ColdFusion 8 ImageDrawTextArea() (Inspired By Barney Boisvert!)

Posted September 28, 2007 at 6:18 PM

Tags: ColdFusion

I wanted to give Barney Boisvert's CFImage contest a try, but unfortunately, this week has just beat on me like I owed it money. However, after looking at Barney's posted solution, there is no way that I would have been able to solve the problem anyway. It involved grabbing the underlying Java AWT graphics object and then using that to get font information and this was way out of my league.

Then, today, when he published his Extra Credit Solution, it totally inspired me. Barney, being the mad scientist that he is, filled my head with a whole lot of ColdFusion know-how, and I just had to put it to good use. And, while my use of ColdFusion 8 image manipulation functionality has not been very extensive, one thing that bothered me very quickly was the text handling. It just doesn't feel very intuitive or natural compared to HTML.

To overcome this deficiency, I have created a ColdFusion 8 user defined function, ImageDrawTextArea(), that works just like the builtin ColdFusion 8 ImageDrawText() method with the added features that you can specify a text area width, line-height, and text alignment. The real winner here, though, is the Width parameter. Being a text area rather than just a line of text, it does what you suspect it might: it wraps the text in such a way that it will fit in the given width.

In addition to the existing font attributes, the TextAlign attribute allows you to left, center, and right justify the text. The LineHeight attribute allows you to control the spacing of the individual lines as they wrap. To give you an idea of how this works, take a look at this snippet of code:

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  • <!--- Draw the text area on the image object. --->
  • <cfset ImageDrawTextArea(
  • imgCanvas,
  • "If you think flattery will get you anywhere with me, well... that's where you're right.",
  • 50,
  • 50,
  • 400,
  • objAttributes
  • ) />
  •  
  • <!--- Write the image to the browser. --->
  • <cfimage
  • action="writetobrowser"
  • source="#imgCanvas#"
  • />

Notice here that we are not breaking up our text in anyway - we are just passing it in as one long string. Then, with our 5th method parameters (value of 400), we are defining the width of the rendered text area (in which text wrapping will happen automatically). Running the above code (incomplete snippet), we get the following ColdFusion 8 image:


  
  
  

 
ColdFusion 8 ImageDrawTextArea() Rendered Image  
 
  
  

Notice that not only did the text wrap automatically, but it is also right-aligned in the text area. You cannot see it in the above snippet, but this is due to the TextAlign attribute being set.

ColdFusion 8 Online Demo: Try ImageDrawTextArea() out for yourself.

Before I output the code, I just wanna give Barney some more praise cause the dude is brilliant and I just would not have been able to figure any of this out without picking through his code (and adding a billion comments ;)). So anyway, here is code for ImageDrawTextArea(), my ColdFusion 8 user defined function:

