docs: add Add-ExcelImage example

Examples/AddPicture/Add-ExcelImage.ps1

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+function Add-ExcelImage {
+    <#
+    .SYNOPSIS
+        Adds an image to a worksheet in an Excel package.
+    .DESCRIPTION
+        Adds an image to a worksheet in an Excel package using the
+        `WorkSheet.Drawings.AddPicture(name, image)` method, and places the
+        image at the location specified by the Row and Column parameters.
+        
+        Additional position adjustment can be made by providing RowOffset and
+        ColumnOffset values in pixels.
+    .EXAMPLE
+        $image = [System.Drawing.Image]::FromFile($octocat)
+        $xlpkg = $data | Export-Excel -Path $path -PassThru
+        $xlpkg.Sheet1 | Add-ExcelImage -Image $image -Row 4 -Column 6 -ResizeCell
+        
+        Where $octocat is a path to an image file, and $data is a collection of
+        data to be exported, and $path is the output path for the Excel document,
+        Add-Excel places the image at row 4 and column 6, resizing the column
+        and row as needed to fit the image.
+    .INPUTS
+        [OfficeOpenXml.ExcelWorksheet]
+    .OUTPUTS
+        None
+    #>
+    [CmdletBinding()]
+    param(
+        # Specifies the worksheet to add the image to.
+        [Parameter(Mandatory, ValueFromPipeline)]
+        [OfficeOpenXml.ExcelWorksheet]
+        $WorkSheet,
+
+        # Specifies the Image to be added to the worksheet.
+        [Parameter(Mandatory)]
+        [System.Drawing.Image]
+        $Image,        
+
+        # Specifies the row where the image will be placed. Rows are counted from 1.
+        [Parameter(Mandatory)]
+        [ValidateRange(1, [int]::MaxValue)]
+        [int]
+        $Row,
+
+        # Specifies the column where the image will be placed. Columns are counted from 1.
+        [Parameter(Mandatory)]
+        [ValidateRange(1, [int]::MaxValue)]
+        [int]
+        $Column,
+
+        # Specifies the name to associate with the image. Names must be unique per sheet.
+        # Omit the name and a GUID will be used instead.
+        [Parameter()]
+        [string]
+        $Name,
+
+        # Specifies the number of pixels to offset the image on the Y-axis. A
+        # positive number moves the image down by the specified number of pixels
+        # from the top border of the cell.
+        [Parameter()]
+        [int]
+        $RowOffset = 1,
+
+        # Specifies the number of pixels to offset the image on the X-axis. A
+        # positive number moves the image to the right by the specified number
+        # of pixels from the left border of the cell.
+        [Parameter()]
+        [int]
+        $ColumnOffset = 1,
+
+        # Increase the column width and row height to fit the image if the current
+        # dimensions are smaller than the image provided.
+        [Parameter()]
+        [switch]
+        $ResizeCell
+    )
+
+    begin {
+        <#
+          These ratios work on my machine but it feels fragile. Need to better
+          understand how row and column sizing works in Excel and what the
+          width and height units represent.
+        #>
+        $widthFactor = 1 / 7
+        $heightFactor = 3 / 4
+    }
+
+    process {
+        if ([string]::IsNullOrWhiteSpace($Name)) {
+            $Name = (New-Guid).ToString()
+        }
+        if ($null -ne $WorkSheet.Drawings[$Name]) {
+            Write-Error "A picture with the name `"$Name`" already exists in worksheet $($WorkSheet.Name)."
+            return
+        }
+
+        <#
+          The row and column offsets of 1 ensures that the image lands just
+          inside the gray cell borders at the top left.
+        #>
+        $picture = $WorkSheet.Drawings.AddPicture($Name, $Image)
+        $picture.SetPosition($Row - 1, $RowOffset, $Column - 1, $ColumnOffset)
+        
+        if ($ResizeCell) {
+            <#
+              Adding 1 to the image height and width ensures that when the
+              row and column are resized, the bottom right of the image lands
+              just inside the gray cell borders at the bottom right.
+            #>
+            $width = $widthFactor * ($Image.Width + 1)
+            $height = $heightFactor * ($Image.Height + 1)
+            $WorkSheet.Column($Column).Width = [Math]::Max($width, $WorkSheet.Column($Column).Width)
+            $WorkSheet.Row($Row).Height = [Math]::Max($height, $WorkSheet.Row($Row).Height)
+        }
+    }
+}

Examples/AddPicture/AddPicture.ps1

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+Add-Type -AssemblyName System.Drawing
+
+. $PSScriptRoot\Add-ExcelImage.ps1
+
+$data = ConvertFrom-Csv @"
+Region,State,Units,Price
+West,Texas,927,923.71
+North,Tennessee,466,770.67
+East,Florida,520,458.68
+East,Maine,828,661.24
+West,Virginia,465,053.58
+North,Missouri,436,235.67
+South,Kansas,214,992.47
+North,North Dakota,789,640.72
+South,Delaware,712,508.55
+"@
+
+$path = "$PSScriptRoot/Add-Picture-test.xlsx"
+Remove-Item $path -ErrorAction SilentlyContinue
+
+
+try {
+    $octocat = "$PSScriptRoot/Octocat.jpg"
+    $image = [System.Drawing.Image]::FromFile($octocat)
+    $xlpkg = $data | Export-Excel -Path $path -PassThru
+    $xlpkg.Sheet1 | Add-ExcelImage -Image $image -Row 4 -Column 6 -ResizeCell
+} finally {
+    $image.Dispose()
+    if ($xlpkg) {
+        Close-ExcelPackage -ExcelPackage $xlpkg -Show
+    }
+}
+
+

Examples/AddPicture/README.md

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+# Add-ExcelImage Example
+
+Adding pictures to an Excel worksheet is possible by calling the `AddPicture(name, image)`
+method on the `Drawings` property of an `ExcelWorksheet` object.
+
+The `Add-ExcelImage` example here demonstrates how to add a picture at a given
+cell location, and optionally resize the row and column to fit the image.
+
+Care has been taken in this example to get the image placement to be just inside
+the cell border, and if the `-ResizeCell` switch is present, the height and width
+of the row and column will be increased, if needed, so that the bottom right of
+the image also lands just inside the cell border.
+
+The Excel row and column sizes are measured in "point" units rather than pixels,
+and at the moment a fixed multiplication factor is used to convert the size of
+the image in pixels, to the corresponding height and width values in Excel.
+
+You may find that images with a different DPI, or different resolution, DPI, or
+text scaling options result in imperfect row and column sizing.