iOS “JWW見れる君” ／ Android “JWW見える子さん”
This guide is the same for iPhone and Android phones.
On iPad the same buttons sit along the top of the screen. It can do the same things.
It also works on a Mac (with Apple silicon M1 or later).
A trackpad works the same as on iPhone and iPad: swipe to move the view, pinch to zoom.
With a mouse, scroll to move the view and hold the option key while scrolling to zoom.
If you practice straight away on a real drawing, when something goes wrong you can’t tell whether it’s the app, your method, or the drawing.
We made a drawing for practice. It is a fictional building that doesn’t exist. The drawing has 【やってみよう】 (“Try it”) notes written in it, so try them in that order.
LINE can’t send a .jww file on its own. So the sender puts it in a ZIP (compressed file) and sends that.
iPhone and iPad can open the ZIP as it is (no need to unzip). On Android, unzip it first, then open it in the app.
In the share row, “JWW見れる君” appears after AirDrop. No unzipping needed.
That’s all the preparation. No conversion on a computer at all.
In the app, use “⊕ Open JWW (multiple OK)” and choose the drawing you saved. You can open several drawings at once. On Android it is “.jww を開く” (Open .jww) (PDF has a separate button).
Move with one finger, zoom in and out with two fingers.
On a Mac, a trackpad works the same. With a mouse, scroll to move and hold the option key while scrolling to zoom.
If you get lost, going back to the whole view is the fastest. How to go back depends on the device: on iPhone and iPad, the “Fit” button (fixed at the top right of the screen); on Android, double-tap the screen.
On Android, double-tap doesn’t work while you are using Measure, Dimension, Offset and so on. That is because one finger is being used to “aim”. Finish that mode first, then double-tap.
Pick two points on the drawing to get the distance, horizontal, vertical and angle. Points snap to endpoints and intersections automatically, so you don’t need to aim exactly. The operation is different on iPhone/iPad and on Android.
Tap “Measure” and the A and B handles (circles) appear on the drawing. Hold a handle and drag it to the end or intersection of the line you want to measure.
While you drag, a magnifier appears above your finger so you can see which point it is snapping to right now (endpoint, intersection, on line). Lift your finger and the dimension appears right away. There is no confirm button.
To redo, drag the handle again or tap “Reposition”; to undo one step, tap “Back”. If you press somewhere away from the handles, A is placed there and a new measurement starts.
The bottom of the screen also shows “1本指で狙い → 離す →「確定」” (aim with one finger → release → Confirm). Follow that hint.
When you lift your finger, the button text changes to 確定（端点） (Confirm: endpoint), 確定（交点） (Confirm: intersection) or 確定（線上） (Confirm: on line). This tells you “where it grabbed”. If the text doesn’t match the place you wanted, move your finger and try again.
With iPad + Apple Pencil, A → B are placed in the order you tap with the pen tip. After placing them you can drag the handles to adjust.
You can get cumulative dimensions one after another from a base point. Like pulling the tape out once and reading the marks in order — that way of measuring.
On iPhone and iPad, keep A on the base point and drag only B to the next point to read the dimensions from the base in order.
To write cumulative dimensions on the drawing, use “Running” in 6. Write.
On Android, a “累進” (Running) button appears when you enter measure mode.
Switch layers shown / hidden to show only what you want to see (hide only the dimensions, see only the services, and so on). The drawing data is not deleted. Only the view changes.
Tap “Layer” to show the layer list, tap “Pick” at the top of the list, then tap the line you want to check. That line’s layer is selected in the list.
Tap a layer name in the list to choose “Show only this”, “Hide” or “Write here”. This is where you choose the layer to write dimensions and offsets on.
The “Layer” button is in the bar at the top of the screen (on iPad, the top toolbar).
You can switch the background between black and white. A white background is easier to see outdoors in bright light, and it is also good for printing as it is.
With the same operation as measuring, you can write dimensions on the drawing.
On iPhone and iPad, tap “Dimension”, drag the A and B handles onto the lines, use the “Position” handle to decide where the dimension line goes,
then tap “Write” to put it on the drawing. Nothing is written on the drawing until you tap “Write”.
You can choose the angle from free, horizontal, vertical or line angle, and use “Running” to add cumulative dimensions.
On Android it is the same “aim → release → 確定 (Confirm)” as measuring; you can choose horizontal, vertical or line angle, and turn on 累進 (Running) to add cumulative dimensions.
Offset draws a line shifted in parallel.
For Offset, the order is enter the “distance” first, then point to the line. It does not ask the distance after you choose the line, so just remember that.
When you use “Save JWW”, the original drawing stays as it is and the drawing with your writing is saved as a separate file. When you send it, send the new file made by saving. (When there is writing, the button shows the count, like “Save 1 to JWW”)
Your writing is not in the file until you save. If you just write and close, it is lost, so make saving a habit.
You can send a saved drawing as it is by LINE or email from Share. The other person can open it normally in Jw_cad on a computer.
PDF drawings open as they are too. Many sites probably get “no JWW, only a PDF”.
A PDF does not contain the information “how many mm this line is”. So just once at the start, you tell it two known points on the drawing and their real distance.
For example, if the drawing says the grid line spacing is 6000, pick those two points and enter “6000”. This is called calibration.
Once calibrated, you can measure real sizes anywhere, just like JWW.
When you open a PDF, the top bar switches to the PDF version. Until you set the base it shows “Uncalibrated”, and the screen tells you what to do next. Once set, it changes to “Calibrated” and you can measure just like JWW.
Measuring is the same as JWW. Both when you set the base and when you measure after that, you choose points with the same operation as 4. Measure. Nothing new to learn.
For the two base points, choose the ends of lines or where lines cross. It is easier if a dimension is written there. Longer dimensions such as grid line spacing or opening widths give better accuracy.
* On iPhone and iPad, you can’t use the middle of a line or an empty spot as a base. The screen tells you when you aim there. (This limit does not apply to PDFs without line data, such as scanned paper.)
PDF measurement depends on the accuracy of the original PDF and the calibration, and small errors can occur. Check exact values on the JWW drawing.
Short videos introduce the app (the videos are in Japanese). For the steps, the hints shown on the app screen are the reference.
Just tell us “which operation” and “what happened”.
You don’t need to send the drawing itself.
A working formwork carpenter and site foreman develops and improves it while using it on site himself.