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https://github.com/servo/servo.git
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layout: Refactor InlineFlow::assign_height to pull out horizontal
position calculation into a separate function.
This commit is contained in:
Patrick Walton
parent
7148a28611
commit
2624b937aa
1 changed files with 154 additions and 139 deletions
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@ -510,6 +510,114 @@ impl InlineFlow {
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// For now, don't traverse the subtree rooted here
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true
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}
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/// Returns the relative offset from the baseline for this box, taking into account the value
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/// of the CSS `vertical-align` property.
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///
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/// The extra boolean is set if and only if `biggest_top` and/or `biggest_bottom` were updated.
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/// That is, if the box has a `top` or `bottom` value, true is returned.
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fn relative_offset_from_baseline(cur_box: @Box,
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ascent: Au,
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parent_text_top: Au,
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parent_text_bottom: Au,
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top_from_base: &mut Au,
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bottom_from_base: &mut Au,
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biggest_top: &mut Au,
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biggest_bottom: &mut Au)
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-> (Au, bool) {
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match cur_box.vertical_align() {
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vertical_align::baseline => (-ascent, false),
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vertical_align::middle => {
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// TODO: x-height value should be used from font info.
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let xheight = Au::new(0);
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(-(xheight + cur_box.box_height()).scale_by(0.5), false)
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},
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vertical_align::sub => {
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// TODO: The proper position for subscripts should be used.
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// Lower the baseline to the proper position for subscripts
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let sub_offset = Au::new(0);
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(sub_offset - ascent, false)
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},
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vertical_align::super_ => {
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// TODO: The proper position for superscripts should be used.
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// Raise the baseline to the proper position for superscripts
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let super_offset = Au::new(0);
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(-super_offset - ascent, false)
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},
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vertical_align::text_top => {
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let box_height = *top_from_base + *bottom_from_base;
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let prev_bottom_from_base = *bottom_from_base;
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*top_from_base = parent_text_top;
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*bottom_from_base = box_height - *top_from_base;
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(*bottom_from_base - prev_bottom_from_base - ascent, false)
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},
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vertical_align::text_bottom => {
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let box_height = *top_from_base + *bottom_from_base;
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let prev_bottom_from_base = *bottom_from_base;
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*bottom_from_base = parent_text_bottom;
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*top_from_base = box_height - *bottom_from_base;
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(*bottom_from_base - prev_bottom_from_base - ascent, false)
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},
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vertical_align::top => {
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if *biggest_top < (*top_from_base + *bottom_from_base) {
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*biggest_top = *top_from_base + *bottom_from_base;
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}
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let offset_top = *top_from_base - ascent;
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(offset_top, true)
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},
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vertical_align::bottom => {
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if *biggest_bottom < (*top_from_base + *bottom_from_base) {
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*biggest_bottom = *top_from_base + *bottom_from_base;
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}
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let offset_bottom = -(*bottom_from_base + ascent);
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(offset_bottom, true)
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},
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vertical_align::Length(length) => (-(length + ascent), false),
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vertical_align::Percentage(p) => {
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let pt_size = cur_box.font_style().pt_size;
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let line_height = cur_box.calculate_line_height(Au::from_pt(pt_size));
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let percent_offset = line_height.scale_by(p);
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(-(percent_offset + ascent), false)
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}
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}
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}
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/// Sets box X positions based on alignment for one line.
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fn set_horizontal_box_positions(boxes: &[@Box], line: &LineBox) {
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// Figure out how much width we have.
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let slack_width = Au::max(Au(0), line.green_zone.width - line.bounds.size.width);
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// Get the text alignment.
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//
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// TODO(burg, issue #222): use 'text-align' property from `InlineFlow`'s block container,
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// not from the style of the first box child.
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let linebox_align = if line.range.begin() < boxes.len() {
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let first_box = boxes[line.range.begin()];
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first_box.nearest_ancestor_element().style().Text.text_align
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} else {
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// Nothing to lay out, so assume left alignment.
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text_align::left
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};
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// Set the box x positions based on that alignment.
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let mut offset_x = line.bounds.origin.x;
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offset_x = offset_x + match linebox_align {
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// So sorry, but justified text is more complicated than shuffling linebox
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// coordinates.
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//
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// TODO(burg, issue #213): Implement `text-align: justify`.
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text_align::left | text_align::justify => Au(0),
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text_align::center => slack_width.scale_by(0.5),
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text_align::right => slack_width,
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};
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for i in line.range.eachi() {
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let box = &boxes[i];
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let size = box.position.get().size;
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box.position.set(Rect(Point2D(offset_x, box.position.get().origin.y), size));
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offset_x = offset_x + size.width;
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}
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}
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}
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impl Flow for InlineFlow {
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@ -589,7 +697,8 @@ impl Flow for InlineFlow {
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fn assign_height(&mut self, _: &mut LayoutContext) {
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debug!("assign_height_inline: assigning height for flow {}", self.base.id);
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// Divide the boxes into lines
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// Divide the boxes into lines.
