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# Copyright (C) 2025 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
import struct
from PySide6.QtCore import Qt, Property, QUrl, Signal, QFile, QPointF
from PySide6.QtGui import QPen, QPainter
from PySide6.QtMultimedia import QAudioFormat, QAudioDecoder
from PySide6.QtQml import QmlElement
from PySide6.QtQuick import QQuickPaintedItem
QML_IMPORT_NAME = "Audio"
QML_IMPORT_MAJOR_VERSION = 1
@QmlElement
class WaveformItem(QQuickPaintedItem):
fileChanged = Signal()
def __init__(self, parent=None):
super().__init__(parent)
self._waveformData = []
self._background_color = Qt.black
audio_format = QAudioFormat()
audio_format.setChannelCount(1)
audio_format.setSampleRate(44100)
audio_format.setSampleFormat(QAudioFormat.Float)
self._file_url: QUrl | None = None
self._audio_file: QFile | None = None
self._decoder = QAudioDecoder()
self._decoder.setAudioFormat(audio_format)
self._decoder.bufferReady.connect(self.onBufferReady)
self._decoder.finished.connect(self.decoderFinished)
def file(self) -> QUrl | None:
return self._file_url
def setFile(self, value: QUrl):
if self._decoder.source() == value:
return
if self._audio_file and self._audio_file.isOpen():
self._audio_file.close()
self._waveformData = []
self._decoder.stop()
self._file_url = value
if "__compiled__" in globals():
path = self._file_url.toString().replace("qrc:/", ":/")
else:
path = self._file_url.path()
self._audio_file = QFile(path)
self._audio_file.open(QFile.ReadOnly)
self._decoder.setSourceDevice(self._audio_file)
self._decoder.start()
self.fileChanged.emit()
def paint(self, painter):
# Fill the bounding rectangle with the specified color
painter.fillRect(self.boundingRect(), self._background_color)
# If no waveform data is available, draw the text
if not self._waveformData:
painter.setPen(Qt.white)
painter.drawText(self.boundingRect(), Qt.AlignCenter, "Waveform not available")
return
painter.setRenderHint(QPainter.Antialiasing)
# Set the pen for drawing the waveform
pen = QPen(Qt.blue)
pen.setWidth(1)
painter.setPen(pen)
# Get container dimensions
rect = self.boundingRect()
data_size = len(self._waveformData)
# Calculate step size and center line
x_step = rect.width() / data_size
center_y = rect.height() / 2.0
# Draw the waveform as connected lines
for i in range(1, data_size):
x1 = (i - 1) * x_step
y1 = center_y - self._waveformData[i - 1] * center_y
x2 = i * x_step
y2 = center_y - self._waveformData[i] * center_y
painter.drawLine(QPointF(x1, y1), QPointF(x2, y2))
@staticmethod
def float_buffer_to_list(data):
# Calculate the number of 32-bit floats in the buffer
float_count = len(data) // 4 # Each float32 is 4 bytes
# Unpack the binary data into a list of floats
return list(struct.unpack(f"{float_count}f", data))
def onBufferReady(self):
buffer = self._decoder.read()
data = buffer.constData()
self._waveformData.extend(self.float_buffer_to_list(data))
self.update()
file: QUrl = Property(QUrl, file, setFile, notify=fileChanged)
def decoderFinished(self):
self._audio_file.close()
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