移动到下一页时加快应用程序

Question

我正在使用 WinForms。在我的表单中，我有一个显示图像文档的图片框。这些图像文件有很多页。我的表单上有一个打开、下一个和上一个按钮。在图片框中打开的文档中，下一个按钮前进一页，上一个按钮后退一页。我的表单上也有标签来指示有多少页，以及用户当前正在查看的页面。

我的代码存在问题，当我在我的图片框中打开大型图像文件时，例如有 1200 页的文档，然后单击下一步。页面加载缓慢。我想提高代码的性能。

如何才能更快地查看图像文档或改进我的代码？

我提供了一个 tif 文件来测试：http://www.filedropper.com/sampletifdocument5pages

    private int int_Current_Page = 0;

    private void btnNextImage_Click_1(object sender, EventArgs e)
    {
        Image image2;
        try
        {
            if (int_Current_Page == Convert.ToInt32(lblNumPages.Text)) // if you have reached the last page it ends here
                                                                  // the "-1" should be there for normalizing the number of pages
            { int_Current_Page = Convert.ToInt32(lblNumPages.Text); }
            else
            {                   
                int_Current_Page++; //page increment

                using (FileStream stream = new FileStream(@"C:\my_Image_document", FileMode.Open, FileAccess.Read))
                {
                    image2 = Image.FromStream(stream);
                    Refresh_Image();
                } 
            }
        }
        catch(Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

    private void btnPrevImage_Click_1(object sender, EventArgs e)
    {
        if (int_Current_Page == 0) // it stops here if you reached the bottom, the first page of the tiff
        { int_Current_Page = 0; }
        else
        {
            int_Current_Page--; // if its not the first page, then go to the previous page
            Refresh_Image(); // refresh the image on the selected page
        }
    }

    private void openButton_Click_1(object sender, EventArgs e)
    {
        Refresh_Image(); //Opens the large image document
    }

    private void Refresh_Image()
    {
        Image myImg; // setting the selected tiff
        Image myBmp; // a new occurance of Image for viewing

        using (FileStream stream = new FileStream(@"C:\my_Image_document", FileMode.Open, FileAccess.Read))
        {
            myImg = Image.FromStream(stream);

            int intPages = myImg.GetFrameCount(System.Drawing.Imaging.FrameDimension.Page); // getting the number of pages of this tiff
            intPages--; // the first page is 0 so we must correct the number of pages to -1
            lblNumPages.Text = Convert.ToString(intPages); // showing the number of pages
            lblCurrPage.Text = Convert.ToString(int_Current_Page); // showing the number of page on which we're on

            myImg.SelectActiveFrame(System.Drawing.Imaging.FrameDimension.Page, int_Current_Page); // going to the selected page

            myBmp = new Bitmap(myImg, pictureBox1.Width, pictureBox1.Height);

            pictureBox1.Image = myBmp; // showing the page in the pictureBox1  
        }
    }

Answer 1

这可能在两个地方之一减慢了速度，加载巨大的文件（希望如此）或选择活动框架。如果这是第一个问题，只需延迟加载一次图像就可以轻松解决：

private int int_Current_Page = 0;

private void btnNextImage_Click_1(object sender, EventArgs e)
{
    Image image2;
    try
    {
        if (int_Current_Page == Convert.ToInt32(lblNumPages.Text)) // if you have reached the last page it ends here
                                                              // the "-1" should be there for normalizing the number of pages
        { int_Current_Page = Convert.ToInt32(lblNumPages.Text); }
        else
        {                   
            int_Current_Page++; //page increment
            Refresh_Image();
        }
    }
    catch(Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

private void btnPrevImage_Click_1(object sender, EventArgs e)
{
    if (int_Current_Page == 0) // it stops here if you reached the bottom, the first page of the tiff
    { int_Current_Page = 0; }
    else
    {
        int_Current_Page--; // if its not the first page, then go to the previous page
        Refresh_Image(); // refresh the image on the selected page
    }
}

private void openButton_Click_1(object sender, EventArgs e)
{
    Refresh_Image(); //Opens the large image document
}
FileStream _stream; 
Image _myImg; // setting the selected tiff
private void Refresh_Image()
{
    // Image myImg; // setting the selected tiff - Now a member variable
    Image myBmp; // a new occurance of Image for viewing

    if (_myImg == null)
    {
        _stream = new FileStream(@"C:\my_Image_document", FileMode.Open, FileAccess.Read)
        _myImg = Image.FromStream(_Stream);
    }
    int intPages = _myImg.GetFrameCount(System.Drawing.Imaging.FrameDimension.Page); // getting the number of pages of this tiff
    intPages--; // the first page is 0 so we must correct the number of pages to -1
    lblNumPages.Text = Convert.ToString(intPages); // showing the number of pages
    lblCurrPage.Text = Convert.ToString(int_Current_Page); // showing the number of page on which we're on

    _myImg.SelectActiveFrame(System.Drawing.Imaging.FrameDimension.Page, int_Current_Page); // going to the selected page

    myBmp = new Bitmap(_myImg, pictureBox1.Width, pictureBox1.Height);

    pictureBox1.Image = myBmp; // showing the page in the pictureBox1  
}

protected override void Dispose(bool disposing)
{
    if (_stream != null) _stream.Dispose();
    base.Dispose(disposing);
}

移动到下一页时加快应用程序

Speed Up Application when Moving to the Next Page

c#

.net

winforms

performance

next