直播平台搭建源码，更改图片透明度

public partial class Form1 : Form<br>{<br>    public Form1()<br>    {<br>        InitializeComponent();<br>    }<br>    Image new_img;<br>    private void ChangeAlpha()<br>    {<br>        pictureBox1.Refresh();<br>        Bitmap source = new Bitmap(pictureBox1.Image);<br>        Bitmap effect = new Bitmap(pictureBox1.Image.Width,pictureBox1.Image.Height);<br>        Graphics _effect = Graphics.FromImage(effect);<br>        float[][] matrixItems ={new float[]{1,0,0,0,0},<br>                                  new float [] {0,1,0,0,0},<br>                                  new float []{0,0,1,0,0},<br>                                  new float []{0,0,0,0,0},<br>                                  new float[]{0,0,0,trackBar1.Value/255f,1}};<br>        ColorMatrix imgMatrix = new ColorMatrix(matrixItems);<br>        ImageAttributes imgEffect = new ImageAttributes();<br>        imgEffect.SetColorMatrix(imgMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);<br>        if (source.Width <= 368)<br>        {<br>            _effect.DrawImage(source, new Rectangle(0, 0, pictureBox1.Image.Width, pictureBox1.Image.Height), 0, 0, pictureBox1.Image.Width, pictureBox1.Image.Height, GraphicsUnit.Pixel, imgEffect);<br>        }<br>        else<br>        {<br>            _effect.DrawImage(pictureBox1.Image, new Rectangle(0, 0, pictureBox1.Image.Width, pictureBox1.Image.Height), 0, 0, pictureBox1.Image.Width, pictureBox1.Image.Height, GraphicsUnit.Pixel, imgEffect);<br>        }<br>        pictureBox1.Image = effect;<br>    }<br>    private void Form1_Load(object sender, EventArgs e)<br>    {<br>    }<br>    private void trackBar1_ValueChanged(object sender, EventArgs e)<br>    {<br>        ChangeAlpha();<br>    }<br>    private void button1_Click(object sender, EventArgs e)<br>    {<br>        if (openFileDialog1.ShowDialog() == DialogResult.OK)<br>        {<br>            pictureBox1.Image = Image.FromFile(openFileDialog1.FileName);<br>        }<br>    }<br>}<br>partial class Form1<br>{<br>    /// <summary><br>    /// 必需的设计器变量。<br>    /// </summary><br>    private System.ComponentModel.IContainer components = null;<br>    /// <summary><br>    /// 清理所有正在使用的资源。<br>    /// </summary><br>    /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param><br>    protected override void Dispose(bool disposing)<br>    {<br>        if (disposing && (components != null))<br>        {<br>            components.Dispose();<br>        }<br>        base.Dispose(disposing);<br>    }<br>    #region Windows 窗体设计器生成的代码<br>    /// <summary><br>    /// 设计器支持所需的方法 - 不要<br>    /// 使用代码编辑器修改此方法的内容。<br>    /// </summary><br>    private void InitializeComponent()<br>    {<br>        this.pictureBox1 = new System.Windows.Forms.PictureBox();<br>        this.trackBar1 = new System.Windows.Forms.TrackBar();<br>        this.button1 = new System.Windows.Forms.Button();<br>        this.openFileDialog1 = new System.Windows.Forms.OpenFileDialog();<br>        ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit();<br>        ((System.ComponentModel.ISupportInitialize)(this.trackBar1)).BeginInit();<br>        this.SuspendLayout();<br>        // <br>        // pictureBox1<br>        // <br>        this.pictureBox1.Location = new System.Drawing.Point(12, 80);<br>        this.pictureBox1.Name = "pictureBox1";<br>        this.pictureBox1.Size = new System.Drawing.Size(424, 258);<br>        this.pictureBox1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.Zoom;<br>        this.pictureBox1.TabIndex = 0;<br>        this.pictureBox1.TabStop = false;<br>        // <br>        // trackBar1<br>        // <br>        this.trackBar1.Location = new System.Drawing.Point(12, 41);<br>        this.trackBar1.Maximum = 100;<br>        this.trackBar1.Minimum = 1;<br>        this.trackBar1.Name = "trackBar1";<br>        this.trackBar1.Size = new System.Drawing.Size(424, 45);<br>        this.trackBar1.TabIndex = 1;<br>        this.trackBar1.TickStyle = System.Windows.Forms.TickStyle.None;<br>        this.trackBar1.Value = 100;<br>        this.trackBar1.ValueChanged += new System.EventHandler(this.trackBar1_ValueChanged);<br>        // <br>        // button1<br>        // <br>        this.button1.Location = new System.Drawing.Point(12, 12);<br>        this.button1.Name = "button1";<br>        this.button1.Size = new System.Drawing.Size(75, 23);<br>        this.button1.TabIndex = 2;<br>        this.button1.Text = "打开图片";<br>        this.button1.UseVisualStyleBackColor = true;<br>        this.button1.Click += new System.EventHandler(this.button1_Click);<br>        // <br>        // openFileDialog1<br>        // <br>        this.openFileDialog1.Filter = "图片文件|*.jpg;*.jpeg;*.png;*.bmp";<br>        // <br>        // Form1<br>        // <br>        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);<br>        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;<br>        this.ClientSize = new System.Drawing.Size(447, 350);<br>        this.Controls.Add(this.pictureBox1);<br>        this.Controls.Add(this.button1);<br>        this.Controls.Add(this.trackBar1);<br>        this.Name = "Form1";<br>        this.Text = "Form1";<br>        this.Load += new System.EventHandler(this.Form1_Load);<br>        ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit();<br>        ((System.ComponentModel.ISupportInitialize)(this.trackBar1)).EndInit();<br>        this.ResumeLayout(false);<br>        this.PerformLayout();<br>    }<br>    #endregion<br>    private System.Windows.Forms.PictureBox pictureBox1;<br>    private System.Windows.Forms.TrackBar trackBar1;<br>    private System.Windows.Forms.Button button1;<br>    private System.Windows.Forms.OpenFileDialog openFileDialog1;<br>}