servo/components/gfx/display_list/mod.rs
2014-09-08 20:21:42 -06:00

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Servo heavily uses display lists, which are retained-mode lists of rendering commands to
//! perform. Using a list instead of rendering elements in immediate mode allows transforms, hit
//! testing, and invalidation to be performed using the same primitives as painting. It also allows
//! Servo to aggressively cull invisible and out-of-bounds rendering elements, to reduce overdraw.
//! Finally, display lists allow tiles to be farmed out onto multiple CPUs and rendered in
//! parallel (although this benefit does not apply to GPU-based rendering).
//!
//! Display items describe relatively high-level drawing operations (for example, entire borders
//! and shadows instead of lines and blur operations), to reduce the amount of allocation required.
//! They are therefore not exactly analogous to constructs like Skia pictures, which consist of
//! low-level drawing primitives.
use color::Color;
use render_context::RenderContext;
use text::glyph::CharIndex;
use text::TextRun;
use collections::dlist::DList;
use collections::dlist;
use geom::{Point2D, Rect, SideOffsets2D, Size2D, Matrix2D};
use libc::uintptr_t;
use servo_net::image::base::Image;
use servo_util::geometry::Au;
use servo_util::range::Range;
use std::fmt;
use std::mem;
use std::slice::Items;
use style::computed_values::border_style;
use sync::Arc;
use std::num::Zero;
use std::ptr;
use azure::AzFloat;
use azure::scaled_font::ScaledFont;
use azure::azure_hl::ColorPattern;
pub mod optimizer;
/// An opaque handle to a node. The only safe operation that can be performed on this node is to
/// compare it to another opaque handle or to another node.
///
/// Because the script task's GC does not trace layout, node data cannot be safely stored in layout
/// data structures. Also, layout code tends to be faster when the DOM is not being accessed, for
/// locality reasons. Using `OpaqueNode` enforces this invariant.
#[deriving(Clone, PartialEq)]
pub struct OpaqueNode(pub uintptr_t);
impl OpaqueNode {
/// Returns the address of this node, for debugging purposes.
pub fn id(&self) -> uintptr_t {
let OpaqueNode(pointer) = *self;
pointer
}
}
trait ScaledFontExtensionMethods {
fn draw_text_into_context(&self,
rctx: &RenderContext,
run: &Box<TextRun>,
range: &Range<CharIndex>,
baseline_origin: Point2D<Au>,
color: Color,
antialias: bool);
}
impl ScaledFontExtensionMethods for ScaledFont {
fn draw_text_into_context(&self,
rctx: &RenderContext,
run: &Box<TextRun>,
range: &Range<CharIndex>,
baseline_origin: Point2D<Au>,
color: Color,
antialias: bool) {
use libc::types::common::c99::uint32_t;
use azure::{struct__AzDrawOptions,
struct__AzGlyph,
struct__AzGlyphBuffer,
struct__AzPoint};
use azure::azure::{AzDrawTargetFillGlyphs};
let target = rctx.get_draw_target();
let pattern = ColorPattern::new(color);
let azure_pattern = pattern.azure_color_pattern;
assert!(azure_pattern.is_not_null());
let fields = if antialias {
0x0200
} else {
0
};
let mut options = struct__AzDrawOptions {
mAlpha: 1f64 as AzFloat,
fields: fields,
};
let mut origin = baseline_origin.clone();
let mut azglyphs = vec!();
azglyphs.reserve(range.length().to_uint());
for (glyphs, _offset, slice_range) in run.iter_slices_for_range(range) {
for (_i, glyph) in glyphs.iter_glyphs_for_char_range(&slice_range) {
let glyph_advance = glyph.advance();
let glyph_offset = glyph.offset().unwrap_or(Zero::zero());
let azglyph = struct__AzGlyph {
mIndex: glyph.id() as uint32_t,
mPosition: struct__AzPoint {
x: (origin.x + glyph_offset.x).to_nearest_px() as AzFloat,
y: (origin.y + glyph_offset.y).to_nearest_px() as AzFloat
}
};
origin = Point2D(origin.x + glyph_advance, origin.y);
azglyphs.push(azglyph)
};
}
let azglyph_buf_len = azglyphs.len();
if azglyph_buf_len == 0 { return; } // Otherwise the Quartz backend will assert.
