如何用gdi32画位图？

http://www.cnblogs.com/flying_bat/articles/757421.html
http://www.cnblogs.com/anchky/archive/2006/10/21/535661.aspx

            Bitmap _Bitmap =new Bitmap(100,100);          //创建图形
            Graphics _Graphics = Graphics.FromImage(_Bitmap);  //获取GDI+绘图
            _Graphics.DrawString("A", new Font("宋体", 20), Brushes.Yellow, 0, 0); //绘制问题
            _Graphics.Dispose();  //释放资源            _Bitmap.Save(@"C:\1.bmp", ImageFormat.Bmp);  //保存文件

谢谢，如何将位图通过"gdi32.dll"画到控件上呢？

gdi+画图太耗资源了，所以得用"gdi32.dll"画

1/**///// <summary>
2/// 改变图像透明度（真透明）
3/// </summary>
4/// <param name="img">所要转变的图像</param>
5/// <param name="alpha">透明度，最大为1，最小为0</param>
6/// <returns>改变后的图像</returns>
7public static Bitmap VitrificationImage(Image img, float alpha)
8{
9    Bitmap _newImg = new Bitmap(img.Width, img.Height);
10
11    using (Graphics _g = Graphics.FromImage(_newImg))
12    {
13        using (ImageAttributes _imageAttrs = new ImageAttributes())
14        {
15            _imageAttrs.SetColorMatrix(new ColorMatrix(CreateAlphaMatrix(alpha)));
16
17            _g.DrawImage(img, new Rectangle(0, 0, img.Width, img.Height),
18                        1, 1, img.Width, img.Height, GraphicsUnit.Pixel, _imageAttrs);
19        }
20    }
21
22    return _newImg;
23}
24
25/**///// <summary>
26/// 创建用于改变图像透明度的颜色矩阵
27/// </summary>
28/// <param name="alpha">所要设置的透明度</param>
29/// <returns>返回用于图像转换的颜色矩阵</returns>
30private static float[][] CreateAlphaMatrix(float alpha)
31{
32    if (alpha > 1)
33        alpha = 1;
34
35    if (alpha < 0)
36        alpha = 0;
37
38    float[][] _matrix =
39    {
40                new float[] {1, 0, 0, 0, 0},
41                new float[] {0, 1, 0, 0, 0},
42                new float[] {0, 0, 1, 0, 0},
43                new float[] {0, 0, 0, alpha, 0},
44                new float[] {0, 0, 0, 0, 1}
45    };
46
47    return _matrix;
48}

用gdi32.dll的如下用C＃来捕获屏幕的源程序代码（Capture.cs）[code=C#]using System ;
  using System.Drawing ;
  using System.Collections ;
  using System.ComponentModel ;
  using System.Windows.Forms ;
  using System.Data ;
  using System.Drawing.Imaging ;
  public class Form1 : Form
  {
   private Button button1 ;
   private System.ComponentModel.Container components = null ;

   public Form1 ( )
   {
   //初始化窗体中的各个组件
   InitializeComponent ( ) ;
   }
   // 清除程序中使用过的资源
   protected override void Dispose ( bool disposing )
   {
   if ( disposing )
   {
   if ( components != null )
   {
   components.Dispose ( ) ;
   }
   }
   base.Dispose ( disposing ) ;
   }
   private void InitializeComponent ( )
   {
   button1 = new Button ( );
   SuspendLayout ( ) ;
   button1.Location = new System.Drawing.Point ( 64 , 40 ) ;
   button1.Name = "button1" ;
   button1.Size = new System.Drawing.Size ( 80 , 32 ) ;
   button1.TabIndex = 0 ;
   button1.Text = "捕获" ;
   button1.Click += new System.EventHandler ( button1_Click ) ;

   AutoScaleBaseSize = new System.Drawing.Size ( 6 , 14 ) ;
   ClientSize = new System.Drawing.Size ( 216 , 125 ) ;
   Controls.Add ( button1 ) ;
   MaximizeBox = false ;
   MinimizeBox = false ;
   Name = "Form1" ;
   Text = "C#捕获当前屏幕！" ;
   ResumeLayout ( false ) ;

   }
   //声明一个API函数
   [ System.Runtime.InteropServices.DllImportAttribute ( "gdi32.dll" ) ]
   private static extern bool BitBlt (
   IntPtr hdcDest , // 目标 DC的句柄
   int nXDest ,
   int nYDest ,
   int nWidth ,
   int nHeight ,
   IntPtr hdcSrc , // 源DC的句柄
   int nXSrc ,
   int nYSrc ,
   System.Int32 dwRop // 光栅的处理数值
   ) ;

   static void Main ( )
   {
   Application.Run ( new Form1 ( ) ) ;
   }
   private void button1_Click ( object sender , System.EventArgs e )
   {
   //获得当前屏幕的大小
   Rectangle rect = new Rectangle ( ) ;
   rect = Screen.GetWorkingArea ( this ) ;
   //创建一个以当前屏幕为模板的图象
   Graphics g1 = this.CreateGraphics ( ) ;
   //创建以屏幕大小为标准的位图
   Image MyImage = new Bitmap ( rect.Width , rect.Height , g1 ) ;
   Graphics g2 = Graphics.FromImage ( MyImage ) ;
   //得到屏幕的DC
   IntPtr dc1 = g1.GetHdc ( ) ;
   //得到Bitmap的DC
   IntPtr dc2 = g2.GetHdc ( ) ;
   //调用此API函数，实现屏幕捕获
   BitBlt ( dc2 , 0 , 0 , rect.Width , rect.Height , dc1 , 0 , 0 , 13369376 ) ;
   //释放掉屏幕的DC
   g1.ReleaseHdc ( dc1 ) ;
   //释放掉Bitmap的DC
   g2.ReleaseHdc ( dc2 ) ;
   //以JPG文件格式来保存
   MyImage.Save ( @"c:\Capture.jpg" , ImageFormat.Jpeg );
   MessageBox.Show ( "当前屏幕已经保存为C盘的capture.jpg文件！" ) ;
   }
  }
  #endregion

谢谢，如何将位图通过"gdi32.dll"画到控件上呢？

一般控件有CreateGraphics()方法可以获得画布(Graphics),然后使用Graphics进行绘图
难的是怎样持久显示图片
对于没有CreateGraphics()方法控件,需要使用API进行获取.

调试易

如何用gdi32画位图？

解决方案 »