Borland Delphi 6 -> Java

[DaneSomdahl]

Basically I'm trying to figure out how I can use the same exact procedure in this Delphi loop, but in Java.

's' is a pointer.

    GetMem(s, RawHdr.Width * RawHdr.Height * 4);
    try
      src.Read(s^, RawHdr.Width * RawHdr.Height * 4);
      GetMem(d, RawHdr.Width * RawHdr.Height * 4);
      try
        dp := d;

        // Red
        for y := RawHdr.Height -1 downto 0 do
        begin
          Cardinal(sp) := Cardinal(s) + y*RawHdr.Width*4 + 2;
          for x := 0 to RawHdr.Width - 1 do
          begin
            dp^ := sp^;
            Inc(dp);
            Inc(sp, 4);
          end;
        end;

        // Green
        for y := RawHdr.Height -1 downto 0 do
        begin
          Cardinal(sp) := Cardinal(s) + y*RawHdr.Width*4 + 1;
          for x := 0 to RawHdr.Width - 1 do
          begin
            dp^ := sp^;
            Inc(dp);
            Inc(sp, 4);
          end;
        end;

        // Blue
        for y := RawHdr.Height -1 downto 0 do
        begin
          Cardinal(sp) := Cardinal(s) + y*RawHdr.Width*4;
          for x := 0 to RawHdr.Width - 1 do
          begin
            dp^ := sp^;
            Inc(dp);
            Inc(sp, 4);
          end;
        end;

        // Alpha
        for y := RawHdr.Height -1 downto 0 do
        begin
          Cardinal(sp) := Cardinal(s) + y*RawHdr.Width*4 + 3;
          for x := 0 to RawHdr.Width - 1 do
          begin
            dp^ := sp^;
            Inc(dp);
            Inc(sp, 4);
          end;
        end;

        dst.Write(d^, RawHdr.Width * RawHdr.Height * 4);

Basically what I need to do is be able to figure out this but in the language Java:

        // Green
        for y := RawHdr.Height -1 downto 0 do
        begin
          Cardinal(sp) := Cardinal(s) + y*RawHdr.Width*4 + 1;
          for x := 0 to RawHdr.Width - 1 do
          begin
            dp^ := sp^;
            Inc(dp);
            Inc(sp, 4);
          end;
        end;

Since I have no idea what these functions are, or the operations used.. I'm stumped.

[ThePuska]

Cardinal(sp) = Cardinal(s) + y * RawHdr.Width * 4 + 1;

Cardinal(s) is a cast; they're casting the image pointer to an unsigned long, the purpose of which is to allow calculating the position of the scanline in memory.

dp^ = sp^;

Both dp and sp are pointers. A caret behind a pointer is a dereference; this statement means that the value where sp points is copied to where dp points.

Inc(dp);
Inc(sp, 4);

Increment

I'm not sure how you'd replicate this kind of code in Java since Java has no pointers. Probably with arrays.

[editline]16th August 2012[/editline]

This is the equivalent C code with single-dimensional arrays instead of pointers.

[cpp]// Red
for (y = RawHdr.Height - 1; y >= 0; y--)
{
i = y * RawHdr.Width * 4 + 2;
for (x = 0; x < RawHdr.Width; x++)
{
d[j] = s[i];
j++;
i += 4;
}
}[/cpp]

[DaneSomdahl]

[QUOTE=ThePuska;37266852]

Cardinal(sp) = Cardinal(s) + y * RawHdr.Width * 4 + 1;

Cardinal(s) is a cast; they're casting the image pointer to an unsigned long, the purpose of which is to allow calculating the position of the scanline in memory.

dp^ = sp^;

Both dp and sp are pointers. A caret behind a pointer is a dereference; this statement means that the value where sp points is copied to where dp points.

Inc(dp);
Inc(sp, 4);

Increment

I'm not sure how you'd replicate this kind of code in Java since Java has no pointers. Probably with arrays.

[editline]16th August 2012[/editline]

This is the equivalent C code with single-dimensional arrays instead of pointers.

[cpp]// Red
for (y = RawHdr.Height - 1; y >= 0; y--)
{
i = y * RawHdr.Width * 4 + 2;
for (x = 0; x < RawHdr.Width; x++)
{
d[j] = s[i];
j++;
i += 4;
}
}[/cpp][/QUOTE]

Thank you very much, your C code equivalent helped me figure it out.

Here's what I got that worked:

	int channels = 4;
	int length = width * height;
	int[] pixels = new int[length * channels];

	for (int i = 0; i < pixels.length; i += channels) {
		pixels[i + 2] = readByte();
		pixels[i + 1] = readByte();
		pixels[i] = readByte();
		pixels[i + 3] = readByte();
	}

The pixel format is BGRA.