izapple2/screen/doubleHiRes.go
2020-10-17 13:31:42 +02:00

110 lines
2.8 KiB
Go

package screen
import (
"image"
"image/color"
)
const (
doubleHiResWidth = 2 * hiResWidth
rgb160Width = 4 * 160
)
func snapshotDoubleHiRes(vs VideoSource, isSecondPage bool, getNTSCMask bool, light color.Color) (*image.RGBA, *image.Alpha) {
dataMain := vs.GetVideoMemory(isSecondPage, false)
dataAux := vs.GetVideoMemory(isSecondPage, true)
return renderDoubleHiRes(dataMain, dataAux, getNTSCMask, light)
}
func renderDoubleHiRes(dataMain []uint8, dataAux []uint8, getNTSCMask bool, light color.Color) (*image.RGBA, *image.Alpha) {
// As described in "Inside the Apple IIe"
size := image.Rect(0, 0, doubleHiResWidth, hiResHeight)
img := image.NewRGBA(size)
// To support RGB-mode 14 we will have a mask to mark where we should not have the NTSC filter applied
// See: https://apple2online.com/web_documents/Video-7%20Manual%20KB.pdf
var ntscMask *image.Alpha
if getNTSCMask {
ntscMask = image.NewAlpha(size)
}
for y := 0; y < hiResHeight; y++ {
offset := getHiResLineOffset(y)
lineParts := [][]uint8{
dataAux[offset : offset+hiResLineBytes],
dataMain[offset : offset+hiResLineBytes],
}
x := 0
// For the NTSC filter to work we have to insert an initial black pixel and skip the last one ¿?
img.Set(x, y, color.Black)
if getNTSCMask {
ntscMask.Set(x, y, color.Opaque)
}
x++
for iByte := 0; iByte < hiResLineBytes; iByte++ {
for iPart := 0; iPart < 2; iPart++ {
b := lineParts[iPart][iByte]
mask := color.Transparent // Apply the NTSC filter
if getNTSCMask && b&0x80 == 0 {
mask = color.Opaque // Do not apply the NTSC filter
}
for j := uint(0); j < 7; j++ {
// Set color
bit := (b >> j) & 1
colour := light
if bit == 0 {
colour = color.Black
}
img.Set(x, y, colour)
// Set mask if requested
if getNTSCMask {
ntscMask.Set(x, y, mask)
}
x++
}
}
}
}
return img, ntscMask
}
func snapshotDoubleHiRes160(vs VideoSource, isSecondPage bool, light color.Color) *image.RGBA {
dataMain := vs.GetVideoMemory(isSecondPage, false)
dataAux := vs.GetVideoMemory(isSecondPage, true)
return renderDoubleHiRes160(dataMain, dataAux, light)
}
func renderDoubleHiRes160(dataMain []uint8, dataAux []uint8, light color.Color) *image.RGBA {
size := image.Rect(0, 0, rgb160Width, hiResHeight)
img := image.NewRGBA(size)
for y := 0; y < hiResHeight; y++ {
offset := getHiResLineOffset(y)
lineParts := [][]uint8{
dataAux[offset : offset+hiResLineBytes],
dataMain[offset : offset+hiResLineBytes],
}
x := 0
for iByte := 0; iByte < hiResLineBytes; iByte++ {
for iPart := 0; iPart < 2; iPart++ {
b := lineParts[iPart][iByte]
for j := uint(0); j < 8; j++ {
// Set color
bit := (b >> j) & 1
colour := light
if bit == 0 {
colour = color.Black
}
img.Set(x, y, colour)
x++
}
}
}
}
return img
}