feat: Turtle.get/set_Fill gradients ( Fixes PoshWeb#294 )

Author: StartAutomating

Turtle.types.ps1xml

@@ -4629,16 +4629,140 @@ if (($this.'.Duration' -is [TimeSpan]) -and $this.PathAnimation) {
       <ScriptProperty>
         <Name>Fill</Name>
         <GetScriptBlock>
-                        if ($this.'.Fill') { 
+                        &lt;#
+.SYNOPSIS
+    Gets a Turtle's fill color
+.DESCRIPTION
+    Gets one or more colors used to fill the Turtle.    
+
+    By default, this is transparent.
+
+    If more than one value is provided, the fill will be a gradient.
+.EXAMPLE
+    # Draw a blue square
+    turtle square 42 fill blue 
+.EXAMPLE
+    # Draw a PowerShell blue square
+    turtle square 42 fill '#4488ff'
+.EXAMPLE
+    # Draw a red, green, blue gradient
+    turtle square 42 fill red green blue show
+.EXAMPLE
+    # Draw a red, green, blue linear gradient
+    turtle square 42 fill red green blue linear show
+.EXAMPLE
+    turtle flower fill red green blue fillrule evenodd show
+#&gt;
+if ($this.'.Fill') { 
     return $this.'.Fill'
 }
 return 'transparent'
                     </GetScriptBlock>
         <SetScriptBlock>
-                        param(
-    [string]$Fill = 'transparent'
+                        &lt;#
+.SYNOPSIS
+    Sets a Turtle's fill color
+.DESCRIPTION
+    Sets one or more colors used to fill the Turtle.    
+
+    By default, this is transparent.
+
+    If more than one value is provided, the fill will be a gradient.
+.EXAMPLE
+    # Draw a blue square
+    turtle square 42 fill blue 
+.EXAMPLE
+    # Draw a PowerShell blue square
+    turtle square 42 fill '#4488ff'
+.EXAMPLE
+    # Draw a red, green, blue gradient
+    turtle square 42 fill red green blue show
+.EXAMPLE
+    # Draw a red, green, blue linear gradient
+    turtle square 42 fill red green blue linear show
+.EXAMPLE
+    turtle flower fill red green blue fillrule evenodd show         
+#&gt;
+param(
+[PSObject[]]
+$Fill = 'transparent'
 )
 
+# If we have no fill information, return
+if (-not $fill) { return }
+
+# If the fill count is greater than one, try to make a graidnet
+if ($fill.Count -gt 1) {
+
+    # Default to a radial gradient
+    $gradientTypeHint = 'radial'
+    # and create a collection for attributes
+    $gradientAttributes = [Ordered]@{
+        # default our identifier to the current id plus `fill-gradient`
+        # (so we could have multiple gradients without a collision)
+        id="$($this.id)-fill-gradient"
+    }
+
+    $fill = @(foreach ($color in $fill) {
+        # If the value matches `linear` or `radial` 
+        if ($color -match '^(linear|radial)') {
+            # take the hint and make it the right type of gradient.
+            $gradientTypeHint = ($color -replace 'gradient').ToLower()
+        }
+        # If the color was `pad`, `reflect`, or `repeat`
+        elseif ($fillColor -in 'pad', 'reflect', 'repeat') {
+            # take the hint and set the spreadMethod
+            $gradientAttributes['spreadMethod'] = $color
+        }
+        # If the fill is a dictionary
+        elseif ($color -is [Collections.IDictionary]) {
+            # propagate the values into attributes.
+            foreach ($gradientAttributeKey in $color.Keys) {
+                $gradientAttributes[$gradientAttributeKey] = $color[$gradientAttributeKey]
+            }
+        }
+        # Otherwise output the color
+        else {
+            $color
+        }
+    })
+        
+    # If we have no fill colors after filtering, return
+    if (-not $fill) { return }
+
+    # If our count is one
+    if ($fill.Count -eq 1) {
+        # it's not really going to be a gradient, so just use the one color.
+        $this | Add-Member -MemberType NoteProperty -Name '.Fill' -Value $Fill -Force
+        return    
+    }
+
+    # Now we have at least two colors we want to be a gradient
+    # We need to make sure the offset starts at 0% an ends at 100%
+    # and so we actually need to divide by one less than our fill color, so we end at 100%.
+    $offsetStep = 1 / ($fill.Count - 1)
+    $Gradient = @(
+        # Construct our gradient element.
+        "&lt;${gradientTypeHint}Gradient$(
+            # propagate our attributes
+            @(foreach ($gradientAttributeKey in $gradientAttributes.Keys) {
+                " $gradientAttributeKey='$($gradientAttributes[$gradientAttributeKey])'"
+            }) -join ''
+        )&gt;"
+        @(
+            # and put in our stop colors
+            for ($fillNumber = 0; $fillNumber -lt $fill.Count; $fillNumber++) {
+                "&lt;stop offset='$($offsetStep * $fillNumber * 100)%' stop-color='$($fill[$fillNumber])' /&gt;"
+            }
+        )        
+        "&lt;/${gradientTypeHint}Gradient&gt;"
+    ) -join [Environment]::NewLine
+
+    # add this gradient to our defines
+    $this.Defines += $Gradient
+    # and set fill to this gradient.
+    $fill = "url(`"#$($gradientAttributes.id)`")"
+}
 if (-not $this.'.Fill') {
     $this | Add-Member -MemberType NoteProperty -Name '.Fill' -Value $Fill -Force
 } else {