let mut glyphbuf = struct__AzGlyphBuffer {
mGlyphs: azglyphs.as_mut_ptr(),
mNumGlyphs: azglyph_buf_len as uint32_t
};
unsafe {
// TODO(Issue #64): this call needs to move into azure_hl.rs
AzDrawTargetFillGlyphs(target.azure_draw_target,
self.get_ref(),
&mut glyphbuf,
azure_pattern,
&mut options,
ptr::mut_null());
}
}
}
/// "Steps" as defined by CSS 2.1 § E.2.
#[deriving(Clone, PartialEq)]
pub enum StackingLevel {
/// The border and backgrounds for the root of this stacking context: steps 1 and 2.
BackgroundAndBordersStackingLevel,
/// Borders and backgrounds for block-level descendants: step 4.
BlockBackgroundsAndBordersStackingLevel,
/// Floats: step 5. These are treated as pseudo-stacking contexts.
FloatStackingLevel,
/// All other content.
ContentStackingLevel,
/// Positioned descendant stacking contexts, along with their `z-index` levels.
///
/// TODO(pcwalton): `z-index` should be the actual CSS property value in order to handle
/// `auto`, not just an integer.
PositionedDescendantStackingLevel(i32)
}
impl StackingLevel {
pub fn from_background_and_border_level(level: BackgroundAndBorderLevel) -> StackingLevel {
match level {
RootOfStackingContextLevel => BackgroundAndBordersStackingLevel,
BlockLevel => BlockBackgroundsAndBordersStackingLevel,
ContentLevel => ContentStackingLevel,
}
}
}
struct StackingContext {
/// The border and backgrounds for the root of this stacking context: steps 1 and 2.
pub background_and_borders: DisplayList,
/// Borders and backgrounds for block-level descendants: step 4.
pub block_backgrounds_and_borders: DisplayList,
/// Floats: step 5. These are treated as pseudo-stacking contexts.
pub floats: DisplayList,
/// All other content.
pub content: DisplayList,
/// Positioned descendant stacking contexts, along with their `z-index` levels.
///
/// TODO(pcwalton): `z-index` should be the actual CSS property value in order to handle
/// `auto`, not just an integer.
pub positioned_descendants: Vec<(i32, DisplayList)>,
}
impl StackingContext {
/// Creates a stacking context from a display list.
fn new(list: DisplayList) -> StackingContext {
let DisplayList {
list: list
} = list;
let mut stacking_context = StackingContext {
background_and_borders: DisplayList::new(),
block_backgrounds_and_borders: DisplayList::new(),
floats: DisplayList::new(),
content: DisplayList::new(),
positioned_descendants: Vec::new(),
};
for item in list.move_iter() {
match item {
ClipDisplayItemClass(box ClipDisplayItem {
base: base,
children: sublist
}) => {
let sub_stacking_context = StackingContext::new(sublist);
stacking_context.merge_with_clip(sub_stacking_context, &base.bounds, base.node)
}
item => {
match item.base().level {
BackgroundAndBordersStackingLevel => {
stacking_context.background_and_borders.push(item)
}
BlockBackgroundsAndBordersStackingLevel => {
stacking_context.block_backgrounds_and_borders.push(item)
}
FloatStackingLevel => stacking_context.floats.push(item),
ContentStackingLevel => stacking_context.content.push(item),
PositionedDescendantStackingLevel(z_index) => {
match stacking_context.positioned_descendants
.mut_iter()
.find(|& &(z, _)| z_index == z) {
Some(&(_, ref mut my_list)) => {
my_list.push(item);
continue
}
None => {}
}
let mut new_list = DisplayList::new();
new_list.list.push(item);
stacking_context.positioned_descendants.push((z_index, new_list))
}
}
}
}
}
stacking_context
}
/// Merges another stacking context into this one, with the given clipping rectangle and DOM
/// node that supplies it.
