C++ fltk — Theming (Flutter)
Date: 2021-08-04Last modified: 2024-02-26
Table of contents
#include <FL/Enumerations.H>
#include <FL/Fl.H>
#include <FL/Fl_Box.H>
#include <FL/Fl_Button.H>
#include <FL/Fl_Window.H>
#include <FL/fl_draw.H>
#include <functional>
#include <iostream>
#define WIDTH 600
#define HEIGHT 400
#define BLUE fl_rgb_color(0x42, 0xA5, 0xF5)
#define SEL_BLUE fl_rgb_color(0x21, 0x96, 0xF3)
#define GRAY fl_rgb_color(0x75, 0x75, 0x75)
#define LIGHT_GRAY fl_rgb_color(211, 211, 211)
using cb_t = std::function<void(Fl_Widget *)>;
class MyBox : public Fl_Box {
public:
MyBox(int x, int y, int w, int h, const char *title = NULL)
: Fl_Box(x, y, w, h, title) {}
virtual void draw() override {
fl_rectf(0, h(), w(), 3, LIGHT_GRAY);
Fl_Box::draw();
}
};
template <typename T>
class WidgetWrapper : public T {
cb_t func_ = NULL;
public:
WidgetWrapper(int x, int y, int w, int h, const char *title = NULL)
: T(x, y, w, h, title) {}
void set_cb(cb_t &&func) {
func_ = func;
auto cb = [](Fl_Widget *w, void *data) {
auto fn = *static_cast<cb_t *>(data);
fn(w);
};
this->callback(cb, &func_);
}
};
int main() {
auto win = new Fl_Window(WIDTH, HEIGHT, "Flutter-like");
auto bar = new WidgetWrapper<MyBox>(0, 0, WIDTH, 60, " FLTK APP");
bar->align(FL_ALIGN_LEFT | FL_ALIGN_INSIDE);
auto txt = new WidgetWrapper<Fl_Box>(
250, 180, 100, 40, "You have pushed the button this many times:");
auto count = new WidgetWrapper<Fl_Box>(txt->x(), txt->y() + 40, 100, 40, "0");
auto but = new WidgetWrapper<Fl_Button>(WIDTH - 100, HEIGHT - 100, 60, 60,
"@+6plus");
win->end();
win->show();
// theming
Fl::background(255, 255, 255);
Fl::visible_focus(false);
bar->box(FL_FLAT_BOX);
bar->labelsize(22);
bar->labelcolor(FL_WHITE);
bar->color(BLUE);
txt->labelsize(18);
txt->labelfont(FL_TIMES);
count->labelsize(36);
count->labelcolor(GRAY);
but->color(BLUE);
but->selection_color(SEL_BLUE);
but->labelcolor(FL_WHITE);
but->box(FL_OFLAT_BOX);
// end theming
but->set_cb([=]([[maybe_unused]] Fl_Widget *b) {
std::cout << "Lambda callback called" << std::endl;
auto label = atoi(count->label());
label += 1;
char buf[12];
(void)snprintf(buf, 12, "%d", label);
count->copy_label(buf);
});
return Fl::run();
}
Possible output
Lambda callback called
Lambda callback called
Lambda callback called