利用linux gtk模擬運動小球的軌跡

1、 背景說明利用linux gtk編寫c/c+程序，模擬小球在sin/cos曲線上進行運動的軌跡。 源碼/* * cairo.cpp * * Created on: Jan 5, 2011 * Author: sjetlin */#include <gtk/gtk.h>#include <math.h>#include <stdio.h>/-double sin_start_x = 0;/sin水平坐標系原點x坐標double cos_start_x = 0;double sin_start_y = 75;double cos_start_y = 225;do

2、uble sin_ball_x = 0;/sin小球圓心坐標double cos_ball_x = 0;/-double sin_ball_speed_rad;/sin小球每次移動的弧度double cos_ball_speed_rad;double round_time;/sin和cos曲線周期，單位是M_PI/-double amplitude = 50;/曲線振幅double width;/水平坐標系包含的像素點，設置與窗口寬度相等double width_rad = 8 * M_PI;/水平坐標系表示的弧度，默認為8M_PI/-void clicked(GtkWidget *widge

3、t, GdkEventExpose *event, gpointer data);void sin_wave(cairo_t *cr);/畫sin曲線void cos_wave(cairo_t *cr);/畫sin小球void sin_ball(cairo_t *cr);/畫cos曲線void cos_ball(cairo_t *cr);/畫cos小球/-/static gboolean on_expose_event(GtkWidget *widget,GdkEventExpose *event,gpointer data)void clicked(GtkWidget *widget, Gd

4、kEventExpose *event, gpointer data)cairo_t* cr = (cairo_t*)data;width = widget->allocation.width;while (sin_ball_x <= width | cos_ball_x <= width) /當兩個小球都在運動時改變畫布內(nèi)容cairo_set_source_rgb(cr, 255, 255, 255);cairo_rectangle(cr, 0, 0, 400, 300);cairo_fill (cr);/清空畫布cairo_set_source_rgb(cr, 255,

5、0, 0);/設置畫筆為紅色cairo_set_line_width(cr, 0.7);/設置畫筆寬度sin_wave(cr);sin_ball(cr);cos_wave(cr);cos_ball(cr);cairo_stroke(cr);g_usleep(0.5 * 1000000);/暫停0.5秒void sin_wave(cairo_t *cr)cairo_move_to(cr, sin_start_x, sin_start_y);cairo_line_to(cr, width, sin_start_y);/畫sin水平坐標系cairo_select_font_face(cr, &quo

6、t;Georgis", CAIRO_FONT_SLANT_NORMAL,CAIRO_FONT_WEIGHT_BOLD);cairo_set_font_size(cr, 12);cairo_move_to(cr, sin_start_x, sin_start_y);cairo_show_text(cr, "0");cairo_move_to(cr, sin_start_x + width - 30, sin_start_y);cairo_show_text(cr, "8 PI");cairo_move_to(cr, sin_start_x, si

7、n_start_y);/曲線起點double x = sin_start_x;double inc_x = 1;while (x <= width)double next_x = x + inc_x;cairo_line_to(cr, x + inc_x, sin_start_y - amplitude * sin(2* width_rad * next_x / round_time / width);x = x + inc_x;void cos_wave(cairo_t *cr)cairo_move_to(cr, cos_start_x, cos_start_y);cairo_line

8、_to(cr, width, cos_start_y);/畫cos水平坐標系cairo_select_font_face(cr, "Georgis", CAIRO_FONT_SLANT_NORMAL,CAIRO_FONT_WEIGHT_BOLD);cairo_set_font_size(cr, 12);cairo_move_to(cr, cos_start_x, cos_start_y);cairo_show_text(cr, "0");cairo_move_to(cr, cos_start_x + width - 30, cos_start_y);ca

9、iro_show_text(cr, "8 PI");cairo_move_to(cr, cos_start_x, cos_start_y - 50);/曲線起點double x = cos_start_x;double inc_x = 1;while (x <= width)double next_x = x + inc_x;cairo_line_to(cr, next_x, cos_start_y - amplitude * cos(2 * width_rad* next_x / round_time / width);x = x + inc_x;void sin_

