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RedBookPlayer/RedBookPlayer.Models/Hardware/Karaoke/KaraokeDisplay.cs
Matt Nadareski 1880d49ee5 Add most of scrolling logic; add notes
2021-11-29 22:16:23 -08:00

335 lines
15 KiB
C#
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namespace RedBookPlayer.Models.Hardware.Karaoke
{
/// <see cref="https://jbum.com/cdg_revealed.html"/>
internal class KaraokeDisplay
{
/// <summary>
/// Display data as a 2-dimensional byte array
/// </summary>
/// <remarks>
// CONFLICTING INFO:
///
/// In the top part of the document, it states:
/// In the CD+G system, 16 color graphics are displayed on a raster field which is
/// 300 x 216 pixels in size. The middle 294 x 204 area is within the TV's
/// "safe area", and that is where the graphics are displayed. The outer border is
/// set to a solid color. The colors are stored in a 16 entry color lookup table.
///
/// And in the bottom part of the document around CDG_BorderPreset, it states:
/// Color refers to a color to clear the screen to. The border area of the screen
/// should be cleared to this color. The border area is the area contained with a
/// rectangle defined by (0,0,300,216) minus the interior pixels which are contained
/// within a rectangle defined by (6,12,294,204).
///
/// With both of these in mind, does that mean that the "drawable" area is:
/// a) (3, 6, 297, 210) [Dimensions of 294 x 204]
/// b) (6, 12, 294, 204) [Dimensions of 288 x 192]
/// </remarks>
public byte[,] DisplayData { get; private set; }
/// <summary>
/// Current 8-entry color table
/// </summary>
/// <remarks>
/// In practice, this should be 8 colors, probably similar to the CGA palette,
/// including the "bright" or "dark" variant (possibly mapping from "high" to "low").
/// The current interpretation of this may be incorrect, as the internal color table
/// may actually include all 16 RGB values immediately.
/// </remarks>
public byte[] ColorTable { get; private set; }
/// <summary>
/// Color currently defined as transparent
/// </summary>
public byte TransparentColor { get; private set; }
/// <summary>
/// Create a new, blank karaoke display
/// </summary>
public KaraokeDisplay()
{
this.DisplayData = new byte[300,216];
this.ColorTable = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7 };
this.TransparentColor = 0x00;
}
/// <summary>
/// Process a subchannel packet and update the display as necessary
/// </summary>
/// <param name="packet">Subchannel packet data to process</param>
public void ProcessData(SubchannelPacket packet)
{
if(!packet.IsCDGPacket())
return;
switch(packet.Instruction)
{
case SubchannelInstruction.MemoryPreset:
var memoryPreset = new MemPreset(packet.Data);
SetScreenColor(memoryPreset);
break;
case SubchannelInstruction.BorderPreset:
var borderPreset = new BorderPreset(packet.Data);
SetBorderColor(borderPreset);
break;
case SubchannelInstruction.TileBlockNormal:
var tileBlockNormal = new TileBlock(packet.Data);
LoadTileBlock(tileBlockNormal, false);
break;
case SubchannelInstruction.ScrollPreset:
var scrollPreset = new Scroll(packet.Data);
ScrollDisplay(scrollPreset, false);
break;
case SubchannelInstruction.ScrollCopy:
var scrollCopy = new Scroll(packet.Data);
ScrollDisplay(scrollCopy, true);
break;
case SubchannelInstruction.DefineTransparentColor:
var transparentColor = new BorderPreset(packet.Data);
this.TransparentColor = transparentColor.Color;
break;
case SubchannelInstruction.LoadColorTableLower:
var loadColorTableLower = new LoadCLUT(packet.Data);
// TODO: Load color table data
break;
case SubchannelInstruction.LoadColorTableUpper:
var loadColorTableUpper = new LoadCLUT(packet.Data);
// TODO: Load color table data
break;
case SubchannelInstruction.TileBlockXOR:
var tileBlockXor = new TileBlock(packet.Data);
LoadTileBlock(tileBlockXor, true);
break;
};
}
/// <summary>
/// Set the screen to a particular color
/// </summary>
/// <param name="memPreset">MemPreset with the new data</param>
/// <param name="consistentData">True if all subchannel data is present, false otherwise</param>
/// <remarks>
/// It is unclear if this is supposed to set the entire screen to the same color or
/// if it is only setting the interior pixels. To err on the side of caution, this sets
/// the viewable area only.
///
/// The area that is considered the border is unclear. Please see the remarks
/// on <see cref="DisplayData"/> for more details.
