qiconmaker

qiconmaker writes a Windows icon (.ico) or a macOS icon (.icns) from a drawing in SVG or PNG. A build runs it, so that a repository keeps the drawing of its icon rather than the icon files.

The images are rendered with QtSvg, the renderer with which a Qt program draws an SVG icon. The program requires Qt 6 with Qt Gui and Qt Svg, and nothing else.

Usage

qiconmaker [--sizes <list>] [--png-dir <dir>] <output> <drawing> [<size>=<file>...]

• output is the file to write. Its suffix selects the format, .ico or .icns. The directory of the output is created if absent.
• drawing is the master drawing, an SVG (.svg, .svgz) or a PNG. It must be square.
• <size>=<file> gives the image of one size its own source, such as a drawing aligned to the pixel grid of 16 pixels. An SVG is rendered at that size, and a PNG must have exactly that size.
• Every other size is made from the master drawing. An SVG master is rendered at the size. A PNG master is reduced to the size, averaging the pixels, and is never enlarged, so a PNG master smaller than a size is an error.
• --sizes replaces the sizes of the format with a list separated by commas.
• --png-dir also writes each image as <size>.png into a directory, for inspection.

The program exits with 0 on success and 1 on an error, which it reports on the standard error. The output is written whole or not at all.

Sizes

Format	Sizes by default	Storage
.ico	16, 20, 24, 30, 32, 36, 40, 48, 60, 64, 72, 80, 96, 256	256 as PNG, the others as 32-bit BGRA bitmaps with an AND mask
.icns	16, 32, 64, 128, 256, 512, 1024	PNG, each image under every element type of its size

The sizes of .ico are the union of the sizes that the title bar, the taskbar and the Start menu of Windows use at each scale. An .icns holds only the sizes of the table. The image of 32 pixels serves 32 points at 1x and 16 points at 2x, as iconutil stores an iconset.

In CMake

find_package(qiconmaker REQUIRED)

set(_icon "${CMAKE_CURRENT_BINARY_DIR}/app.ico")
add_custom_command(OUTPUT "${_icon}"
    COMMAND qiconmaker::qiconmaker "${_icon}" "${CMAKE_CURRENT_SOURCE_DIR}/icons/app.svg"
        "16=${CMAKE_CURRENT_SOURCE_DIR}/icons/app-16.svg"
    DEPENDS
        "${CMAKE_CURRENT_SOURCE_DIR}/icons/app.svg"
        "${CMAKE_CURRENT_SOURCE_DIR}/icons/app-16.svg"
    VERBATIM
)

A target of the same directory that lists ${_icon} as a source builds the icon first. qm_add_win_rc and qm_add_mac_bundle of qmsetup accept such an icon, called in the directory of the custom command.

The program creates a QGuiApplication for the fonts of a drawing with text, and uses the offscreen platform if QT_QPA_PLATFORM is not set, so that it runs on a build machine without a display. On Windows the DLLs of Qt must be found, for example through PATH.

Building

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=/path/to/Qt/<version>/<compiler>
cmake --build build
cmake --install build --prefix /path/to/prefix

-DQICONMAKER_BUILD_TESTS=ON builds the tests, which ctest --test-dir build runs. On macOS a test checks the .icns with iconutil, because Apple publishes no specification of the format.

License

MIT, see LICENSE.