Advanced Features

Click the '+' button in the Protractor panel to add more protractors to your workspace. Each protractor maintains its own set of rays and measurements independently. Use the Duplicate button (copy icon) to create a copy of an existing protractor with the same settings - the copy appears offset by 50 pixels. This is useful when you need to measure multiple angles with consistent settings. Select different protractors by clicking on them - the selected one shows a blue outline. You can have as many protractors as needed for complex diagrams.

Click the camera icon in the top toolbar to upload an image. The image automatically scales to 60% of the viewport with margins for comfortable working. Images are always placed on the bottom layer, so protractors and measurements stay visible on top. Use the Opacity slider in the Image panel to make the image semi-transparent - this helps you see both the image and your measurements clearly. Adjust between 0% (invisible) and 100% (fully opaque) to find the right balance for your work.

The right panel provides exact numeric controls for all elements. For protractors, enter specific X and Y coordinates for pixel-perfect positioning. Set rotation to exact degrees (0-360). Adjust scale with decimal precision (0.1 to 3.0). For images, the same controls apply - position, rotation, and scale can all be set to exact values. This is essential when you need to align measurements with specific points in technical drawings or when recreating measurements from saved data.

Enable the grid overlay from the Settings panel to see alignment guides. Adjust grid spacing from 10 to 200 pixels to match your needs - smaller spacing for detailed work, larger for general alignment. Change grid opacity (10-100%) to make it more or less prominent. The ruler overlay shows pixel measurements along the edges of the canvas. Both grid and ruler help you position protractors and verify distances. Toggle them on or off independently as needed.

Enable angle snapping in the Settings panel to automatically snap rays to whole-degree increments. The default snap step is 1 degree, but you can change it to 5, 10, 15, or 45 degrees for common angles. When snapping is active, you'll see a visual indicator as your ray approaches a snap point. The snap threshold (default 10 pixels) determines how close you need to be before snapping occurs. This feature is invaluable for measuring standard angles like 30°, 45°, 60°, or 90°.

In the Statistics panel, switch between degrees and radians for angle units. Adjust decimal precision from 0 to 4 places - use 0 for whole degrees, 2-3 for most technical work, 4 for high-precision calculations. Toggle between inner and outer angles by clicking on the angle value itself. The inner angle is the smaller angle between two rays (0-180°), while the outer angle is 360° minus the inner angle. Choose the display that makes sense for your specific measurement.

Use the lock button (padlock icon) in the panel to lock protractors, rays, or images. Locked elements cannot be moved, rotated, scaled, or deleted - they're completely protected from accidental changes. This is crucial when working with complex setups where you've positioned multiple elements precisely. Lock completed measurements before adding new ones. You can always unlock an element later if you need to make changes. The lock status is saved when you export your workspace.

Export your workspace as JSON to save everything - all protractors, rays, images, and settings. Reload this file later to continue working exactly where you left off. Export as CSV to get a spreadsheet with all angle measurements, including protractor ID, ray IDs, angle value, and timestamp. For images, choose PNG for transparent backgrounds or JPEG for smaller file sizes. Select resolution: 1x for screen viewing, 2x for high-DPI displays, 4x for printing. Choose background color: transparent (PNG only), white, or black to match your document needs.

Press V to activate Select tool, M for Measure Angle tool, or Space for Pan View tool. Use Cmd/Ctrl+Z to undo and Cmd/Ctrl+Shift+Z to redo - the history stack holds up to 50 steps. Press Delete or Backspace to remove selected elements. Hold Space and drag to pan the canvas even when another tool is active. These shortcuts significantly speed up your workflow, especially when making many measurements. The current tool is always highlighted in the left toolbar.

Start by uploading your image and adjusting its opacity. Add your first protractor and position it at the first measurement point. Complete all measurements for that protractor, then lock it. Add additional protractors for other measurement points. Use consistent colors to group related measurements - for example, all horizontal angles in blue, vertical in red. Export your workspace as JSON periodically to save progress. When finished, export as CSV for data analysis and as a high-resolution image for documentation. This systematic approach prevents errors and makes complex projects manageable.