Shape Manipulation Issues with Logarithmic Scale Engine

[imad-miftek]

When using shapes like AnnotatedRectangle with a logarithmic scale engine on the BasePlot, there are significant problems with shape resizing and movement. While shapes work correctly in linear scale mode, switching to logarithmic scale causes erratic behavior:

• When trying to move the shapes, the entire plot resizes erratically while moving.
• Shape manipulation doesn't follow mouse movements correctly.

Code sample:

import sys
from PySide6.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout
from PySide6.QtCore import Qt
from plotpy.plot import BasePlot, PlotManager
from plotpy.tools import SelectTool, AnnotatedRectangleTool

class Plot(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Base Plot")
        self.setGeometry(100, 100, 800, 600)

        # Create the main widget and layout
        main_widget = QWidget()
        self.setCentralWidget(main_widget)
        layout = QVBoxLayout(main_widget)

        # Create PlotWidget
        self.plot = BasePlot()
        self.plot.set_axis_scale(BasePlot.X_BOTTOM, "log", autoscale=False)
        self.plot.set_axis_scale(BasePlot.Y_LEFT, "log", autoscale=False)

        # self.plot.setMouseTracking(True)
        layout.addWidget(self.plot)

        self.manager = PlotManager(self.plot)
        self.manager.add_plot(self.plot)

        self.select_tool = self.manager.add_tool(SelectTool)
        self.select_tool.activate()
        self.rect_tool = self.manager.add_tool(AnnotatedRectangleTool, handle_final_shape_cb=self.handle_final_shape, switch_to_default_tool=True)

        self.plot.setContextMenuPolicy(Qt.ContextMenuPolicy.ActionsContextMenu)
        self.plot.addAction("Add Rectangle", lambda: self.rect_tool.activate())

    def handle_final_shape(self, shape):
        print(f"Final shape: {shape}")
        self.plot.unselect_all()
        self.plot.select_item(shape)

    def add_shape(self, tool):
        self.manager.get_tool(tool).activate()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = Plot()
    window.show()
    sys.exit(app.exec())

[PierreRaybaut]

See #36: as image items do not support non-linear scales, and now that there is an explicit warning, and assuming that shapes are always used with images, we may close this one.

See #36 for an alternative way of handling logarithmic scales.