235 lines
7.1 KiB
Go
235 lines
7.1 KiB
Go
// 25 february 2014
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package ui
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import (
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"fmt"
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)
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// A Grid arranges Controls in a two-dimensional grid.
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// The height of each row and the width of each column is the maximum preferred height and width (respectively) of all the controls in that row or column (respectively).
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// Controls are aligned to the top left corner of each cell.
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// All Controls in a Grid maintain their preferred sizes by default; if a Control is marked as being "filling", it will be sized to fill its cell.
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// Even if a Control is marked as filling, its preferred size is used to calculate cell sizes.
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// One Control can be marked as "stretchy": when the Window containing the Grid is resized, the cell containing that Control resizes to take any remaining space; its row and column are adjusted accordingly (so other filling controls in the same row and column will fill to the new height and width, respectively).
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// A stretchy Control implicitly fills its cell.
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// All cooridnates in a Grid are given in (row,column) form with (0,0) being the top-left cell.
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//
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// As a special rule, to ensure proper appearance, non-standalone Labels are automatically made filling.
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type Grid interface {
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Control
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// SetFilling marks the given Control of the Grid as filling its cell instead of staying at its preferred size.
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// It panics if the given coordinate is invalid.
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SetFilling(row int, column int)
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// SetStretchy marks the given Control of the Grid as stretchy.
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// Stretchy implies filling.
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// Only one control can be stretchy per Grid; calling SetStretchy multiple times merely changes which control is stretchy (preserving the previous filling value).
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// It panics if the given coordinate is invalid.
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SetStretchy(row int, column int)
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}
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type grid struct {
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controls [][]Control
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filling [][]bool
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stretchyrow, stretchycol int
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stretchyfill bool
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widths, heights [][]int // caches to avoid reallocating each time
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rowheights, colwidths []int
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}
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// NewGrid creates a new Grid with the given Controls.
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// NewGrid needs to know the number of Controls in a row (alternatively, the number of columns); it will determine the number in a column from the number of Controls given.
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// NewGrid panics if not given a full grid of Controls.
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// Example:
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// grid := NewGrid(3,
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// control00, control01, control02,
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// control10, control11, control12,
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// control20, control21, control22)
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func NewGrid(nPerRow int, controls ...Control) Grid {
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if len(controls)%nPerRow != 0 {
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panic(fmt.Errorf("incomplete grid given to NewGrid() (not enough controls to evenly divide %d controls into rows of %d controls each)", len(controls), nPerRow))
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}
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nRows := len(controls) / nPerRow
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cc := make([][]Control, nRows)
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cf := make([][]bool, nRows)
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cw := make([][]int, nRows)
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ch := make([][]int, nRows)
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i := 0
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for row := 0; row < nRows; row++ {
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cc[row] = make([]Control, nPerRow)
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cf[row] = make([]bool, nPerRow)
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cw[row] = make([]int, nPerRow)
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ch[row] = make([]int, nPerRow)
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for x := 0; x < nPerRow; x++ {
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cc[row][x] = controls[i]
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if l, ok := controls[i].(Label); ok && !l.isStandalone() {
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cf[row][x] = true
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}
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i++
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}
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}
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return &grid{
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controls: cc,
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filling: cf,
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stretchyrow: -1,
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stretchycol: -1,
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widths: cw,
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heights: ch,
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rowheights: make([]int, nRows),
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colwidths: make([]int, nPerRow),
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}
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}
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func (g *grid) SetFilling(row int, column int) {
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if row < 0 || column < 0 || row > len(g.filling) || column > len(g.filling[row]) {
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panic(fmt.Errorf("coordinate (%d,%d) out of range passed to Grid.SetFilling()", row, column))
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}
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g.filling[row][column] = true
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}
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func (g *grid) SetStretchy(row int, column int) {
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if row < 0 || column < 0 || row > len(g.filling) || column > len(g.filling[row]) {
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panic(fmt.Errorf("coordinate (%d,%d) out of range passed to Grid.SetStretchy()", row, column))
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}
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if g.stretchyrow != -1 || g.stretchycol != -1 {
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g.filling[g.stretchyrow][g.stretchycol] = g.stretchyfill
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}
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g.stretchyrow = row
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g.stretchycol = column
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g.stretchyfill = g.filling[g.stretchyrow][g.stretchycol] // save previous value in case it changes later
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g.filling[g.stretchyrow][g.stretchycol] = true
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}
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func (g *grid) setParent(parent *controlParent) {
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for _, col := range g.controls {
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for _, c := range col {
