Terminal-based user interface toolkit
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package cview
import (
"math"
"sync"
"github.com/gdamore/tcell/v2"
)
// gridItem represents one primitive and its possible position on a grid.
type gridItem struct {
Item Primitive // The item to be positioned. May be nil for an empty item.
Row, Column int // The top-left grid cell where the item is placed.
Width, Height int // The number of rows and columns the item occupies.
MinGridWidth, MinGridHeight int // The minimum grid width/height for which this item is visible.
Focus bool // Whether or not this item attracts the layout's focus.
visible bool // Whether or not this item was visible the last time the grid was drawn.
x, y, w, h int // The last position of the item relative to the top-left corner of the grid. Undefined if visible is false.
}
// Grid is an implementation of a grid-based layout. It works by defining the
// size of the rows and columns, then placing primitives into the grid.
//
// Some settings can lead to the grid exceeding its available space. SetOffset()
// can then be used to scroll in steps of rows and columns. These offset values
// can also be controlled with the arrow keys (or the "g","G", "j", "k", "h",
// and "l" keys) while the grid has focus and none of its contained primitives
// do.
type Grid struct {
*Box
// The items to be positioned.
items []*gridItem
// The definition of the rows and columns of the grid. See
// SetRows()/SetColumns() for details.
rows, columns []int
// The minimum sizes for rows and columns.
minWidth, minHeight int
// The size of the gaps between neighboring primitives. This is automatically
// set to 1 if borders is true.
gapRows, gapColumns int
// The number of rows and columns skipped before drawing the top-left corner
// of the grid.
rowOffset, columnOffset int
// Whether or not borders are drawn around grid items. If this is set to true,
// a gap size of 1 is automatically assumed (which is filled with the border
// graphics).
borders bool
// The color of the borders around grid items.
bordersColor tcell.Color
sync.RWMutex
}
// NewGrid returns a new grid-based layout container with no initial primitives.
//
// Note that Grid will have a transparent background by default so that any
// areas not covered by any primitives will show primitives behind the Grid.
// To disable this transparency:
//
// grid.SetBackgroundTransparent(false)
func NewGrid() *Grid {
g := &Grid{
Box: NewBox(),
bordersColor: Styles.GraphicsColor,
}
g.SetBackgroundTransparent(true)
g.focus = g
return g
}
// SetColumns defines how the columns of the grid are distributed. Each value
// defines the size of one column, starting with the leftmost column. Values
// greater 0 represent absolute column widths (gaps not included). Values less
// or equal 0 represent proportional column widths or fractions of the remaining
// free space, where 0 is treated the same as -1. That is, a column with a value
// of -3 will have three times the width of a column with a value of -1 (or 0).
// The minimum width set with SetMinSize() is always observed.
//
// Primitives may extend beyond the columns defined explicitly with this
// function. A value of 0 is assumed for any undefined column. In fact, if you
// never call this function, all columns occupied by primitives will have the
// same width. On the other hand, unoccupied columns defined with this function
// will always take their place.
//
// Assuming a total width of the grid of 100 cells and a minimum width of 0, the
// following call will result in columns with widths of 30, 10, 15, 15, and 30
// cells:
//
// grid.SetColumns(30, 10, -1, -1, -2)
//
// If a primitive were then placed in the 6th and 7th column, the resulting
// widths would be: 30, 10, 10, 10, 20, 10, and 10 cells.
//
// If you then called SetMinSize() as follows:
//
// grid.SetMinSize(15, 20)
//
// The resulting widths would be: 30, 15, 15, 15, 20, 15, and 15 cells, a total
// of 125 cells, 25 cells wider than the available grid width.
func (g *Grid) SetColumns(columns ...int) {
g.Lock()
defer g.Unlock()
g.columns = columns
}
// SetRows defines how the rows of the grid are distributed. These values behave
// the same as the column values provided with SetColumns(), see there for a
// definition and examples.
