Fix mix mode 40 columns text

screen.go

@@ -194,17 +194,13 @@ func (a *Apple2) Snapshot() *image.RGBA {
 }
 
 func mixSnapshots(top, bottom *image.RGBA) *image.RGBA {
-	topWidth := top.Bounds().Dx()
 	bottomWidth := bottom.Bounds().Dx()
-	factor := (topWidth - 4) / (bottomWidth - 4)
 
-	// Copy bottom's bottom on top's bottom, applying the factor
+	// Copy bottom's bottom on top's bottom
 	for y := hiResHeightMixed; y < hiResHeight; y++ {
-		for x := 0; x < topWidth; x++ {
+		for x := 0; x < bottomWidth; x++ {
 			c := bottom.At(x, y)
-			for f := 0; f < factor; f++ {
+			top.Set(x, y, c)
-				top.Set(x*factor+f, y, c)
-			}
 		}
 	}
 

screenNtscFilter.go

@@ -1,6 +1,7 @@
 package izapple2
 
 import (
+	"fmt"
 	"image"
 	"image/color"
 )
@@ -65,6 +66,10 @@ func filterNTSCColor(in *image.RGBA, mask *image.Alpha) *image.RGBA {
 	size := image.Rect(0, 0, width+4, height)
 	out := image.NewRGBA(size)
 
+	if width < 2*hiResWidth {
+		panic(fmt.Sprintf("The image has width %v. We can't apply the NTSC filter.", width))
+	}
+
 	for y := 0; y < height; y++ {
 		// We store the last four bits. We start with 0000
 		v := 0

screenText.go

@@ -9,10 +9,10 @@ import (
 )
 
 const (
-	charWidth   = 7
+	charWidth     = 7
-	charHeight  = 8
+	charHeight    = 8
-	textColumns = 40
+	text40Columns = 40
-	textLines   = 24
+	textLines     = 24
 
 	textPage1Address = uint16(0x0400)
 	textPage2Address = uint16(0x0800)
@@ -70,11 +70,11 @@ func getTextFromMemory(mem *memoryRange, isSecondPage bool) []uint8 {
 	addressEnd := addressStart + textPageSize
 	data := mem.subRange(addressStart, addressEnd)
 
-	text := make([]uint8, textLines*textColumns)
+	text := make([]uint8, textLines*text40Columns)
 	for l := 0; l < textLines; l++ {
-		for c := 0; c < textColumns; c++ {
+		for c := 0; c < text40Columns; c++ {
 			char := data[getTextCharOffset(c, l)]
-			text[textColumns*l+c] = char
+			text[text40Columns*l+c] = char
 		}
 	}
 	return text
@@ -96,11 +96,12 @@ func renderTextMode(a *Apple2, text []uint8, colorMap []uint8, light color.Color
 
 	columns := len(text) / textLines
 	if text == nil {
-		columns = textColumns
+		columns = text40Columns
 	}
 	width := columns * charWidth
 	height := textLines * charHeight
-	size := image.Rect(0, 0, width, height)
+
+	size := image.Rect(0, 0, 2*hiResWidth, hiResHeight)
 	img := image.NewRGBA(size)
 
 	for x := 0; x < width; x++ {
@@ -147,7 +148,12 @@ func renderTextMode(a *Apple2, text []uint8, colorMap []uint8, light color.Color
 				colour = color.Black
 			}
 
-			img.Set(x, y, colour)
+			if columns == text40Columns {
+				img.Set(x*2, y, colour)
+				img.Set(x*2+1, y, colour)
+			} else {
+				img.Set(x, y, colour)
+			}
 		}
 	}