commit 1b5357248039af13e8019bc3a447f3c64285d012
Author: hippoz <paperplanelive@gmail.com>
Date:   Sat Jan 22 17:51:54 2022 +0200

    Initial commit.
    
    This commit adds some basic components.
    Currently, there is an issue with the drawing order of the text.

diff --git a/meson.build b/meson.build
new file mode 100644
index 0000000..0c58a1c
--- /dev/null
+++ b/meson.build
@@ -0,0 +1,8 @@
+project('blit', 'cpp')
+
+
+cairomm_dep = dependency('cairomm-1.0')
+pangocairo_dep = dependency('pangocairo')
+xlib_dep = dependency('x11')
+
+executable('blit_app', './src/main.cpp', dependencies : [cairomm_dep, xlib_dep, pangocairo_dep])
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
new file mode 100644
index 0000000..0ff8d19
--- /dev/null
+++ b/src/main.cpp
@@ -0,0 +1,342 @@
+#include <string>
+#include <vector>
+#include <iostream>
+#include <cairomm-1.0/cairomm/xlib_surface.h>
+#include <cairomm-1.0/cairomm/context.h>
+#include <cairomm-1.0/cairomm/surface.h>
+#include <pango/pangocairo.h>
+
+
+void panic(int exit_code, const char *message) {
+    fputs(message, stderr);
+    exit(exit_code);
+}
+
+namespace Blit {
+
+bool collide_point_rect(double x, double y, double w, double h, double x1, double y1) {
+    return x1 >= x && x + w >= x1 &&
+        y1 >= y && y + h >= y1;
+}
+
+
+enum TextAlign {
+    TEXT_ALIGN_NONE,
+    TEXT_ALIGN_CENTER_LEFT,
+    TEXT_ALIGN_CENTER
+};
+
+
+class RGB {
+public:
+    double r, g, b;
+public:
+    RGB(double r, double g, double b) : r(r), g(g), b(b) {
+
+    }
+};
+
+
+class BaseElement {
+public:
+    BaseElement() {}
+    virtual ~BaseElement() {}
+
+    bool should_get_x_events = true;
+    virtual void draw() = 0;
+    virtual void handle_event(XEvent *e) = 0;
+};
+
+
+class Window {
+public:
+    Cairo::RefPtr<Cairo::Context> cr;
+    Display *dsp;
+private:
+    std::vector<Blit::BaseElement *> m_attached_elements;
+public:
+    Window(int x, int y)
+    {
+        Drawable da;
+        int screen;
+
+        if ((dsp = XOpenDisplay(NULL)) == NULL)
+            panic(1, "Failed to open display");
+
+        screen = DefaultScreen(dsp);
+        da = XCreateSimpleWindow(dsp, DefaultRootWindow(dsp), 0, 0, x, y, 0, 0, 0);
+        XSelectInput(dsp, da, ButtonPressMask | ButtonReleaseMask | KeyPressMask | PointerMotionMask);
+        XMapWindow(dsp, da);
+
+        auto x_surface = Cairo::XlibSurface::create(
+            dsp,
+            da,
+            DefaultVisual(dsp, screen),
+            x,
+            y
+        );
+        cr = Cairo::Context::create(x_surface);
+    }
+
+    void attach_element_init(Blit::BaseElement *element) {
+        m_attached_elements.push_back(element);
+    }
+
+    void attach_element(Blit::BaseElement *element) {
+        m_attached_elements.push_back(element);
+        element->draw();
+    }
+
+    void redraw_all() {
+        for (Blit::BaseElement * element : m_attached_elements) {
+            element->draw();
+        }
+    }
+
+    void handle_x_event(XEvent *e) {
+        for (Blit::BaseElement * element : m_attached_elements) {
+            if (element->should_get_x_events)
+                element->handle_event(e);
+        }
+    }
+};
+
+
+class Text : public BaseElement {
+public:
+    PangoFontDescription *font_description;
+    bool should_get_x_events = false;
+    Blit::TextAlign text_align = Blit::TextAlign::TEXT_ALIGN_NONE;
+    double x, y, box_x, box_y, box_w, box_h = 0;
+    std::string text;
+    Blit::RGB fg;
+
+    Cairo::RefPtr<Cairo::Context> cr;
+public:
+    Text(Cairo::RefPtr<Cairo::Context> cr, std::string& text, PangoFontDescription *font_description) :
+        cr(cr),
+        text(text),
+        font_description(font_description),
+        fg(0.0, 0.0, 0.0)
+    {}
+
+    virtual ~Text() {}
+
+    void draw() {
+        cr->save();
+        cr->set_source_rgb(fg.r, fg.g, fg.b);
+
+        if (text_align == Blit::TextAlign::TEXT_ALIGN_NONE) {
+            PangoLayout *layout = pango_cairo_create_layout(cr->cobj());
+            pango_layout_set_font_description(layout, font_description);
+            pango_layout_set_text(layout, text.c_str(), -1);
+            cr->move_to(x, y);
+            pango_cairo_show_layout(cr->cobj(), layout);
+            g_object_unref(layout);
+        } else if (text_align == Blit::TextAlign::TEXT_ALIGN_CENTER_LEFT) {
+            PangoLayout *layout = pango_cairo_create_layout(cr->cobj());
+            int font_width;
+            int font_height;
+
+            pango_layout_set_font_description(layout, font_description);
+            pango_layout_set_text(layout, text.c_str(), -1);
+            pango_layout_get_pixel_size(layout, &font_width, &font_height);
+
+            double x = box_x + ((box_w - font_width) / 2);
+            double y = box_y + ((box_h - font_height) / 2);
+
+            // TODO: unhardcode the padding
+            x = box_x + 4;
+
+            cr->move_to(x, y);
+            pango_cairo_show_layout(cr->cobj(), layout);
+            g_object_unref(layout);
+        } else if (text_align == Blit::TextAlign::TEXT_ALIGN_CENTER) {
