まずは、 Mac OS X Lion に brew で cairo をインストール。
インストール先が /usr/local/include や /usr/local/lib じゃないので注意。
$ brew install cairo
==> Installing cairo dependency: pixman
==> Downloading http://cairographics.org/releases/pixman-0.22.2.tar.gz
######################################################################## 100.0%
==> ./configure --prefix=/usr/local/Cellar/pixman/0.22.2 --enable-gtk=no
==> make install
/usr/local/Cellar/pixman/0.22.2: 9 files, 1.0M, built in 23 seconds
==> Installing cairo
==> Downloading http://www.cairographics.org/releases/cairo-1.10.2.tar.gz
######################################################################## 100.0%
==> ./configure --prefix=/usr/local/Cellar/cairo/1.10.2 --with-x
==> make install
==> Caveats
This formula is keg-only, so it was not symlinked into /usr/local.
Mac OS X already provides this program and installing another version in
parallel can cause all kinds of trouble.
The Cairo provided by Leopard is too old for newer software to link against.
Generally there are no consequences of this for you.
If you build your own software and it requires this formula, you'll need
to add its lib & include paths to your build variables:
LDFLAGS -L/usr/local/Cellar/cairo/1.10.2/lib
CPPFLAGS -I/usr/local/Cellar/cairo/1.10.2/include
==> Summary
/usr/local/Cellar/cairo/1.10.2: 91 files, 6.5M, built in 59 seconds
PNG画像を読み込んで縦横2倍の大きさに拡大して新しいファイルとして保存するサンプルコード。
#include <string>
#include <cairo/cairo.h>
int main(void){
double factor = 2.0;
// load image
std::string in_path = "input.png";
cairo_surface_t* in_surface;
in_surface = cairo_image_surface_create_from_png(in_path.c_str());
int in_width = cairo_image_surface_get_width(in_surface);
int in_height = cairo_image_surface_get_height(in_surface);
// create image surface
std::string path = "output.png";
int width = (int)(in_width * factor);
int height = (int)(in_height * factor);
cairo_surface_t* surface;
surface = cairo_image_surface_create(
CAIRO_FORMAT_ARGB32, width, height);
cairo_t* c = cairo_create(surface);
// draw image
cairo_scale(c, factor, factor);
cairo_set_source_surface(c, in_surface, 0.0, 0.0);
cairo_paint(c);
// save image
cairo_status_t status =
cairo_surface_write_to_png(surface, path.c_str());
// delete objects
cairo_destroy(c);
cairo_surface_destroy(surface);
cairo_surface_destroy(in_surface);
return 0;
}
cairo_scale でスケーリング処理をしている。
cairo_matrix_t と cairo_transform を使うともっといろんなアフィン変換が可能っぽい。
コンパイルして実行。
$ g++ -I/usr/local/Cellar/cairo/1.10.2/include -L/usr/local/Cellar/cairo/1.10.2/lib -lcairo ./cairo_scaling_image.cpp
$ ./a.out
入力画像:
出力画像:
Ref.
- cairographics.org
- Cairo: A Vector Graphics Library
tags: cairo c++ mac_os_x
Posted by NI-Lab. (@nilab)
