QuickNote app for PocketBook InkPad 3

//QuickNote application for PocketBook Inkpad 3 by Faguss (ofp-faguss.com) 31.07.2018




    // Headers
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "inkview.h"




    // Global variables
ifont* normal_font = NULL;
ifont* small_font  = NULL;

int SW = 0; // screen width
int SH = 0; // screen height

const int TEXT_BUFFER_SIZE = 1024 * 1024;
static char text[TEXT_BUFFER_SIZE];
int TEXT_X = 0;
int TEXT_Y = 0;
int TEXT_W = 0;
int TEXT_H = 0;

int BUTTON_ROWS    = 6;
int BUTTON_COLUMNS = 10;
int BUTTON_X       = 0;
int BUTTON_Y       = 0;
int BUTTON_W       = 0;
int BUTTON_H       = 0;
bool SHIFT         = false;

const int KEY_BUFFER_SIZE  = 10;
const char keyboard_buttons[][KEY_BUFFER_SIZE] = {
    "`", "-", "=", "[", "]", "\\", ";", "BACKSPACE", "EXIT",
    "1", "2", "3", "4", "5", "6", "7", "8", "9", "0",
    "q", "w", "e", "r", "t", "y", "u", "i", "o", "p",
    "a", "s", "d", "f", "g", "h", "j", "k", "l", "'",
    "z", "x", "c", "v", "b", "n", "m", ",", ".", "/",
    "SHIFT", " ", "ENTER",
};

const int number_of_keyboard_buttons = sizeof(keyboard_buttons) / sizeof(keyboard_buttons[0]);
int key_x[number_of_keyboard_buttons];
int key_y[number_of_keyboard_buttons];
int key_w[number_of_keyboard_buttons];
int key_h[number_of_keyboard_buttons];




    // Functions

// Replace a character if SHIFT key was pressed
void shift_key(char *current_key)
{
    if (SHIFT  &&  strlen(current_key)==1) {
        char key = current_key[0];

        switch(key) {
            case '`' : key='~'; break;
            case '1' : key='!'; break;
            case '2' : key='@'; break;
            case '3' : key='#'; break;
            case '4' : key='$'; break;
            case '5' : key='%'; break;
            case '6' : key='^'; break;
            case '7' : key='&'; break;
            case '8' : key='*'; break;
            case '9' : key='('; break;
            case '0' : key=')'; break;
            case '-' : key='_'; break;
            case '=' : key='+'; break;
            case '[' : key='{'; break;
            case ']' : key='}'; break;
            case '\\': key='|'; break;
            case ';' : key=':'; break;
            case '\'': key='"'; break;
            case ',' : key='<'; break;
            case '.' : key='>'; break;
            case '/' : key='?'; break;
            default  : {
                if (key>=97 && key<=122)
                    key-=32;
            }; break;
        }

        current_key[0] = key;
    }
}



// Display rectangles with letters in them
void draw_keyboard()
{
    FillArea(BUTTON_X, BUTTON_Y, SW, SH - BUTTON_Y, WHITE);

    int column = 0;
    int row    = 0;
    bool small = 0;

    for (int i=0; i<number_of_keyboard_buttons; i++) {
        key_x[i] = column>0 ? key_x[i-1] + key_w[i-1] : BUTTON_X;
        key_y[i] = BUTTON_Y + BUTTON_H * row;
        key_w[i] = BUTTON_W;
        key_h[i] = BUTTON_H;

        if (row==0 && column==7)    // backspace
            key_w[i] *= 2;

        if (row==5 && column==1)    // space
            key_w[i] *= 6;

        if (row==5 && (column==0 || column==2)) // shift, enter
            key_w[i] *= 2;

        char current_key[KEY_BUFFER_SIZE];
        strcpy(current_key, keyboard_buttons[i]);
        shift_key(current_key);
        const char *text_to_add = current_key;

        small = strlen(text_to_add) > 2;
        if (small)
            SetFont(small_font, DGRAY);
        else
            SetFont(normal_font, DGRAY);

