ex_bitmap_file.c

/* This example displays a picture on the screen, with support for
 * command-line parameters, multi-screen, screen-orientation and
 * zooming. It is a little different from ex_bitmap in the sense
 * that it uses the ALLEGRO_FILE interface.
 */
#include <stdio.h>
#include <stdlib.h>
#include "allegro5/allegro.h"
#include "allegro5/allegro_image.h"

#include "common.c"

int main(int argc, char **argv)
{
    const char *filename;
    char *fileextension = NULL;
    ALLEGRO_DISPLAY *display;
    ALLEGRO_FILE *file;
    ALLEGRO_BITMAP *bitmap = NULL;
    ALLEGRO_TIMER *timer;
    ALLEGRO_EVENT_QUEUE *queue;

    bool redraw = true;
    double zoom = 1;
    double t0;
    double t1;

    /* The first commandline argument can optionally specify an
     * image to display instead of the default. Allegro's image
     * addon supports BMP, DDS, PCX, TGA and can be compiled with
     * PNG and JPG support on all platforms. Additional formats
     * are supported by platform specific libraries and support for
     * image formats can also be added at runtime.
     */
    if (argc > 1) {
       filename = argv[1];
    }
    else {
       filename = "data/mysha.pcx";
    }

    if (!al_init()) {
       abort_example("Could not init Allegro.\n");
    }

    // Initializes and displays a log window for debugging purposes.
    open_log();

    /* The second parameter to the process can optionally specify what
     * adapter to use.
     */
    if (argc > 2) {
       al_set_new_display_adapter(atoi(argv[2]));
    }

    /* Allegro requires installing drivers for all input devices before
     * they can be used.
     */
    al_install_mouse();
    al_install_keyboard();

    /* Initialize the image addon. Requires the allegro_image addon
     * library.
     */
    al_init_image_addon();

    // Helper functions from common.c.
    init_platform_specific();

    // Create a new display that we can render the image to.
    display = al_create_display(640, 480);
    if (!display) {
       abort_example("Error creating display\n");
    }

    al_set_window_title(display, filename);

    // Load the image and time how long it took for the log.
    t0 = al_get_time();
    file = al_fopen(filename, "rb");
    if (file) {
        fileextension = strrchr(filename, '.');
        bitmap = al_load_bitmap_f(file, fileextension);
        al_fclose( file );
    }
    t1 = al_get_time();
    if (!bitmap) {
       abort_example("%s not found or failed to load\n", filename);
    }

    log_printf("Loading took %.4f seconds\n", t1 - t0);

    // Create a timer that fires 30 times a second.
    timer = al_create_timer(1.0 / 30);
    queue = al_create_event_queue();
    al_register_event_source(queue, al_get_keyboard_event_source());
    al_register_event_source(queue, al_get_display_event_source(display));
    al_register_event_source(queue, al_get_timer_event_source(timer));
    al_start_timer(timer); // Start the timer

    // Primary 'game' loop.
    while (1) {
        ALLEGRO_EVENT event;
        al_wait_for_event(queue, &event); // Wait for and get an event.
        if (event.type == ALLEGRO_EVENT_DISPLAY_ORIENTATION) {
            int o = event.display.orientation;
            if (o == ALLEGRO_DISPLAY_ORIENTATION_0_DEGREES) {
                log_printf("0 degrees\n");
            }
            else if (o == ALLEGRO_DISPLAY_ORIENTATION_90_DEGREES) {
                log_printf("90 degrees\n");
            }
            else if (o == ALLEGRO_DISPLAY_ORIENTATION_180_DEGREES) {
                log_printf("180 degrees\n");
            }
            else if (o == ALLEGRO_DISPLAY_ORIENTATION_270_DEGREES) {
                log_printf("270 degrees\n");
            }
            else if (o == ALLEGRO_DISPLAY_ORIENTATION_FACE_UP) {
                log_printf("Face up\n");
            }
            else if (o == ALLEGRO_DISPLAY_ORIENTATION_FACE_DOWN) {
                log_printf("Face down\n");
            }
        }
        if (event.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
            break;
        /* Use keyboard to zoom image in and out.
         * 1: Reset zoom.
         * +: Zoom in 10%
         * -: Zoom out 10%
         * f: Zoom to width of window
         */
        if (event.type == ALLEGRO_EVENT_KEY_CHAR) {
            if (event.keyboard.keycode == ALLEGRO_KEY_ESCAPE)
                break; // Break the loop and quite on escape key.
            if (event.keyboard.unichar == '1')
                zoom = 1;
            if (event.keyboard.unichar == '+')
                zoom *= 1.1;
            if (event.keyboard.unichar == '-')
                zoom /= 1.1;
            if (event.keyboard.unichar == 'f')
                zoom = (double)al_get_display_width(display) /
                    al_get_bitmap_width(bitmap);
        }

        // Trigger a redraw on the timer event
        if (event.type == ALLEGRO_EVENT_TIMER)
            redraw = true;

        // Redraw, but only if the event queue is empty
        if (redraw && al_is_event_queue_empty(queue)) {
            redraw = false;
            // Clear so we don't get trippy artifacts left after zoom.
            al_clear_to_color(al_map_rgb_f(0, 0, 0));
            if (zoom == 1)
                al_draw_bitmap(bitmap, 0, 0, 0);
            else
                al_draw_scaled_rotated_bitmap(
                    bitmap, 0, 0, 0, 0, zoom, zoom, 0, 0);
            al_flip_display();
        }
    }

    al_destroy_bitmap(bitmap);

    close_log(false);

    return 0;
}

/* vim: set sts=4 sw=4 et: */