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, 75 insertions, 0 deletions

diff --git a/src/draw/ao_copy.c b/src/draw/ao_copy.c
new file mode 100644
index 00000000..47067bb8
--- /dev/null
+++ b/src/draw/ao_copy.c
@@ -0,0 +1,75 @@
+/*
+ * 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,other) do {		\
+		if (val < 0) {			\
+			other -= val;		\
+			val = 0;		\
+		}				\
+		if (val > max) {		\
+			other -= (val - max);	\
+			val = max;		\
+		}				\
+	} while (0)
+
+#define bound2(a, max_a, b, max_b) do {		\
+		bound(a, max_a, b);		\
+		bound(b, max_b, a);		\
+	} while (0)
+
+void
+ao_copy(const struct ao_bitmap	*dst,
+	int16_t			dst_x,
+	int16_t			dst_y,
+	int16_t			width,
+	int16_t			height,
+	const struct ao_bitmap	*src,
+	int16_t			src_x,
+	int16_t			src_y,
+	uint8_t			rop)
+{
+	int16_t		dst_x2 = dst_x + width, dst_y2 = dst_y + height;
+	int16_t		src_x2 = src_x + width, src_y2 = src_y + height;
+	uint8_t		reverse = 0;
+	uint8_t		upsidedown = 0;
+
+	bound2(dst_x, dst->width, src_x, src->width);
+	bound2(dst_x2, dst->width, src_x2, src->width);
+	bound2(dst_y, dst->height, src_y, src->height);
+	bound2(dst_y2, dst->height, src_y2, src->height);
+
+	if (dst == src) {
+		reverse = (dst_x > src_x);
+		upsidedown = (dst_y > src_y);
+	}
+
+	if (dst_x < dst_x2 && dst_y < dst_y2) {
+		ao_blt(src->base + src_y * src->stride,
+		       src->stride,
+		       src_x,
+		       dst->base + dst_y * dst->stride,
+		       dst->stride,
+		       dst_x,
+		       dst_x2 - dst_x,
+		       dst_y2 - dst_y,
+		       rop,
+		       reverse,
+		       upsidedown);
+	}
+}
+