//
// The provided values correspond to row heights, the first value defining
// the height of the topmost row.
func (g *Grid) SetRows(rows ...int) {
g.Lock()
defer g.Unlock()
g.rows = rows
}
// SetSize is a shortcut for SetRows() and SetColumns() where all row and column
// values are set to the given size values. See SetColumns() for details on sizes.
func (g *Grid) SetSize(numRows, numColumns, rowSize, columnSize int) {
g.Lock()
defer g.Unlock()
g.rows = make([]int, numRows)
for index := range g.rows {
g.rows[index] = rowSize
}
g.columns = make([]int, numColumns)
for index := range g.columns {
g.columns[index] = columnSize
}
}
// SetMinSize sets an absolute minimum width for rows and an absolute minimum
// height for columns. Panics if negative values are provided.
func (g *Grid) SetMinSize(row, column int) {
g.Lock()
defer g.Unlock()
if row < 0 || column < 0 {
panic("Invalid minimum row/column size")
}
g.minHeight, g.minWidth = row, column
}
// SetGap sets the size of the gaps between neighboring primitives on the grid.
// If borders are drawn (see SetBorders()), these values are ignored and a gap
// of 1 is assumed. Panics if negative values are provided.
func (g *Grid) SetGap(row, column int) {
g.Lock()
defer g.Unlock()
if row < 0 || column < 0 {
panic("Invalid gap size")
}
g.gapRows, g.gapColumns = row, column
}
// SetBorders sets whether or not borders are drawn around grid items. Setting
// this value to true will cause the gap values (see SetGap()) to be ignored and
// automatically assumed to be 1 where the border graphics are drawn.
func (g *Grid) SetBorders(borders bool) {
g.Lock()
defer g.Unlock()
g.borders = borders
}
// SetBordersColor sets the color of the item borders.
func (g *Grid) SetBordersColor(color tcell.Color) {
g.Lock()
defer g.Unlock()
g.bordersColor = color
}
// AddItem adds a primitive and its position to the grid. The top-left corner
// of the primitive will be located in the top-left corner of the grid cell at
// the given row and column and will span "rowSpan" rows and "colSpan" columns.
// For example, for a primitive to occupy rows 2, 3, and 4 and columns 5 and 6:
//
// grid.AddItem(p, 2, 5, 3, 2, 0, 0, true)
//
// If rowSpan or colSpan is 0, the primitive will not be drawn.
//
// You can add the same primitive multiple times with different grid positions.
// The minGridWidth and minGridHeight values will then determine which of those
// positions will be used. This is similar to CSS media queries. These minimum
// values refer to the overall size of the grid. If multiple items for the same
// primitive apply, the one that has at least one highest minimum value will be
// used, or the primitive added last if those values are the same. Example:
//
// grid.AddItem(p, 0, 0, 0, 0, 0, 0, true). // Hide in small grids.
// AddItem(p, 0, 0, 1, 2, 100, 0, true). // One-column layout for medium grids.
// AddItem(p, 1, 1, 3, 2, 300, 0, true) // Multi-column layout for large grids.
//
// To use the same grid layout for all sizes, simply set minGridWidth and
// minGridHeight to 0.
//
// If the item's focus is set to true, it will receive focus when the grid
// receives focus. If there are multiple items with a true focus flag, the last
// visible one that was added will receive focus.
func (g *Grid) AddItem(p Primitive, row, column, rowSpan, colSpan, minGridHeight, minGridWidth int, focus bool) {
g.Lock()
defer g.Unlock()
g.items = append(g.items, &gridItem{
Item: p,
Row: row,
Column: column,
Height: rowSpan,
Width: colSpan,
MinGridHeight: minGridHeight,
MinGridWidth: minGridWidth,
Focus: focus,
})
}
// RemoveItem removes all items for the given primitive from the grid, keeping
// the order of the remaining items intact.
func (g *Grid) RemoveItem(p Primitive) {
g.Lock()
defer g.Unlock()
for index := len(g.items) - 1; index >= 0; index-- {
if g.items[index].Item == p {
g.items = append(g.items[:index], g.items[index+1:]...)
