Colorpicker for PyQt5

MyColorpicker.py

# (c) Teigigutesiegel, 2021
# used code from https://gist.github.com/sjdv1982/75899d10e6983b878f63083e3c47b39b, copyright (c) 2017 Sjoerd de Vries

"""
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

from PyQt5.QtWidgets import QWidget, QSlider, QHBoxLayout, QSizePolicy
from PyQt5.QtCore import Qt, QRect, QPointF, QLineF, pyqtSignal
from PyQt5.QtGui import QColor, QPainter, QPaintEvent, QResizeEvent, QConicalGradient, QRadialGradient, QMouseEvent

class ColorCircle(QWidget):
    currentColorChanged = pyqtSignal(QColor)

    def __init__(self, parent=None, startupcolor: list = [255, 255, 255], margin=10) -> None:
        super().__init__(parent=parent)
        self.radius = 0
        self.selected_color = QColor(
            startupcolor[0], startupcolor[1], startupcolor[2], 1)
        self.x = 0.5
        self.y = 0.5
        self.h = self.selected_color.hueF()
        self.s = self.selected_color.saturationF()
        self.v = self.selected_color.valueF()
        self.margin = margin

        qsp = QSizePolicy(QSizePolicy.Preferred,
                          QSizePolicy.Preferred)
        qsp.setHeightForWidth(True)
        self.setSizePolicy(qsp)

    def resizeEvent(self, ev: QResizeEvent) -> None:
        size = min(self.width(), self.height()) - self.margin * 2
        self.radius = size / 2
        self.square = QRect(0, 0, size, size)
        self.square.moveCenter(self.rect().center())

    def paintEvent(self, ev: QPaintEvent) -> None:
        center = QPointF(self.width()/2, self.height()/2)
        p = QPainter(self)
        p.setViewport(self.margin, self.margin, self.width() -
                      2*self.margin, self.height()-2*self.margin)
        hsv_grad = QConicalGradient(center, 90)
        for deg in range(360):
            col = QColor.fromHsvF(deg / 360, 1, self.v)
            hsv_grad.setColorAt(deg / 360, col)

        val_grad = QRadialGradient(center, self.radius)
        val_grad.setColorAt(0.0, QColor.fromHsvF(0.0, 0.0, self.v, 1.0))
        val_grad.setColorAt(1.0, Qt.transparent)

        p.setPen(Qt.transparent)
        p.setBrush(hsv_grad)
        p.drawEllipse(self.square)
        p.setBrush(val_grad)
        p.drawEllipse(self.square)

        p.setPen(Qt.black)
        p.setBrush(self.selected_color)
        line = QLineF.fromPolar(self.radius * self.s, 360 * self.h + 90)
        line.translate(self.rect().center())
        p.drawEllipse(line.p2(), 10, 10)

    def recalc(self) -> None:
        self.selected_color.setHsvF(self.h, self.s, self.v)
        self.currentColorChanged.emit(self.selected_color)
        self.repaint()

    def map_color(self, x: int, y: int) -> QColor:
        line = QLineF(QPointF(self.rect().center()), QPointF(x, y))
        s = min(1.0, line.length() / self.radius)
        h = (line.angle() - 90) / 360 % 1.
        return h, s, self.v

    def processMouseEvent(self, ev: QMouseEvent) -> None:
        if ev.button() == Qt.MouseButton.RightButton:
            self.h, self.s, self.v = 0, 0, 1
        else:
            self.h, self.s, self.v = self.map_color(ev.x(), ev.y())
        self.x = ev.x() / self.width()
        self.y = ev.y() / self.height()
        self.recalc()

    def mouseMoveEvent(self, ev: QMouseEvent) -> None:
        self.processMouseEvent(ev)

    def mousePressEvent(self, ev: QMouseEvent) -> None:
        self.processMouseEvent(ev)

    def setHue(self, hue: float) -> None:
        if 0 <= hue <= 1:
            self.h = float(hue)
            self.recalc()
        else:
            raise TypeError("Value must be between 0.0 and 1.0")

    def setSaturation(self, saturation: float) -> None:
        if 0 <= saturation <= 1:
            self.s = float(saturation)
            self.recalc()
        else:
            raise TypeError("Value must be between 0.0 and 1.0")

    def setValue(self, value: float) -> None:
        if 0 <= value <= 1:
            self.v = float(value)
            self.recalc()
        else:
            raise TypeError("Value must be between 0.0 and 1.0")

    def setColor(self, color: QColor) -> None:
        self.h = color.hueF()
        self.s = color.saturationF()
        self.v = color.valueF()
        self.recalc()

    def getHue(self) -> float:
        return self.h

    def getSaturation(self) -> float:
        return self.s

    def getValue(self) -> float:
        return self.v

    def getColor(self) -> QColor:
        return self.selected_color


class ColorCircleDialog(QWidget):
    currentColorChanged = pyqtSignal(QColor)

    def __init__(self, parent=None, width: int = 500, startupcolor: list = [255, 255, 255]) -> None:
        super().__init__(parent=parent)
        self.resize(width, width)

        mainlay = QHBoxLayout()
        wid = ColorCircle(self, startupcolor=startupcolor)
        wid.currentColorChanged.connect(
            lambda x: self.currentColorChanged.emit(x))
        mainlay.addWidget(wid)
        fader = QSlider()
        fader.setMinimum(0)
        fader.setMaximum(511)
        fader.setValue(511)
        fader.valueChanged.connect(lambda x: wid.setValue(x/511))
        mainlay.addWidget(fader)

        self.setLayout(mainlay)


if __name__ == '__main__':
    import sys
    from PyQt5.QtWidgets import QApplication
    app = QApplication(sys.argv)

    window = ColorCircleDialog()
    window.currentColorChanged.connect(lambda x: print(x.red(), x.green(), x.blue()))
    window.show()
    sys.exit(app.exec_())

Nice concept, but there's no need for a custom layout, you can just use the min(self.width(), self.height()) size for a square and center it to self.rect().center(), all in the resizeEvent() to store it and use in the paint functions:

    def resizeEvent(self, ev: QResizeEvent) -> None:
        size = min(self.width(), self.height()) - self.margin * 2
        self.radius = size / 2
        self.square = QRect(0, 0, size, size)
        self.square.moveCenter(self.rect().center())

    def paintEvent(self, ev: QPaintEvent) -> None:
        # ...
        p.setBrush(hsv_grad)
        p.drawEllipse(self.square)
        p.setBrush(val_grad)
        p.drawEllipse(self.square)

The above also makes setting the viewport of the painter unnecessary.

Numpy is also an unnecessary requirement: the "cursor" can be easily mapped using hue (angle) and saturation (distance):

        line = QLineF.fromPolar(self.radius * self.s, 360 * self.h + 90)
        line.translate(self.rect().center())
        p.drawEllipse(line.p2(), 10, 10)

The color can be mapped with the same logic, inverted:

    def map_color(self, x: int, y: int) -> QColor:
        line = QLineF(QPointF(self.rect().center()), QPointF(x, y))
        s = min(1.0, line.length() / self.radius)
        h = (line.angle() - 90) / 360 % 1.
        return h, s, self.v

Thank you for your input, I have incorporated it into the file