commit 86d0e88d78b87a1318c7728656f9ad26c5b847a8
Author: aabacchus <ben@bvnf.space>
Date: Mon, 27 Sep 2021 01:40:31 +0100
initial commit: write blocks of colour to a PNG
Diffstat:
| A | Makefile | | | 18 | ++++++++++++++++++ |
| A | stroke.c | | | 60 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
2 files changed, 78 insertions(+), 0 deletions(-)
diff --git a/Makefile b/Makefile
@@ -0,0 +1,18 @@
+.POSIX:
+
+DEBUG = -g
+XCFLAGS = $(CFLAGS) -Wall -Wextra -Wpedantic $(DEBUG)
+CAIROFLAGS = $$(pkgconf --cflags --libs cairo)
+
+BINS = \
+ stroke
+
+all: $(BINS)
+
+$(BINS): $(BINS:=.c)
+ $(CC) $(XCFLAGS) $(CAIROFLAGS) -o $@ $<
+
+clean:
+ rm -f $(BINS)
+
+.PHONY: clean
diff --git a/stroke.c b/stroke.c
@@ -0,0 +1,60 @@
+/*
+ * stroke.c
+ * Copyright (c) 2021 Ben Fuller
+ *
+ * This program makes a PNG image "stroke.png" consisting of blocks of colour
+ * in a gradient. The dimensions of the image, and size of <<pixels>> can be
+ * easily adjusted - try setting the number of rows and columns to the width
+ * and height so that each block is one pixel.
+ *
+ * Between each pixel is left a small gap, and the background is coloured in
+ * black.
+ */
+#include <cairo.h>
+#include <stdio.h>
+
+int
+main(void)
+{
+ double width, height, scale;
+ int nx, ny;
+ cairo_surface_t *surface;
+ cairo_t *cr;
+
+ width = 600;
+ height = 600;
+ scale = 1;
+ /* number of columns and rows */
+ nx = 60;
+ ny = 60;
+
+ surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
+ cr = cairo_create(surface);
+ cairo_scale(cr, scale, scale);
+
+ /* background fill */
+ cairo_set_source_rgb(cr, 0, 0, 0);
+ cairo_rectangle(cr, 0, 0, width/scale, height/scale);
+ cairo_fill(cr);
+
+ for (int i = 0; i < nx; i++) {
+ for (int j = 0; j < ny; j++) {
+ cairo_set_source_rgb(cr,
+ (double)j / ny,
+ (double)i / nx,
+ 0);
+ cairo_rectangle(cr, i * width/nx/scale, j * height/ny/scale,
+ width/nx/scale * 0.9,
+ height/ny/scale * 0.9);
+ cairo_fill(cr);
+ }
+ }
+ printf("cairo_status: %s\n", cairo_status_to_string(cairo_status(cr)));
+
+ /* Write output and clean up */
+ cairo_surface_write_to_png(surface, "stroke.png");
+ cairo_destroy(cr);
+ cairo_surface_destroy(surface);
+
+ return 0;
+}
