如何防止粘贴的图像溢出其边界？答案

【问题标题】：How can I prevent the pasted image from overflowing its boundaries?如何防止粘贴的图像溢出其边界？
【发布时间】：2016-06-24 06:55:02
【问题描述】：

我将图像插入 Excel 范围，如下所示：

    private System.Drawing.Image _logo;

    public ProduceUsageRpt(..., System.Drawing.Image logo)
    {
        . . .
        _logo = logo;
    }
    . . .
    var logoRange = _xlSheet.Range[
    _xlSheet.Cells[LOGO_FIRST_ROW, _grandTotalsColumn], _xlSheet.Cells[LOGO_LAST_ROW, _grandTotalsColumn]];
Clipboard.SetDataObject(_logo, true);
_xlSheet.Paste(logoRange, _logo);

很遗憾，图片对于该范围来说太大了（目前是第 1 行到第 4 行第 16 列）。它没有做礼貌的事情并缩小自身以适应规定的范围，而是溢出并超出其指定的垂直和水平位置。

如何让图像按比例缩小并将其自身限制在“框”内？

【问题讨论】：

标签： c# image scaling excel-interop image-scaling

【解决方案1】：

我在一个相关问题here 上改编了一个答案。

只要我使范围足够大，就可以了：

    . . .
    var logoRange = _xlSheet.Range[
        _xlSheet.Cells[LOGO_FIRST_ROW, _grandTotalsColumn], _xlSheet.Cells[LOGO_LAST_ROW, _grandTotalsColumn+1]];
    PlacePicture(_logo, logoRange);
}

// From Jürgen Tschandl
private void PlacePicture(Image picture, Range destination)
{
    Worksheet ws = destination.Worksheet;
    Clipboard.SetImage(picture);
    ws.Paste(destination, false);
    Pictures p = ws.Pictures(System.Reflection.Missing.Value) as Pictures;
    Picture pic = p.Item(p.Count) as Picture;
    ScalePicture(pic, (double)destination.Width, (double)destination.Height);
}

// Also from Jürgen Tschandl
private void ScalePicture(Picture pic, double width, double height)
{
    double fX = width / pic.Width;
    double fY = height / pic.Height;
    double oldH = pic.Height;
    if (fX < fY)
    {
        pic.Width *= fX;
        if (pic.Height == oldH) // no change if aspect ratio is locked
            pic.Height *= fX;
        pic.Top += (height - pic.Height) / 2;
    }
    else
    {
        pic.Width *= fY;
        if (pic.Height == oldH) // no change if aspect ratio is locked
            pic.Height *= fY;
        pic.Left += (width - pic.Width) / 2;
    }
}

【讨论】：