Why is ruler showing different numbers than a rectangle width?

[david1122]

An AI bot has been helping me try to use Draw to generate a 1280x720 PNG file, by treating it as a 128mm by 72mm page. It summarizes my problem as follows, and seems stuck:

The Core Problem

You’ve set:

• Page size: 128 mm × 72 mm
• Drawing scale: 1:1
• Unit of measurement: Millimeter
• Ruler: Set to millimeters

Yet the ruler shows 1280 units across the top, and a rectangle sized to 128 mm appears tiny—not filling the page as expected.

This is not just a pixel-vs-mm issue. It’s a breakdown in how Draw is rendering and scaling the canvas, even when using its native units.

[Hrbrgr]

@david1122

An AI bot

Perhaps the AI bot hasn’t read the manuals yet:
https://documentation.libreoffice.org/en/english-documentation/

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Starting with Draw

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And who set the page size?

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With me:

Version: 25.2.4.3 (X86_64) / LibreOffice Community
Build ID: 33e196637044ead23f5c3226cde09b47731f7e27
CPU threads: 8; OS: Windows 10 X86_64 (10.0 build 19045); UI render: Skia/Raster; VCL: win
Locale: de-DE (de_DE); UI: de-DE
Calc: CL threaded

[david1122]

Hrbrgr This is pretty much what my settings look like. Neither I nor the AI bot can figure out why the ruler is ten times longer than the rectangle.

[EarnestAl]

If you click on the rectangle, what dimensions does it show in the status bar? or in Format - Position and Size?

If an AI bot did the drawing then what units was it using?

If you draw the rectangle in draw at 128 mm what size do you get?

[david1122]

EarnestAl When I click my rectangle, the dimensions shown in the status bar at the bottom of the Draw screen are 128.00x72.00. The same numbers, followed by “mm”, are shown in Format > Position and Size (note that I changed the standard units to millimeters). The AI Bot was not doing the drawing–AI Bots do not yet have that capability–I did the drawing. I’m not sure how to answer that last question because millimeters are not my daily measurement experience. The ruler across the top of the workspace counts from 0 to 1280 . The rectangle is a little less than an inch in width, visually. I’m using an HP laptop running Windows 11 Home.with Scale=150% (recommended), Display Resolution=1920x1080 (recommended), Display orientation=landscape.

[david1122]

It turns out that I specified Page > Page Properties > Page as 1280 mm by 720 mm, and that’s what I got. I must have been so overwhelmed by trying to make it work that I just didn’t notice this. When I changed the page size to 128 mm by 72 mm Landscape, I got the standard screen aspect ratio that I wanted (16:9), so I was able to export a PNG file of exactly 1280x720 pixels, which is what YouTube wants for video thumbnails.

So this is the solution for easy compositing for full screen page output. I hope others can learn from my mistakes.