plot lines thanks to dcat - ploot - simple plotting tools
HTML git clone git://bitreich.org/ploot git://enlrupgkhuxnvlhsf6lc3fziv5h2hhfrinws65d7roiv6bfj7d652fid.onion/ploot
DIR Log
DIR Files
DIR Refs
DIR Tags
DIR README
DIR LICENSE
---
DIR commit bb9f77683b2a4c23a519b71baaea8bec6eb5be90
DIR parent 6e13cd89684d0129aa13995c3f0e2ba4f0a7aae1
HTML Author: Josuah Demangeon <mail@josuah.net>
Date: Mon, 30 Apr 2018 14:25:31 +0200
plot lines thanks to dcat
Diffstat:
M .gitignore | 1 +
M font.c | 55 ++++++++++++++++++++++---------
2 files changed, 41 insertions(+), 15 deletions(-)
---
DIR diff --git a/.gitignore b/.gitignore
@@ -1,2 +1,3 @@
*.o
+*.core
ploot
DIR diff --git a/font.c b/font.c
@@ -1,5 +1,9 @@
/*
* Render bitmapped font as a farbfeld image
+ *
+ * The convention used: y
+ * - (0,0) is at the lower left corner of the canvas. |
+ * - (0,1) is above it. +--x
*/
#include <arpa/inet.h>
@@ -32,6 +36,10 @@ void
ffdraw_pixel(Canvas *can, Color c,
int x, int y)
{
+/* Make it segfault early.
+ x = MIN(can->w - 1, x);
+ y = MIN(can->h - 1, y);
+*/
memcpy(can->b + x + (can->h - 1 - y) * can->w, c, sizeof(*can->b));
}
@@ -50,20 +58,37 @@ ffdraw_rectangle(Canvas *can, Color c,
ffdraw_pixel(can, c, x, y);
}
-void
+/*
+ * Adapted from Bresenham's line algorithm and dcat's tplot.
+ */
+static void
ffdraw_line(Canvas *can, Color c,
- int x1, int y1,
- int x2, int y2)
+ int x0, int y0,
+ int x1, int y1)
{
- int x, y;
-
- (void)c;
- (void)can;
-
- x = x1;
- y = y1;
- while (x < x2 && y < y2) {
- x++; y++;
+ int dx, dy, sx, sy, err, e;
+
+ sx = x0 < x1 ? 1 : -1;
+ sy = y0 < y1 ? 1 : -1;
+ dx = abs(x1 - x0);
+ dy = abs(y1 - y0);
+ err = (dx > dy ? dx : -dy) / 2;
+
+ for (;;) {
+ ffdraw_pixel(can, c, x0, y0);
+
+ if (x0 == x1 && y0 == y1)
+ break;
+
+ e = err;
+ if (e > -dx) {
+ x0 += sx;
+ err -= dy;
+ }
+ if (e < dy) {
+ y0 += sy;
+ err += dx;
+ }
}
}
@@ -80,9 +105,9 @@ ffdraw(Canvas *can)
Color c2 = { 0x3333, 0xffff, 0x8888, 0xffff };
ffdraw_fill(can, c1);
- ffdraw_rectangle(can, c2,
- 0, 20,
- can->w - 10, 4);
+ ffdraw_line(can, c2,
+ 0, 0,
+ 50 - 1, 80 - 1);
}
void