From 266f20e8f0b688ba075ee0f5e81cfd9e4b0af18a Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Tue, 31 Aug 2021 20:35:33 +0200
Subject: Changed render target to a basic X window

---
 Makefile |  4 ++--
 text.c   | 79 +++++++++++++++++++++++++++++++++++++++++++++++++---------------
 2 files changed, 63 insertions(+), 20 deletions(-)

diff --git a/Makefile b/Makefile
index b27a35c..d48d49c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CFLAGS += -Wall -Wextra -Wpedantic
-CFLAGS += `pkg-config --cflags cairo pango pangocairo`
-LDLIBS += -lm `pkg-config --libs cairo pango pangocairo`
+CFLAGS += `pkg-config --cflags cairo pango pangocairo xcb xcb-util`
+LDLIBS += -lm `pkg-config --libs cairo pango pangocairo xcb xcb-util`
 
 all: text
 
diff --git a/text.c b/text.c
index 1e488a5..f0bd074 100644
--- a/text.c
+++ b/text.c
@@ -1,12 +1,16 @@
-#include <math.h>
+#include <stdint.h>
 #include <stdio.h>
 
 #include <cairo.h>
+#include <cairo-xcb.h>
 #include <glib-object.h>
 #include <pango/pango.h>
 #include <pango/pangocairo.h>
+#include <xcb/xcb.h>
+#include <xcb/xcb_util.h>
 
 void draw_text(cairo_t *, const char *);
+xcb_visualtype_t * find_visual(xcb_screen_t *);
 
 static const int MARGIN = 20;
 static const int WIDTH = 800;
@@ -16,36 +20,75 @@ static const char * FONT = "Serif 34";
 
 int main(int argc, const char ** argv)
 {
-	if (1 >= argc)
+	const char * text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";
+	if (2 == argc)
+		text = argv[2];
+	xcb_connection_t * c = xcb_connect(NULL, NULL);
+	if (xcb_connection_has_error(c))
 	{
-		dprintf(2, "Usage: %s OUTPUT [TEXT]\n", argv[0]);
+		dprintf(2, "Could not connect to X11 server");
 		return 1;
 	}
-	const char * filename = argv[1];
-	const char * text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";
-	if (3 == argc)
-		text = argv[2];
-	cairo_surface_t * surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, WIDTH, HEIGHT);
+	xcb_screen_t * s = xcb_setup_roots_iterator(xcb_get_setup(c)).data;
+	xcb_window_t w = xcb_generate_id(c);
+	const uint32_t mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
+	const uint32_t values[] = {s->white_pixel, XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_KEY_PRESS};
+	xcb_visualtype_t * visual = find_visual(s);
+	xcb_create_window(
+		c, XCB_COPY_FROM_PARENT, w, s->root, 0, 0, WIDTH, HEIGHT, 0, XCB_WINDOW_CLASS_INPUT_OUTPUT,
+		s->root_visual, mask, values);
+	xcb_map_window(c, w);
+	cairo_surface_t * surface = cairo_xcb_surface_create(c, w, visual, WIDTH, HEIGHT);
 	cairo_t * ctx = cairo_create(surface);
-	cairo_scale(ctx, 1, 1);
-	cairo_set_source_rgb(ctx, 1., 1., 1.);
-	cairo_paint(ctx);
-	cairo_set_source_rgb(ctx, 0., 0., 0.);
-	draw_text(ctx, text);
+	xcb_flush(c);
+	int done = 0;
+	xcb_generic_event_t * e;
+	while (!done)
+	{
+		e = xcb_wait_for_event(c);
+		if (NULL == e)
+			break;
+		switch (XCB_EVENT_RESPONSE_TYPE(e))
+		{
+		default:
+			break;
+		case XCB_KEY_PRESS:
+			done = 1;
+			break;
+		case XCB_EXPOSE:
+			cairo_set_source_rgb(ctx, 1., 1., 1.);
+			cairo_paint(ctx);
+			cairo_set_source_rgb(ctx, 0., 0., 0.);
+			draw_text(ctx, text);
+			cairo_surface_flush(surface);
+			xcb_flush(c);
+			break;
+		}
+		free(e);
+	}
 	cairo_destroy(ctx);
-	cairo_status_t status = cairo_surface_write_to_png(surface, filename);
 	cairo_surface_destroy(surface);
-	if (CAIRO_STATUS_SUCCESS != status)
+	xcb_disconnect(c);
+}
+
+
+xcb_visualtype_t * find_visual(xcb_screen_t * s)
+{
+	xcb_depth_iterator_t d = xcb_screen_allowed_depths_iterator(s);
+	for (; d.rem; xcb_depth_next(&d))
 	{
-		dprintf(2, "Could not save output to %s\n", filename);
-		return 1;
+		xcb_visualtype_iterator_t v = xcb_depth_visuals_iterator(d.data);
+		for (; v.rem; xcb_visualtype_next(&v))
+			if (v.data->visual_id == s->root_visual)
+				return v.data;
 	}
+	return NULL;
 }
 
 
 void draw_text(cairo_t * ctx, const char * text)
 {
-	cairo_translate(ctx, MARGIN, MARGIN);
+	cairo_move_to(ctx, MARGIN, MARGIN);
 	PangoLayout * layout = pango_cairo_create_layout(ctx);
 	PangoFontDescription * desc = pango_font_description_from_string(FONT);
 	pango_layout_set_font_description(layout, desc);
-- 
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