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  • <cffunction
  • name="ImageDrawTextArea"
  • access="public"
  • returntype="void"
  • output="true"
  • hint="Draws a text area on the given canvas.">
  •  
  • <cfargument
  • name="Source"
  • type="any"
  • required="true"
  • hint="The image on which we are going to write the text."
  • />
  •  
  • <cfargument
  • name="Text"
  • type="string"
  • required="true"
  • hint="The text value that we are going to write."
  • />
  •  
  • <cfargument
  • name="X"
  • type="numeric"
  • required="true"
  • hint="The X coordinate of the start of the text."
  • />
  •  
  • <cfargument
  • name="Y"
  • type="numeric"
  • required="true"
  • hint="The Y coordinate of the baseline of the start of the text."
  • />
  •  
  • <cfargument
  • name="Width"
  • type="numeric"
  • required="true"
  • hint="The width of the text area in which the text should fit."
  • />
  •  
  • <cfargument
  • name="Attributes"
  • type="struct"
  • required="false"
  • default="#StructNew()#"
  • hint="The attributes of the font (including TextAlign and LineHeight)."
  • />
  •  
  •  
  • <!--- Define the local scope. --->
  • <cfset var LOCAL = {} />
  •  
  •  
  • <!---
  • From the ColdFusion image, get the underlying Java AWT
  • object. This will allow us access to properties that
  • we will need to space and style the font.
  • --->
  • <cfset LOCAL.Graphics = ImageGetBufferedImage( ARGUMENTS.Source ).GetGraphics() />
  •  
  • <!---
  • Get the font that is currently set in the image. From
  • this, we will be able to default the properties of our
  • text attributes.
  • --->
  • <cfset LOCAL.CurrentFont = LOCAL.Graphics.GetFont() />
  •  
  •  
  • <!---
  • Now, we are going to check to see if the passed in
  • attributes has all the properties that we need to
  • properly render the new font. If it does not, then we
  • are gonna default that attribute to what is in the
  • current font of the graphic.
  • --->
  •  
  •  
  • <!--- Check for a defined size.--->
  • <cfif NOT StructKeyExists( ARGUMENTS.Attributes, "Size" )>
  •  
  • <!--- Get size from current font. --->
  • <cfset ARGUMENTS.Attributes.Size = LOCAL.CurrentFont.GetSize() />
  •  
  • </cfif>
  •  
  •  
  • <!--- Check for a defined font. --->
  • <cfif NOT StructKeyExists( ARGUMENTS.Attributes, "Font" )>
  •  
  • <cfset ARGUMENTS.Attributes.Font = LOCAL.CurrentFont.GetFontName() />
  •  
  • </cfif>
  •  
  •  
  • <!--- Check for a defined style. --->
  • <cfif NOT StructKeyExists( ARGUMENTS.Attributes, "Style" )>
  •  
  • <!---
  • When it comes to defaulting the style, we need to
  • build not only the font attributes, but also the
  • font style argument for creating our new font (for
  • the Font Metrics). Because of that, we will be
  • building a bit-mask for the style.
  •  
  • Because the Styles are just constants, we can pull
  • them out of our Current Font object.
  • --->
  • <cfif (
  • LOCAL.CurrentFont.IsBold() AND
  • LOCAL.CurrentFont.IsItalic()
  • )>
  •  
  • <!--- Set the style. --->
  • <cfset ARGUMENTS.Attributes.Style = "bolditalic" />
  •  
  • <!--- Set the bit mask. --->
  • <cfset LOCAL.FontStyleMask = BitOR(
  • LOCAL.CurrentFont.BOLD,
  • LOCAL.CurrentFont.ITALIC
  • ) />
  •  
  • <cfelseif LOCAL.CurrentFont.IsBold()>
  •  
  • <!--- Set the style. --->
  • <cfset ARGUMENTS.Attributes.Style = "bold" />
  •  
  • <!--- Set the bit mask. --->
  • <cfset LOCAL.FontStyleMask = LOCAL.CurrentFont.BOLD />
  •  
  • <cfelseif LOCAL.CurrentFont.IsItalic()>
  •  
  • <!--- Set the style. --->
  • <cfset ARGUMENTS.Attributes.Style = "italic" />
  •  
  • <!--- Set the bit mask. --->
  • <cfset LOCAL.FontStyleMask = LOCAL.CurrentFont.ITALIC />
