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Optimize Adam7 (eliminate virtual calls)

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This commit is contained in:
Jason Nelson 2024-05-04 20:10:35 -07:00
parent bb5a9d0b60
commit 7e1244f72f
1 changed files with 22 additions and 26 deletions
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48
src/UglyToad.PdfPig/Images/Png/Adam7.cs
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@ -1,33 +1,29 @@
namespace UglyToad.PdfPig.Images.Png
{
using System.Collections.Generic;
internal static class Adam7
{
/// <summary>
/// For a given pass number (1 indexed) the scanline indexes of the lines included in that pass in the 8x8 grid.
/// </summary>
private static readonly IReadOnlyDictionary<int, int[]> PassToScanlineGridIndex = new Dictionary<int, int[]>
{
{ 1, [0] },
{ 2, [0] },
{ 3, [4] },
{ 4, [0, 4] },
{ 5, [2, 6] },
{ 6, [0, 2, 4, 6] },
{ 7, [1, 3, 5, 7] }
};
private static readonly int[][] PassToScanlineGridIndex = [
[0],
[0],
[4],
[0, 4],
[2, 6],
[0, 2, 4, 6],
[1, 3, 5, 7]
];
private static readonly IReadOnlyDictionary<int, int[]> PassToScanlineColumnIndex = new Dictionary<int, int[]>
{
{ 1, [0] },
{ 2, [4] },
{ 3, [0, 4] },
{ 4, [2, 6] },
{ 5, [0, 2, 4, 6] },
{ 6, [1, 3, 5, 7] },
{ 7, [0, 1, 2, 3, 4, 5, 6, 7] }
};
private static readonly int[][] PassToScanlineColumnIndex = [
[0],
[4],
[0, 4],
[2, 6],
[0, 2, 4, 6],
[1, 3, 5, 7],
[0, 1, 2, 3, 4, 5, 6, 7]
];
/*
* To go from raw image data to interlaced:
@ -50,7 +46,7 @@
public static int GetNumberOfScanlinesInPass(ImageHeader header, int pass)
{
var indices = PassToScanlineGridIndex[pass + 1];
var indices = PassToScanlineGridIndex[pass];
var mod = header.Height % 8;
@ -75,7 +71,7 @@
public static int GetPixelsPerScanlineInPass(ImageHeader header, int pass)
{
var indices = PassToScanlineColumnIndex[pass + 1];
var indices = PassToScanlineColumnIndex[pass];
var mod = header.Width % 8;
@ -100,8 +96,8 @@
public static (int x, int y) GetPixelIndexForScanlineInPass(ImageHeader header, int pass, int scanlineIndex, int indexInScanline)
{
var columnIndices = PassToScanlineColumnIndex[pass + 1];
var rows = PassToScanlineGridIndex[pass + 1];
var columnIndices = PassToScanlineColumnIndex[pass];
var rows = PassToScanlineGridIndex[pass];
var actualRow = scanlineIndex % rows.Length;
var actualCol = indexInScanline % columnIndices.Length;