學習 Evas

這陣子開始需要用 Evas 寫一些東西…
個人覺得學一個 library 最快的方法就是去真的拿它去寫程式。
如我的一個好友常說的：學中作，作中學 ^^
所以就寫了支小小的玩具… 和大家分享…


亂畫一個方塊，設定一個重力場，和一個 boundary反彈機制. ( 和一些阻泥 (mark 掉了)) 加上一個色彩空間的旋轉。就玩起來了 ^^

程式:

Filename: toy.c

#include <Ecore_Evas.h>
#include <Ecore.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#define WIDTH 400
#define HEIGHT 400

Ecore_Evas  *   ee;
Evas        *   evas;
Evas_Object *   base_rect;

double rotation[3][3] = { {0 , 0 , 1},
                          {1, 0, 0}, 
                          {0   , 1, 0}
};

struct bouncer {
        Evas_Object *o;
        int w,h;
        double xs,ys;
        double x,y;
        double color[3];
}; 

inline void change_color(struct bouncer *bounce) {
        double X[3];
        int i,j;
        int R,G,B;
        for (i=0;i<3;i++) {
                X[i]=bounce->color[i];
                bounce->color[i]=0;
        }
        for (i=0;i<3;i++) {
                for (j=0;j<3;j++) {
                        bounce->color[i] += rotation[i][j]*X[j];
                }
        }
        R=bounce->color[0] < 0 ? bounce->color[0] + 255: bounce->color[0];
        G=bounce->color[1] < 0 ? bounce->color[1] + 255: bounce->color[1];
        B=bounce->color[2] < 0 ? bounce->color[2] + 255: bounce->color[2];
        evas_object_color_set( bounce->o , R, G, B, 255);
}

inline void center(struct bouncer *bounce,double *x,double *y) {
        *x = bounce->x + bounce->w/2;
        *y = bounce->y + bounce->h/2;
}

inline void grav(struct bouncer *bounce) {
        const double G=300;
        double Gx,Gy,Gs;
        double x,y;
        double dist;
        center(bounce,&x,&y);

        dist = pow(pow(WIDTH/2-x,2) + pow(HEIGHT/2-y,2),0.5);
        Gs = G/pow(dist,2);
        Gx = (WIDTH/2 - x)/dist;
        Gy = (HEIGHT/2 -y)/dist;
        Gx = Gx * Gs;
        Gy = Gy * Gs;

        bounce->xs += Gx;
        bounce->ys += Gy;

        // Slow down~~
        //bounce->xs = abs(bounce->xs) > 13 ? bounce->xs *(1/ pow(bounce->xs-10,2)): bounce->xs;
        //bounce->ys = abs(bounce->ys) > 13 ? bounce->ys *(1/ pow(bounce->ys-10,2)): bounce->ys;
        printf ("x=%2.2f y=%2.2f dist=%4.2f Gs=%2.2f Gx=%2.2f Gy=%2.2f xs=%2.2f ys=%2.2f\n",x,y,dist,Gs,Gx,Gy,bounce->xs,bounce->ys);
}
inline void calculate_pos(struct bouncer *bounce) {
        grav(bounce);
        bounce->x += bounce->xs;
        bounce->y += bounce->ys;

        // bounce 
        bounce->xs = bounce->x >=0 ?  bounce->x + bounce->w <= WIDTH ? bounce->xs : -bounce->xs : -bounce->xs; 
        bounce->ys = bounce->y >=0 ? bounce->y + bounce->h <= HEIGHT? bounce->ys : - bounce->ys : - bounce->ys;
}

int move(void *data) {
        struct bouncer *bounce =(struct bouncer *)data;
        calculate_pos(bounce);
        evas_object_move(bounce->o,bounce->x,bounce->y);
        change_color(bounce);
        return 1;
}

int main() {
        struct bouncer bounce;
        ecore_evas_init();

        ee = ecore_evas_software_x11_new(NULL, 0,  0, 0, WIDTH, HEIGHT);
        ecore_evas_title_set(ee, "Tick's Evas Study");
//      ecore_evas_borderless_set(ee, 1);  // borderless
        ecore_evas_borderless_set(ee, 0);  // border
        ecore_evas_show(ee);


        evas = ecore_evas_get(ee);
        evas_font_path_append(evas, "fonts/");


        bounce.o = evas_object_rectangle_add(evas);
        bounce.w=bounce.h= (double)WIDTH/4;
        bounce.x=(double)(WIDTH - bounce.w)/3;
        bounce.y=(double)(HEIGHT-  bounce.h)/6;
        bounce.xs=-1.1; bounce.ys=1.1;
        bounce.color[0]=128;
        bounce.color[1]=64;
        bounce.color[2]=255;
        change_color(&bounce);
        evas_object_resize( bounce.o,  bounce.w,  bounce.h);
        evas_object_move( bounce.o,bounce.x,bounce.y);
        evas_object_show( bounce.o);

        ecore_timer_add((double)0.01,move,&bounce);

        ecore_main_loop_begin();

        return 0;
}