}
}
}
// Clear removes all items from the grid.
func (g *Grid) Clear() {
g.Lock()
defer g.Unlock()
g.items = nil
}
// SetOffset sets the number of rows and columns which are skipped before
// drawing the first grid cell in the top-left corner. As the grid will never
// completely move off the screen, these values may be adjusted the next time
// the grid is drawn. The actual position of the grid may also be adjusted such
// that contained primitives that have focus remain visible.
func (g *Grid) SetOffset(rows, columns int) {
g.Lock()
defer g.Unlock()
g.rowOffset, g.columnOffset = rows, columns
}
// GetOffset returns the current row and column offset (see SetOffset() for
// details).
func (g *Grid) GetOffset() (rows, columns int) {
g.RLock()
defer g.RUnlock()
return g.rowOffset, g.columnOffset
}
// Focus is called when this primitive receives focus.
func (g *Grid) Focus(delegate func(p Primitive)) {
g.Lock()
items := g.items
g.Unlock()
for _, item := range items {
if item.Focus {
delegate(item.Item)
return
}
}
g.Lock()
g.hasFocus = true
g.Unlock()
}
// Blur is called when this primitive loses focus.
func (g *Grid) Blur() {
g.Lock()
defer g.Unlock()
g.hasFocus = false
}
// HasFocus returns whether or not this primitive has focus.
func (g *Grid) HasFocus() bool {
g.RLock()
defer g.RUnlock()
for _, item := range g.items {
if item.visible && item.Item.GetFocusable().HasFocus() {
return true
}
}
return g.hasFocus
}
// InputHandler returns the handler for this primitive.
func (g *Grid) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
return g.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
g.Lock()
defer g.Unlock()
if HitShortcut(event, Keys.MoveFirst, Keys.MoveFirst2) {
g.rowOffset, g.columnOffset = 0, 0
} else if HitShortcut(event, Keys.MoveLast, Keys.MoveLast2) {
g.rowOffset = math.MaxInt32
} else if HitShortcut(event, Keys.MoveUp, Keys.MoveUp2, Keys.MovePreviousField) {
g.rowOffset--
} else if HitShortcut(event, Keys.MoveDown, Keys.MoveDown2, Keys.MoveNextField) {
g.rowOffset++
} else if HitShortcut(event, Keys.MoveLeft, Keys.MoveLeft2) {
g.columnOffset--
} else if HitShortcut(event, Keys.MoveRight, Keys.MoveRight2) {
g.columnOffset++
}
})
}
// Draw draws this primitive onto the screen.
func (g *Grid) Draw(screen tcell.Screen) {
if !g.GetVisible() {
return
}
g.Box.Draw(screen)
g.Lock()
defer g.Unlock()
x, y, width, height := g.GetInnerRect()
screenWidth, screenHeight := screen.Size()
// Make a list of items which apply.
items := make(map[Primitive]*gridItem)
for _, item := range g.items {
item.visible = false
if item.Width <= 0 || item.Height <= 0 || width < item.MinGridWidth || height < item.MinGridHeight {
continue
}
previousItem, ok := items[item.Item]
if ok && item.MinGridWidth < previousItem.MinGridWidth && item.MinGridHeight < previousItem.MinGridHeight {
continue
}
items[item.Item] = item
}
// How many rows and columns do we have?
rows := len(g.rows)
columns := len(g.columns)
for _, item := range items {
rowEnd := item.Row + item.Height
if rowEnd > rows {
rows = rowEnd
}
columnEnd := item.Column + item.Width
if columnEnd > columns {
columns = columnEnd
}
}
if rows == 0 || columns == 0 {
return // No content.
}
// Where are they located?
rowPos := make([]int, rows)
rowHeight := make([]int, rows)
columnPos := make([]int, columns)
columnWidth := make([]int, columns)
// How much space do we distribute?
remainingWidth := width
remainingHeight := height
proportionalWidth := 0
proportionalHeight := 0
for index, row := range g.rows {
if row > 0 {
if row < g.minHeight {
row = g.minHeight
}
remainingHeight -= row
rowHeight[index] = row
} else if row == 0 {
proportionalHeight++
} else {
proportionalHeight += -row
}
}
for index, column := range g.columns {
if column > 0 {
if column < g.minWidth {
column = g.minWidth
}
remainingWidth -= column
columnWidth[index] = column
} else if column == 0 {
proportionalWidth++
} else {
proportionalWidth += -column
}
}
if g.borders {
remainingHeight -= rows + 1
remainingWidth -= columns + 1
} else {
remainingHeight -= (rows - 1) * g.gapRows
remainingWidth -= (columns - 1) * g.gapColumns
}
if rows > len(g.rows) {
proportionalHeight += rows - len(g.rows)
}
if columns > len(g.columns) {
proportionalWidth += columns - len(g.columns)
}
// Distribute proportional rows/columns.
for index := 0; index < rows; index++ {
row := 0
if index < len(g.rows) {
row = g.rows[index]
}
if row > 0 {
if row < g.minHeight {
row = g.minHeight
}
continue // Not proportional. We already know the width.
} else if row == 0 {
row = 1
} else {
row = -row
}
rowAbs := row * remainingHeight / proportionalHeight
remainingHeight -= rowAbs
proportionalHeight -= row
if rowAbs < g.minHeight {
rowAbs = g.minHeight
}
rowHeight[index] = rowAbs
}
for index := 0; index < columns; index++ {
column := 0
if index < len(g.columns) {
column = g.columns[index]
}
if column > 0 {
if column < g.minWidth {
column = g.minWidth
}
continue // Not proportional. We already know the height.
} else if column == 0 {
column = 1
} else {
column = -column
}
columnAbs := column * remainingWidth / proportionalWidth
remainingWidth -= columnAbs
proportionalWidth -= column
if columnAbs < g.minWidth {
columnAbs = g.minWidth
}
columnWidth[index] = columnAbs
}
// Calculate row/column positions.
var columnX, rowY int
if g.borders {
columnX++
rowY++
}
for index, row := range rowHeight {
rowPos[index] = rowY
gap := g.gapRows
if g.borders {
gap = 1
}
rowY += row + gap
}
for index, column := range columnWidth {
columnPos[index] = columnX
gap := g.gapColumns
if g.borders {
gap = 1
}
columnX += column + gap
}
// Calculate primitive positions.
var focus *gridItem // The item which has focus.
for primitive, item := range items {
px := columnPos[item.Column]
py := rowPos[item.Row]
var pw, ph int
for index := 0; index < item.Height; index++ {
ph += rowHeight[item.Row+index]
}
for index := 0; index < item.Width; index++ {
pw += columnWidth[item.Column+index]
}
if g.borders {
pw += item.Width - 1
ph += item.Height - 1
} else {
pw += (item.Width - 1) * g.gapColumns
ph += (item.Height - 1) * g.gapRows
}
item.x, item.y, item.w, item.h = px, py, pw, ph
item.visible = true
if primitive.GetFocusable().HasFocus() {
focus = item
}
}
// Calculate screen offsets.
var offsetX, offsetY int
add := 1
if !g.borders {
add = g.gapRows
}
for index, height := range rowHeight {
if index >= g.rowOffset {
break
}
offsetY += height + add
}
if !g.borders {
add = g.gapColumns
}
for index, width := range columnWidth {
if index >= g.columnOffset {
break
}
offsetX += width + add
}
// Line up the last row/column with the end of the available area.
var border int
if g.borders {
border = 1
}
last := len(rowPos) - 1
if rowPos[last]+rowHeight[last]+border-offsetY < height {
offsetY = rowPos[last] - height + rowHeight[last] + border
}
last = len(columnPos) - 1
if columnPos[last]+columnWidth[last]+border-offsetX < width {
offsetX = columnPos[last] - width + columnWidth[last] + border
}
// The focused item must be within the visible area.
if focus != nil {
if focus.y+focus.h-offsetY >= height {
offsetY = focus.y - height + focus.h
}
if focus.y-offsetY < 0 {
offsetY = focus.y
}
if focus.x+focus.w-offsetX >= width {
offsetX = focus.x - width + focus.w
}
if focus.x-offsetX < 0 {
offsetX = focus.x
}
}
// Adjust row/column offsets based on this value.
var from, to int
for index, pos := range rowPos {
if pos-offsetY < 0 {
from = index + 1
}
if pos-offsetY < height {
to = index
}
}
if g.rowOffset < from {
g.rowOffset = from
}
if g.rowOffset > to {
g.rowOffset = to
}
from, to = 0, 0
for index, pos := range columnPos {
if pos-offsetX < 0 {
from = index + 1
}
if pos-offsetX < width {
to = index
}
}
if g.columnOffset < from {
g.columnOffset = from
}
if g.columnOffset > to {
g.columnOffset = to
}
// Draw primitives and borders.
for primitive, item := range items {
// Final primitive position.
if !item.visible {
continue
}
item.x -= offsetX
item.y -= offsetY
if item.x >= width || item.x+item.w <= 0 || item.y >= height || item.y+item.h <= 0 {
item.visible = false
continue
}
if item.x+item.w > width {
item.w = width - item.x
}
if item.y+item.h > height {
item.h = height - item.y
}
if item.x < 0 {
item.w += item.x
item.x = 0
}
if item.y < 0 {
item.h += item.y
item.y = 0
}
if item.w <= 0 || item.h <= 0 {
item.visible = false
continue
}
item.x += x
item.y += y
primitive.SetRect(item.x, item.y, item.w, item.h)
// Draw primitive.
if item == focus {
defer primitive.Draw(screen)
} else {
primitive.Draw(screen)
}
// Draw border around primitive.
if g.borders {
for bx := item.x; bx < item.x+item.w; bx++ { // Top/bottom lines.
if bx < 0 || bx >= screenWidth {
continue
}
by := item.y - 1
if by >= 0 && by < screenHeight {
PrintJoinedSemigraphics(screen, bx, by, Borders.Horizontal, g.bordersColor)
}
by = item.y + item.h
if by >= 0 && by < screenHeight {
PrintJoinedSemigraphics(screen, bx, by, Borders.Horizontal, g.bordersColor)
}
}
for by := item.y; by < item.y+item.h; by++ { // Left/right lines.
if by < 0 || by >= screenHeight {
continue
}
bx := item.x - 1
if bx >= 0 && bx < screenWidth {
PrintJoinedSemigraphics(screen, bx, by, Borders.Vertical, g.bordersColor)
}
bx = item.x + item.w
if bx >= 0 && bx < screenWidth {
PrintJoinedSemigraphics(screen, bx, by, Borders.Vertical, g.bordersColor)
}
}
bx, by := item.x-1, item.y-1 // Top-left corner.
if bx >= 0 && bx < screenWidth && by >= 0 && by < screenHeight {
PrintJoinedSemigraphics(screen, bx, by, Borders.TopLeft, g.bordersColor)
}
bx, by = item.x+item.w, item.y-1 // Top-right corner.
if bx >= 0 && bx < screenWidth && by >= 0 && by < screenHeight {
PrintJoinedSemigraphics(screen, bx, by, Borders.TopRight, g.bordersColor)
}
bx, by = item.x-1, item.y+item.h // Bottom-left corner.
if bx >= 0 && bx < screenWidth && by >= 0 && by < screenHeight {
PrintJoinedSemigraphics(screen, bx, by, Borders.BottomLeft, g.bordersColor)
}
bx, by = item.x+item.w, item.y+item.h // Bottom-right corner.
if bx >= 0 && bx < screenWidth && by >= 0 && by < screenHeight {
PrintJoinedSemigraphics(screen, bx, by, Borders.BottomRight, g.bordersColor)
}
}
}
}
// MouseHandler returns the mouse handler for this primitive.
func (g *Grid) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
return g.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
if !g.InRect(event.Position()) {
return false, nil
}
// Pass mouse events along to the first child item that takes it.
for _, item := range g.items {
consumed, capture = item.Item.MouseHandler()(action, event, setFocus)
if consumed {
return
}
}
return
})
}