        DrawRect(key_x[i], key_y[i], key_w[i], key_h[i], LGRAY);
        DrawString(
            key_x[i] + key_w[i] / 2 - StringWidth(text_to_add) / 2,
            key_y[i] + key_h[i] / 2 - ((small ? small_font : normal_font)->height) / 2 ,
            text_to_add
        );

        column++;

        if (column >= BUTTON_COLUMNS  ||  (row==0 && column>8)) {
            column = 0;
            row++;
        }
    }
}



// Display text area
void draw_text()
{
    SetFont(small_font, BLACK);
    FillArea(TEXT_X, TEXT_Y, TEXT_W, TEXT_H, WHITE);
    DrawTextRect(TEXT_X, TEXT_Y, TEXT_W, TEXT_H, text, ALIGN_LEFT | VALIGN_TOP);
};



// Main program
int main_handler(int type, int par1, int par2)
{
    switch(type)
    {
        case EVT_INIT:
        {
            SetPanelType(0);
            normal_font = OpenFont(DEFAULTFONT, BUTTON_H - BUTTON_H/3  , 1);
            small_font  = OpenFont(DEFAULTFONT, BUTTON_H - BUTTON_H/1.5, 1);
        }
        break;


        case EVT_SHOW:
        {
            draw_text();
            draw_keyboard();
            FullUpdate();
        }
        break;


        case EVT_POINTERUP:
        {
            int x = par1;
            int y = par2;

            if (y > BUTTON_Y) {
                for (int i=0; i<number_of_keyboard_buttons; i++) {
                    if (x > key_x[i]  &&  y > key_y[i]  &&  x < key_x[i]+key_w[i]  &&  y < key_y[i]+key_h[i]) {
                        int length = strlen(text);

                        if (strcmp(keyboard_buttons[i],"EXIT") == 0) {
                            CloseApp();
                        } else
                        if (strcmp(keyboard_buttons[i],"SHIFT") == 0) {
                            SHIFT = !SHIFT;
                            draw_keyboard();
                            PartialUpdate(BUTTON_X, BUTTON_Y, SW, SH - BUTTON_Y);
                        } else {
                            if (strcmp(keyboard_buttons[i],"BACKSPACE") == 0) {
                                if (length > 0)
                                    text[length-1] = '\0';
                            } else {
                                if (length < TEXT_BUFFER_SIZE-1) {
                                    if (strcmp(keyboard_buttons[i],"ENTER") == 0)
                                        strcat(text,"\n");
                                    else {
                                        char current_key[KEY_BUFFER_SIZE];
                                        strcpy(current_key, keyboard_buttons[i]);
                                        shift_key(current_key);
                                        strcat(text, current_key);
                                    }
                                }
                            }

                            draw_text();
                            PartialUpdate(TEXT_X, TEXT_Y, TEXT_W, TEXT_H);
                        }
                    }
                }
            } else
                FullUpdate();
        }
        break;

        case EVT_EXIT:
        {
            FILE *f = fopen("//mnt/ext1/.QuickNote.txt", "w");
            if (f) {
                fprintf(f, "%s", text);
                fclose(f);
            };

            CloseFont(normal_font);
            CloseFont(small_font);
            normal_font = NULL;
            small_font  = NULL;
        };
        break;

        default:
            break;
    }

    return 0;

}




// Initialization
int main()
{
    FILE *f = fopen("//mnt/ext1/.QuickNote.txt", "r");
    if (f) {
        fread(text, sizeof(char), TEXT_BUFFER_SIZE-1, f);
        fclose(f);
    };

    OpenScreen();
    SW       = ScreenWidth();
    SH       = ScreenHeight();
    BUTTON_W = SW / BUTTON_COLUMNS;
    BUTTON_H = BUTTON_W - 5;
    BUTTON_Y = SH - BUTTON_H * BUTTON_ROWS;
    TEXT_W   = SW;
    TEXT_H   = BUTTON_Y;

    InkViewMain(main_handler);
    return 0;
}