fn merge_with_clip(&mut self,
other: StackingContext,
clip_rect: &Rect<Au>,
clipping_dom_node: OpaqueNode) {
let StackingContext {
background_and_borders,
block_backgrounds_and_borders,
floats,
content,
positioned_descendants: positioned_descendants
} = other;
let push = |destination: &mut DisplayList, source: DisplayList, level| {
if !source.is_empty() {
let base = BaseDisplayItem::new(*clip_rect, clipping_dom_node, level);
destination.push(ClipDisplayItemClass(box ClipDisplayItem::new(base, source)))
}
};
push(&mut self.background_and_borders,
background_and_borders,
BackgroundAndBordersStackingLevel);
push(&mut self.block_backgrounds_and_borders,
block_backgrounds_and_borders,
BlockBackgroundsAndBordersStackingLevel);
push(&mut self.floats, floats, FloatStackingLevel);
push(&mut self.content, content, ContentStackingLevel);
for (z_index, list) in positioned_descendants.move_iter() {
match self.positioned_descendants
.mut_iter()
.find(|& &(existing_z_index, _)| z_index == existing_z_index) {
Some(&(_, ref mut existing_list)) => {
push(existing_list, list, PositionedDescendantStackingLevel(z_index));
continue
}
None => {}
}
let mut new_list = DisplayList::new();
push(&mut new_list, list, PositionedDescendantStackingLevel(z_index));
self.positioned_descendants.push((z_index, new_list));
}
}
}
/// Which level to place backgrounds and borders in.
pub enum BackgroundAndBorderLevel {
RootOfStackingContextLevel,
BlockLevel,
ContentLevel,
}
/// A list of rendering operations to be performed.
#[deriving(Clone)]
pub struct DisplayList {
pub list: DList<DisplayItem>,
}
pub enum DisplayListIterator<'a> {
EmptyDisplayListIterator,
ParentDisplayListIterator(Items<'a,DisplayList>),
}
impl<'a> Iterator<&'a DisplayList> for DisplayListIterator<'a> {
#[inline]
fn next(&mut self) -> Option<&'a DisplayList> {
match *self {
EmptyDisplayListIterator => None,
ParentDisplayListIterator(ref mut subiterator) => subiterator.next(),
}
}
}
impl DisplayList {
/// Creates a new display list.
pub fn new() -> DisplayList {
DisplayList {
list: DList::new(),
}
}
/// Appends the given item to the display list.
pub fn push(&mut self, item: DisplayItem) {
self.list.push(item)
}
/// Appends the given display list to this display list, consuming the other display list in
/// the process.
pub fn push_all_move(&mut self, other: DisplayList) {
self.list.append(other.list)
}
pub fn debug(&self) {
if log_enabled!(::log::DEBUG) {
for item in self.list.iter() {
item.debug_with_level(0);
}
}
}
/// Draws the display list into the given render context. The display list must be flattened
/// first for correct painting.
pub fn draw_into_context(&self, render_context: &mut RenderContext,
current_transform: &Matrix2D<AzFloat>) {
debug!("Beginning display list.");
for item in self.list.iter() {
item.draw_into_context(render_context, current_transform)
}
debug!("Ending display list.");
}
/// Returns a preorder iterator over the given display list.
pub fn iter<'a>(&'a self) -> DisplayItemIterator<'a> {
ParentDisplayItemIterator(self.list.iter())
}
/// Returns true if this list is empty and false otherwise.
fn is_empty(&self) -> bool {
self.list.len() == 0
}
/// Flattens a display list into a display list with a single stacking level according to the
/// steps in CSS 2.1 § E.2.