  •  
  • <cfelse>
  •  
  • <!--- Set the style. --->
  • <cfset ARGUMENTS.Attributes.Style = "plain" />
  •  
  • <!--- Set the bit mask. --->
  • <cfset LOCAL.FontStyleMask = LOCAL.CurrentFont.PLAIN />
  •  
  • </cfif>
  •  
  • <cfelse>
  •  
  • <!--- Set the plain font mask. --->
  • <cfset LOCAL.FontStyleMask = LOCAL.CurrentFont.PLAIN />
  •  
  • </cfif>
  •  
  •  
  • <!---
  • Now that we have our Font attributes all paramed, we
  • need to create a new Font object (that will be used to
  • get the Font Metrics for the user's text).
  • --->
  • <cfset LOCAL.NewFont = CreateObject(
  • "java",
  • "java.awt.Font"
  • ).Init(
  • JavaCast( "string", ARGUMENTS.Attributes.Font ),
  • JavaCast( "int", LOCAL.FontStyleMask ),
  • JavaCast( "int", ARGUMENTS.Attributes.Size )
  • )
  • />
  •  
  •  
  • <!---
  • ASSERT: At this point, we have paramed the
  • font attributes that are required for a
  • normal ImageDrawText() call.
  • --->
  •  
  •  
  • <!---
  • In additional the standard attributes defined above,
  • this function allows for a few additional font
  • attributes. Let's give them some default values.
  • --->
  • <cfparam
  • name="ARGUMENTS.Attributes.LineHeight"
  • type="numeric"
  • default="#(1.4 * ARGUMENTS.Attributes.Size)#"
  • />
  •  
  • <cfparam
  • name="ARGUMENTS.Attributes.TextAlign"
  • type="string"
  • default="left"
  • />
  •  
  •  
  •  
  • <!---
  • Now that we have our new Font set up, get the
  • Font Metrics for our graphic in the context of
  • the new Font.
  • --->
  • <cfset LOCAL.FontMetrics = LOCAL.Graphics.GetFontMetrics(
  • LOCAL.NewFont
  • ) />
  •  
  •  
  • <!---
  • Now, that we have our font-testing environment set up,
  • it's time to start figuring out how we are gonna layout
  • the text. To begin, we are going to take the user's text
  • and split it up into an array of word tokens (based on
  • single spaces).
  • --->
  • <cfset LOCAL.Words = ARGUMENTS.Text.Split(
  • JavaCast( "string", " " )
  • ) />
  •  
  • <!---
  • As we loop through the words, we are going to keep
  • track of which words fit onto each line and the
  • dimensions that that line occupies. To store this, we
  • will use an array of Line structures.
  • --->
  • <cfset LOCAL.Lines = [] />
  •  
  • <!---
  • Create the first line item. Here, the Text is the
  • string data for the line and the Width / Height are
  • the physical dimensions of the text.
  • --->
  • <cfset LOCAL.Lines[ 1 ] = {
  • Text = "",
  • Width = 0,
  • Height = 0
  • } />
  •  
  •  
  • <!--- Loop over all the words. --->
  • <cfloop
  • index="LOCAL.WordIndex"
  • from="1"
  • to="#ArrayLen( LOCAL.Words )#"
  • step="1">
  •  
  • <!--- Get a short hand to the current word. --->
  • <cfset LOCAL.Word = LOCAL.Words[ LOCAL.WordIndex ] />
  •  
  • <!--- Get a short hand to the current line. --->
  • <cfset LOCAL.Line = LOCAL.Lines[ ArrayLen( LOCAL.Lines ) ] />
  •  
  •  
  • <!---
  • Using the Font Metrics, get the bounds of the
  • current text line with the addition of the next
  • word.
  • --->
  • <cfset LOCAL.TextBounds = LOCAL.FontMetrics.GetStringBounds(
  • JavaCast(
  • "string",
  • Trim( LOCAL.Line.Text & " " & LOCAL.Word )
  • ),
  • LOCAL.Graphics
  • ) />
  •  
  •  
  • <!---
  • Now that we have the physical dimensions, we need to
  • check to see if new line would be too wide for the
  • text area. If it is too wide and there is not text
  • on the line yet, then add it anyway as it simply is
  • too wide for the text area.
  • --->
  • <cfif (
  • (LOCAL.TextBounds.GetWidth() LTE ARGUMENTS.Width) OR
  • (NOT Len( LOCAL.Line.Text ))
  • )>
  •  
  • <!---
  • The current word will fit on the current line