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//
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// TODO(#226): Get the CSS `line-height` property from the containing block's style to
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// determine minimum linebox height.
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//
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@ -607,68 +716,20 @@ impl Flow for InlineFlow {
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let mut line_height_offset = Au::new(0);
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// Now, go through each line and lay out the boxes inside
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// Now, go through each line and lay out the boxes inside.
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for line in self.lines.mut_iter() {
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// We need to distribute extra width based on text-align.
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let mut slack_width = line.green_zone.width - line.bounds.size.width;
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if slack_width < Au::new(0) {
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slack_width = Au::new(0);
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}
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// Get the text alignment.
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// TODO(Issue #222): use 'text-align' property from InlineFlow's
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// block container, not from the style of the first box child.
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let linebox_align = if line.range.begin() < self.boxes.len() {
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let first_box = self.boxes[line.range.begin()];
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first_box.nearest_ancestor_element().style().Text.text_align
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} else {
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// Nothing to lay out, so assume left alignment.
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text_align::left
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};
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// Set the box x positions
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let mut offset_x = line.bounds.origin.x;
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match linebox_align {
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// So sorry, but justified text is more complicated than shuffling linebox coordinates.
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// TODO(Issue #213): implement `text-align: justify`
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text_align::left | text_align::justify => {
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for i in line.range.eachi() {
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let box = &self.boxes[i];
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box.position.mutate().ptr.origin.x = offset_x;
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offset_x = offset_x + box.position.get().size.width;
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}
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}
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text_align::center => {
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offset_x = offset_x + slack_width.scale_by(0.5);
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for i in line.range.eachi() {
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let box = &self.boxes[i];
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box.position.mutate().ptr.origin.x = offset_x;
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offset_x = offset_x + box.position.get().size.width;
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}
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}
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text_align::right => {
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offset_x = offset_x + slack_width;
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for i in line.range.eachi() {
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let box = &self.boxes[i];
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box.position.mutate().ptr.origin.x = offset_x;
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offset_x = offset_x + box.position.get().size.width;
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}
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}
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};
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// Lay out boxes horizontally.
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InlineFlow::set_horizontal_box_positions(self.boxes, line);
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// Set the top y position of the current linebox.
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// `line_height_offset` is updated at the end of the previous loop.
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line.bounds.origin.y = line.bounds.origin.y + line_height_offset;
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// Calculate the distance from baseline to the top of the linebox.
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let mut topmost = Au::new(0);
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// Calculate the distance from baseline to the bottom of the linebox.
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let mut bottommost = Au::new(0);
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// Calculate the biggest height among boxes with 'top' value.
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let mut biggest_top = Au::new(0);
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// Calculate the biggest height among boxes with 'bottom' value.
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let mut biggest_bottom = Au::new(0);
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// Calculate the distance from baseline to the top and bottom of the linebox.
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let (mut topmost, mut bottommost) = (Au(0), Au(0));
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// Calculate the biggest height among boxes with 'top' and 'bottom' values
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// respectively.
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let (mut biggest_top, mut biggest_bottom) = (Au(0), Au(0));
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for box_i in line.range.eachi() {
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let cur_box = self.boxes[box_i];
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@ -678,8 +739,8 @@ impl Flow for InlineFlow {
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ImageBox(ref image_box) => {
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let mut height = image_box.image_height(cur_box);
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// TODO: margin, border, padding's top and bottom should be calculated in advance,
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// since baseline of image is bottom margin edge.
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// TODO: margin, border, padding's top and bottom should be calculated in
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// advance, since baseline of image is bottom margin edge.
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let mut top;
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let mut bottom;
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{
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@ -726,92 +787,45 @@ impl Flow for InlineFlow {
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fail!("Unscanned text boxes should have been scanned by now.")
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}
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};
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let mut top_from_base = top_from_base;
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let mut bottom_from_base = bottom_from_base;
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// To calculate text-top and text-bottom value of 'vertical-align',
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// we should find the top and bottom of the content area of parent box.
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// The content area is defined in "http://www.w3.org/TR/CSS2/visudet.html#inline-non-replaced".
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// TODO: We should extract em-box info from font size of parent
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// and calcuate the distances from baseline to the top and the bottom of parent's content area.
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// The content area is defined in:
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// http://www.w3.org/TR/CSS2/visudet.html#inline-non-replaced
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//
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// TODO: We should extract em-box info from the font size of the parent and
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// calculate the distances from the baseline to the top and the bottom of the
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// parent's content area.
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// It should calculate the distance from baseline to the top of parent's content area.
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// But, it is assumed now as font size of parent.
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// We should calculate the distance from baseline to the top of parent's content
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// area. But for now we assume it's the parent's font size.
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let mut parent_text_top;
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// It should calculate the distance from baseline to the bottom of parent's content area.
