Added Get-ImageCodecInfo

Author: alan-null

Photo.Shell/Public/Get-ImageCodecInfo.ps1

@@ -0,0 +1,30 @@
+function Get-ImageCodecInfo {
+    [CmdletBinding()]
+    param (
+        # [byte[]] or [System.IO.Stream]
+        [Parameter(Mandatory = $true, Position = 0 )]
+        $Image
+    )
+
+    begin {
+        Write-Verbose "Cmdlet Get-ImageCodecInfo - Begin"
+    }
+
+    process {
+        Write-Verbose "Cmdlet Get-ImageCodecInfo - Process"
+
+        if ($Image.PSTypeNames -contains [System.IO.Stream]) {
+            $Image = $Image.ToArray()
+        }
+
+        [System.Drawing.Imaging.ImageCodecInfo]::GetImageEncoders() | ? {
+            [byte[]]$pattern = $_.SignaturePatterns  | Select-Object -First 1
+            [byte[]]$header = $Image  | Select-Object -First $pattern.Length
+            [System.Linq.Enumerable]::SequenceEqual([byte[]]$pattern, [byte[]]$header)
+        } | Select-Object -First 1
+    }
+
+    end {
+        Write-Verbose "Cmdlet Get-ImageCodecInfo - End"
+    }
+}

Tests/Photo.Shell.Tests.ps1

@@ -0,0 +1,44 @@
+Clear-Host
+Import-Module -Name Pester -Force
+Import-Module .\Photo.Shell\Photo.Shell.psm1 -Force
+
+function Get-TestImage {
+    param (
+        [Parameter(Mandatory = $false, Position = 0 )]
+        [System.Drawing.Imaging.ImageFormat]$Format = [System.Drawing.Imaging.ImageFormat]::Png
+    )
+    $bitmap = [System.Drawing.Bitmap]::new(1000, 800, [System.Drawing.Imaging.PixelFormat]::Format32bppPArgb)
+    $graphics = [System.Drawing.Graphics]::FromImage($bitmap)
+    $pen1 = [System.Drawing.Pen]::new([System.Drawing.Color]::FromKnownColor([System.Drawing.KnownColor]::Red), 2)
+    $graphics.DrawEllipse($pen1, 10, 10, 900, 700)
+
+    $result = [System.IO.MemoryStream]::new()
+    $bitmap.Save($result, $Format)
+    $result.ToArray()
+}
+
+Describe 'Photo.Shell.Tests' {
+    Context "Get-ImageCodecInfo" {
+        $testImage = Get-TestImage
+        $codecInfo = Get-ImageCodecInfo $testImage
+
+        It "should not be null" {
+            $codecInfo | Should -Not -BeNullOrEmpty
+        }
+
+        It "should have valid type" {
+            $codecInfo | Should -BeOfType [System.Drawing.Imaging.ImageCodecInfo]
+        }
+
+        It "given img.<Format>, it returns '<Expected>'" -TestCases @(
+            @{ Format = [System.Drawing.Imaging.ImageFormat]::Png; Expected = 'image/png' }
+            @{ Format = [System.Drawing.Imaging.ImageFormat]::Jpeg; Expected = 'image/jpeg' }
+            @{ Format = [System.Drawing.Imaging.ImageFormat]::Bmp; Expected = 'image/bmp' }
+            @{ Format = [System.Drawing.Imaging.ImageFormat]::Gif; Expected = 'image/gif' }
+        ) {
+            param ($Format, $Expected)
+            $img = Get-TestImage -Format $Format
+            Get-ImageCodecInfo $img | Select-Object -ExpandProperty MimeType  | Should -BeExactly $Expected
+        }
+    }
+}