private void DrawNineBox(Graphics graphics, int x, int y, int colorIndex)
{
graphics.FillRectangle(Brushes.Gray, new Rectangle(x - ColorBoxBorder, y - ColorBoxBorder, ColorBoxBorder * 4 + ColorBoxSize * 3, ColorBoxBorder * 4 + ColorBoxSize * 3));
for (int i = 0; i < 3; i++)
for (int j = 0; j < 3; j++)
{
Rectangle rect = new Rectangle(
x + (ColorBoxSize + ColorBoxBorder) * i,
y + (ColorBoxSize + ColorBoxBorder) * j,
ColorBoxSize,
ColorBoxSize);
graphics.FillRectangle(paletteBrushes[colorIndex + 3 * j + i], rect);
graphics.DrawString(paletteLabels[colorIndex + 3 * j + i], textFont, oppositePaletteBrushes[colorIndex + 3 * j + i], rect, stringFormat);
}
}