  • so add it to the string data of the line. If
  • this is NOT the first word, be sure to add a
  • preceeding space.
  • --->
  • <cfset LOCAL.Line.Text &= (
  • IIF(
  • Len( LOCAL.Line.Text ),
  • DE( " " ),
  • DE( "" )
  • ) &
  • LOCAL.Word
  • ) />
  •  
  • <!---
  • Since the text data of this line has been
  • updated, we need to get the updated dimensions
  • of the line. When it comes go getting the width,
  • we have to be careful about lines that are too
  • wide for the text area. We never want to record
  • any width that is larger than the text area.
  • --->
  • <cfset LOCAL.Line.Width = Min(
  • LOCAL.TextBounds.GetWidth(),
  • ARGUMENTS.Width
  • ) />
  •  
  • <!--- Get height. --->
  • <cfset LOCAL.Line.Height = LOCAL.TextBounds.GetHeight() />
  •  
  • <cfelse>
  •  
  • <!---
  • Due to the dimensions of the potential line, we
  • are going to have to move the current word to a
  • new line. For this we must create a new line
  • object and insert the word.
  • --->
  •  
  • <!---
  • Get the bounds of the new line (which will be
  • the same as the bounds of the current word).
  • --->
  • <cfset LOCAL.TextBounds = LOCAL.FontMetrics.GetStringBounds(
  • JavaCast( "string", LOCAL.Word ),
  • LOCAL.Graphics
  • ) />
  •  
  • <!--- Create a new line object. --->
  • <cfset LOCAL.Line = {
  • Text = LOCAL.Word,
  • Width = LOCAL.TextBounds.GetWidth(),
  • Height = LOCAL.TextBounds.GetHeight()
  • } />
  •  
  • <!--- Append the new line object to our array. --->
  • <cfset ArrayAppend(
  • LOCAL.Lines,
  • LOCAL.Line
  • ) />
  •  
  • </cfif>
  •  
  • </cfloop>
  •  
  •  
  • <!---
  • ASSERT: At this point, we have determined which text
  • will go on which lines of our rendered text area. We
  • also know the dimensions of each line of text.
  • --->
  •  
  •  
  • <!---
  • Now, it's time to actually draw the text on the passed
  • in image object. Loop over the lines array.
  • --->
  • <cfloop
  • index="LOCAL.LineIndex"
  • from="1"
  • to="#ArrayLen( LOCAL.Lines )#"
  • step="1">
  •  
  • <!--- Get a shorthand to the current line object. --->
  • <cfset LOCAL.Line = LOCAL.Lines[ LOCAL.LineIndex ] />
  •  
  •  
  • <!---
  • Let's determine the X-coordinate of this line of
  • text. This will depend on the alignment of the text
  • (left, center, right).
  • --->
  • <cfswitch expression="#ARGUMENTS.Attributes.TextAlign#">
  •  
  • <!--- Right aligned text. --->
  • <cfcase value="right">
  •  
  • <cfset LOCAL.X = (
  • ARGUMENTS.X +
  • ARGUMENTS.Width -
  • LOCAL.Line.Width
  • ) />
  •  
  • </cfcase>
  •  
  • <!--- Center align text. --->
  • <cfcase value="center">
  •  
  • <cfset LOCAL.X = (
  • ARGUMENTS.X +
  • Fix(
  • (ARGUMENTS.Width - LOCAL.Line.Width) /
  • 2
  • )) />
  •  
  • </cfcase>
  •  
  • <!--- Left aligned text. --->
  • <cfdefaultcase>
  •  
  • <cfset LOCAL.X = ARGUMENTS.X />
  •  
  • </cfdefaultcase>
  • </cfswitch>
  •  
  •  
  • <!---
  • When getting the Y value of the line, we have to
  • take into account line height and count of the
  • current line. This is for the baseline of the text,
  • NOT the top-left-most corner.
  • --->
  • <cfset LOCAL.Y = (
  • ARGUMENTS.Y +
  • (
  • (LOCAL.LineIndex - 1) *
  • ARGUMENTS.Attributes.LineHeight
  • )) />
  •  
  •  
  •  
  • <!---
  • Draw the text at the given coordinates. Pass in
  • the structure that we got. This Attributes structure
  • will contain extraneous information (TextAlign,
  • LineHeight), but this will not throw an error.
  • --->
  • <cfset ImageDrawText(
  • ARGUMENTS.Source,
  • LOCAL.Line.Text,
  • LOCAL.X,
  • LOCAL.Y,
  • ARGUMENTS.Attributes
  • ) />
  •  
  • </cfloop>
  •  
  •  
  • <!--- Return out. --->
  • <cfreturn />
  • </cffunction>

