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Temporary implementation of Canvas.MeasureText

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paulrouget committed Sep 21, 2019
1 parent 748fa72 commit 3695fb1eb4182b47b80ed31983a5651c8148aef6
@@ -24,6 +24,7 @@ use crate::dom::globalscope::GlobalScope;
use crate::dom::htmlcanvaselement::{CanvasContext, HTMLCanvasElement};
use crate::dom::imagedata::ImageData;
use crate::dom::node::{Node, NodeDamage};
use crate::dom::textmetrics::TextMetrics;
use crate::unpremultiplytable::UNPREMULTIPLY_TABLE;
use canvas_traits::canvas::{Canvas2dMsg, CanvasId, CanvasMsg};
use canvas_traits::canvas::{CompositionOrBlending, FillOrStrokeStyle, FillRule};
@@ -873,6 +874,15 @@ impl CanvasState {
self.send_canvas_2d_msg(Canvas2dMsg::FillText(parsed_text, x, y, max_width));
}

// https://html.spec.whatwg.org/multipage/#textmetrics
pub fn MeasureText(&self, global: &GlobalScope, _text: DOMString) -> DomRoot<TextMetrics> {
// FIXME: for now faking the implementation of MeasureText().
// See https://github.com/servo/servo/issues/5411#issuecomment-533776291
TextMetrics::new(
global, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
)
}

// https://html.spec.whatwg.org/multipage/#dom-context-2d-linewidth
pub fn LineWidth(&self) -> f64 {
self.state.borrow().line_width
@@ -1671,6 +1681,11 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
self.mark_as_dirty();
}

// https://html.spec.whatwg.org/multipage/#textmetrics
fn MeasureText(&self, text: DOMString) -> DomRoot<TextMetrics> {
self.canvas_state.borrow().MeasureText(&self.global(), text)
}

// https://html.spec.whatwg.org/multipage/#dom-context-2d-drawimage
fn DrawImage(&self, image: CanvasImageSource, dx: f64, dy: f64) -> ErrorResult {
self.canvas_state
@@ -484,6 +484,7 @@ pub mod text;
pub mod textcontrol;
pub mod textdecoder;
pub mod textencoder;
pub mod textmetrics;
pub mod texttrack;
pub mod texttrackcue;
pub mod texttrackcuelist;
@@ -23,6 +23,7 @@ use crate::dom::globalscope::GlobalScope;
use crate::dom::htmlcanvaselement::HTMLCanvasElement;
use crate::dom::imagedata::ImageData;
use crate::dom::offscreencanvas::OffscreenCanvas;
use crate::dom::textmetrics::TextMetrics;
use dom_struct::dom_struct;
use euclid::default::Size2D;

@@ -244,6 +245,11 @@ impl OffscreenCanvasRenderingContext2DMethods for OffscreenCanvasRenderingContex
self.canvas_state.borrow().FillText(text, x, y, max_width)
}

// https://html.spec.whatwg.org/multipage/#textmetrics
fn MeasureText(&self, text: DOMString) -> DomRoot<TextMetrics> {
self.canvas_state.borrow().MeasureText(&self.global(), text)
}

// https://html.spec.whatwg.org/multipage/#dom-context-2d-linewidth
fn LineWidth(&self) -> f64 {
self.canvas_state.borrow().LineWidth()
@@ -0,0 +1,158 @@
/* 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 https://mozilla.org/MPL/2.0/. */

use crate::dom::bindings::codegen::Bindings::TextMetricsBinding;
use crate::dom::bindings::codegen::Bindings::TextMetricsBinding::TextMetricsMethods;
use crate::dom::bindings::num::Finite;
use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
use crate::dom::bindings::root::DomRoot;
use crate::dom::globalscope::GlobalScope;
use dom_struct::dom_struct;

#[dom_struct]
pub struct TextMetrics {
reflector_: Reflector,
width: Finite<f64>,
actualBoundingBoxLeft: Finite<f64>,
actualBoundingBoxRight: Finite<f64>,
fontBoundingBoxAscent: Finite<f64>,
fontBoundingBoxDescent: Finite<f64>,
actualBoundingBoxAscent: Finite<f64>,
actualBoundingBoxDescent: Finite<f64>,
emHeightAscent: Finite<f64>,
emHeightDescent: Finite<f64>,
hangingBaseline: Finite<f64>,
alphabeticBaseline: Finite<f64>,
ideographicBaseline: Finite<f64>,
}

