C# GDI+

.NET GDI

System.Drawing
System.Drawing.2D
System.Drawing.Imaging
System.Drawing.Text

Drawing

Color.FromArgb
Color.FromName

Size(w,h)
Point(x,y)
Rectangle()

Graphics g = this.CreateGraphics();
Pen pen = new Pen(Color.Red, 2);
Brush brush = new SolidBrush(Color.Blue);
Font font = new Font("宋体", 25);
Rectangle rect = new Rectangle(20, 120, 100, 160);
g.DrawLine(pen, 20, 100, 100, 100);
g.DrawRectangle(pen, rect);
g.DrawString("GDI+图形编程", font, brush, 20, 20);
brush.Dispose(); font.Dispose(); pen.Dispose();
g.Dispose();

Graphics

DrawARC：绘制圆弧
DrawBezier：绘制贝塞尔曲线
DrawClosedCurve：绘制封闭曲线
DrawCurve：绘制曲线
DrawEllipse：绘制椭圆 **
DrawIcon：绘制图标
DrawImage：绘制图像 **
DrawLine：绘制直线
DrawString：绘制文本
DrawRectangle：绘制矩形

FillXXX：绘制实心

Pen

Pen pen = new Pen(Color.Blue,5);

PenAlignment
DashStyle

Brush

抽象类，不能被实例化

双缓冲技术

DoubleBuffered

原理：

Bitmap bmp = new Bitmap(600,600);
Graphics g = Graphics.FromImage(bmp);
g.FillEllipse(brush, i10, j10, 10, 10);
g.DrawLine();
g.DrawString();
this.CreateGraphics().DrawImage(bmp, 0, 0);

图像处理

Image 抽象类，主要使用 Bitmap，处理BMP、Jpg、Gif、Png

• bitmap.GetPixel(x,y); 获得像素点
• 使用指针

using System;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Imaging;
public unsafe class UnsafeBitmap
{
  
    Bitmap bitmap;
    int stride;
    BitmapData bitmapData = null;
    Byte* pBase = null;
  
    public UnsafeBitmap(Bitmap bitmap)
    {
        this.bitmap = new Bitmap(bitmap);
    }
  
    public UnsafeBitmap(int width, int height)
    {
        this.bitmap = new Bitmap(width, height, PixelFormat.Format24bppRgb);
    }
  
    public void Dispose()
    {
        bitmap.Dispose();
    }
  
    public Bitmap Bitmap
    {
        get
        {
            return (bitmap);
        }
    }
  
    public struct PixelData
    {
        public byte blue;
        public byte green;
        public byte red;
    }
  
    private Point PixelSize
    {
        get
        {
            GraphicsUnit unit = GraphicsUnit.Pixel;
            RectangleF bounds = bitmap.GetBounds(ref unit); return new Point((int)bounds.Width, (int)bounds.Height);
        }
    }
  
    public void LockBitmap()
    {
  
        GraphicsUnit unit = GraphicsUnit.Pixel;
  
        RectangleF boundsF = bitmap.GetBounds(ref unit);
        Rectangle bounds = new Rectangle((int)boundsF.X,
             (int)boundsF.Y,
             (int)boundsF.Width,
              (int)boundsF.Height);
  
          
  
        bitmapData = bitmap.LockBits(bounds, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
        pBase = (Byte*)bitmapData.Scan0.ToPointer();
  
        stride = bitmapData.Stride;
        //stride = (int)boundsF.Width * sizeof(PixelData);
        //if (stride % 4 != 0)
        //{
        //    stride = 4 * (stride / 4 + 1);
        //}
  
    }
  
    public PixelData GetPixel(int x, int y)
    {
        PixelData returnValue = *PixelAt(x, y);
        return returnValue;
    }
  
    public void SetPixel(int x, int y, PixelData colour)
    {
        PixelData* pixel = PixelAt(x, y);
        *pixel = colour;
    }
  
    public void UnlockBitmap()
    {
        bitmap.UnlockBits(bitmapData);
        bitmapData = null;
        pBase = null;
    }
  
    public PixelData* PixelAt(int x, int y)
    {
        return (PixelData*)(pBase + y * stride + x * sizeof(PixelData));
    }
  
}
  
public class Test {
  
    static void Main()
    {
      
        Bitmap bitmap = new Bitmap(@"1.jpg");
        UnsafeBitmap bitmap2 = new UnsafeBitmap( bitmap );
  
        System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
        sw.Start();
        for( int i=0; i<bitmap.Width; i++) for( int j=0; j<bitmap.Height; j++ )
        {
            Color c = bitmap.GetPixel( i,j );
        }
        sw.Stop();
        Console.WriteLine( sw.ElapsedTicks );
  
        sw.Reset();
        sw.Start();
        bitmap2.LockBitmap(); 
        for( int i=0; i<bitmap.Width; i++) for( int j=0; j<bitmap.Height; j++ )
        {
            UnsafeBitmap.PixelData c = bitmap2.GetPixel( i,j );
        }
        bitmap2.UnlockBitmap();
        sw.Stop();
        Console.WriteLine( sw.ElapsedTicks );
    }
}