xdraw

commit 5629be88954d57fa54305c2ac1f7e77ecb04046b
Author: Louis Burda <quent.burda@gmail.com>
Date:   Fri, 14 Jun 2024 01:11:03 +0200

Basic version

Diffstat:
A
.gitignore
 | 
1
+
A
Makefile
 | 
19
+++++++++++++++++++
A
sdraw.c
 | 
182
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 202 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+sdraw
diff --git a/Makefile b/Makefile
@@ -0,0 +1,19 @@
+PREFIX ?= /usr/local
+BINDIR ?= /bin
+
+LDLIBS = -lglfw -lGL
+
+all: sdraw
+
+sdraw: sdraw.c
+
+clean:
+	rm -f sdraw
+
+install:
+	install -m755 sdraw -t "$(DESTDIR)$(PREFIX)$(BINDIR)"
+
+uninstall:
+	rm "$(DESTDIR)$(PREFIX)$(BINDIR)/sdraw"
+
+.PHONY: all clean install uninstall
diff --git a/sdraw.c b/sdraw.c
@@ -0,0 +1,182 @@
+#include <GL/gl.h>
+#include <GLFW/glfw3.h>
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdbool.h>
+
+struct point {
+	double x, y;
+};
+
+struct line {
+	struct point *points;
+	size_t count, cap;
+};
+
+static struct line *lines = NULL;
+static size_t line_count = 0;
+static size_t line_cap = 0;
+
+static double cursor_x = 0;
+static double cursor_y = 0;
+
+static int window_width = 0;
+static int window_height = 0;
+
+static bool drawing = false;
+
+static void
+die(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fputs("sdraw: ", stderr);
+	vfprintf(stderr, fmt, ap);
+	if (*fmt && fmt[strlen(fmt)] == ':')
+		perror(NULL);
+	else
+		putc('\n', stderr);
+	va_end(ap);
+
+	exit(1);
+}
+
+static void *
+append(void *_array, size_t *count, size_t *cap, size_t size)
+{
+	uint8_t **array = _array;
+	if (*count == *cap) {
+		if (*cap == 0) *cap = 1;
+		*cap *= 2;
+		*array = realloc(*array, *cap * size);
+		if (!*array) die("realloc:");
+	}
+	return (void *) (*array + (*count)++ * size);
+}
+
+static void
+glfwerror(int rc, const char *error)
+{
+	die("glfw error (%i): %s", rc, error);
+}
+
+static void
+onresize(GLFWwindow *window, int width, int height)
+{
+	window_width = width;
+	window_height = height;
+	glViewport(0, 0, width, height);
+	glClear(GL_COLOR_BUFFER_BIT);
+	glLoadIdentity();
+	glOrtho(0, width, height, 0, -1, 1);
+}
+
+static void
+onmove(GLFWwindow *window, double x, double y)
+{
+	cursor_x = x;
+	cursor_y = y;
+	if (drawing && line_count) {
+		struct line *line = &lines[line_count-1];
+		if (line->count > 0) {
+			struct point *last_point = &line->points[line->count-1];
+			if (cursor_x == last_point->x && cursor_y == last_point->y)
+				return;
+		}
+		struct point *point = append(&line->points,
+			&line->count, &line->cap, sizeof(struct point));
+		point->x = cursor_x;
+		point->y = cursor_y;
+	}
+}
+
+static void
+onclick(GLFWwindow *window, int button, int action, int mods)
+{
+	if (button != GLFW_MOUSE_BUTTON_LEFT) return;
+
+	if (action == GLFW_PRESS) {
+		struct line *line = append(&lines,
+			&line_count, &line_cap, sizeof(struct line));
+		line->count = line->cap = 0;
+		line->points = NULL;
+		struct point *point = append(&line->points,
+			&line->count, &line->cap, sizeof(struct point));
+		point->x = cursor_x;
+		point->y = cursor_y;
+		drawing = true;
+	} else if (action == GLFW_RELEASE) {
+		drawing = false;
+	}
+}
+
+static void
+onpress(GLFWwindow *window, int key, int scancode, int action, int mods)
+{
+	if (action != GLFW_PRESS) return;
+
+	if ((mods & GLFW_MOD_CONTROL) && !strcmp(glfwGetKeyName(key, scancode), "z")) {
+		if (line_count) {
+			line_count -= 1;
+			free(lines[line_count].points);
+		}
+	} else if ((mods & GLFW_MOD_CONTROL) && !strcmp(glfwGetKeyName(key, scancode), "c")) {
+		for (size_t i = 0; i < line_count; i++)
+			free(lines[i].points);
+		line_count = 0;
+	}
+}
+
+int
+main(void)
+{
+	glfwSetErrorCallback(glfwerror);
+
+	if (!glfwInit()) die("glfwInit");
+
+	GLFWwindow *window = glfwCreateWindow(640, 480, "sdraw", NULL, NULL);
+	if (!window) die("glfwCreateWindow");
+
+	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_HIDDEN);
+	glfwSetWindowSizeCallback(window, onresize);
+	glfwSetCursorPosCallback(window, onmove);
+	glfwSetMouseButtonCallback(window, onclick);
+	glfwSetKeyCallback(window, onpress);
+	glfwMakeContextCurrent(window);
+
+	glClearColor(0, 0, 0, 0);
+	glColor3f(1, 1, 1);
+	glLineWidth(2);
+	glPointSize(2);
+
+	glfwGetCursorPos(window, &cursor_x, &cursor_y);
+	glfwGetWindowSize(window, &window_width, &window_height);
+
+	onresize(window, window_width, window_height);
+
+	while (!glfwWindowShouldClose(window)) {
+		glClear(GL_COLOR_BUFFER_BIT);
+
+		for (size_t i = 0; i < line_count; i++) {
+			struct line *line = &lines[i];
+			glBegin(GL_LINE_STRIP);
+			for (size_t k = 0; k < line->count; k++)
+				glVertex2f(line->points[k].x, line->points[k].y);
+			glEnd();
+		}
+
+		glBegin(GL_POINTS);
+		glVertex2f(cursor_x, cursor_y);
+		glEnd();
+
+		glfwSwapBuffers(window);
+
+		glfwPollEvents();
+	}
+
+	glfwTerminate();
+}