Ghost OS - Canvas sample code

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 *                                                                           *
 *             Canvas example for the Ghost operating system                 *
 *                                                                           *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#include <ghostuser/ui/ui.hpp>
#include <ghostuser/ui/window.hpp>
#include <ghostuser/ui/canvas.hpp>
#include <ghostuser/ui/textfield.hpp>
#include <iostream>
#include <math.h>

/**
 * This example application creates a window with a canvas and draws one of the
 * cairo samples on it.
 */
int main(int argc, char** argv) {

    // Open the UI
    g_ui_open_status open_stat = g_ui::open();
    if (open_stat != G_UI_OPEN_STATUS_SUCCESSFUL) {
        std::cerr << "User interface could not be initialized" << std::endl;
        return -1;
    }

    // Create a window
    g_window* window = g_window::create();
    window->setTitle("Test Window");

    // Create the canvas
    g_canvas* canvas = g_canvas::create();
    window->addChild(canvas);

    // Resize the window
    g_rectangle windowBounds(200, 200, 270, 270);
    window->setBounds(windowBounds);
    window->setVisible(true);
    canvas->setBounds(g_rectangle(0, 0, windowBounds.width, windowBounds.height));

    // Variables for our surface
    cairo_surface_t* surface = 0;
    g_color_argb* surfaceBuffer = 0;

    while (true) {
        // Resize canvas when window is resized
        auto windowBounds = window->getBounds();
        if (canvas->getBounds() != windowBounds) {
            canvas->setBounds(g_rectangle(0, 0, windowBounds.width, windowBounds.height));
        }

        // Get buffer
        auto bufferInfo = canvas->getBuffer();
        if (bufferInfo.buffer == 0) {
            g_sleep(100);
            continue;
        }

        // Get the surface ready and go:
        if (surface == 0 || surfaceBuffer != bufferInfo.buffer) {
            surface = cairo_image_surface_create_for_data((uint8_t*) bufferInfo.buffer, CAIRO_FORMAT_ARGB32,
                    bufferInfo.width, bufferInfo.height, cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32,
                    bufferInfo.width));
            surfaceBuffer = bufferInfo.buffer;
        }

        // Perform the painting
        auto cr = cairo_create(surface);

        // Clear the background
        cairo_save(cr);
        cairo_set_source_rgba(cr, 0, 0, 0, 0);
        cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
        cairo_paint(cr);
        cairo_restore(cr);

        // Draw the example
        double xc = 128.0;
        double yc = 128.0;
        double radius = 100.0;
        double angle1 = 45.0 * (M_PI / 180.0);
        double angle2 = 180.0 * (M_PI / 180.0);

        cairo_set_line_width(cr, 10.0);
        cairo_arc_negative(cr, xc, yc, radius, angle1, angle2);
        cairo_stroke(cr);

        cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.6);
        cairo_set_line_width(cr, 6.0);

        cairo_arc(cr, xc, yc, 10.0, 0, 2 * M_PI);
        cairo_fill(cr);

        cairo_arc(cr, xc, yc, radius, angle1, angle1);
        cairo_line_to(cr, xc, yc);
        cairo_arc(cr, xc, yc, radius, angle2, angle2);
        cairo_line_to(cr, xc, yc);
        cairo_stroke(cr);

        // Blit the content to screen
        canvas->blit(g_rectangle(0, 0, bufferInfo.width, bufferInfo.height));

        g_sleep(100);
    }
}