+            PangoLayout *layout = pango_cairo_create_layout(cr->cobj());
+            int font_width;
+            int font_height;
+
+            pango_layout_set_font_description(layout, font_description);
+            pango_layout_set_text(layout, text.c_str(), -1);
+            pango_layout_get_pixel_size(layout, &font_width, &font_height);
+
+            double x = box_x + ((box_w - font_width) / 2);
+            double y = box_y + ((box_h - font_height) / 2);
+
+            cr->move_to(x, y);
+            pango_cairo_show_layout(cr->cobj(), layout);
+            g_object_unref(layout);
+        }
+
+        cr->fill();
+        cr->restore();
+    }
+
+    void handle_event(XEvent *e) {}
+
+    void set_x(double val) {
+        x = val;
+        draw();
+    }
+    void set_y(double val) {
+        y = val;
+        draw();
+    }
+    void set_box_x(double val) {
+        box_x = val;
+        draw();
+    }
+    void set_box_y(double val) {
+        box_y = val;
+        draw();
+    }
+    void set_box_w(double val) {
+        box_w = val;
+        draw();
+    }
+    void set_box_h(double val) {
+        box_h = val;
+        draw();
+    }
+    void set_text(std::string& text) {
+        text = text;
+        draw();
+    }
+    void set_text_align(Blit::TextAlign val) {
+        text_align = val;
+        draw();
+    }
+    void set_current_fg(Blit::RGB val) {
+        fg = val;
+        draw();
+    }
+};
+
+
+class Button : public BaseElement {
+public:
+    bool should_get_x_events = true;
+    double x, y, w, h, border_radius = 0;
+    Blit::RGB current_bg, bg, sel_bg;
+
+    bool is_hot, is_active = false;
+
+    Cairo::RefPtr<Cairo::Context> cr;
+public:
+    Button(Cairo::RefPtr<Cairo::Context> cr) :
+        should_get_x_events(true),
+        current_bg(0.0, 0.0, 0.0),
+        sel_bg(0.0, 0.0, 0.0),
+        bg(0.0, 0.0, 0.0),
+        cr(cr)
+    {}
+
+    virtual ~Button() {}
+
+    void draw() {
+        cr->save();
+        cr->set_source_rgb(current_bg.r, current_bg.g, current_bg.b);
+        if (border_radius > 0) {
+            double aspect = 1.0;
+            double radius = border_radius / aspect;
+            double degrees = M_PI / 180.0;
+
+            cr->begin_new_sub_path();
+            cr->arc(x + w - radius, y + radius, radius, -90 * degrees, 0 * degrees);
+            cr->arc(x + w - radius, y + h - radius, radius, 0 * degrees, 90 * degrees);
+            cr->arc(x + radius, y + h - radius, radius, 90 * degrees, 180 * degrees);
+            cr->arc(x + radius, y + radius, radius, 180 * degrees, 270 * degrees);
+            cr->close_path();
+        } else {
+            cr->rectangle(x, y, w, h);
+        }
+        cr->fill();
+        cr->restore();
+    }
+
+    void handle_event(XEvent *e) {
+        char keybuf[8];
+        KeySym key;
+
+        switch (e->type) {
+            case MotionNotify:
+                bool is_hot_now = Blit::collide_point_rect(x, y, w, h, e->xmotion.x, e->xmotion.y);
+                if (!is_hot && is_hot_now) { // just became hot
+                    set_current_bg(sel_bg);
+                    is_hot = true;
+                } else if (is_hot && !is_hot_now) { // just became not hot
+                    set_current_bg(bg);
+                    is_hot = false;
+                }
+                break;
+        }
+    }
+
+    void set_x(double val) {
+        x = val;
+        draw();
+    }
+    void set_y(double val) {
+        y = val;
+        draw();
+    }
+    void set_w(double val) {
+        w = val;
+        draw();
+    }
+    void set_h(double val) {
+        h = val;
+        draw();
+    }
+    void set_border_radius(double val) {
+        border_radius = val;
+        draw();
+    }
+    void set_current_bg(Blit::RGB val) {
+        current_bg = val;
+        draw();
+    }
+};
+
+}
+
+int main() {
+    std::string text = "click me now";
+    XEvent e;
+    PangoFontDescription *font_description = pango_font_description_new();
+
+    pango_font_description_set_family(font_description, "sans-serif");
+    pango_font_description_set_weight(font_description, PANGO_WEIGHT_NORMAL);
+    pango_font_description_set_absolute_size(font_description, 16 * PANGO_SCALE);
+
+    Blit::Window window(800, 600);
+    Blit::Button button(window.cr);
+    Blit::Text button_text(window.cr, text, font_description);
+
+    button.x = 20.0;
+    button.y = 20.0;
+    button.w = 100.0;
+    button.h = 30.0;
+    button.border_radius = 0.0;
+    button.bg = Blit::RGB(1.0, 0.0, 0.0);
+    button.sel_bg = Blit::RGB(0.0, 1.0, 0.0);
+
+    button_text.x = button.x;
+    button_text.y = button.y;
+    button_text.box_x = button.x;
+    button_text.box_y = button.y;
+    button_text.box_w = button.w;
+    button_text.box_h = button.h;
+    button_text.fg = Blit::RGB(1.0, 1.0, 1.0);
+    button_text.text_align = Blit::TextAlign::TEXT_ALIGN_CENTER;
+    
+    window.attach_element(&button);
+    window.attach_element(&button_text);
+
+    for (;;) {
+        XNextEvent(window.dsp, &e);
+        window.handle_x_event(&e);
+    }
+
+    return 0;
+}