用.net在画出镂空图片

最近的一个项目需要用到这个东西，冥思苦想了好几天。还是在同事的帮助下，完成此项难题，希望能够帮助以后的博友们 ！

废话不多说，先看看效果图吧。



首先写一下讲一下思路，首先画一张图，当你的背景，然后在图上写字，写的字体最好是粗体，不好太多字，颜色最后用一般不常用的颜色，然后读取这些颜色所在的位置，

设置成透明的，即可。

#region 文字生成镂空图片

static string BuildTextImage(string text, string bgImage)
{
int ImgWidth = 0, ImgHeight = 0, StartSize = 30;

#region 复制背景图特殊颜色填写文字--

var bucket = OpenUtility.GetBucket(bgImage);
var result = FileHub.GetStream(bucket, bgImage);
if (result.Status != UFile.Data.ActionStatus.SUCCESS)
{
return "";
}

var stream = result.Data;

Bitmap bitmap = new Bitmap(stream);

ImgWidth = bitmap.Width;
ImgHeight = bitmap.Height;

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);

#endregion

#region 画格子

Bitmap reff = new Bitmap(ImgWidth, ImgHeight);
Graphics gi = Graphics.FromImage(reff);

Image img = Image.FromStream(stream);
gi.DrawImage(img, 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();

gi.Dispose();

string path = string.Empty;
//reff.Save("d:\\"+Guid.NewGuid.ToString() + "_cover.png", ImageFormat.Png);
using (var ms = new System.IO.MemoryStream())
{
reff.Save(ms, ImageFormat.Png);

var mime = OpenUtility.GetMimeType(bgImage);

path = "/Uploads/Files/" + string.Format("{0:yyyy/MM/dd}", DateTime.Now) + "/" + Guid.NewGuid().ToString() + ".png";
FileHub.Put(bucket, path, ms, mime);
}
#endregion

return path;

}

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;
} #endregion