Add AtPosition to TypeSetter

debug/debug.go

@@ -0,0 +1,28 @@
+package debug
+
+import "image/draw"
+import "image/color"
+import "golang.org/x/image/math/fixed"
+import "git.tebibyte.media/tomo/typeset"
+import "git.tebibyte.media/tomo/typeset/internal"
+
+// DrawBounds draws the LayoutBounds, MinimumSize, and LayoutBoundsSpace of a
+// TypeSetter to the given image using these colors:
+//   - Red:   LayoutBounds
+//   - Green: MinimumSize
+//   - Blue:  LayoutBoundsSpace
+func DrawBounds (destination draw.Image, setter *typeset.TypeSetter, offset fixed.Point26_6) {
+	blue  := color.RGBA { B: 255, A: 255 }
+	red   := color.RGBA { R: 255, A: 255 }
+	green := color.RGBA { G: 255, A: 255 }
+
+	layoutBoundsSpace := setter.LayoutBoundsSpace()
+	layoutBounds      := setter.LayoutBounds()
+	
+	minimum     := setter.MinimumSize()
+	minimumRect := internal.RoundRect(fixed.Rectangle26_6 { Max: minimum }.Add(offset).Add(layoutBounds.Min))
+	internal.DrawRectangleOutline(destination, minimumRect, green)
+	
+	internal.DrawRectangleOutline(destination, internal.RoundRect(layoutBoundsSpace.Add(offset)), blue)
+	internal.DrawRectangleOutline(destination, internal.RoundRect(layoutBounds.Add(offset)), red)
+}

draw.go

@@ -6,6 +6,7 @@ import "image/draw"
 import "image/color"
 import "golang.org/x/image/font"
 import "golang.org/x/image/math/fixed"
+import "git.tebibyte.media/tomo/typeset/internal"
 
 // Draw draws the contents of a TypeSetter to an image at the given offset. It
 // returns a rectangle containing all pixels in the image that were updated.
@@ -49,27 +50,6 @@ func Draw (destination draw.Image, setter *TypeSetter, offset fixed.Point26_6, c
 	return updatedRegion
 }
 
-// DrawBounds draws the LayoutBounds, MinimumSize, and LayoutBoundsSpace of a
-// TypeSetter to the given image using these colors:
-//   - Red:   LayoutBounds
-//   - Green: MinimumSize
-//   - Blue:  LayoutBoundsSpace
-func DrawBounds (destination draw.Image, setter *TypeSetter, offset fixed.Point26_6) {
-	blue  := color.RGBA { B: 255, A: 255 }
-	red   := color.RGBA { R: 255, A: 255 }
-	green := color.RGBA { G: 255, A: 255 }
-
-	layoutBoundsSpace := setter.LayoutBoundsSpace()
-	layoutBounds      := setter.LayoutBounds()
-	
-	minimum     := setter.MinimumSize()
-	minimumRect := roundRect(fixed.Rectangle26_6 { Max: minimum }.Add(offset).Add(layoutBounds.Min))
-	drawRectangleOutline(destination, minimumRect, green)
-	
-	drawRectangleOutline(destination, roundRect(layoutBoundsSpace.Add(offset)), blue)
-	drawRectangleOutline(destination, roundRect(layoutBounds.Add(offset)), red)
-}
-
 func drawTofu (
 	char rune,
 	destination draw.Image,
@@ -78,29 +58,8 @@ func drawTofu (
 	col         color.Color,
 ) {
 	bounds, _ := tofuBounds(face)
-	rectBounds := roundRect(bounds).Add(image.Pt (
+	rectBounds := internal.RoundRect(bounds).Add(image.Pt (
 		position.X.Round(),
 		position.Y.Round()))
-	drawRectangleOutline(destination, rectBounds, col)
-}
-
-func drawRectangleOutline (destination draw.Image, bounds image.Rectangle, col color.Color) {
-	for x := bounds.Min.X; x < bounds.Max.X; x ++ {
-		destination.Set(x, bounds.Min.Y, col)
-	}
-	for y := bounds.Min.Y; y < bounds.Max.Y; y ++ {
-		destination.Set(bounds.Min.X, y, col)
-		destination.Set(bounds.Max.X - 1, y, col)
-	}
-	for x := bounds.Min.X; x < bounds.Max.X; x ++ {
-		destination.Set(x, bounds.Max.Y - 1, col)
-	}
-}
-
-func roundRect (rectangle fixed.Rectangle26_6) image.Rectangle {
-	return image.Rect (
-		rectangle.Min.X.Round(),
-		rectangle.Min.Y.Round(),
-		rectangle.Max.X.Round(),
-		rectangle.Max.Y.Round())
+	internal.DrawRectangleOutline(destination, rectBounds, col)
 }

