fb-dash/fbdash.c

/*
 * fbdash.c
 *
 * Adapted by Florian Klemenz for use in the fb_dash project
 *
 * Source and all credit goes to 
 * http://raspberrycompote.blogspot.com/
 * -------------------------------------------------------------------------------------------- 
 *
 * http://raspberrycompote.blogspot.ie/2014/03/low-level-graphics-on-raspberry-pi-part_14.html
 *
 * Original work by J-P Rosti (a.k.a -rst- and 'Raspberry Compote')
 *
 * Licensed under the Creative Commons Attribution 3.0 Unported License
 * (http://creativecommons.org/licenses/by/3.0/deed.en_US)
 *
 * Distributed in the hope that this will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 */


#include "fblib.h"
#include "fbfonts.h"

#include <stdio.h>
#include <math.h>

#define WIDTH 240
#define HEIGHT 320

#define FONTH 8 // 37
#define FONTW 8 // 22


// 'global' variables to store screen info
char *fbp = 0;

/*
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
*/



void render_string(char *fbp, char* font, char *text, int x, int y, int r, int g, int b)
{
    int text_length = strlen(text);
    printf("text_length = %d\n", text_length);
    
    int bytes_per_line = ceil(FONTW / 8.0);
    printf("bytes_per_line = %d\n", bytes_per_line);

    int char_offset = bytes_per_line * FONTH;

    // each character
    for (int char_pos = 0; char_pos < text_length; char_pos++) {
        //int char_code = 0;
        int char_code = *(text + char_pos);
        int x_offset = char_pos * FONTW + x;

        // each line of pixels
        for (int line = 0; line < FONTH; line++) {
            int y_pos = line + y;

            // each byte in a line of pixels
            for (int byte_num = 0; byte_num < bytes_per_line; byte_num++) {
                int byte_offset = line * bytes_per_line + byte_num;
                char current_byte = *((font + char_code * char_offset) + byte_offset);

                // each bit/pixel in a byte
                for (int bit_number = 0; bit_number < 8; bit_number++) {
                    char mask = 1 << bit_number;
                    if(current_byte & mask) {
                        // plot the pixel
                        printf("x");

                        int x_pos = x_offset + byte_num * 8 + bit_number;
                        put_pixel(fbp, x_pos, y_pos, 255, 255, 255);
                    }
                    else {
                        // leave empty (or maybe plot 'text backgr color')
                        printf(" ");
                    }
                } // end "for bit_number"

            } // end "for byte_num"

			printf("\n");

        } // end "for line"

    } // end "for char_pos"
}





// helper function for drawing - no more need to go mess with
// the main function when just want to change what to draw...
void draw() {
   
    clear_screen(fbp);

    // horizontal spacersint x_space = 10;
    int y_step_width = HEIGHT / 4;
    for (int i = 1; i < 4; i++) {
        int x0 = 15;
        int x1 = WIDTH - x0;
        int y = y_step_width * i;

        int r = 225;
        int g = 32;
        int b = 32;
        
        draw_line(fbp, x0, y-1, x1, y-1, r, g, b);
        draw_line(fbp, x0, y  , x1, y  , r, g, b);
        draw_line(fbp, x0, y+1, x1, y+1, r, g, b);
    }




	char *text = "Hello world!";
    //render_string(fbp, (char*)arial_16x16, text, 0, 0, 255, 255, 255);
    render_string(fbp, (char*)font8x8_basic, text, 0, 0, 255, 255, 255);
}

// application entry point
int main(int argc, char* argv[])
{

    int fbfd = 0;
    //struct fb_var_screeninfo orig_vinfo;
    long int screensize = 0;

    // Open the framebuffer file for reading and writing
    fbfd = open("/dev/fb1", O_RDWR);
    if (fbfd == -1) {
        printf("Error: cannot open framebuffer device.\n");
        return(1);
    }
    printf("The framebuffer device was opened successfully.\n");


    /*
    // Get variable screen information
    if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
        printf("Error reading variable information.\n");
    }
    printf("Variable info: %dx%d, %dbpp\n", 
            vinfo.xres, vinfo.yres, 
            vinfo.bits_per_pixel );

    // Get fixed screen information
    if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo)) {
        printf("Error reading fixed information.\n");
    }
    printf("Fixed info: smem_len %d, line_length %d\n", finfo.smem_len, finfo.line_length);
*/

    // map fb to user mem 
    //screensize = finfo.smem_len;
    screensize = WIDTH*HEIGHT*2;
    fbp = (char*)mmap(0, 
              screensize, 
              PROT_READ | PROT_WRITE, 
              MAP_SHARED, 
              fbfd, 
              0);

    if ((int)fbp == -1) {
        printf("Failed to mmap.\n");
    }
    else {
        // draw...
        draw();
    }

    // cleanup
    //clear_screen(fbp);
    // unmap fb file from memory
    munmap(fbp, screensize);
    // close fb file    
    close(fbfd);

    return 0;
  
}