slint/demos/home-automation/ui/components/dial/dial.slint

// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: MIT
import { Palette } from "../../common.slint";

export global DialState {
    out property <int> totalLights: 60;
    out property <angle> degreesFilledWithLights: 360deg - (startAngle - endAngle);
    out property <angle> startAngle: 104deg;
    out property <angle> endAngle: -startAngle;
    in-out property <length> elementRadius: 120px;
}

export component Dial {
    pure public function normalizeAngle(angle: angle) -> angle {
        return (angle + 360deg).mod(360deg);
    }

    in property <bool> interactive: true;
    property <bool> moving: ta.firstTouch;
    in-out property <angle> dialAngle: DialState.startAngle;
    out property <int> volume: ((dialAngle - DialState.startAngle) / DialState.degreesFilledWithLights) * DialState.totalLights;

    width: 212px;
    height: 213px;
    knob := Rectangle {
        base := Rectangle {
            Image {
                x: 0px;
                y: 9px;
                source: @image-url("../../images/dial-frame.png");
            }

            Image {
                source: @image-url("../../images/lines.png");
                colorize: Palette.dark-color-scheme ? #fff : #000;
                rotation-angle: root.dialAngle;
                width: self.source.width * 0.55 * 1px;
                height: self.source.height * 0.55 * 1px;
                opacity: 0.03;
            }

            ta := TouchArea {
                property <length> centerX: self.width / 2;
                property <length> centerY: self.height / 2;
                property <length> relativeX;
                property <length> relativeY;
                property <angle> newAngle;
                property <angle> deltaDegrees;
                property <bool> firstTouch: false;
                width: parent.width;
                height: parent.height;
                enabled: root.interactive;

                changed pressed => {
                    if !self.pressed {
                        firstTouch = false;
                    }
                }

                moved => {
                    relativeX = ta.mouse-x - centerX;
                    relativeY = ta.mouse-y - centerY;
                    newAngle = normalizeAngle(atan2(relativeY / 1px, relativeX / 1px));
                    if !firstTouch {
                        firstTouch = true;
                        deltaDegrees = normalizeAngle(root.dialAngle - newAngle);
                    } else {
                        root.dialAngle = normalizeAngle(deltaDegrees + newAngle).clamp(DialState.startAngle, 260deg);
                    }
                }
            }
        }
    }

    Rectangle {
        width: 1px;
        height: 1px;
        x: 106px;
        y: 105px;
        Rectangle {
            width: 0px;
            height: 0px;
            x: 55px * root.dialAngle.cos();
            y: 55px * root.dialAngle.sin();
            Image {
                source: @image-url("../../images/notch.png");
            }
        }
    }
}