor that is applied to the layer. Since some layers may
    149   // have page scale applied and others not, this may differ between layers.
    150   float page_scale_factor;
    151 
    152   // The device scale factor that is applied to the layer.
    153   float device_scale_factor;
    154 };
    155 
    156 }  // namespace cc
    157 
    158 #endif  // CC_LAYERS_DRAW_PROPERTIES_H_
    159