// 25 june 2014 package ui type allocation struct { x int y int width int height int this Control neighbor Control } type sizingbase struct { xmargin int ymargin int xpadding int ypadding int } type controlSizing interface { allocate(x int, y int, width int, height int, d *sizing) []*allocation preferredSize(*sizing) (int, int) commitResize(*allocation, *sizing) getAuxResizeInfo(*sizing) } // on Windows, this is only embedded by window, as all other containers cannot have their own children; beginResize() points to an instance method literal (TODO get correct term) from window // on GTK+ and Mac OS X, one is embedded by window and all containers; beginResize() points to a global function (TODO NOT GOOD; ideally the sizing data should be passed across size-allocate requests) type container struct { child Control } // set to true to apply spacing to all windows var spaced bool = false func (c *container) resize(x, y, width, height int) { if c.child == nil { // no children; nothing to do return } d := c.beginResize() allocations := c.child.allocate(x + d.xmargin, y + d.ymargin, width - (2 * d.xmargin), height - (2 * d.ymargin), d) c.translateAllocationCoords(allocations, width, height) // move in reverse so as to approximate right->left order so neighbors make sense for i := len(allocations) - 1; i >= 0; i-- { allocations[i].this.commitResize(allocations[i], d) } }