It's a lot of code, but it's not crazy complicated when you break it down piece by piece. The key to this whole algorithm is the ability to get the bounding dimensions (width and height) of a given string based the graphics "Font Metrics" in the context of the given Font.

On my ColdFusion 8 Test Server, I have set up a demo page (same link as above). If you are interested in the code that powers that page, here it is:

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  • <!--- Kill extra output. --->
  • <cfsilent>
  •  
  • <!--- Param the form values. --->
  • <cfparam
  • name="FORM.font"
  • type="string"
  • default="courier new"
  • />
  •  
  • <cfparam
  • name="FORM.size"
  • type="numeric"
  • default="24"
  • />
  •  
  • <cfparam
  • name="FORM.text_align"
  • type="string"
  • default="right"
  • />
  •  
  • <cfparam
  • name="FORM.line_height"
  • type="numeric"
  • default="#Fix(FORM.size * 1.5)#"
  • />
  •  
  • <cfparam
  • name="FORM.text"
  • type="string"
  • default="I hope this doesn't come off as offensive, but seeing you in that dress will most definately be the highlight of my day."
  • />
  •  
  • <cfparam
  • name="FORM.width"
  • type="numeric"
  • default="400"
  • />
  •  
  • </cfsilent>
  •  
  • <cfoutput>
  •  
  • <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  • <html>
  • <head>
  • <title>ImageDrawTextArea() ColdFusion 8 Demo</title>
  •  
  • <style type="text/css">
  •  
  • body {
  • font-family: verdana ;
  • font-size: 62.5% ;
  • }
  •  
  • p {
  • clear: both ;
  • font-size: 1.2em ;
  • }
  •  
  • label {
  • float: left ;
  • font-weight: bold ;
  • width: 120px ;
  • }
  •  
  • input,
  • select {
  • width: 400px ;
  • }
  •  
  • </style>
  • </head>
  • <body>
  •  
  • <h1>
  • ImageDrawTextArea() ColdFusion 8 Demo
  • </h1>
  •  
  • <form action="#CGI.script_name#" method="post">
  •  
  • <p>
  • <label>Font:</label>
  •  
  • <select name="font">
  • <cfloop
  • index="strFont"
  • list="verdana,arial,courier new,georgia"
  • delimiters=",">
  •  
  • <option value="#strFont#"
  • <cfif (FORM.font EQ strFont)>
  • selected="true"
  • </cfif>
  • >#strFont#</option>
  • </cfloop>
  • </select>
  • </p>
  •  
  • <p>
  • <label>Size:</label>
  •  
  • <select name="size">
  • <cfloop
  • index="intSize"
  • from="8"
  • to="40"
  • step="1">
  •  
  • <option value="#intSize#"
  • <cfif (FORM.size EQ intSize)>
  • selected="true"
  • </cfif>
  • >#intSize#</option>
  • </cfloop>
  • </select>
  • </p>
  •  
  • <p>
  • <label>Align:</label>
  •  
  • <select name="text_align">
  • <cfloop
  • index="strAlign"
  • list="left,center,right"
  • delimiters=",">
  •  
  • <option value="#strAlign#"
  • <cfif (FORM.text_align EQ strAlign)>
  • selected="true"
  • </cfif>
  • >#strAlign#</option>
  • </cfloop>
  • </select>
  • </p>
  •  
  • <p>
  • <label>Line Height:</label>
  •  
  • <select name="line_height">
  • <cfloop
  • index="intHeight"
  • from="10"
  • to="50"
  • step="1">
  •  
  • <option value="#intHeight#"
  • <cfif (FORM.line_height EQ intHeight)>
  • selected="true"
  • </cfif>
  • >#intHeight#</option>
  • </cfloop>
  • </select>
  • </p>
  •  
  • <p>
  • <label>Text:</label>
  •  
  • <input type="text" name="text" value="#HtmlEditFormat( FORM.text )#" />
  • </p>
  •  
  • <p>
  • <label>Textarea Width:</label>
  •  
  • <select name="width">
  • <cfloop
  • index="intWidth"
  • list="100,200,300,400,500"
  • delimiters=",">
  •  
  • <option value="#intWidth#"
  • <cfif (FORM.width EQ intWidth)>
  • selected="true"
  • </cfif>
  • >#intWidth#</option>
  • </cfloop>
  • </select>
  • </p>
  •  
  • <p>
  • <button type="submit">
  • Generate Image &raquo;
  • </button>
  • </p>
  •  
  • </form>
  •  
  •  
  • <h2>
  • Rendered Image and Text Area
  • </h2>
  •  
  •  
  • <!--- Create a new canvas. --->
  • <cfset imgCanvas = ImageNew( "", 545, 350, "rgb" ) />
  •  
  • <!--- Set up the font attributes. --->
  • <cfset objAttributes = {
  • Font = FORM.font,
  • Size = FORM.size,
  • TextAlign = FORM.text_align,
  • LineHeight = FORM.line_height
  • } />
  •  
  • <!--- Turn on anti-aliasing for nicer rendering. --->
  • <cfset ImageSetAntialiasing(
  • imgCanvas,
  • "on"
  • ) />
  •  
  • <!--- Draw the text area on the image object. --->
  • <cfset ImageDrawTextArea(
  • imgCanvas,
  • FORM.text,
  • 50,
  • 50,
  • FORM.width,
  • objAttributes
  • ) />
  •  
  • <!--- Write the image to the browser. --->
  • <cfimage
  • action="writetobrowser"
  • source="#imgCanvas#"
  • />
  •  
  •  
  • </body>
  • </html>
  •  
  • </cfoutput>

