Canvas: added arcTo() support.

This commit is contained in:
Mátyás Mustoha 2015-03-26 16:43:34 +01:00
parent ba0d28e002
commit 56303e21cc
20 changed files with 81 additions and 76 deletions

View file

@ -16,6 +16,7 @@ use util::vec::byte_swap;
use cssparser::RGBA;
use std::borrow::ToOwned;
use std::num::Float;
use std::sync::mpsc::{channel, Sender};
#[derive(Clone)]
@ -34,6 +35,7 @@ pub enum CanvasMsg {
QuadraticCurveTo(Point2D<f32>, Point2D<f32>),
BezierCurveTo(Point2D<f32>, Point2D<f32>, Point2D<f32>),
Arc(Point2D<f32>, f32, f32, f32, bool),
ArcTo(Point2D<f32>, Point2D<f32>, f32),
SetFillStyle(FillOrStrokeStyle),
SetStrokeStyle(FillOrStrokeStyle),
SetTransform(Matrix2D<f32>),
@ -230,6 +232,9 @@ impl<'a> CanvasPaintTask<'a> {
CanvasMsg::Arc(ref center, radius, start, end, ccw) => {
painter.arc(center, radius, start, end, ccw)
}
CanvasMsg::ArcTo(ref cp1, ref cp2, radius) => {
painter.arc_to(cp1, cp2, radius)
}
CanvasMsg::SetFillStyle(style) => painter.set_fill_style(style),
CanvasMsg::SetStrokeStyle(style) => painter.set_stroke_style(style),
CanvasMsg::SetTransform(ref matrix) => painter.set_transform(matrix),
@ -344,6 +349,61 @@ impl<'a> CanvasPaintTask<'a> {
self.path_builder.arc(*center, radius, start_angle, end_angle, ccw)
}
fn arc_to(&self,
cp1: &Point2D<AzFloat>,
cp2: &Point2D<AzFloat>,
radius: AzFloat) {
let cp0 = self.path_builder.get_current_point();
let cp1 = *cp1;
let cp2 = *cp2;
if (cp0.x == cp1.x && cp0.y == cp1.y) || cp1 == cp2 || radius == 0.0 {
self.line_to(&cp1);
return;
}
// if all three control points lie on a single straight line,
// connect the first two by a straight line
let direction = (cp2.x - cp1.x) * (cp0.y - cp1.y) + (cp2.y - cp1.y) * (cp1.x - cp0.x);
if direction == 0.0 {
self.line_to(&cp1);
return;
}
// otherwise, draw the Arc
let a2 = (cp0.x - cp1.x).powi(2) + (cp0.y - cp1.y).powi(2);
let b2 = (cp1.x - cp2.x).powi(2) + (cp1.y - cp2.y).powi(2);
let d = {
let c2 = (cp0.x - cp2.x).powi(2) + (cp0.y - cp2.y).powi(2);
let cosx = (a2 + b2 - c2) / (2.0 * (a2 * b2).sqrt());
let sinx = (1.0 - cosx.powi(2)).sqrt();
radius / ((1.0 - cosx) / sinx)
};
// first tangent point
let anx = (cp1.x - cp0.x) / a2.sqrt();
let any = (cp1.y - cp0.y) / a2.sqrt();
let tp1 = Point2D::<AzFloat>(cp1.x - anx * d, cp1.y - any * d);
// second tangent point
let bnx = (cp1.x - cp2.x) / b2.sqrt();
let bny = (cp1.y - cp2.y) / b2.sqrt();
let tp2 = Point2D::<AzFloat>(cp1.x - bnx * d, cp1.y - bny * d);
// arc center and angles
let anticlockwise = direction < 0.0;
let cx = tp1.x + any * radius * if anticlockwise { 1.0 } else { -1.0 };
let cy = tp1.y - anx * radius * if anticlockwise { 1.0 } else { -1.0 };
let angle_start = (tp1.y - cy).atan2(tp1.x - cx);
let angle_end = (tp2.y - cy).atan2(tp2.x - cx);
self.line_to(&tp1);
if [cx, cy, angle_start, angle_end].iter().all(|x| x.is_finite()) {
self.arc(&Point2D::<AzFloat>(cx, cy), radius,
angle_start, angle_end, anticlockwise);
}
}
fn set_fill_style(&mut self, style: FillOrStrokeStyle) {
self.fill_style = style.to_azure_pattern(&self.drawtarget)
}