examples/test/main.go

@@ -9,6 +9,7 @@ import "image/color"
 import "golang.org/x/image/math/fixed"
 import "git.tebibyte.media/tomo/typeset"
 import "golang.org/x/image/font/basicfont"
+import "git.tebibyte.media/tomo/typeset/debug"
 
 func main () {
 	img := image.NewRGBA(image.Rect(0, 0, 2048, 1024))
@@ -122,7 +123,7 @@ func drawText (destination subDrawImage, setter *typeset.TypeSetter, bounds imag
 		Y: metrics.Ascent + fixed.I(bounds.Min.Y),
 	}
 	// typeset.Draw(destination, setter, offset, color.Black)
-	typeset.DrawBounds(subImage, setter, offset)
+	debug.DrawBounds(subImage, setter, offset)
 	typeset.Draw(subImage, setter, offset, color.Black)
 	
 }

internal/draw.go

@@ -0,0 +1,27 @@
+package internal
+
+import "image"
+import "image/draw"
+import "image/color"
+import "golang.org/x/image/math/fixed"
+
+func DrawRectangleOutline (destination draw.Image, bounds image.Rectangle, col color.Color) {
+	for x := bounds.Min.X; x < bounds.Max.X; x ++ {
+		destination.Set(x, bounds.Min.Y, col)
+	}
+	for y := bounds.Min.Y; y < bounds.Max.Y; y ++ {
+		destination.Set(bounds.Min.X, y, col)
+		destination.Set(bounds.Max.X - 1, y, col)
+	}
+	for x := bounds.Min.X; x < bounds.Max.X; x ++ {
+		destination.Set(x, bounds.Max.Y - 1, col)
+	}
+}
+
+func RoundRect (rectangle fixed.Rectangle26_6) image.Rectangle {
+	return image.Rect (
+		rectangle.Min.X.Round(),
+		rectangle.Min.Y.Round(),
+		rectangle.Max.X.Round(),
+		rectangle.Max.Y.Round())
+}

typesetter.go

@@ -89,6 +89,34 @@ type TypeSetter struct {
 	layoutBoundsSpace fixed.Rectangle26_6
 }
 
+// AtPosition returns the index of the rune at the specified position.
+func (this *TypeSetter) AtPosition (position fixed.Point26_6) int {
+	metrics := this.face.Metrics()
+	lastValidIndex := 0
+	index          := 0
+	for _, tok := range this.tokens {
+		pos := tok.position
+		yValid :=
+			position.Y >= pos.Y - metrics.Ascent &&
+			position.Y <= pos.Y + metrics.Descent
+		if !yValid { index += len(tok.runes); continue }
+		
+		for _, runl := range tok.runes {
+			x := pos.X + runl.x
+			xValid := position.X >= pos.X + runl.x
+			if xValid {
+				lastValidIndex = index
+			} else if x > position.X {
+				return lastValidIndex
+			}
+
+			index ++
+		}
+	}
+	index ++
+	return lastValidIndex
+}
+
 // Runes returns an iterator for all runes in the TypeSetter, and their positions.
 func (this *TypeSetter) Runes () RuneIter {
 	this.needFlow()