impl TextMetrics {
fn new_inherited(
width: f64,
actualBoundingBoxLeft: f64,
actualBoundingBoxRight: f64,
fontBoundingBoxAscent: f64,
fontBoundingBoxDescent: f64,
actualBoundingBoxAscent: f64,
actualBoundingBoxDescent: f64,
emHeightAscent: f64,
emHeightDescent: f64,
hangingBaseline: f64,
alphabeticBaseline: f64,
ideographicBaseline: f64,
) -> TextMetrics {
TextMetrics {
reflector_: Reflector::new(),
width: Finite::wrap(width),
actualBoundingBoxLeft: Finite::wrap(actualBoundingBoxLeft),
actualBoundingBoxRight: Finite::wrap(actualBoundingBoxRight),
fontBoundingBoxAscent: Finite::wrap(fontBoundingBoxAscent),
fontBoundingBoxDescent: Finite::wrap(fontBoundingBoxDescent),
actualBoundingBoxAscent: Finite::wrap(actualBoundingBoxAscent),
actualBoundingBoxDescent: Finite::wrap(actualBoundingBoxDescent),
emHeightAscent: Finite::wrap(emHeightAscent),
emHeightDescent: Finite::wrap(emHeightDescent),
hangingBaseline: Finite::wrap(hangingBaseline),
alphabeticBaseline: Finite::wrap(alphabeticBaseline),
ideographicBaseline: Finite::wrap(ideographicBaseline),
}
}

pub fn new(
global: &GlobalScope,
width: f64,
actualBoundingBoxLeft: f64,
actualBoundingBoxRight: f64,
fontBoundingBoxAscent: f64,
fontBoundingBoxDescent: f64,
actualBoundingBoxAscent: f64,
actualBoundingBoxDescent: f64,
emHeightAscent: f64,
emHeightDescent: f64,
hangingBaseline: f64,
alphabeticBaseline: f64,
ideographicBaseline: f64,
) -> DomRoot<TextMetrics> {
reflect_dom_object(
Box::new(TextMetrics::new_inherited(
width,
actualBoundingBoxLeft,
actualBoundingBoxRight,
fontBoundingBoxAscent,
fontBoundingBoxDescent,
actualBoundingBoxAscent,
actualBoundingBoxDescent,
emHeightAscent,
emHeightDescent,
hangingBaseline,
alphabeticBaseline,
ideographicBaseline,
)),
global,
TextMetricsBinding::Wrap,
)
}
}

impl TextMetricsMethods for TextMetrics {
/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-width
fn Width(&self) -> Finite<f64> {
self.width
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-actualboundingboxleft
fn ActualBoundingBoxLeft(&self) -> Finite<f64> {
self.actualBoundingBoxLeft
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-actualboundingboxright
fn ActualBoundingBoxRight(&self) -> Finite<f64> {
self.actualBoundingBoxRight
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-fontboundingboxascent
fn FontBoundingBoxAscent(&self) -> Finite<f64> {
self.fontBoundingBoxAscent
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-fontboundingboxascent
fn FontBoundingBoxDescent(&self) -> Finite<f64> {
self.fontBoundingBoxDescent
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-actualboundingboxascent
fn ActualBoundingBoxAscent(&self) -> Finite<f64> {
self.actualBoundingBoxAscent
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-actualboundingboxdescent
fn ActualBoundingBoxDescent(&self) -> Finite<f64> {
self.actualBoundingBoxDescent
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-emheightascent
fn EmHeightAscent(&self) -> Finite<f64> {
self.emHeightAscent
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-emheightdescent
fn EmHeightDescent(&self) -> Finite<f64> {
self.emHeightDescent
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-hangingbaseline
fn HangingBaseline(&self) -> Finite<f64> {
self.hangingBaseline
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-alphabeticbaseline
fn AlphabeticBaseline(&self) -> Finite<f64> {
self.alphabeticBaseline
}

/// https://html.spec.whatwg.org/multipage/#dom-textmetrics-ideographicbaseline
fn IdeographicBaseline(&self) -> Finite<f64> {
self.ideographicBaseline
}
}
@@ -153,7 +153,8 @@ interface CanvasText {
optional unrestricted double maxWidth);
//void strokeText(DOMString text, unrestricted double x, unrestricted double y,
// optional unrestricted double maxWidth);
//TextMetrics measureText(DOMString text);
[Pref="dom.canvas-text.enabled"]
TextMetrics measureText(DOMString text);
};

[Exposed=(PaintWorklet, Window, Worker), NoInterfaceObject]
@@ -0,0 +1,23 @@
/* 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 https://mozilla.org/MPL/2.0/. */

// https://html.spec.whatwg.org/multipage/#textmetrics
[Exposed=(PaintWorklet, Window, Worker), Pref="dom.canvas-text.enabled"]
interface TextMetrics {
// x-direction
readonly attribute double width; // advance width
readonly attribute double actualBoundingBoxLeft;
readonly attribute double actualBoundingBoxRight;

// y-direction
readonly attribute double fontBoundingBoxAscent;
readonly attribute double fontBoundingBoxDescent;
readonly attribute double actualBoundingBoxAscent;
readonly attribute double actualBoundingBoxDescent;
readonly attribute double emHeightAscent;
readonly attribute double emHeightDescent;
readonly attribute double hangingBaseline;
readonly attribute double alphabeticBaseline;
readonly attribute double ideographicBaseline;
};

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