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// But, it is assumed now as 0.
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let parent_text_bottom = Au::new(0);
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// Get parent node
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let parent = cur_box.node.parent_node();
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// We should calculate the distance from baseline to the bottom of the parent's
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// content area. But for now we assume it's zero.
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let parent_text_bottom = Au::new(0);
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let parent = cur_box.node.parent_node();
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let font_size = parent.unwrap().style().Font.font_size;
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parent_text_top = font_size;
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// This flag decides whether topmost and bottommost are updated or not.
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// That is, if the box has top or bottom value, no_update_flag becomes true.
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let mut no_update_flag = false;
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// Calculate a relative offset from baseline.
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let offset = match cur_box.vertical_align() {
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vertical_align::baseline => {
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-ascent
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},
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vertical_align::middle => {
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// TODO: x-height value should be used from font info.
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let xheight = Au::new(0);
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-(xheight + cur_box.box_height()).scale_by(0.5)
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},
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vertical_align::sub => {
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// TODO: The proper position for subscripts should be used.
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// Lower the baseline to the proper position for subscripts
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let sub_offset = Au::new(0);
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(sub_offset - ascent)
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},
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vertical_align::super_ => {
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// TODO: The proper position for superscripts should be used.
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// Raise the baseline to the proper position for superscripts
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let super_offset = Au::new(0);
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(-super_offset - ascent)
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},
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vertical_align::text_top => {
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let box_height = top_from_base + bottom_from_base;
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let prev_bottom_from_base = bottom_from_base;
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top_from_base = parent_text_top;
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bottom_from_base = box_height - top_from_base;
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(bottom_from_base - prev_bottom_from_base - ascent)
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},
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vertical_align::text_bottom => {
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let box_height = top_from_base + bottom_from_base;
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let prev_bottom_from_base = bottom_from_base;
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bottom_from_base = parent_text_bottom;
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top_from_base = box_height - bottom_from_base;
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(bottom_from_base - prev_bottom_from_base - ascent)
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},
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vertical_align::top => {
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if biggest_top < (top_from_base + bottom_from_base) {
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biggest_top = top_from_base + bottom_from_base;
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}
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let offset_top = top_from_base - ascent;
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no_update_flag = true;
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offset_top
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},
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vertical_align::bottom => {
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if biggest_bottom < (top_from_base + bottom_from_base) {
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biggest_bottom = top_from_base + bottom_from_base;
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}
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let offset_bottom = -(bottom_from_base + ascent);
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no_update_flag = true;
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offset_bottom
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},
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vertical_align::Length(length) => {
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-(length + ascent)
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},
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vertical_align::Percentage(p) => {
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let pt_size = cur_box.font_style().pt_size;
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let line_height = cur_box.calculate_line_height(Au::from_pt(pt_size));
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let percent_offset = line_height.scale_by(p);
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-(percent_offset + ascent)
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}
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};
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// Calculate a relative offset from the baseline.
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//
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// The no-update flag decides whether `biggest_top` and `biggest_bottom` are
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// updated or not. That is, if the box has a `top` or `bottom` value,
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// `no_update_flag` becomes true.
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let (offset, no_update_flag) =
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InlineFlow::relative_offset_from_baseline(cur_box,
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ascent,
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parent_text_top,
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parent_text_bottom,
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&mut top_from_base,
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&mut bottom_from_base,
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&mut biggest_top,
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&mut biggest_bottom);
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// If the current box has 'top' or 'bottom' value, no_update_flag is true.
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// Otherwise, topmost and bottomost are updated.
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@ -825,15 +839,15 @@ impl Flow for InlineFlow {
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cur_box.position.mutate().ptr.origin.y = line.bounds.origin.y + offset;
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}
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// Calculate the distance from baseline to the top of the biggest box with 'bottom' value.
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// Then, if necessary, update the topmost.
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// Calculate the distance from baseline to the top of the biggest box with 'bottom'
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// value. Then, if necessary, update the topmost.
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let topmost_of_bottom = biggest_bottom - bottommost;
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if topmost_of_bottom > topmost {
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topmost = topmost_of_bottom;
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}
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// Calculate the distance from baseline to the bottom of the biggest box with 'top' value.
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// Then, if necessary, update the bottommost.
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// Calculate the distance from baseline to the bottom of the biggest box with 'top'
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// value. Then, if necessary, update the bottommost.
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let bottommost_of_top = biggest_top - topmost;
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if bottommost_of_top > bottommost {
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bottommost = bottommost_of_top;
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@ -856,7 +870,8 @@ impl Flow for InlineFlow {
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}
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// This is used to set the top y position of the next linebox in the next loop.
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line_height_offset = line_height_offset + topmost + bottommost - line.bounds.size.height;
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line_height_offset = line_height_offset + topmost + bottommost -
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line.bounds.size.height;
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line.bounds.size.height = topmost + bottommost;
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} // End of `lines.each` loop.
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