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         screen_space_transform_is_animating(false),
  24         can_use_lcd_text(false),
  25         render_target(nullptr),
  26         num_unclipped_descendants(0),
  27         layer_or_descendant_has_copy_request(false),
  28         layer_or_descendant_has_input_handler(false),
  29         has_child_with_a_scroll_parent(false),
  30         index_of_first_descendants_addition(0),
  31         num_descendants_added(0),
  32         index_of_first_render_surface_layer_list_addition(0),
  33         num_render_surfaces_added(0),
  34         last_drawn_render_surface_layer_list_id(0),
  35         maximum_animation_contents_scale(0.f),
  36         starting_animation_contents_scale(0.f) {}
  37
  38   // Transforms objects from content space to target surface space, where
  39   // this layer would be drawn.
  40   gfx::Transform target_space_transform;
  41
  42   // Transforms objects from content space to screen space (viewport space).
  43   gfx::Transform screen_space_transform;
  44
  45   // Known occlusion above the layer mapped to the content space of the layer.
  46   Occlusion occlusion_in_content_space;
  47
  48   // DrawProperties::opacity may be different than LayerType::opacity,
  49   // particularly in the case when a RenderSurface re-parents the layer's
  50   // opacity, or when opacity is compounded by the hierarchy.
  51   float opacity;
  52
  53   // DrawProperties::blend_mode may be different than LayerType::blend_mode,
  54   // when a RenderSurface re-parents the layer's blend_mode.
  55   SkXfermode::Mode blend_mode;
  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 screen_space_transform_is_animating;
  62
  63   // True if the layer can use LCD text.
  64   bool can_use_lcd_text;
  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   // This rect is a bounding box around what part of the layer is visible, in
  72   // the layer's coordinate space.
  73   gfx::Rect visible_layer_rect;
  74
  75   // In target surface space, the rect that encloses the clipped, drawable
  76   // content of the layer.
  77   gfx::Rect drawable_content_rect;
  78
  79   // In target surface space, the original rect that clipped this layer. This
  80   // value is used to avoid unnecessarily changing GL scissor state.
  81   gfx::Rect clip_rect;
  82
  83   // Number of descendants with a clip parent that is our ancestor. NB - this
  84   // does not include our clip children because they are clipped by us.
  85   size_t num_unclipped_descendants;
  86
  87   // If true, the layer or some layer in its sub-tree has a CopyOutputRequest
  88   // present on it.
  89   bool layer_or_descendant_has_copy_request;
  90
  91   // If true, the layer or one of its descendants has a wheel or touch handler.
  92   bool layer_or_descendant_has_input_handler;
  93
  94   // This is true if the layer has any direct child that has a scroll parent.
  95   // This layer will not be the scroll parent in this case. This information
  96   // lets us avoid work in CalculateDrawPropertiesInternal -- if none of our
  97   // children have scroll parents, we will not need to recur out of order.
  98   bool has_child_with_a_scroll_parent;
  99
 100   // If this layer is visited out of order, its contribution to the descendant
 101   // and render surface layer lists will be put aside in a temporary list.
 102   // These values will allow for an efficient reordering of these additions.
 103   size_t index_of_first_descendants_addition;
 104   size_t num_descendants_added;
 105   size_t index_of_first_render_surface_layer_list_addition;
 106   size_t num_render_surfaces_added;
 107
 108   // Each time we generate a new render surface layer list, an ID is used to
 109   // identify it. |last_drawn_render_surface_layer_list_id| is set to the ID
 110   // that marked the render surface layer list generation which last updated
 111   // these draw properties and determined that this layer will draw itself.
 112   // If these draw properties are not a part of the render surface layer list,
 113   // or the layer doesn't contribute anything, then this ID will be either out
 114   // of date or 0.
 115   int last_drawn_render_surface_layer_list_id;
 116
 117   // The maximum scale during the layers current animation at which content
 118   // should be rastered at to be crisp.
 119   float maximum_animation_contents_scale;
 120
 121   // The scale during the layer animation start at which content should be
 122   // rastered at to be crisp.
 123   float starting_animation_contents_scale;
 124 };
 125
 126 }  // namespace cc
 127
 128 #endif  // CC_LAYERS_DRAW_PROPERTIES_H_