xpt2046 0.3.0

Embedded-hal based XPT2046 driver for TFT LCD displays
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119

use super::CalibrationData;
use crate::error::CalibrationError;
use embedded_graphics::{
    primitives::{Line, Primitive, PrimitiveStyle},
    Drawable,
};
use embedded_graphics_core::{
    draw_target::DrawTarget,
    geometry::Point,
    pixelcolor::{Rgb565, RgbColor},
};

#[cfg(feature = "with_defmt")]
use defmt::{write, Format, Formatter};

#[derive(Debug, Clone)]
pub struct CalibrationPoint {
    pub a: Point,
    pub b: Point,
    pub c: Point,
}

impl CalibrationPoint {
    pub fn delta(&self) -> i32 {
        (self.a[0] - self.c[0]) * (self.b[1] - self.c[1])
            - (self.b[0] - self.c[0]) * (self.a[1] - self.c[1])
    }
}

#[cfg(feature = "with_defmt")]
impl Format for CalibrationPoint {
    fn format(&self, fmt: Formatter) {
        write!(
            fmt,
            "a[x: {} y:{}]\nb[x: {} y: {}]\nc[x:{} y:{}]",
            self.a.x, self.a.y, self.b.x, self.b.y, self.c.x, self.c.y,
        )
    }
}

/*
 *  TODO:
 *  Find a way to hide this behind a feature
 */
pub(crate) fn calibration_draw_point<DT: DrawTarget<Color = Rgb565>>(dt: &mut DT, p: &Point) {
    let _ = Line::new(Point::new(p.x - 4, p.y), Point::new(p.x + 4, p.y))
        .into_styled(PrimitiveStyle::with_stroke(Rgb565::WHITE, 1))
        .draw(dt);
    let _ = Line::new(Point::new(p.x, p.y - 4), Point::new(p.x, p.y + 4))
        .into_styled(PrimitiveStyle::with_stroke(Rgb565::WHITE, 1))
        .draw(dt);
}

pub(crate) fn calculate_calibration(
    old_cp: &CalibrationPoint,
    new_cp: &CalibrationPoint,
) -> Result<CalibrationData, CalibrationError> {
    /*
     * We need delta calculated from the new points
     */
    let delta = new_cp.delta() as f32;

    /*
     * 3 point triangulation
     */
    let alpha_x = ((old_cp.a[0] - old_cp.c[0]) * (new_cp.b[1] - new_cp.c[1])
        - (old_cp.b[0] - old_cp.c[0]) * (new_cp.a[1] - new_cp.c[1])) as f32
        / delta;
    /*
     * We might end up reading garabge from SPI
     * so we must test for the weird floats
     */
    if !alpha_x.is_normal() {
        return Err(CalibrationError::Alpha);
    }
    let beta_x = ((new_cp.a[0] - new_cp.c[0]) * (old_cp.b[0] - old_cp.c[0])
        - (new_cp.b[0] - new_cp.c[0]) * (old_cp.a[0] - old_cp.c[0])) as f32
        / delta;
    if !beta_x.is_normal() {
        return Err(CalibrationError::Beta);
    }
    let delta_x = ((old_cp.a[0]) * (new_cp.b[0] * new_cp.c[1] - new_cp.c[0] * new_cp.b[1])
        - (old_cp.b[0]) * (new_cp.a[0] * new_cp.c[1] - new_cp.c[0] * new_cp.a[1])
        + (old_cp.c[0]) * (new_cp.a[0] * new_cp.b[1] - new_cp.b[0] * new_cp.a[1]))
        as f32
        / delta;
    if !delta_x.is_normal() {
        return Err(CalibrationError::Delta);
    }
    let alpha_y = ((old_cp.a[1] - old_cp.c[1]) * (new_cp.b[1] - new_cp.c[1])
        - (old_cp.b[1] - old_cp.c[1]) * (new_cp.a[1] - new_cp.c[1])) as f32
        / delta;
    if !alpha_y.is_normal() {
        return Err(CalibrationError::Alpha);
    }
    let beta_y = ((new_cp.a[0] - new_cp.c[0]) * (old_cp.b[1] - old_cp.c[1])
        - (new_cp.b[0] - new_cp.c[0]) * (old_cp.a[1] - old_cp.c[1])) as f32
        / delta;
    if !beta_y.is_normal() {
        return Err(CalibrationError::Beta);
    }
    let delta_y = ((old_cp.a[1]) * (new_cp.b[0] * new_cp.c[1] - new_cp.c[0] * new_cp.b[1])
        - (old_cp.b[1]) * (new_cp.a[0] * new_cp.c[1] - new_cp.c[0] * new_cp.a[1])
        + (old_cp.c[1]) * (new_cp.a[0] * new_cp.b[1] - new_cp.b[0] * new_cp.a[1]))
        as f32
        / delta;
    if !delta_y.is_normal() {
        return Err(CalibrationError::Delta);
    }

    Ok(CalibrationData {
        alpha_x,
        beta_x,
        delta_x,
        alpha_y,
        beta_y,
        delta_y,
    })
}