Starting custom editor window

editor.go

@@ -0,0 +1,189 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/bloeys/gopad/settings"
+	"github.com/inkyblackness/imgui-go/v4"
+)
+
+const (
+	linesPerNode int = 100
+)
+
+type Line struct {
+	chars []rune
+}
+
+type LinesNode struct {
+	Lines [linesPerNode]Line
+	Next  *LinesNode
+}
+
+type Editor struct {
+	FileName     string
+	FilePath     string
+	FileContents string
+
+	CursorX int
+	CursorY int
+
+	SelectionStart  int
+	SelectionLength int
+
+	IsModified bool
+
+	LinesHead *LinesNode
+	LineCount int
+}
+
+func (e *Editor) SetCursorPos(x, y int) {
+	e.CursorX = x
+	e.CursorY = y
+}
+
+func (e *Editor) Render(drawStartPos, winSize *imgui.Vec2) {
+
+	e.CursorY = clampInt(e.CursorY, 0, e.LineCount)
+	e.CursorX = clampInt(e.CursorX, 0, e.GetLineCharCount(e.CursorY))
+
+	//Draw window
+	imgui.SetNextWindowPos(*drawStartPos)
+	imgui.SetNextWindowSize(*winSize)
+	imgui.BeginV("editorText", nil, imgui.WindowFlagsNoCollapse|imgui.WindowFlagsNoDecoration|imgui.WindowFlagsNoMove)
+
+	imgui.PushStyleColor(imgui.StyleColorFrameBg, settings.EditorBgColor)
+	imgui.PushStyleColor(imgui.StyleColorTextSelectedBg, settings.TextSelectionColor)
+
+	//Add padding to text
+	drawStartPos.X += 10
+	drawStartPos.Y += 10
+
+	//Draw lines
+	lineHeight := imgui.TextLineHeightWithSpacing()
+	linesToDraw := int(winSize.Y / lineHeight)
+	println("Lines to draw:", linesToDraw)
+
+	dl := imgui.WindowDrawList()
+	for i := 0; i < linesToDraw; i++ {
+		dl.AddText(*drawStartPos, imgui.PackedColorFromVec4(imgui.Vec4{X: 1, Y: 1, Z: 1, W: 1}), string(e.GetLine(e.CursorY+i).chars))
+		drawStartPos.Y += lineHeight
+	}
+}
+
+func (e *Editor) GetLine(lineNum int) *Line {
+
+	if lineNum > e.LineCount {
+		return &Line{
+			chars: []rune{},
+		}
+	}
+
+	curr := e.LinesHead
+
+	//Advance to correct node
+	nodeNum := lineNum / linesPerNode
+	lineNum -= nodeNum * linesPerNode
+	for nodeNum > 0 {
+		curr = curr.Next
+		nodeNum--
+	}
+
+	return &curr.Lines[lineNum]
+}
+
+func (e *Editor) GetLineCharCount(lineNum int) int {
+
+	curr := e.LinesHead
+
+	//Advance to correct node
+	nodeNum := lineNum / linesPerNode
+	lineNum -= nodeNum * linesPerNode
+	for nodeNum > 0 {
+		curr = curr.Next
+		nodeNum--
+	}
+
+	return len(curr.Lines[lineNum].chars)
+}
+
+func ParseLines(fileContents string) (*LinesNode, int) {
+
+	head := NewLineNode()
+
+	lineCount := 0
+	start := 0
+	end := 0
+	currLine := 0
+	currNode := head
+	for i := 0; i < len(fileContents); i++ {
+
+		if fileContents[i] != '\n' {
+			end++
+			continue
+		}
+
+		lineCount++
+		currNode.Lines[currLine].chars = []rune(fileContents[start:end])
+
+		end++
+		start = end
+		currLine++
+		if currLine == linesPerNode {
+			currLine = 0
+			currNode.Next = NewLineNode()
+			currNode = currNode.Next
+		}
+	}
+
+	return head, lineCount
+}
+
+func NewLineNode() *LinesNode {
+
+	n := LinesNode{}
+	for i := 0; i < len(n.Lines); i++ {
+		n.Lines[i].chars = []rune{}
+	}
+
+	return &n
+}
+
+func clampInt(x, min, max int) int {
+
+	if x > max {
+		return max
+	}
+
+	if x < min {
+		return min
+	}
+
+	return x
+}
+
+func NewScratchEditor() *Editor {
+
+	e := &Editor{
+		FileName:  "**scratch**",
+		LinesHead: NewLineNode(),
+	}
+	return e
+}
+
+func NewEditor(fPath string) *Editor {
+
+	b, err := os.ReadFile(fPath)
+	if err != nil {
+		panic(err)
+	}
+
+	e := &Editor{
+		FileName:     filepath.Base(fPath),
+		FilePath:     fPath,
+		FileContents: string(b),
+	}
+	e.LinesHead, e.LineCount = ParseLines(e.FileContents)
+	return e
+}