| Value | Meaning |
|---|---|
| FILL0 | stretch to fill all space if possible, center if no meaningful way to stretch |
| START1 | snap to left or top side, leaving space on right or bottom |
| END2 | snap to right or bottom side, leaving space on left or top |
| CENTER3 | center natural width of widget inside the allocation |
| BASELINE4 | align the widget according to the baseline. Since 3.10. |
Controls how a widget deals with extra space in a single (x or y) dimension.
Alignment only matters if the widget receives a “too large” allocation, for example if you packed the widget with the expand flag inside a gtk.Box, then the widget might get extra space. If you have for example a 16x16 icon inside a 32x32 space, the icon could be scaled and stretched, it could be centered, or it could be positioned to one side of the space.
Note that in horizontal context GTK_ALIGN_START and GTK_ALIGN_END are interpreted relative to text direction.
GTK_ALIGN_BASELINE support for it is optional for containers and widgets, and it is only supported for vertical alignment. When its not supported by a child or a container it is treated as GTK_ALIGN_FILL.