/// </remarks>
private void SetScreenColor(MemPreset memPreset, bool consistentData = false)
{
if(memPreset == null)
return;
// Skip in a consistent data case
if(consistentData && memPreset.Repeat > 0)
return;
for(int x = 3; x < 297; x++)
for(int y = 6; y < 210; y++)
{
this.DisplayData[x,y] = memPreset.Color;
}
}
/// <summary>
/// Set the border to a particular color
/// </summary>
/// <param name="borderPreset">BorderPreset with the new data</param>
/// <remarks>
/// The area that is considered the border is unclear. Please see the remarks
/// on <see cref="DisplayData"/> for more details.
/// </remarks>
private void SetBorderColor(BorderPreset borderPreset)
{
if(borderPreset == null)
return;
for(int x = 0; x < 3; x++)
for(int y = 0; y < 216; y++)
{
this.DisplayData[x,y] = borderPreset.Color;
}
for(int x = 297; x < 300; x++)
for(int y = 0; y < 216; y++)
{
this.DisplayData[x,y] = borderPreset.Color;
}
for(int x = 0; x < 300; x++)
for(int y = 0; y < 6; y++)
{
this.DisplayData[x,y] = borderPreset.Color;
}
for(int x = 0; x < 300; x++)
for(int y = 210; y < 216; y++)
{
this.DisplayData[x,y] = borderPreset.Color;
}
}
/// <summary>
/// Load a block of pixels with a certain pattern
/// </summary>
/// <param name="tileBlock">TileBlock with the pattern data</param>
/// <param name="xor">
/// If true, the color values are combined with the color values
/// that are already onscreen using the XOR operator
/// </param>
private void LoadTileBlock(TileBlock tileBlock, bool xor)
{
if(tileBlock == null)
return;
// Extract out the "bitmap" into a byte pattern
byte[,] pattern = new byte[12,6];
for(int i = 0; i < tileBlock.TilePixels.Length; i++)
{
byte b = tileBlock.TilePixels[i];
pattern[i,0] = (byte)(b & (1 << 0));
pattern[i,1] = (byte)(b & (1 << 1));
pattern[i,2] = (byte)(b & (1 << 2));
pattern[i,3] = (byte)(b & (1 << 3));
pattern[i,4] = (byte)(b & (1 << 4));
pattern[i,5] = (byte)(b & (1 << 5));
}
// Now load the bitmap starting in the correct place
for(int x = 0; x < 12; x++)
for(int y = 0; y < 6; y++)
{
int adjustedX = x + tileBlock.Column;
int adjustedY = y + tileBlock.Row;
int colorIndex = pattern[x,y] == 0 ? tileBlock.Color0 : tileBlock.Color1;
if(xor)
this.DisplayData[adjustedX, adjustedY] = (byte)(this.ColorTable[colorIndex] ^ this.DisplayData[adjustedX, adjustedY]);
else
this.DisplayData[adjustedX, adjustedY] = this.ColorTable[colorIndex];
}
}
/// <summary>
/// Scroll the display according to the instruction
/// </summary>
/// <param name="scroll">Scroll with the new data</param>
/// <param name="copy">True if data wraps around on scroll, false if filled by a solid color</param>
/// <remarks>
/// Based on the documentation, there's a bit of ambiguity how the Offset fields are used.
/// The current best understanding is that the offset can be combined with any scroll command
/// to add (or subtract) between 0 and 5 pixels in a particular axis.