Hopefully, this will make drawing text on a ColdFusion 8 image a whole lot easier.

Download Code Snippet ZIP File

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Reader Comments

Wow, I love it.

Posted by Ryan Stille on Sep 29, 2007 at 2:24 PM


@Ryan,

Thanks. It was a lot of fun to write.

Posted by Ben Nadel on Sep 29, 2007 at 6:12 PM


Excellent work, Ben, but I'd have to say I think you're thinking about this problem in the wrong way because of the difference between textarea and CFIMAGE. You can't make a UDF to wrap text onto a CFIMAGE in the same way a textarea does because a CFIMAGE doesn't have a scrollbar. If you enter 100 for the width on your demo and leave the default text there, you can't see most of the string because it goes below the image area.

Your solution will work for some situations, but you still have to do the work of picking the right font size for the area available. This will be hunky-dory in some situations with mainly static content but as soon as you have dynamic text, you may run into the problem with text vanishing outside the bounds of the CFIMAGE.

I'm working on a UDF where you pass a string, and have the function scale the font to fit inside the CFIMAGE area. I started this a while back and nearly got it working but ran out of time. I posted the code in a comment on Ray's blog, in a CFIMAGE related entry on 17/9 (I only remember that because it's the day before my birthday :p). I can't remember how much of it I got working but if it's of interest, go have a look. I might have some time this afternoon to actually finish it off!

Posted by George Bridgeman on Sep 30, 2007 at 7:10 AM


@George,

Interesting. I never thought of auto-scaling. It would be an interesting problem. You would have to have some conditional loop. See, you can't just figure out the font size once because each time to you adjust the font size, it will adjust the spacing between lines as well as the number of lines that need to be rendered. So, you'd have to kind of loop OVER the meat of my algorithm until the entire set of dimensions lines up nicely.

I will have to take a look at what you posted on Ray's blog.

Posted by Ben Nadel on Sep 30, 2007 at 1:20 PM


Oh, that´s great. This is what i need. Cause i search exatly this code for my own little project. Thanks for share it! Very usefully

Posted by Webdesign Agentur on Dec 29, 2007 at 1:52 PM


Very interesting article. I try to learn ColdFusion 8, because i think it would be nice for my next project to work with ColdFusion 8.... And now i search many informations about ColdFusion. Thanks for it ;)

Posted by Werbeagentur on Jan 23, 2008 at 7:29 AM


Great tips.

Posted by ana on May 6, 2008 at 3:30 PM


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