Five types of overlay are supported:

  • Rectangle

  • Ellipse

  • Line

  • Point

  • Text

Overlays are added using the add_overlay function. This returns a reference to the overlay. This can be later passed to remove_overlay to delete the overlay. Alternatively, all overlays can be removed using clear_overlays.

To create a rectangular overlay:

from image_display import ImageDisplay
imDisplay = ImageDisplay()

imDisplay.add_overlay(ImageDisplay.RECTANGLE, x, y, w, h, pen, fill)

where x and y are the x and y co-ordinates of the top left of the rectangle, respectively, and w and h are the width and height. These co-ordinates are specified in terms of pixels in the original image (i.e. not screen pixels). Co-ordinates outside the image can be specified in which case the overlay will be clipped.

The pen and fill should be a QPen and QBrush respectively. For example:

overlay = imDisplay.add_overlay(ImageDisplay.RECTANGLE, 90, 100, 30, 40, QPen(Qt.blue, 2, Qt.SolidLine), QBrush(Qt.red))

generates a rectangle with a blue solid outer line of thickness 2 and a red fill. For a transparent fill, pass None for fill.

To add an ellipse, the structure is:

overlay = imDisplay.add_overlay(ImageDisplay.ELLIPSE, x, y, w, h, pen, fill)

For a line:

overlay = imDisplay.add_overlay(ImageDisplay.LINE, x, y, w, h, pen)

For a point:

overlay = imDisplay.add_overlay(ImageDisplay.POINT, x, y, pen)

Note that no fill is specified for lines and points.

To add a text overlay:

overlay = imDisplay.add_overlay(ImageDisplay.TEXT, x, y, pen, text)

where text is the string to add. The co-ordinates are the lower left of the bounding rectangle of the text box.

To remove any overlay, use:


where overlay is the reference returned when creating the overlay using add_overlay.

To clear all overlays use: