tamasszekeres / cairo-cr Goto Github PK

It would be nice to have some examples using just Cairo without neccessarily using an x11 surface.
For example using the available svg or pdf surfaces for pdf/svg creation.

Make crystal classes to use cairo oo-style.

Example:

my_surface.draw do |ctx|
  ctx.rectangle(0, 0, 20, 10)
  ctx.fill
  # or directly: ctx.rectangle(0, 0, 20, 10).fill
end

I'm trying to draw the same surface as in the high-level x11 window example using the code below.
While I can create a nice png image with

surface.write_to_png "test.png"

... I can't find a way to write it to svg. There doesn't seem to be a write_to_svg ..?
When I run the code below, however, an empty "test.svg" is written

require "cairo"

module SvgCreation
  include Cairo

  def self.main
    surface = Cairo::SvgSurface.new "test.svg", 400, 300
    # surface.restrict_to_version Cairo::SvgVersion::V_1_2
    context = Cairo::Context.new surface


    context.set_source_rgba 1.0, 0.0, 1.0, 1.0
    context.rectangle 0.0, 0.0, 400.0, 300.0
    context.fill

    context.set_source_rgb 0.0, 0.0, 0.0
    context.move_to 0.0, 0.0
    context.line_to 400.0, 300.0
    context.move_to 400.0, 0.0
    context.line_to 0.0, 300.0
    context.line_width = 10.0
    context.stroke

    context.rectangle 0.0, 0.0, 200.0, 150.0
    context.set_source_rgba 1.0, 0.0, 0.0, 0.80
    context.fill

    context.rectangle 0.0, 150.0, 200.0, 150.0
    context.set_source_rgba 0.0, 1.0, 0.0, 0.60
    context.fill

    context.rectangle 200.0, 0.0, 200.0, 150.0
    context.set_source_rgba 0.0, 0.0, 1.0, 0.40
    context.fill

    # surface.write_to_png "test.png"
  end

  main
end

Is there a close/destroy/save method or something that I'm missing?

Add Glyphs class which encapsulates more PGlyphT pointers in an array.

I'm trying to access the raw png data of the surface without calling surface.write_to_png(<filename>).

current code:

require "cairo"

at_exit do
  GC.collect
end

surface = Cairo::Surface.new Cairo::Format::ARGB32, 400, 300
ctx = Cairo::Context.new surface

ctx.set_source_rgba 1.0, 0.0, 1.0, 1.0
ctx.rectangle 0.0, 0.0, 400.0, 300.0
ctx.fill

# ...
# somehow call surface.write_to_png_stream to access png data without writing to disk...
# ...

surface.finish

I don't quite understand how to use the implemented version:

def write_to_png_stream(write_func : LibCairo::WriteFuncT, closure : Void*) : Status
  Status.new(LibCairo.surface_write_to_png_stream(@surface, write_func, closure).value)
end

Error in cairo_tst.cr:42: instantiating 'Cairo::Context#font_face()'

ff = context.font_face
^~~~~~~~~

in lib/cairo/src/cairo/context.cr:472: wrong number of arguments for 'Cairo::C::LibCairo#get_font_face' (given 2, expected 1)

  LibCairo.get_font_face(@cairo, font_face.to_unsafe)
           ^~~~~~~~~~~~~

Fix

def font_face : FontFace
  #font_face = FontFace.new
  #LibCairo.get_font_face(@cairo, font_face.to_unsafe)
  #font_face
  font_face = LibCairo.get_font_face(@cairo)
  FontFace.new(font_face)
end

Steps to Reproduce

• Delete shard.lock and lib/ folder
• Add the provided dependency from the README

# shard.yml
# ...

dependencies:
  x11:
    github: TamasSzekeres/x11-cr

  cairo:
    github: TamasSzekeres/cairo-cr

• Then, upon executing shards install, I got:

Resolving dependencies
Fetching https://github.com/TamasSzekeres/x11-cr.git
Fetching https://github.com/TamasSzekeres/cairo-cr.git
Unable to satisfy the following requirements:

- `x11 (*)` required by `shard.yml`
- `x11 (branch master)` required by `cairo 0.3.0`
Failed to resolve dependencies

Solution

By commenting out cairo and running shards install with only the x11 dependency, and then uncommenting the cairo line and running shards install again, everything installed correctly.

dependencies:
  x11:
    github: TamasSzekeres/x11-cr

#  cairo:
#    github: TamasSzekeres/cairo-cr

Disclaimer

I'm very new to the crystal language and eco-system, so this might not be an issue with this repository specifically, but just thought I'd point it out anyway.

I was reading the source for different methods to explore and decided to try some at random.
When calling get_type on the SvgSurface i go the following error:

In lib/cairo/src/cairo/surface.cr:141:20

 141 | def get_type : SurfaceType
                      ^
Error: undefined constant SurfaceType

Did you mean 'SurfaceTypeT'?

require "cairo"

module SvgCreation
  include Cairo

  def self.main
    surface = Cairo::SvgSurface.new "test.svg", 400, 400
    context = Cairo::Context.new surface

    # context.set_source(surface)

    context.rectangle 0.0, 0.0, 200.0, 150.0
    context.set_source_rgb 0.0, 10.0, 0.0
    context.fill

    puts surface.get_type
  end

  main
end

By editing the implementation on line 141 in surface.cr from

def get_type : SurfaceType
      SurfaceType.new(LibCairo.surface_get_type(@surface).value)
end

to

def get_type : SurfaceTypeT
      SurfaceTypeT.new(LibCairo.surface_get_type(@surface).value)
end

the error disappears and "SVG" is printed as expected.

Add TextClusters class which encapsulates more TextClusterT structures in an array.

Upon simply running crystal test.cr
where test.cr is:

require "cairo"

puts "Hello, World!"

I get the following error:

In lib/cairo/src/cairo/c/lib_cairo.cr:60:7

 60 | SUCCESS = 0,
      ^
Error: expecting ';', 'end' or newline after enum member

In my shard.yml:

dependencies:
  x11:
    github: TamasSzekeres/x11-cr
    branch: master
  cairo:
    github: TamasSzekeres/cairo-cr
    branch: master

Error:

$ crystal deps
Updating https://github.com/TamasSzekeres/x11-cr.git
Updating https://github.com/TamasSzekeres/cairo-cr.git
Error resolving x11 (*, 0.2.1)

Note that using branch: high-level under cairo: allows it to install just fine