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c.setParent(parent)
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}
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}
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}
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func (g *grid) allocate(x int, y int, width int, height int, d *sizing) (allocations []*allocation) {
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max := func(a int, b int) int {
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if a > b {
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return a
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}
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return b
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}
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var current *allocation // for neighboring
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if len(g.controls) == 0 {
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return nil
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}
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// 0) inset the available rect by the needed padding
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width -= (len(g.colwidths) - 1) * d.xpadding
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height -= (len(g.rowheights) - 1) * d.ypadding
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// 1) clear data structures
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for i := range g.rowheights {
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g.rowheights[i] = 0
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}
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for i := range g.colwidths {
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g.colwidths[i] = 0
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}
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// 2) get preferred sizes; compute row/column sizes
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for row, xcol := range g.controls {
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for col, c := range xcol {
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w, h := c.preferredSize(d)
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g.widths[row][col] = w
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g.heights[row][col] = h
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g.rowheights[row] = max(g.rowheights[row], h)
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g.colwidths[col] = max(g.colwidths[col], w)
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}
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}
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// 3) handle the stretchy control
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if g.stretchyrow != -1 && g.stretchycol != -1 {
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for i, w := range g.colwidths {
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if i != g.stretchycol {
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width -= w
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}
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}
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for i, h := range g.rowheights {
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if i != g.stretchyrow {
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height -= h
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}
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}
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g.colwidths[g.stretchycol] = width
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g.rowheights[g.stretchyrow] = height
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}
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// 4) draw
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startx := x
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for row, xcol := range g.controls {
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current = nil // reset on new columns
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for col, c := range xcol {
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w := g.widths[row][col]
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h := g.heights[row][col]
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if g.filling[row][col] {
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w = g.colwidths[col]
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h = g.rowheights[row]
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}
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as := c.allocate(x, y, w, h, d)
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if current != nil { // connect first left to first right
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current.neighbor = c
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}
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if len(as) != 0 {
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current = as[0] // next left is first subwidget
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} else {
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current = nil // spaces don't have allocation data
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}
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allocations = append(allocations, as...)
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x += g.colwidths[col] + d.xpadding
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}
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x = startx
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y += g.rowheights[row] + d.ypadding
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}
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return
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}
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// filling and stretchy are ignored for preferred size calculation
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func (g *grid) preferredSize(d *sizing) (width int, height int) {
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max := func(a int, b int) int {
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if a > b {
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return a
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}
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return b
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}
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width -= (len(g.colwidths) - 1) * d.xpadding
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height -= (len(g.rowheights) - 1) * d.ypadding
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// 1) clear data structures
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for i := range g.rowheights {
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g.rowheights[i] = 0
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}
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for i := range g.colwidths {
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g.colwidths[i] = 0
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}
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// 2) get preferred sizes; compute row/column sizes
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for row, xcol := range g.controls {
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for col, c := range xcol {
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w, h := c.preferredSize(d)
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g.widths[row][col] = w
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g.heights[row][col] = h
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g.rowheights[row] = max(g.rowheights[row], h)
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g.colwidths[col] = max(g.colwidths[col], w)
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}
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}
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// 3) now compute
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for _, w := range g.colwidths {
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width += w
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}
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for _, h := range g.rowheights {
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height += h
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}
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return width, height
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}
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func (g *grid) commitResize(c *allocation, d *sizing) {
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// this is to satisfy Control; nothing to do here
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}
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func (g *grid) getAuxResizeInfo(d *sizing) {
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// this is to satisfy Control; nothing to do here
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}
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