Good day!
This week I published an article where I gave a brief description of the main methods of the CImg library and analyzed the simplest example. Frankly, the post was intended to invite, but nevertheless, I tried to make it as informative as possible. As a matter of fact, as it was planned earlier and considering the wish of skor , I decided to try to write an elementary screensaver using CImg . It became interesting - welcome under the cat!

Foreword

Immediately make a reservation, the program does not pretend to the "title" of a full screen saver. The goal was to try to disassemble a more complex example of using the above library.

Code

//  CImg #include "CImg.h" //   #define PI 3.14 //     std  cimg_library      using namespace cimg_library; using namespace std; //    int main (int argc, char **argv){ //  ,     //  - , ,   ,     //      CImg<float> logo, logo_layer_1 = CImg<>(800,600,1,1,0); //     //      "Welcome to CImg simple screensaver" logo_layer_1.draw_text(120,5,"Welcome to", CImg<>::vector(255).data(),CImg<>::vector(0).data(),1,128); logo_layer_1.draw_text(300,140,"CImg", CImg<>::vector(255).data(),CImg<>::vector(0).data(),1,128); logo_layer_1.draw_text(250,285, "simple", CImg<>::vector(255).data(),CImg<>::vector(0).data(),1,128); logo_layer_1.draw_text(120,425,"screensaver!", CImg<>::vector(255).data(),CImg<>::vector(0).data(),1,128); //     logo_layer_1.blur(6); //   logo_layer_1.normalize(0,255); //     CImg<float> logo_layer_2 = CImg<>(logo_layer_1.width(),logo_layer_1.height(),1,1,0); //      logo_layer_2.noise(80,1); //       2 logo_layer_2.deriche(2,0,'y',false); //      10 logo_layer_2.deriche(10,0,'x',false); //         logo logo = logo_layer_1 + logo_layer_2 + logo_layer_1; //      //  ,    ,     get_gradient(), //    "Compute the list of images, corresponding to the XY-gradients of an image" // -  "  ,  XY- " //    CimgList //    ,          CImgList<float> grad = logo.get_gradient(); //      normalize   (-140,140) cimglist_apply(grad,normalize)(-140,140); //    logo logo.normalize(0,255); //  ,   ,     "", //  ,       logo CImg<float> light = CImg<>(300 + 2*logo.width(),300 + 2*logo.height()); //       light.draw_gaussian(0.5f*light.width(),0.5f*light.height(),80,CImg<>::vector(255).data()); //    CImg<unsigned char> img(logo.width(),logo.height(),1,3,0); //  ,      CImgDisplay disp(img," ",true); //     disp.toggle_fullscreen(false); float t = 0; //  ,     'ESC'  'Q' while (!disp.is_closed() && !disp.is_keyQ() && !disp.is_keyESC()) { int pos_x, pos_y, gx, gy; float val; //      pos_x = (int)(img.width()/2 + img.width()*cos(1*t)/2); pos_y = (int)(img.height()/2 + img.height()*sin(3*t)/2); // cimg_forXY -   ,     //  - http://cimg.sourceforge.net/reference/group__cimg__loops.html cimg_forXY(img,x,y) { //   ,         gx = (int)grad[0](x,y); gy = (int)grad[1](x,y); val = 20 + (gx + gy)/2 + light(light.width()/2 + pos_x - x + gx,light.height()/2 + pos_y - y + gy); img(x,y,0) = img(x,y,1) = img(x,y,2) = (unsigned char)(val>255?255:val<0?0:val); } t = t >= 2*PI ? 0 : t+0.02f; //     disp.display(img.draw_image(0,0,0,1,logo,0.1f)); } return 0; } 

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Observations

In my opinion, the conclusions are not very comforting.

Of the minuses:

• compiles for a long time;
• spends up to 90% of CPU time;
• not fast animation;

Of the benefits:

probably only one can be distinguished:

• CImg is a good tool for “lazy” programming: a simple, intuitive interface of classes, a fairly voluminous functionality (many different filters, etc.). You can very quickly write an application, which unfortunately will not be easy enough and productive.

findings

At this stage in my study of CImg, I want to allow myself to notice that CImg is not quite suitable for creating dynamic scenes. However, as long as there is a desire to continue the study, in the next article we will try to “chew” a complex example for working with statics together with you.
Waiting for comments and suggestions.
Thank you for attention!

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PS Tested only under Linux