how I can place an image just in one cell using np

问题:

I'm using npoi to generate excel docs. I have a requirement to add images to cells. Using the following code i can insert images into my doc. However the image span many cells. How can i ensure that the image just fits inside once cell.

public ActionResult NPOICreate()
{
    try
    {
        FileStream fs = new FileStream(Server.MapPath(@"\Content\NPOITemplate.xls"), FileMode.Open, FileAccess.ReadWrite);
        HSSFWorkbook templateWorkbook = new HSSFWorkbook(fs, true);
        var sheet = templateWorkbook.GetSheet("Sheet1");
        var patriarch = sheet.CreateDrawingPatriarch();
        HSSFClientAnchor anchor;
        anchor = new HSSFClientAnchor(0, 0, 0, 0, (short)4, 2, (short)6, 5);
        anchor.AnchorType = 2;
        var picture = patriarch.CreatePicture(anchor, LoadImage(@"D:\dev\Website/HumpbackWhale.jpg", templateWorkbook));
        picture.Resize();
        picture.LineStyle = HSSFPicture.LINESTYLE_DASHDOTGEL;
        sheet.ForceFormulaRecalculation = true;
        MemoryStream ms = new MemoryStream();
        templateWorkbook.Write(ms);
        TempData["Message"] = "Excel report created successfully!";
        return File(ms.ToArray(), "application/vnd.ms-excel", "NPOINewFile.xls");
    }
    catch (Exception ex)
    {
        TempData["Message"] = "Oops! Something went wrong.";

        return RedirectToAction("NPOI");
    }

}

回答1:

To the best of my knowledge, it isn't possible to assign an image object to a particular cell within Excel.
This is not a limitation of POI/NPOI, but rather the way Excel works: Pictures inserted into a spreadsheet just float (over the spreadsheet grid per se)...
At best one can make believe it is in the cell by ensuring that the size and position of the cell and of the picture match perfectly. There is a property of the picture (See "Format Picture" dialog, Properties section, also accessible through POI I'm sure) which allows to specify whether the picture will move and/or resize itself following actions on rows/cells surrounding it, but in the end, pictures remain a floating object very loosely related to a cell at best.

A common trick to assign a picture to a cell is by way of comments. The picture is then more formally bound to the cell but it is not shown as content but rather a comment data.
See for example this recipe. The idea is to use the background of the comment to be a color with a special fill effect which is the picture we wish to associate with the cell. Here again, there's got to be a way of achieving this programmatically with NPOI, but I cannot affirm this firsthand.

回答2:

here's something you can try:

You see that property, anchor.AnchorType = 2;? try setting that to 0 or 3 and see what it does. In the C# (NPOI) port, 0 will fit the image in just one cell with option 0.

Here's some example code (used in a C# Asp.net project, just in case someone wanders here that needs it):

HSSFWorkbook hssfworkbook = new HSSFWorkbook();
HSSFSheet sheet1 = hssfworkbook.CreateSheet(sheetName);
//map the path to the img folder
string imagesPath = System.IO.Path.Combine(Server.MapPath("~"), "img");
//grab the image file
imagesPath = System.IO.Path.Combine(imagesPath, "image.png");
//create an image from the path
System.Drawing.Image image = System.Drawing.Image.FromFile(imagesPath);
MemoryStream ms = new MemoryStream();
//pull the memory stream from the image (I need this for the byte array later)
image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
//the drawing patriarch will hold the anchor and the master information
HSSFPatriarch patriarch = sheet1.CreateDrawingPatriarch();
//store the coordinates of which cell and where in the cell the image goes
HSSFClientAnchor anchor = new HSSFClientAnchor(20, 0, 40, 20, 3, 10, 4, 11);
//types are 0, 2, and 3. 0 resizes within the cell, 2 doesn't
anchor.AnchorType = 2;
//add the byte array and encode it for the excel file
int index = hssfworkbook.AddPicture(ms.ToArray(), HSSFPicture.PICTURE_TYPE_PNG);
HSSFPicture signaturePicture = patriarch.CreatePicture(anchor, index);

回答3:

It's possible by three steps. First, you should insert the picture Second, add the ClientAnchor to the file to locate the picture to some cells Third, resize the picture using tricky way otherwise it's hard to make a picture inside a cell