///
/// This must be called before `draw_into_context()` is for correct results.
pub fn flatten(self, resulting_level: StackingLevel) -> DisplayList {
// TODO(pcwalton): Sort positioned children according to z-index.
let mut result = DisplayList::new();
let StackingContext {
background_and_borders,
block_backgrounds_and_borders,
floats,
content,
positioned_descendants: mut positioned_descendants
} = StackingContext::new(self);
// Steps 1 and 2: Borders and background for the root.
result.push_all_move(background_and_borders);
// TODO(pcwalton): Sort positioned children according to z-index.
// Step 3: Positioned descendants with negative z-indices.
for &(ref mut z_index, ref mut list) in positioned_descendants.mut_iter() {
if *z_index < 0 {
result.push_all_move(mem::replace(list, DisplayList::new()))
}
}
// Step 4: Block backgrounds and borders.
result.push_all_move(block_backgrounds_and_borders);
// Step 5: Floats.
result.push_all_move(floats);
// TODO(pcwalton): Step 6: Inlines that generate stacking contexts.
// Step 7: Content.
result.push_all_move(content);
// Steps 8 and 9: Positioned descendants with nonnegative z-indices.
for &(ref mut z_index, ref mut list) in positioned_descendants.mut_iter() {
if *z_index >= 0 {
result.push_all_move(mem::replace(list, DisplayList::new()))
}
}
// TODO(pcwalton): Step 10: Outlines.
result.set_stacking_level(resulting_level);
result
}
/// Sets the stacking level for this display list and all its subitems.
fn set_stacking_level(&mut self, new_level: StackingLevel) {
for item in self.list.mut_iter() {
item.mut_base().level = new_level;
match item.mut_sublist() {
None => {}
Some(sublist) => sublist.set_stacking_level(new_level),
}
}
}
}
/// One drawing command in the list.
#[deriving(Clone)]
pub enum DisplayItem {
SolidColorDisplayItemClass(Box<SolidColorDisplayItem>),
TextDisplayItemClass(Box<TextDisplayItem>),
ImageDisplayItemClass(Box<ImageDisplayItem>),
BorderDisplayItemClass(Box<BorderDisplayItem>),
LineDisplayItemClass(Box<LineDisplayItem>),
ClipDisplayItemClass(Box<ClipDisplayItem>),
/// A pseudo-display item that exists only so that queries like `ContentBoxQuery` and
/// `ContentBoxesQuery` can be answered.
///
/// FIXME(pcwalton): This is really bogus. Those queries should not consult the display list
/// but should instead consult the flow/box tree.
PseudoDisplayItemClass(Box<BaseDisplayItem>),
}
/// Information common to all display items.
#[deriving(Clone)]
pub struct BaseDisplayItem {
/// The boundaries of the display item.
///
/// TODO: Which coordinate system should this use?
pub bounds: Rect<Au>,
/// The originating DOM node.
pub node: OpaqueNode,
/// The stacking level in which this display item lives.
pub level: StackingLevel,
}
impl BaseDisplayItem {
pub fn new(bounds: Rect<Au>, node: OpaqueNode, level: StackingLevel) -> BaseDisplayItem {
BaseDisplayItem {
bounds: bounds,
node: node,
level: level,
}
}
}
/// Renders a solid color.
#[deriving(Clone)]
pub struct SolidColorDisplayItem {
pub base: BaseDisplayItem,
pub color: Color,
}
/// Renders text.
#[deriving(Clone)]
pub struct TextDisplayItem {
/// Fields common to all display items.
pub base: BaseDisplayItem,
/// The text run.
pub text_run: Arc<Box<TextRun>>,
/// The range of text within the text run.
pub range: Range<CharIndex>,
/// The color of the text.
pub text_color: Color,
pub baseline_origin: Point2D<Au>,
pub orientation: TextOrientation,
}
#[deriving(Clone, Eq, PartialEq)]
pub enum TextOrientation {
Upright,
SidewaysLeft,
SidewaysRight,
}
/// Renders an image.
#[deriving(Clone)]
pub struct ImageDisplayItem {
pub base: BaseDisplayItem,
pub image: Arc<Box<Image>>,
/// The dimensions to which the image display item should be stretched. If this is smaller than
/// the bounds of this display item, then the image will be repeated in the appropriate
/// direction to tile the entire bounds.
pub stretch_size: Size2D<Au>,
}
/// Renders a border.
#[deriving(Clone)]
pub struct BorderDisplayItem {
pub base: BaseDisplayItem,
/// The border widths
pub border: SideOffsets2D<Au>,
/// The border colors.
pub color: SideOffsets2D<Color>,
/// The border styles.
pub style: SideOffsets2D<border_style::T>
}
/// Renders a line segment.
#[deriving(Clone)]
pub struct LineDisplayItem {
pub base: BaseDisplayItem,
/// The line segment color.
pub color: Color,
/// The line segment style.
pub style: border_style::T
}
/// Clips a list of child display items to this display item's boundaries.
#[deriving(Clone)]
pub struct ClipDisplayItem {
/// The base information.
pub base: BaseDisplayItem,
/// The child nodes.
pub children: DisplayList,
}
impl ClipDisplayItem {
pub fn new(base: BaseDisplayItem, children: DisplayList) -> ClipDisplayItem {
ClipDisplayItem {
base: base,
children: children,
}
}
}
pub enum DisplayItemIterator<'a> {
EmptyDisplayItemIterator,
ParentDisplayItemIterator(dlist::Items<'a,DisplayItem>),
}
impl<'a> Iterator<&'a DisplayItem> for DisplayItemIterator<'a> {
#[inline]
fn next(&mut self) -> Option<&'a DisplayItem> {
match *self {
EmptyDisplayItemIterator => None,
ParentDisplayItemIterator(ref mut subiterator) => subiterator.next(),
}
}
}
impl DisplayItem {
/// Renders this display item into the given render context.
fn draw_into_context(&self, render_context: &mut RenderContext,
current_transform: &Matrix2D<AzFloat>) {
// This should have been flattened to the content stacking level first.
assert!(self.base().level == ContentStackingLevel);
match *self {
SolidColorDisplayItemClass(ref solid_color) => {
render_context.draw_solid_color(&solid_color.base.bounds, solid_color.color)
}
ClipDisplayItemClass(ref clip) => {
render_context.draw_push_clip(&clip.base.bounds);
for item in clip.children.iter() {
(*item).draw_into_context(render_context, current_transform);
}
render_context.draw_pop_clip();
}
TextDisplayItemClass(ref text) => {
debug!("Drawing text at {}.", text.base.bounds);
// Optimization: Dont set a transform matrix for upright text,
// and pass a strart point to `draw_text_into_context`.
// For sideways text, its easier to do the rotation such that its center
// (the baselines start point) is at (0, 0) coordinates.
let baseline_origin = match text.orientation {
Upright => text.baseline_origin,
SidewaysLeft => {
let x = text.baseline_origin.x.to_nearest_px() as AzFloat;
let y = text.baseline_origin.y.to_nearest_px() as AzFloat;
render_context.draw_target.set_transform(&current_transform.mul(
&Matrix2D::new(
0., -1.,
1., 0.,
x, y
)
));
Zero::zero()
},
SidewaysRight => {
let x = text.baseline_origin.x.to_nearest_px() as AzFloat;
let y = text.baseline_origin.y.to_nearest_px() as AzFloat;
render_context.draw_target.set_transform(&current_transform.mul(
&Matrix2D::new(
0., 1.,
-1., 0.,
x, y
)
));
Zero::zero()
}
};
render_context.font_ctx.get_render_font_from_template(
&text.text_run.font_template,
text.text_run.pt_size,
render_context.opts.render_backend
).borrow().draw_text_into_context(
render_context,
&*text.text_run,
&text.range,
baseline_origin,
text.text_color,
render_context.opts.enable_text_antialiasing
);
// Undo the transform, only when we did one.
