[rrd-users] alpha channel on rrdtool PNG vs. TCPDF (Solved)

[Livio Zanol Puppim]

I've used PNG files on TCPDF without any problem...

[]'s
Lívio Zanol Puppim

2008/6/29 Valter Douglas Lisbôa Jr. <douglas at trenix.com.br>:
> I solved it! So, I'm posting the solution for others with a similar problem
> (Some versions of IE appear can't be capable to handle a PNG with
> transparency).
>
> It's a snip of my PHP OO code.
>
> ---------------------- snip ----------------------
> // Creates a PDF with the graphs requireds.
> public function getPDF() {
>  try {
>    $pdf = new TCPDF();
>    $pdf->Open();
>
>    ... // A lot of boring PDF preparation code
>
>    // Temporary file
>    $png = tempnam("../tmp/", "graph");
>
>    // Calls the rrdtool command to generate the PNG
>    $this->getCPU($png, ... other parameters ...); //
>
>    // Load, Remove all alpha and save in a new file
>    $img =  ImageCreateFromPNG($png);
>    imageAlphaBlending($img, false);
>    imageSaveAlpha($img, false);
>    imagePNG($img, "$png.png");
>
>    // Load to PDF
>    $pdf->Image("$png.png", 30, 50);
>
>    // Remove all temporaries
>    unlink($png);
>    unlink("$png.png");
>
>    // Put PDF on screen
>    $pdf->Output();
>
>  } catch(Exception $err) {
>    throw new Exception('Graph Exception: ' . $err->getMessage());
>  }
> }
> ---------------------- snip ----------------------
>
> The tip is using imageAlphaBlending + imageSaveAlpha. The file size drops from
> 32KB to 21KB (better for me, I botter for PDF size ;-) ) and loads normally
> on TCPDF.
>
> Three hours of research before a I send the first post, more some minutes
> to "google" the solution after that! Never Give up! :-D
>
> If someone has another solution, it will be welcome.
>
> On Sunday 29 June 2008 12:39:09 Valter Douglas Lisbôa Jr. wrote:
>> Hello All!
>>
>> I'm new on this list, and this is my first post.
>>
>> Creating a System to load the graph generated in PNG format from rrdtool
>> with PHP 5, I was very sucefull. However, when I try to put it on a PDF
>> utilizing TCPDF 3.1.001 PHP class, I got a error.
>>
>> TCPDF error: Alpha channel not supported: file.png
>>
>> This class has a limitation from loading PNG with transparent colors, it's
>> a known bug not corrected yet, and this is the only format in common with
>> rrdtool. So, I try to remove the PNG's alpha channel by rrdtool, definning
>> every color with -c or in LINE/AREA/etc with the solid attribute (FF) on
>> the end of color. It wasn't exactly a success :-( the error continues.
>>
>> Then I "googling" for PHP functions to find a way to remove the alpha
>> channel, I already try to detect if exists a color with
>> imagecolortransparent(), with another failure (it returns -1).
>>
>> Going to the point! How can I generate with rrdtool 1.2.x a PNG without a
>> alpha channel? Or does anyone can point me the way to do this with another
>> software on-the-fly?
>>
>> Thanks in advance
>
> --
> Valter Douglas Lisbôa Jr.
> Sócio-Diretor
> Trenix - IT Solutions
> "Nossas Idéias, suas Soluções!"
> www.trenix.com.br
> contato at trenix.com.br
> Tel. +55 19 3402.2957
> Cel. +55 19 9183.4244
>
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>



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Lívio Zanol Puppim