ScreenMeasure — calibration and measuring distances on an image

ScreenMeasure — lightweight desktop utility for Windows that allows you to calibrate scale using a known length and accurately measure segments and polylines on any image/screenshot. All measurements remain on the picture with a length label.

Why

• Quick measurements on drawings, diagrams, screenshots, photos.
• Matching real object sizes using a reference (ruler in photo, known span, etc.).
• Preparing visual illustrations: export image with applied measurements.

How it works

1. Open an image (Ctrl+O) or paste from clipboard (Ctrl+V).
2. Calibration (C): click two points with a known real distance → enter length and units (mm/cm/m/inches, etc.).
   The scale will be saved; all existing measurements will be recalculated automatically.
3. Line measurement (L): click two points — a line with a length label will appear.
4. Polyline measurement (P): click several points → RMB to finish. Length is labeled in the middle of the path.
5. Export:
   – CSV with the list of measurements (Ctrl+E)
   – Image with measurements (Export Annotated Image button).

Features

• Persistent objects on the image: lines and polylines with automatic length labels.
• Good visibility on any background: double outline (black border + colored line).
• Guides (horizontal/vertical/±45°) for aligning points:
  • Appear only in active modes (calibration/line/polyline).
  • Anchored to the last LMB point, do not move during pan/zoom.
  • Thin when tool is selected but points are not placed yet; thicker during construction.
  • Toggles: Horizontal, Vertical, 45° guides.
• Canvas control: zoom with wheel, pan with MMB or space + LMB.
• Measurement history: Undo (last), Delete selected, Clear measurements, Clear image + measurements.
• Recalibration automatically recalculates all measurements.

Hotkeys

Action	Key
Paste from clipboard	Ctrl+V
Open file	Ctrl+O
Export CSV	Ctrl+E
Reset view	R
Calibration	C
Line	L
Polyline	P
Finish polyline	RMB
Undo last	Ctrl+Z
Cancel mode/clear temporary points	Esc
Pan	MMB or Space + LMB

Export and saving

• CSV: time, type, units, length, point coordinates.
• PNG/JPG image with applied lines, labels, and (if needed) current temporary geometry.

System requirements

• Windows 10/11
• Python 3.9+ and PySide6 (for running from source) or ready .exe.

Privacy

All operations are performed locally, data is not sent anywhere.

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If necessary, we will add hotkeys for hiding/showing guides and snapping to axes/45° while holding Shift.