Adds a Canvas

So far you can just fill them in with solid colours
and draw homogenous rectangles within it

_demos/windows.go

@@ -8,6 +8,7 @@ import (
 
 var window, fancyWindow *windeau.Window
 var focusableWindow *windeau.FocusableWindow
+var canvas *windeau.Canvas
 
 func main() {
 	termbox.Init()
@@ -62,6 +63,7 @@ func draw() {
 	window.Draw()
 	fancyWindow.Draw()
 	focusableWindow.Draw()
+	canvas.Draw()
 	termbox.Flush()
 }
 
@@ -84,4 +86,9 @@ func prepareWindows() {
 	unfocusColor := windeau.WindowState{FgColor: termbox.ColorWhite, BgColor: termbox.ColorBlack}
 	focusableWindow = &windeau.FocusableWindow{FocusOn: focusColor, FocusOff: unfocusColor, Focused: false}
 	focusableWindow.SetParent(underlyingWindow)
+
+	canvas = windeau.MakeCanvas(70, 5, 10, 10)
+	canvas.Fill('x', termbox.ColorYellow, termbox.ColorYellow)
+	canvas.FilledRect('y', termbox.ColorBlack, termbox.ColorYellow, windeau.Rect{75, 7, 3, 3})
+	canvas.FilledRect('z', termbox.ColorBlue, termbox.ColorDefault, windeau.Rect{72, 12, 2, 3})
 }

canvas.go

@@ -0,0 +1,66 @@
+package windeau
+
+import (
+	"github.com/nsf/termbox-go"
+)
+
+type Cell struct {
+	Char   rune
+	Fg, Bg termbox.Attribute
+}
+
+var BlankCell Cell = Cell{' ', termbox.ColorDefault, termbox.ColorDefault}
+
+type Canvas struct {
+	X, Y, Width, Height int
+	Parent              *Drawable
+	cells               [][]Cell
+}
+
+func MakeCanvas(x, y, w, h int) *Canvas {
+	canvas := &Canvas{X: x, Y: y, Width: w, Height: h}
+	canvas.initialize()
+	return canvas
+}
+
+func (c *Canvas) GetRect() Rect {
+	return Rect{c.X, c.Y, c.Width, c.Height}
+}
+
+func (c *Canvas) Fill(char rune, fg, bg termbox.Attribute) {
+	c.FilledRect(char, fg, bg, c.GetRect())
+}
+
+func (c *Canvas) FilledRect(char rune, fg, bg termbox.Attribute, rect Rect) {
+	if c.GetRect().DoesNotContain(rect) {
+		return
+	}
+
+	offsetX := rect.X - c.X
+	offsetY := rect.Y - c.Y
+
+	for i := 0; i < rect.Width; i++ {
+		for j := 0; j < rect.Height; j++ {
+			c.cells[i+offsetX][j+offsetY] = Cell{char, fg, bg}
+		}
+	}
+}
+
+func (c *Canvas) Draw() {
+	for x, row := range c.cells {
+		for y, cell := range row {
+			termbox.SetCell(x+c.X, y+c.Y, cell.Char, cell.Fg, cell.Bg)
+		}
+	}
+}
+
+func (c *Canvas) Cells() [][]Cell {
+	return c.cells
+}
+
+func (c *Canvas) initialize() {
+	c.cells = make([][]Cell, c.Width)
+	for i := range c.cells {
+		c.cells[i] = make([]Cell, c.Height)
+	}
+}

canvas_test.go

@@ -0,0 +1,37 @@
+package windeau
+
+import (
+	"fmt"
+	"github.com/nsf/termbox-go"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func assert_canvas_cells(t *testing.T, c rune, fg, bg termbox.Attribute, cells [][]Cell) {
+	for _, row := range cells {
+		for _, cell := range row {
+			assert_canvas_cell(t, c, fg, bg, cell)
+		}
+	}
+}
+
+func assert_canvas_cell(t *testing.T, c rune, fg, bg termbox.Attribute, cell Cell) {
+	assert.Equal(t, c, cell.Char, fmt.Sprintf("Cell should've been %v but was %v instead", c, cell.Char))
+	assert.Equal(t, fg, cell.Fg, "Cell foreground colour should be Red")
+	assert.Equal(t, bg, cell.Bg, "Cell background colour should be Default")
+}
+
+func TestFillingCanvas(t *testing.T) {
+	canvas := MakeCanvas(0, 0, 2, 2)
+	canvas.Fill('x', termbox.ColorRed, termbox.ColorDefault)
+	cells := canvas.Cells()
+	assert_canvas_cells(t, 'x', termbox.ColorRed, termbox.ColorDefault, cells)
+}
+
+func TestFillingARegionInsideTheCanvas(t *testing.T) {
+	canvas := MakeCanvas(0, 0, 5, 5)
+	canvas.Fill('x', termbox.ColorRed, termbox.ColorDefault)
+	canvas.FilledRect('y', termbox.ColorGreen, termbox.ColorDefault, Rect{2, 2, 1, 1})
+	cells := canvas.Cells()
+	assert_canvas_cell(t, 'y', termbox.ColorGreen, termbox.ColorDefault, cells[2][2])
+}

rect.go

@@ -12,3 +12,16 @@ func (r Rect) WithinRect(x, y int) bool {
 	}
 	return false
 }
+
+func (r Rect) Contains(other Rect) bool {
+	if r.X <= other.X && r.X+r.Width >= other.X+other.Width {
+		if r.Y <= other.Y && r.Y+r.Height >= other.Y+other.Height {
+			return true
+		}
+	}
+	return false
+}
+
+func (r Rect) DoesNotContain(other Rect) bool {
+	return !r.Contains(other)
+}