Recommended test
Use a fabrication drawing or product image containing one clearly dimensioned feature.
- Press I and import a PNG, JPEG, or WebP under 10 MB.
- Drag the image to a useful position and set opacity near 35–50%.
- Click Calibrate, then click both ends of a known dimension on the image.
- Enter its real distance in millimetres and choose Apply scale.
- Confirm the first point stays fixed. Undo and redo the calibration, then test Hide and Show.
01 · IMPORT
Choose a safe image file
Choose Reference from the left tool rail or press I. Cadivari accepts PNG, JPEG, and WebP files up to 10 MB and validates the decoded pixel dimensions before adding the image.
The longest image side is initially shown as 250 mm so it remains manageable on the canvas. Calibration supplies the authoritative size.
Imported image data is owned by the document entity rather than by the SVG renderer. This prepares the image for later project save/open support.
02 · PREPARE
Control image placement and appearance
The image is always rendered behind drawing geometry. Select it and drag anywhere on its surface to reposition it, or enter exact X and Y coordinates in Properties.
W and H preserve the original pixel aspect ratio: changing one automatically updates the other. The opacity slider ranges from 8% to 100% and commits one history entry when released. Hide removes the image from the canvas without deleting it.
03 · SCALE
Calibrate from two landmarks
Select the image and choose Calibrate. Snapping is intentionally suspended during calibration so the clicks can land on the actual image pixels. The normal pointer moves clear of the exact target while a circular 4× loupe shows the source image under a fine crosshair. The loupe automatically moves to a clear side near viewport edges. Click the first landmark; a dashed guide then follows the second target live in both the drawing and magnified view. Hold Shift to constrain that guide to the nearest horizontal or vertical axis before clicking the second landmark. The numbered markers and connecting line remain visible while you enter the real distance.
All calibration distances are millimetres. A zero, invalid, or unreasonably large result is rejected instead of changing the document.
04 · PREDICTABLE RESIZING
The first landmark stays fixed
Applying calibration scales the entire image around the first clicked point. That landmark therefore stays at the same document coordinate while the second landmark moves to the correct distance.
An alignment landmark—for example, a mounting-hole centre, component datum, or guitar bridge location—can remain aligned with existing geometry instead of drifting when the image scale changes.
This anchored behavior follows the useful AutoStrek reference-image workflow and is committed as one undoable document edit.
REFERENCE
Controls
IMPLEMENTATION NOTE
Document model
A reference image stores source pixels plus its independent millimetre placement and presentation state. The drawing renderer only displays that data.
{
"kind": "reference-image",
"name": "reference-plan.png",
"x": 20,
"y": 20,
"width": 360,
"height": 1000,
"opacity": 0.45,
"visible": true
}Calibration changes x, y, width, and height together. The original pixel dimensions remain unchanged and continue to define the aspect ratio.
CURRENT SCOPE
Not implemented yet
- Image rotation and perspective correction
- Cropping and image filters
- Locking a reference against accidental selection
- Multiple calibration dimensions or distortion correction
- Fit-drawing behavior that includes reference images
- Persistent project save/open
- External image-link management