altos/draw: Add a reasonable API for drawing, add lines.lisp

Also, move the demo drawing into the stm-vga app and out of the vga
driver.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/src/draw/ao_rect.c b/src/draw/ao_rect.c
new file mode 100644
index 00000000..fee7bbd5
--- /dev/null
+++ b/src/draw/ao_rect.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao.h"
+#include "ao_draw.h"
+#include "ao_draw_int.h"
+
+#define bound(val,max) do {			\
+		if (val < 0) {			\
+			val = 0;		\
+		}				\
+		if (val > max) {		\
+			val = max;		\
+		}				\
+	} while (0)
+
+void
+ao_rect(const struct ao_bitmap	*dst,
+	int16_t			x,
+	int16_t			y,
+	int16_t			width,
+	int16_t			height,
+	uint32_t		fill,
+	uint8_t			rop)
+{
+	int16_t	x2 = x + width;
+	int16_t y2 = y + height;
+
+	bound(x, dst->width);
+	bound(x2, dst->width);
+	bound(y, dst->height);
+	bound(y2, dst->height);
+
+	if (x < x2 && y < y2) {
+		ao_solid(ao_and(rop, fill),
+			 ao_xor(rop, fill),
+			 dst->base + y * dst->stride,
+			 dst->stride,
+			 x,
+			 x2 - x,
+			 y2 - y);
+	}
+}
+