cc/layers/draw_properties.h

   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 "cc/trees/occlusion.h"
  10 #include "third_party/skia/include/core/SkXfermode.h"
  11 #include "ui/gfx/geometry/rect.h"
  12 #include "ui/gfx/transform.h"
  13
  14 namespace cc {
  15
  16 // Container for properties that layers need to compute before they can be
  17 // drawn.
  18 template <typename LayerType>
  19 struct CC_EXPORT DrawProperties {
  20   DrawProperties()
  21       : opacity(0.f),
  22         blend_mode(SkXfermode::kSrcOver_Mode),
  23         target_space_transform_is_animating(false),
  24         screen_space_transform_is_animating(false),
  25         can_use_lcd_text(false),
  26         render_target(nullptr),
  27         num_unclipped_descendants(0),
  28         layer_or_descendant_has_copy_request(false),
  29         layer_or_descendant_has_input_handler(false),
  30         has_child_with_a_scroll_parent(false),
  31         index_of_first_descendants_addition(0),
  32         num_descendants_added(0),
  33         index_of_first_render_surface_layer_list_addition(0),
  34         num_render_surfaces_added(0),
  35         last_drawn_render_surface_layer_list_id(0),
  36         maximum_animation_contents_scale(0.f),
  37         starting_animation_contents_scale(0.f) {}
  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   // Known occlusion above the layer mapped to the content space of the layer.
  47   Occlusion occlusion_in_content_space;
  48
  49   // DrawProperties::opacity may be different than LayerType::opacity,
  50   // particularly in the case when a RenderSurface re-parents the layer's
  51   // opacity, or when opacity is compounded by the hierarchy.
  52   float opacity;
  53
  54   // DrawProperties::blend_mode may be different than LayerType::blend_mode,
  55   // when a RenderSurface re-parents the layer's blend_mode.
  56   SkXfermode::Mode blend_mode;
  57
  58   // xxx_is_animating flags are used to indicate whether the DrawProperties
  59   // are actually meaningful on the main thread. When the properties are
  60   // animating, the main thread may not have the same values that are used
  61   // to draw.
  62   bool target_space_transform_is_animating;
  63   bool screen_space_transform_is_animating;
  64
  65   // True if the layer can use LCD text.
  66   bool can_use_lcd_text;
  67
  68   // The layer whose coordinate space this layer draws into. This can be
  69   // either the same layer (draw_properties_.render_target == this) or an
  70   // ancestor of this layer.
  71   LayerType* render_target;
  72
  73   // This rect is a bounding box around what part of the layer is visible, in
  74   // the layer's coordinate space.
  75   gfx::Rect visible_layer_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   // Number of descendants with a clip parent that is our ancestor. NB - this
  86   // does not include our clip children because they are clipped by us.
  87   size_t num_unclipped_descendants;
  88
  89   // If true, the layer or some layer in its sub-tree has a CopyOutputRequest
  90   // present on it.
  91   bool layer_or_descendant_has_copy_request;
  92
  93   // If true, the layer or one of its descendants has a wheel or touch handler.
  94   bool layer_or_descendant_has_input_handler;
  95
  96   // This is true if the layer has any direct child that has a scroll parent.
  97   // This layer will not be the scroll parent in this case. This information
  98   // lets us avoid work in CalculateDrawPropertiesInternal -- if none of our
  99   // children have scroll parents, we will not need to recur out of order.
 100   bool has_child_with_a_scroll_parent;
 101
 102   // If this layer is visited out of order, its contribution to the descendant
 103   // and render surface layer lists will be put aside in a temporary list.
 104   // These values will allow for an efficient reordering of these additions.
 105   size_t index_of_first_descendants_addition;
 106   size_t num_descendants_added;
 107   size_t index_of_first_render_surface_layer_list_addition;
 108   size_t num_render_surfaces_added;
 109
 110   // Each time we generate a new render surface layer list, an ID is used to
 111   // identify it. |last_drawn_render_surface_layer_list_id| is set to the ID
 112   // that marked the render surface layer list generation which last updated
 113   // these draw properties and determined that this layer will draw itself.
 114   // If these draw properties are not a part of the render surface layer list,
 115   // or the layer doesn't contribute anything, then this ID will be either out
 116   // of date or 0.
 117   int last_drawn_render_surface_layer_list_id;
 118
 119   // The maximum scale during the layers current animation at which content
 120   // should be rastered at to be crisp.
 121   float maximum_animation_contents_scale;
 122
 123   // The scale during the layer animation start at which content should be
 124   // rastered at to be crisp.
 125   float starting_animation_contents_scale;
 126 };
 127
 128 }  // namespace cc
 129
 130 #endif  // CC_LAYERS_DRAW_PROPERTIES_H_