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Re: Free Hand Drawing in FLTK
You can do free hand drawing using openGL if you wish, or you can use the fltk drawing functions.
For both openGL and fltk, I can think of two approaches.
1) You can store data for each of the shapes or lines or points the user draws.
2) You could just allow the user to click on the screen to change the color of the pixel where the user clicks.
I attach a few examples:
freedraw1 (uses opengL and method 1)
freedraw11.cpp (uses openGL and method 2)
freedraw2.cpp (uses fltk drawing functions and method 1)
freedraw21 (uses fltk drawing functions and method 2)
--freedraw1-
#include <FL/Fl.h>
#include <FL/Fl_Gl_Window.h>
#include <FL/gl.h>
struct point {
point(){x=0;y=0;}
int x;
int y;
};
class glwin : public Fl_Gl_Window {
public:
glwin(int x,int y,int w,int h,const char *lab=0):Fl_Gl_Window(x,y,w,h,lab){
index=0;
}
int handle(int event){
if(event==FL_PUSH){
return 1;
}
if(event==FL_DRAG){
points[index].x=Fl::event_x();
points[index].y=h()-Fl::event_y();
if(index<99)
index++;
else
index=0;
redraw();
}//drag
return Fl_Gl_Window::handle(event);
}
void draw(void){
glLoadIdentity();
glViewport(0,0,w(),h());
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0,w(),0,h(),-1,1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClearColor(1.0,1.0,1.0,1.0);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glBegin(GL_LINE_STRIP);
gl_color(FL_BLACK);
for(int i=0;i<100;i++)
glVertex2i(points[i].x,points[i].y);
glEnd();
}
int index;
point points[100];
};
int main(void){
glwin g1(0,0,300,300);
g1.show();
return Fl::run();
}//int main
--freedraw11--
#include <FL/Fl.h>
#include <FL/Fl_Gl_Window.h>
#include <FL/gl.h>
struct point {
point(){x=0;y=0;}
int x;
int y;
};
class glwin : public Fl_Gl_Window {
public:
glwin(int x,int y,int w,int h,const char *lab=0):Fl_Gl_Window(x,y,w,h,lab){
index=0;
for(int i=0;i<300;i++)
for(int j=0;j<300;j++)
points[i][j]=FL_BLACK;
}
int handle(int event){
if(event==FL_PUSH){
return 1;
}
if(event==FL_DRAG){
int x=Fl::event_x();
int y=h()-Fl::event_y();
points[x][y]==FL_BLACK ? points[x][y]=FL_WHITE : points[x][y]=FL_BLACK;
redraw();
}//drag
return Fl_Gl_Window::handle(event);
}
void draw(void){
glLoadIdentity();
glViewport(0,0,w(),h());
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0,w(),0,h(),-1,1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClearColor(1.0,1.0,1.0,1.0);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glBegin(GL_POINTS);
for(int i=0;i<300;i++)
for(int j=0;j<300;j++){
gl_color(points[i][j]);
glVertex2i(i,j);
}
glEnd();
}
int index;
Fl_Color points[300][300];
};
int main(void){
glwin g1(0,0,300,300);
g1.show();
return Fl::run();
}//int main
--freedraw2--
#include <FL/Fl.h>
#include <Fl/Fl_Window.h>
#include <Fl/fl_draw.h>
struct point {
point(){x=0;y=0;}
int x;
int y;
};
class canvas : public Fl_Window {
public:
canvas(int x,int y,int w,int h,const char *lab=0) : Fl_Window(x,y,w,h,lab){
index=0;
end();
}
int handle(int event){
if(event==FL_PUSH){
return 1;
}
if(event==FL_DRAG){
points[index].x=Fl::event_x();
points[index].y=Fl::event_y();
if(index<99)
index++;
else
index=0;
redraw();
}//drag
}//handle
void draw(void){
Fl_Window::draw();
fl_color(FL_BLACK);
for(int i=0;i<99;i++)
fl_line(points[i].x,points[i].y,points[i+1].x,points[i+1].y);
}//draw
int index;
point points[100];
};
int main(void){
canvas c(0,0,300,300);
c.show();
return Fl::run();
}
--freedraw21--
#include <FL/Fl.h>
#include <Fl/Fl_Window.h>
#include <Fl/Fl_Double_Window.h>
#include <Fl/fl_draw.h>
struct point {
point(){x=0;y=0;}
int x;
int y;
};
class canvas : public Fl_Double_Window {
public:
canvas(int x,int y,int w,int h,const char *lab=0) : Fl_Double_Window(x,y,w,h,lab){
index=0;
for(int i=0;i<300;i++)
for(int j=0;j<300;j++)
points[i][j]=FL_BLACK;
end();
}
int handle(int event){
if(event==FL_PUSH){
return 1;
}
if(event==FL_DRAG){
int x=Fl::event_x();
int y=Fl::event_y();
points[x][y]==FL_BLACK ? points[x][y]=FL_WHITE : points[x][y]=FL_BLACK;
redraw();
}//drag
return Fl_Double_Window::handle(event);
}
void draw(void){
Fl_Double_Window::draw();
fl_color(FL_BLACK);
for(int i=0;i<300;i++)
for(int j=0;j<300;j++)
fl_color(points[i][j]),fl_point(i,j);
}
Fl_Color points[300][300];
};
int main(void){
canvas c(0,0,300,300);
c.show();
return Fl::run();
}
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24-Aug-2007, 05:27
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