[cairo] cairo with loading PDF and related questions

[Fan Zhang]

Hello all,

I'm new to cairo, and was introduced to cairo because we thought it 
might be the solution for vector graphic library in our php project.
So here's a little detail of the setup:

1. using cairo 1.6.4 fc9. (we are running fedora core 9)
2. lampp installed with pear, that's how to get to install cairo_wrapper.
3. running php 5 and the project is developed in php 5.

And here's the scope and objective of the project
1. Able to generate text images (single or multiple lines), giving the 
text string, font size, font color, etc. (completed)
2. Able to display text images in PNG format in the browser. (completed 
with cairo_surface_show_png in cairo_wrapper)
3. Able to generate PDF file contain the vector graphics of the text 
image. (completed with cairo_text_path)
4. Able to load PDF file generated by Adobe Illustrator (assuming one 
vector graphic only), change the fill color of the content to solid or 
gradient color. (no solution yet)
5. Generate both PNG and PDF file after the modification of the PDF file 
in 4, display the PNG file similar to "show png". (no solution yet)
6. Able to generate a layered PDF file from different source (png, pdf, 
eps etc). (no solution yet)
7. Future support for loading AI file and construct a canvas editor 
similar to AI, with path editor and abstract drawings.

Our project is developed half way to the point where we don't know if 
the functions could be supported by cairo, or we have to find another 
solution.


For goal no.4, the original idea is to have vector shapes saved as pdf 
file and loaded into cairo, right now cairo wrapper does not support 
reading form pdf (cairo_pdf_surface_create_from_pdf, or something like 
that). We are going to develop in the way to allow user drawing the 
shape instead of loading it. But the question is: can cairo support 
loading from pdf? Since it could generate a vector format (with path) 
pdf, is loading it back in and change the color too difficult?

For goal no.5, how to generate PNG from PDF surface? Maybe "how to load 
PDF as PNG"? Because I think to convert between PNG and PDF is not the 
case of cairo.

For goal no.6, The final PDF generated will be from texts and shapes 
previously output from cairo, I understand cairo is not a PDF generator, 
but is it possible to have layered context in cairo?

All this comes to text->path->png->pdf->more text->transform text->load 
shape->change color->transform shape->generate PNG for proof->generate 
PDF for printing and editing.

We've tried GD, Imagicks, and now cairo. We don't know whether any one 
of these libraries can help or several of them, even to write our own 
libraries?

Please help, we don't want to end up switch it to a .net project as this 
will cost too much. We can only stay with php.

Fan