Question

我想在Windows窗体上打印图像，但是我想在页面上打印尽可能大的图像而不破坏其宽高比。就像我要在A4纸上打印一个简单的正方形一样，使用以下脚本将其变成矩形：

private void Page(object sender, PrintPageEventArgs e)
{
    Bitmap i = image;
    if(e.PageBounds.Height > e.PageBounds.Width)
    {
        if (i.Width > i.Height)
            i.RotateFlip(RotateFlipType.Rotate90FlipNone);
    }
    else if(e.PageBounds.Width > e.PageBounds.Height)
    {
        if (i.Height > i.Width)
            i.RotateFlip(RotateFlipType.Rotate90FlipNone);
    }
    e.Graphics.DrawImage(i, new Rectangle(0, 0, e.PageBounds.Width, e.PageBounds.Height));
    i.Dispose();
}

原件： 500x500 square

我得到了什么（PDF格式）： A rectangle on the A4 paper

另一个例子：

原文：Original image(313x234)

打印：Print image

我不想破坏图像的长宽比

Answer 1

尝试一下：

private void Page(object sender, PrintPageEventArgs e)
{
    using (Bitmap i = image)  //are you *really sure* you want to dispose this after printing? 
    {
        var pageRatio = e.PageBounds.Width / (double)e.PageBounds.Height;
        var imageRatio = i.Width / (double)i.Height;

        //do we need to rotate?
        if ( (pageRatio < 1 && imageRatio > 1) || (pageRatio < 1 && imageRatio > 1))
        {
            i.RotateFlip(RotateFlipType.Rotate90FlipNone);
            imageRatio = i.Width / (double)i.Height; //ratio will have changed after rotation
        }         

        var scale = 1.0D;
        //do we need to scale?
        if (pageRatio > imageRatio)
        { //the page is wider than the image, so scale to the height
             scale = e.PageBounds.Height / (double)i.Height;
        }
        else if (pageRatio < imageRatio)
        { //the page is narrower than the image, so scale to width
            scale = e.PageBounds.Width / (double)i.Width;
        }

        var W = (int)(scale * i.Width);
        var H = (int)(scale * i.Height);

        e.Graphics.DrawImage(i, new Rectangle(0, 0, W, H));
    }
}

这将始终从左上角绘制。如果要使其居中，则需要进行其他调整：

private void Page(object sender, PrintPageEventArgs e)
{
    using (Bitmap i = image)  //are you *really sure* you want to dispose this after printing? 
    {
        var pageRatio = e.PageBounds.Width / (double)e.PageBounds.Height;
        var imageRatio = i.Width / (double)i.Height;

        //do we need to rotate?
        if ( (pageRatio < 1 && imageRatio > 1) || (pageRatio < 1 && imageRatio > 1))
        {
            i.RotateFlip(RotateFlipType.Rotate90FlipNone);
            imageRatio = i.Width / (double)i.Height; //ratio will have changed after rotation
        }         

        int T = 0, L = 0; //top, left
        var scale = 1.0D;
        int W = i.Width, H = i.Height;

        //do we need to scale?
        if (pageRatio > imageRatio)
        { //the page is wider than the image, so scale to the height
             scale = e.PageBounds.Height / (double)i.Height;
             W = (int)(scale * i.Width); 
             H = (int)(scale * i.Height);
             L = (e.PageBounds.Width - W)/2;
        }
        else if (pageRatio < imageRatio)
        { //the page is narrower than the image, so scale to width
            scale = e.PageBounds.Width / (double)i.Width;
            W = (int)(scale * i.Width); 
            H = (int)(scale * i.Height);
            T = (e.PageBounds.Height - H)/2;
        }

        e.Graphics.DrawImage(i, new Rectangle(L, T, W+L, H+T));
    }
}

重要的是宽度和高度都调整为相同的比例 ...，即乘以相同的数字。

C＃表单打印图像尽可能大

1 个答案: