alpha channel on rrdtool PNG vs. TCPDF

[Valter Douglas Lisbôa Jr.]

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@...
Tel. [phone]
Cel. +55 19 9183.4244

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[Valter Douglas Lisbôa Jr.]

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@...
Tel. [phone]
Cel. +55 19 9183.4244

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rrd-users mailing list
rrd-users@...
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[Livio Zanol]

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

[]'s
Lívio Zanol Puppim

2008/6/29 Valter Douglas Lisbôa Jr. <douglas@...>:

> 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@...
> Tel. [phone]
> Cel. +55 19 9183.4244
>
> _______________________________________________
> rrd-users mailing list
> rrd-users@...
> https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
>

--
[]'s

Lívio Zanol Puppim

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[Valter Douglas Lisbôa Jr.]

Strange! What's the rrdtool/TCPDF version you use? All images generates by my
rrd caused the sames error, and only work with that code I post.

On Monday 30 June 2008 12:49:18 Livio Zanol Puppim wrote:
> I've used PNG files on TCPDF without any problem...
>
> []'s
> Lívio Zanol Puppim
>
--
Valter Douglas Lisbôa Jr.
Sócio-Diretor
Trenix - IT Solutions
"Nossas Idéias, suas Soluções!"
www.trenix.com.br
contato@...
Tel. [phone]
Cel. +55 19 9183.4244

_______________________________________________
rrd-users mailing list
rrd-users@...
https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users