/// TODO: Offsets are not currently implemented in the code below
/// </remarks>
private void ScrollDisplay(Scroll scroll, bool copy)
{
if(scroll == null)
return;
// If we're scrolling horizontally
if(scroll.HScrollCommand == ScrollCommand.Positive)
{
for(int y = 0; y < 216; y++)
{
byte[] overflow = new byte[6];
for(int x = 299; x >= 0; x--)
{
if(x + 6 >= 300)
overflow[(x + 6) % 300] = this.DisplayData[x,y];
else
this.DisplayData[x + 6, y] = this.DisplayData[x,y];
}
// Fill in the now-empty pixels
this.DisplayData[0,y] = copy ? overflow[0] : this.ColorTable[scroll.Color];
this.DisplayData[1,y] = copy ? overflow[1] : this.ColorTable[scroll.Color];
this.DisplayData[2,y] = copy ? overflow[2] : this.ColorTable[scroll.Color];
this.DisplayData[3,y] = copy ? overflow[3] : this.ColorTable[scroll.Color];
this.DisplayData[4,y] = copy ? overflow[4] : this.ColorTable[scroll.Color];
this.DisplayData[5,y] = copy ? overflow[5] : this.ColorTable[scroll.Color];
}
}
else if(scroll.HScrollCommand == ScrollCommand.Negative)
{
for(int y = 0; y < 216; y++)
{
byte[] overflow = new byte[6];
for(int x = 0; x < 300; x++)
{
if(x - 6 < 0)
overflow[x] = this.DisplayData[x,y];
else
this.DisplayData[x - 6, y] = this.DisplayData[x,y];
}
// Fill in the now-empty pixels
this.DisplayData[294,y] = copy ? overflow[0] : this.ColorTable[scroll.Color];
this.DisplayData[295,y] = copy ? overflow[1] : this.ColorTable[scroll.Color];
this.DisplayData[296,y] = copy ? overflow[2] : this.ColorTable[scroll.Color];
this.DisplayData[297,y] = copy ? overflow[3] : this.ColorTable[scroll.Color];
this.DisplayData[298,y] = copy ? overflow[4] : this.ColorTable[scroll.Color];
this.DisplayData[299,y] = copy ? overflow[5] : this.ColorTable[scroll.Color];
}
}
// If we're scrolling vertically
if(scroll.VScrollCommand == ScrollCommand.Positive)
{
for(int x = 0; x < 300; x++)
{
byte[] overflow = new byte[12];
for(int y = 215; y >= 0; y--)
{
if(y + 12 >= 216)
overflow[(y + 12) % 216] = this.DisplayData[x,y];
else
this.DisplayData[x, y + 12] = this.DisplayData[x,y];
}
// Fill in the now-empty pixels
this.DisplayData[x,0] = copy ? overflow[0] : this.ColorTable[scroll.Color];
this.DisplayData[x,1] = copy ? overflow[1] : this.ColorTable[scroll.Color];
this.DisplayData[x,2] = copy ? overflow[2] : this.ColorTable[scroll.Color];
this.DisplayData[x,3] = copy ? overflow[3] : this.ColorTable[scroll.Color];
this.DisplayData[x,4] = copy ? overflow[4] : this.ColorTable[scroll.Color];
this.DisplayData[x,5] = copy ? overflow[5] : this.ColorTable[scroll.Color];
this.DisplayData[x,6] = copy ? overflow[6] : this.ColorTable[scroll.Color];
this.DisplayData[x,7] = copy ? overflow[7] : this.ColorTable[scroll.Color];
this.DisplayData[x,8] = copy ? overflow[8] : this.ColorTable[scroll.Color];
this.DisplayData[x,9] = copy ? overflow[9] : this.ColorTable[scroll.Color];
this.DisplayData[x,10] = copy ? overflow[10] : this.ColorTable[scroll.Color];
this.DisplayData[x,11] = copy ? overflow[11] : this.ColorTable[scroll.Color];
}
}
else if(scroll.VScrollCommand == ScrollCommand.Negative)
{
for(int x = 0; x < 300; x++)
{
byte[] overflow = new byte[12];
for(int y = 0; y < 216; y++)
{
if(y - 12 < 0)
overflow[y] = this.DisplayData[x,y];
else
this.DisplayData[x, y - 12] = this.DisplayData[x,y];
}
// Fill in the now-empty pixels
this.DisplayData[x,204] = copy ? overflow[0] : this.ColorTable[scroll.Color];
this.DisplayData[x,205] = copy ? overflow[1] : this.ColorTable[scroll.Color];
this.DisplayData[x,206] = copy ? overflow[2] : this.ColorTable[scroll.Color];
this.DisplayData[x,207] = copy ? overflow[3] : this.ColorTable[scroll.Color];
this.DisplayData[x,208] = copy ? overflow[4] : this.ColorTable[scroll.Color];
this.DisplayData[x,209] = copy ? overflow[5] : this.ColorTable[scroll.Color];
this.DisplayData[x,210] = copy ? overflow[6] : this.ColorTable[scroll.Color];
this.DisplayData[x,211] = copy ? overflow[7] : this.ColorTable[scroll.Color];
this.DisplayData[x,212] = copy ? overflow[8] : this.ColorTable[scroll.Color];
this.DisplayData[x,213] = copy ? overflow[9] : this.ColorTable[scroll.Color];
this.DisplayData[x,214] = copy ? overflow[10] : this.ColorTable[scroll.Color];
this.DisplayData[x,215] = copy ? overflow[11] : this.ColorTable[scroll.Color];
}
}
}
}
}
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