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Question

我想制作一个屏幕缩放器，它可以捕获屏幕的一部分并将其缩放。下面的代码现在可以捕获屏幕并在 PictureBox 中播放。但是我有这个问题，当我打开程序时，我的内存不断增长。我想一定是有些资源没有释放，不知道怎么释放。

我把它做成了一个媒体播放器，但不是播放视频，而是播放当前屏幕的一部分。

public partial class Form1 : Form
{

    PictureBox picBox;
    Bitmap bit;
    Graphics g;

    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        picBox = pictureBox;
    }

    private void CopyScreen()
    {

        bit = new Bitmap(this.Width, this.Height);
        g = Graphics.FromImage(bit as Image);

        Point upperLeftSource = new Point(
            Screen.PrimaryScreen.Bounds.Width / 2 - this.Width / 2,
            Screen.PrimaryScreen.Bounds.Height / 2 - this.Height / 2);

        g.CopyFromScreen(upperLeftSource, new Point(0, 0), bit.Size);

        picBox.Image = Image.FromHbitmap(bit.GetHbitmap());

        bit.Dispose();
        g.Dispose();
    }

    private void timer_Tick(object sender, EventArgs e)
    {
        CopyScreen();
    }

Answer 1

问题在于您对 GetHbitmap 的使用，以及当您将新的 Image 分配给 [=15] 时您没有处理之前的 Image =].

https://msdn.microsoft.com/en-us/library/1dz311e4(v=vs.110).aspx 状态：

You are responsible for calling the GDI DeleteObject method to free the memory used by the GDI bitmap object.

（你没有做）

考虑更改代码以避免需要 GetHbitmap 调用（以及 Dispose 之前的 Image）：

private void CopyScreen()
{
    bit = new Bitmap(this.Width, this.Height);
    g = Graphics.FromImage(bit);

    Point upperLeftSource = new Point(
        Screen.PrimaryScreen.Bounds.Width / 2 - this.Width / 2,
        Screen.PrimaryScreen.Bounds.Height / 2 - this.Height / 2);

    g.CopyFromScreen(upperLeftSource, new Point(0, 0), bit.Size);

    var oldImage = picBox.Image;
    picBox.Image = bit;
    oldImage?.Dispose();

    g.Dispose();
}

为了进一步简化它，删除您在 class 顶部声明的字段，然后只使用：

private void CopyScreen()
{
    var picBox = pictureBox;
    var bit = new Bitmap(this.Width, this.Height);

    using (var g = Graphics.FromImage(bit))
    {
        var upperLeftSource = new Point(
            Screen.PrimaryScreen.Bounds.Width / 2 - this.Width / 2,
            Screen.PrimaryScreen.Bounds.Height / 2 - this.Height / 2);

        g.CopyFromScreen(upperLeftSource, new Point(0, 0), bit.Size);

        var oldImage = picBox.Image;
        picBox.Image = bit;
        oldImage?.Dispose();
    }
}

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