if text.orientation != Upright {
render_context.draw_target.set_transform(current_transform)
}
}
ImageDisplayItemClass(ref image_item) => {
debug!("Drawing image at {:?}.", image_item.base.bounds);
let mut y_offset = Au(0);
while y_offset < image_item.base.bounds.size.height {
let mut x_offset = Au(0);
while x_offset < image_item.base.bounds.size.width {
let mut bounds = image_item.base.bounds;
bounds.origin.x = bounds.origin.x + x_offset;
bounds.origin.y = bounds.origin.y + y_offset;
bounds.size = image_item.stretch_size;
render_context.draw_image(bounds, image_item.image.clone());
x_offset = x_offset + image_item.stretch_size.width;
}
y_offset = y_offset + image_item.stretch_size.height;
}
}
BorderDisplayItemClass(ref border) => {
render_context.draw_border(&border.base.bounds,
border.border,
border.color,
border.style)
}
LineDisplayItemClass(ref line) => {
render_context.draw_line(&line.base.bounds,
line.color,
line.style)
}
PseudoDisplayItemClass(_) => {}
}
}
pub fn base<'a>(&'a self) -> &'a BaseDisplayItem {
match *self {
SolidColorDisplayItemClass(ref solid_color) => &solid_color.base,
TextDisplayItemClass(ref text) => &text.base,
ImageDisplayItemClass(ref image_item) => &image_item.base,
BorderDisplayItemClass(ref border) => &border.base,
LineDisplayItemClass(ref line) => &line.base,
ClipDisplayItemClass(ref clip) => &clip.base,
PseudoDisplayItemClass(ref base) => &**base,
}
}
pub fn mut_base<'a>(&'a mut self) -> &'a mut BaseDisplayItem {
match *self {
SolidColorDisplayItemClass(ref mut solid_color) => &mut solid_color.base,
TextDisplayItemClass(ref mut text) => &mut text.base,
ImageDisplayItemClass(ref mut image_item) => &mut image_item.base,
BorderDisplayItemClass(ref mut border) => &mut border.base,
LineDisplayItemClass(ref mut line) => &mut line.base,
ClipDisplayItemClass(ref mut clip) => &mut clip.base,
PseudoDisplayItemClass(ref mut base) => &mut **base,
}
}
pub fn bounds(&self) -> Rect<Au> {
self.base().bounds
}
pub fn children<'a>(&'a self) -> DisplayItemIterator<'a> {
match *self {
ClipDisplayItemClass(ref clip) => ParentDisplayItemIterator(clip.children.list.iter()),
SolidColorDisplayItemClass(..) |
TextDisplayItemClass(..) |
ImageDisplayItemClass(..) |
BorderDisplayItemClass(..) |
LineDisplayItemClass(..) |
PseudoDisplayItemClass(..) => EmptyDisplayItemIterator,
}
}
/// Returns a mutable reference to the sublist contained within this display list item, if any.
fn mut_sublist<'a>(&'a mut self) -> Option<&'a mut DisplayList> {
match *self {
ClipDisplayItemClass(ref mut clip) => Some(&mut clip.children),
SolidColorDisplayItemClass(..) |
TextDisplayItemClass(..) |
ImageDisplayItemClass(..) |
BorderDisplayItemClass(..) |
LineDisplayItemClass(..) |
PseudoDisplayItemClass(..) => None,
}
}
pub fn debug_with_level(&self, level: uint) {
let mut indent = String::new();
for _ in range(0, level) {
indent.push_str("| ")
}
debug!("{}+ {}", indent, self);
for child in self.children() {
child.debug_with_level(level + 1);
}
}
}
impl fmt::Show for DisplayItem {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{} @ {} ({:x})",
match *self {
SolidColorDisplayItemClass(_) => "SolidColor",
TextDisplayItemClass(_) => "Text",
ImageDisplayItemClass(_) => "Image",
BorderDisplayItemClass(_) => "Border",
LineDisplayItemClass(_) => "Line",
ClipDisplayItemClass(_) => "Clip",
PseudoDisplayItemClass(_) => "Pseudo",
},
self.base().bounds,
self.base().node.id(),
)
}
}