From 643bbf1116014f1c0788f611cc5f61722cfe011f Mon Sep 17 00:00:00 2001
From: Sasha Koshka <supergriffin64@gmail.com>
Date: Sat, 8 Apr 2023 19:23:23 -0400
Subject: [PATCH] Grid draws the glyphs inside of cells

---
 elements/grid.go     | 58 +++++++++++++++++++++++++++++++++++++++++---
 elements/terminal.go |  4 +--
 2 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/elements/grid.go b/elements/grid.go
index 8b9d302..fc37466 100644
--- a/elements/grid.go
+++ b/elements/grid.go
@@ -1,10 +1,12 @@
 package elements
 
 import "image"
+import "unicode"
 import "image/color"
 import "golang.org/x/image/font"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/input"
+import "git.tebibyte.media/sashakoshka/tomo/fixedutil"
 import "git.tebibyte.media/sashakoshka/tomo/artist/shapes"
 import "git.tebibyte.media/sashakoshka/tomo/default/theme"
 import "git.tebibyte.media/sashakoshka/tomo/default/config"
@@ -46,6 +48,7 @@ type Grid struct {
 
 	ignorePush bool
 
+	ascent int
 	face   font.Face
 	config config.Wrapped
 	theme  theme.Wrapped
@@ -195,6 +198,7 @@ func (element *Grid) updateFontAndColors () {
 	metrics    := element.face.Metrics()
 	element.cellWidth  = emSpace.Round()
 	element.cellHeight = metrics.Height.Round()
+	element.ascent = metrics.Ascent.Round()
 
 	for index := range element.colors {
 		element.colors[index] = element.theme.Color (
@@ -243,16 +247,18 @@ func (element *Grid) bound (index int) image.Rectangle {
 	}
 }
 
-func (element *Grid) draw (force bool) image.Rectangle {
+func (element *Grid) draw (force bool) (updatedRegion image.Rectangle) {
 	bounds := element.Bounds()
 
 	for index, cell := range element.cells {
 	if force || !cell.clean {
-		// TODO
+		cellBounds := element.bound(index)
+		updatedRegion = updatedRegion.Union(cellBounds)
 		shapes.FillColorRectangle (
 			element.core,
 			element.colors[cell.Background],
-			element.bound(index))
+			cellBounds)
+		element.drawCellGlyph(cellBounds, cell.Cell)
 	}}
 
 	if force {
@@ -262,5 +268,49 @@ func (element *Grid) draw (force bool) image.Rectangle {
 			bounds, element.gridBounds)
 	}
 
-	return bounds // FIXME
+	return
 }
+
+func (element *Grid) drawCellGlyph (cellBounds image.Rectangle, cell Cell) {
+	if cell.Rune < 32 || unicode.IsSpace(cell.Rune) { return }
+
+	glyphColor := element.colors[cell.Foreground]
+	destinationRectangle, mask, maskPoint, _, ok := element.face.Glyph (
+		fixedutil.Pt(cellBounds.Min),
+		cell.Rune)
+
+	if !ok {
+		// tofu
+		shapes.StrokeColorRectangle (
+			element.core, glyphColor, cellBounds.Inset(1), 1)
+		return
+	}
+
+	maxX := destinationRectangle.Dx()
+	maxY := destinationRectangle.Dy()
+
+	data, stride := element.core.Buffer()
+	
+	for y := 0; y < maxY; y ++ {
+	for x := 0; x < maxX; x ++ {
+		_, _, _,
+		alpha := mask.At(x + maskPoint.X, y + maskPoint.Y).RGBA()
+		dstX := x + destinationRectangle.Min.X
+		dstY := y + destinationRectangle.Min.Y + element.ascent
+		dstIndex := dstX + dstY * stride
+		data[dstIndex] =  blend (
+				data[dstIndex],
+				glyphColor,
+				float64(alpha) / 0xFFFF)
+	}}
+}
+
+func blend (bottom, top color.RGBA, fac float64) color.RGBA {
+	return color.RGBA {
+		R: uint8(float64(bottom.R) * (1 - fac) + float64(top.R) * fac),
+		G: uint8(float64(bottom.G) * (1 - fac) + float64(top.G) * fac),
+		B: uint8(float64(bottom.B) * (1 - fac) + float64(top.B) * fac),
+		A: 0xFF,
+	}
+}
+
diff --git a/elements/terminal.go b/elements/terminal.go
index b8b4b61..2f4f617 100644
--- a/elements/terminal.go
+++ b/elements/terminal.go
@@ -25,11 +25,11 @@ func (element *Terminal) handleResize () {
 	element.Set(image.Pt(0, 0), Cell {
 		Rune: 'X',
 		Background: tomo.ColorRed,
-		Foreground: tomo.ColorBlack,
+		Foreground: tomo.ColorBrightWhite,
 	})
 	element.Set(image.Pt(15, 10), Cell {
 		Rune: 'Y',
-		Background: tomo.ColorBrightBlue,
+		Background: tomo.ColorBrightYellow,
 		Foreground: tomo.ColorBlack,
 	})
 }