10、ball(cairo_t *cr)if (sin_ball_x <= width)double sin_ball_radius = 10;double sin_ball_y = sin_start_y - amplitude * sin(2 * width_rad* sin_ball_x / round_time / width);cairo_move_to(cr, sin_ball_x + sin_ball_radius, sin_ball_y);cairo_arc(cr, sin_ball_x, sin_ball_y, sin_ball_radius, 0, 2 * M_PI);si

11、n_ball_x = sin_ball_x + sin_ball_speed_rad *M_PI*width/ width_rad;void cos_ball(cairo_t *cr)if (cos_ball_x <= width)double cos_ball_radius = 10;double cos_ball_y = cos_start_y - amplitude * cos(2 * width_rad* cos_ball_x / round_time / width);cairo_move_to(cr, cos_ball_x + cos_ball_radius, cos_bal

12、l_y);cairo_arc(cr, cos_ball_x, cos_ball_y, cos_ball_radius, 0, 2 * M_PI);cos_ball_x = cos_ball_x + cos_ball_speed_rad *M_PI*width/ width_rad;int main(int argc, char *argv)printf("請輸入一個實數(shù)，代表曲線周期，單位是PI n");scanf("%lf", &round_time);printf("請輸入一個實數(shù)，代表第一個小球移動的弧度,單位是PI n"

13、;);scanf("%lf", &sin_ball_speed_rad);printf("請輸入一個實數(shù)，代表第二個小球移動的弧度,單位是PI n");scanf("%lf", &cos_ball_speed_rad);printf("n已生成窗口，點擊窗口中的空白區(qū)域即可查看動畫nn");gtk_init(&argc, &argv);GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);gtk_window_set_titl

14、e(GTK_WINDOW(window), "sin cos && ball");gtk_window_set_default_size(GTK_WINDOW(window), 400, 300);gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);gtk_widget_set_app_paintable(window, TRUE);gtk_widget_show_all(window);cairo_t *cr = gdk_cairo_create(window->window

15、);/創(chuàng)建畫布gtk_widget_add_events(window,GDK_BUTTON_PRESS_MASK);g_signal_connect(window, "button-press-event", G_CALLBACK(clicked), cr);/注冊點擊事件g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);gtk_main();return 0;源碼說明1. 編程和編譯環(huán)境：Linux + Eclipse + CDT，文件名sport.c，可執(zhí)行文件

16、sport2. 程序運行時需輸入3個變量，分別是曲線周期、sin小球運動速度、cos小球運動速度3. 程序的設計思想是先創(chuàng)建一塊畫布，畫布的內(nèi)容在小球運動時動態(tài)改變，直至兩小球都運動到終點時停止。4. 小球運動時畫布改變順序如下： 先用一塊白布將畫布上的所有內(nèi)容抹掉 用一根紅筆畫出sin曲線、cos曲線、sin小球、cos小球5. 當畫布上的內(nèi)容更新一次時暫停0.5秒，時間到時重復4的步驟，此時曲線不變，小球的圓心改變。6. 畫sin曲線時先畫出x軸，標出起終點的水平坐標（08PI），該曲線眾多的點和小線段組成，點是經(jīng)過精確計算的在sin曲線上的點，而線段則由這些點連接起來，并最終匯總成為一條曲線。7. 畫移動的小球時，小球每次移動的弧度由鍵盤輸入，將該弧度轉(zhuǎn)換為轉(zhuǎn)化水平像素點，再加上上一個圓心的x坐標，即可確定出目前小球圓心所在的x坐標，取該x坐標對應于曲線上的一點作為小球的圓心。運行截圖1. 進入文件目錄2. 編譯3. 執(zhí)行 首先，程序會給出輸入提示信息，輸入相應信息