Initial commit

Makefile

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+build:
+	gcc -Wall -lSDL2 -std=c99 ./src/*.c -o ./app
+
+run:
+	./app
+
+clean:
+	rm ./app

README.md

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+# SingleDigitDrawer
+## Motivation
+I'm working on project that will eventually become a digital clock widget-like app for personal use. While doing that I ran across a problem: turned out I had no nice-looking digits for the clock's face. That's why I made this utility that can draw a single digit imitating a seven segment display.
+
+## Installation
+The app uses SDL2 library so SDL2 is required to build and run it. Use my Makefile or write the gcc command manually.
+
+## Usage
+This utility is meant mostly for my personal use so it is pretty junky and I don't plan on adding a -\-help  flag or anything. Either way if you want to play around with it this is what you should know:
+1) You can set height and width of the window with -h and -w flags respectively (naturally you'll need to enter an integer after each flag)
+2) After that the program will expect you to enter a digit that you want it to display. If you enter a number larger than 9 it will take its last digit and draw that.
+3) To quit enter any negative number (no, it does not accept ctrl+C signal and it doesn't read any input from your mouse. <sub><sup> It's SDL, baby, those buttons aren't functional till I say so! B-) </sup></sub> )

src/main.c

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+#include <stdio.h>
+#include <SDL2/SDL.h>
+#include <stdint.h>
+
+SDL_Window *window = NULL;
+SDL_Renderer *renderer = NULL;
+int init_window(int, int, int, int);
+int destroy_window(void);
+int running = 1;
+
+
+SDL_Rect segments[7];
+struct scaler
+{
+	int smaller_side_size;
+	int larger_side_size;
+	int margin;
+} sc;
+
+const uint8_t states[10] = 
+{
+	0x77,//0
+	0x24,//1
+	0x5d,//2
+	0x6d,//3
+	0x2e,//4
+	0x6b,//5
+	0x7b,//6
+	0x25,//7
+	0x7f,//8
+	0x6f//9
+};
+
+void draw_digit(int);
+void init_segments(void);
+void calculate_scale(int, int);
+
+int main(int argc, char* argv[])
+{
+	int width = 400, height = 780;
+	int pos_x = SDL_WINDOWPOS_CENTERED, pos_y =SDL_WINDOWPOS_CENTERED;
+	for (int i = 1; i < argc; i++)
+	{
+		if (strcmp(argv[i], "-w") == 0 || strcmp(argv[i], "--width") == 0)
+		{
+			if(sscanf(argv[++i], "%d", &width));
+			else width = 400;
+		} else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--height") == 0)
+		{
+			if(sscanf(argv[++i], "%d", &height));
+			else height = 800;
+		}
+	}
+	init_window(width, height, pos_x, pos_y);
+	calculate_scale(width, height);
+	init_segments();
+	int n = 0;
+	while (running)
+	{
+		draw_digit(n);
+		if (scanf("%d", &n))
+		{
+			if (n<0) running = 0;
+		}
+		else 
+		{
+			printf("Invalid input!!!\n");
+		}
+		n = n%10;
+	}
+	destroy_window();
+	return 0;
+}
+
+void calculate_scale(int w, int h)
+{
+	if (h > 2*w)
+	{
+		sc.smaller_side_size = w/10;
+		sc.margin = sc.smaller_side_size/5;
+		sc.larger_side_size = w - 2*sc.smaller_side_size - 2*sc.margin;
+	} else
+	{
+		sc.smaller_side_size = h/20;
+		sc.margin = sc.smaller_side_size/5;
+		sc.larger_side_size = (h - 3*sc.smaller_side_size - 4*sc.margin)/2;
+	}
+}
+
+void draw_digit(int n)
+{
+	SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
+	SDL_RenderClear(renderer);
+	for (int i = 0; i<7; i++)
+	{
+		if((states[n]>>i) & 1)
+			SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
+		else
+			SDL_SetRenderDrawColor(renderer, 64, 64, 64, 128);
+		SDL_RenderFillRect(renderer, &segments[i]);
+	}
+	SDL_RenderPresent(renderer);
+}
+
+void init_segments(void)
+{
+	for (int i = 0; i<7; i++)
+	{
+		if(i%3 == 0) 
+		{
+			segments[i].w = sc.larger_side_size; 
+			segments[i].h = sc.smaller_side_size;
+		}
+		else 
+		{
+			segments[i].h = sc.larger_side_size; 
+			segments[i].w = sc.smaller_side_size;
+		}
+	}
+	segments[0].x = sc.smaller_side_size + sc.margin;
+	segments[0].y = 0;
+
+	segments[1].x = 0;
+	segments[1].y = sc.smaller_side_size + sc.margin;
+
+	segments[2].x = sc.larger_side_size + sc.smaller_side_size + 2*sc.margin;
+	segments[2].y = sc.smaller_side_size + sc.margin;
+
+	segments[3].x = sc.smaller_side_size + sc.margin;
+	segments[3].y = sc.larger_side_size + sc.smaller_side_size + 2*sc.margin;
+
+	segments[4].x = 0;
+	segments[4].y = sc.larger_side_size + 2*(sc.smaller_side_size + sc.margin);
+
+	segments[5].x = sc.larger_side_size + sc.smaller_side_size + 2*sc.margin;;
+	segments[5].y = sc.larger_side_size + 2*(sc.smaller_side_size + sc.margin);
+
+	segments[6].x = sc.smaller_side_size + sc.margin;
+	segments[6].y = 2*sc.larger_side_size + 2*sc.smaller_side_size + 4*sc.margin;
+}
+
+int init_window(int w, int h, int pos_x, int pos_y)
+{
+	if(SDL_Init(SDL_INIT_EVERYTHING) != 0)
+	{
+		fprintf(stderr, "Error initializing SDL.\n");
+		return 1;
+	}
+	window = SDL_CreateWindow(
+		"SevenSegment",
+		pos_x,
+		pos_y,
+		w,
+		h,
+		SDL_WINDOW_SHOWN //| SDL_WINDOW_BORDERLESS
+	);
+	if (!window)
+	{
+		fprintf(stderr, "Error initializing window.\n");
+		return 1;
+	}
+	renderer = SDL_CreateRenderer(window, -1, 0);
+	if (!renderer)
+	{
+		fprintf(stderr, "Error initializing renderer.\n");
+		return 1;
+	}
+	return 0;
+}
+
+int destroy_window(void)
+{
+	SDL_DestroyRenderer(renderer);
+	SDL_DestroyWindow(window);
+	SDL_Quit();
+	return 0;
+}