Offer standard web and print canvas formats

The canvas was two spin buttons, so "an Instagram story" or "A4 at 300 dpi"
was a number the user had to work out. src/core/canvas.cpp now holds one
table of standard sizes both front-ends read: a web format is a fixed pixel
size, a print format a sheet in millimetres that becomes pixels at a dpi.
Adding a format is a line in canvasFormats() — the dropdown, --format and
--help all walk the table.

The pixels stay the truth everywhere; renderChain never hears about formats.
A format is the presentation of a canvas, carried alongside the pixels in
Options and Project and empty for a custom size, and where one is named it
decides the pixels — so a project saved as A4 reopens as A4 rather than as
whatever it happened to measure.

In the interface a format fills the width and height in and greys them out
rather than hiding them: the size a sheet works out to is worth seeing. A
print format also shows a DPI row, and Custom hands the spins back keeping
the last size, which makes starting from a format and then tweaking it the
ordinary path.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

This commit is contained in:

2026-09-18 22:34:17 +02:00

co-authored by

Claude Opus 5

parent f4d8457828

commit d48a81c665

12 changed files with 494 additions and 24 deletions

									
										CMakeLists.txt
									
		+1
		
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				@@ -23,6 +23,7 @@ find_package(Threads REQUIRED)

				# --- core: effects and image handling, no GUI ---------------------------------

				add_library(effector_core STATIC

				    src/core/canvas.cpp

				    src/core/chain.cpp

				    src/core/effect.cpp

				    src/core/image.cpp