找到镂空图片的坐标

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace BuildLogoImageCoord
{
public partial class FormMain : Form
{
public FormMain()
{
InitializeComponent();
}

private void btnText_Click(object sender, EventArgs e)
{
FindCoords(BuildTextImage(txtText.Text), txtText.Text);
MessageBox.Show("Done!");
}

const int ImgWidth = 1920;
const int ImgHeight = 1200;
static Bitmap BuildTextImage(string text)
{
Bitmap bitmap = new Bitmap(ImgWidth, ImgHeight);
Graphics g = Graphics.FromImage(bitmap);
g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAliasGridFit;
g.FillRectangle(new SolidBrush(Color.White), 0, 0, bitmap.Width, bitmap.Height);
using (Font font1 = new Font("Arial", 1200, FontStyle.Bold, GraphicsUnit.Pixel))
{
Rectangle rect1 = new Rectangle(0, 100, ImgWidth, ImgHeight);
StringFormat stringFormat = new StringFormat();
stringFormat.Alignment = StringAlignment.Center;
stringFormat.LineAlignment = StringAlignment.Center;
g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;

Font goodFont = FindGoodFont(g, text, rect1.Size, font1, GraphicsUnit.Pixel);
g.DrawString(text, goodFont, Brushes.Black, rect1, stringFormat);
}
g.Dispose();
bitmap.Save(text + ".jpg", ImageFormat.Jpeg);
return bitmap;
}

private static Font FindGoodFont(Graphics Graf, string sStringToFit,
Size TextRoomAvail,
Font FontToUse,
GraphicsUnit FontUnit)
{
// Find out what the current size of the string in this font is
SizeF RealSize = Graf.MeasureString(sStringToFit, FontToUse);
if ((RealSize.Width <= TextRoomAvail.Width) && (RealSize.Height <= TextRoomAvail.Height))
{
// The current font is fine...
return FontToUse;
}

// Either width or height is too big...
// Usually either the height ratio or the width ratio
// will be less than 1. Work them out...
float HeightScaleRatio = TextRoomAvail.Height / RealSize.Height;
float WidthScaleRatio = TextRoomAvail.Width / RealSize.Width;

// We'll scale the font by the one which is furthest out of range...
float ScaleRatio = (HeightScaleRatio < WidthScaleRatio) ? ScaleRatio = HeightScaleRatio : ScaleRatio = WidthScaleRatio;
float ScaleFontSize = FontToUse.Size * ScaleRatio;

// Retain whatever the style was in the old font...
FontStyle OldFontStyle = FontToUse.Style;

// Get rid of the old non working font...
FontToUse.Dispose();

// Tell the caller to use this newer smaller font.
FontToUse = new Font(FontToUse.FontFamily,
ScaleFontSize,
OldFontStyle,
FontUnit);
return FontToUse;
}

private const int StartSize = 30;

static void FindCoords(Bitmap bitmap, string text)
{
Bitmap reff = new Bitmap(ImgWidth, ImgHeight);
Graphics g = Graphics.FromImage(reff);
g.DrawImage(Image.FromFile("bgImage.jpg"), new Rectangle(0, 0, ImgWidth, ImgHeight));

var rows = ImgHeight/StartSize;
var cols = ImgWidth/StartSize;
var coords = new List<string>();
for (int j = 0; j < rows; j++)
{
for (int i = 0; i < cols; i++)
{
var total = StartSize*StartSize;
var cur = 0;
for (int ii = 0; ii < StartSize; ii++)
{
for (int jj = 0; jj < StartSize; jj++)
{
var posx = i*StartSize + ii;
var posy = j*StartSize + jj;
byte color = bitmap.GetPixel(posx, posy).R;
if (color == 0)
{
cur++;
reff.SetPixel(posx, posy, Color.Transparent);
}
}
}
if (cur > total * 0.02)
{
coords.Add("[" + i + "," + j + "]");
}
}
}

StreamWriter sw = new StreamWriter(text + ".txt");
sw.Write("[" + string.Join(",", coords.ToArray()) + "]");
sw.Close();

g.Dispose();
reff.Save(text + "_cover.png", ImageFormat.Png);
}
}
}