shithub: slug

Download patch

ref: f5e46949cee9ce3053d87b38f3b9e36dc2d9af1b
parent: 0013776c4e5e6cdb9da6b90157bd58da960c872a
author: phil9 <telephil9@gmail.com>
date: Wed Nov 30 03:27:24 EST 2022 

double-buffered drawing

	drawing is now done on a dedicated Image which is drawn on screen
	at the end of the setup() and draw() calls.


--- a/a.h
+++ b/a.h
@@ -16,8 +16,10 @@
 	Image *i;
 };
 
+void	drawcanvas(void);
 void	initstate(void);
 void	registerfuncs(lua_State*);
 
 Image*	getcolor(int);
 
+extern Image* canvas;
--- a/api.c
+++ b/api.c
@@ -1,5 +1,6 @@
 #include "a.h"
 
+Image *canvas;
 int nostroke;
 Image *stroke;
 int strokewidth;
@@ -9,6 +10,10 @@
 void
 initstate(void)
 {
+	Rectangle r;
+
+	r = rectsubpt(screen->r, screen->r.min);
+	canvas = allocimage(display, r, screen->chan, 0, DNofill);
 	nostroke = 0;
 	stroke = display->black;
 	strokewidth = 1;
@@ -16,6 +21,13 @@
 	fill = display->white;
 }
 
+void
+drawcanvas(void)
+{
+	draw(screen, screen->r, canvas, nil, ZP);
+	flushimage(display, 1);
+}
+
 int
 cbackground(lua_State *L)
 {
@@ -24,7 +36,7 @@
 
 	n = luaL_checkinteger(L, 1);
 	i = getcolor(n);
-	draw(screen, screen->r, i, nil, ZP);
+	draw(canvas, canvas->r, i, nil, ZP);
 	return 0;
 }
 
@@ -85,10 +97,10 @@
 	y1 = luaL_checkinteger(L, 2);
 	x2 = luaL_checkinteger(L, 3);
 	y2 = luaL_checkinteger(L, 4);
-	p1 = addpt(screen->r.min, Pt(x1, y1));
-	p2 = addpt(screen->r.min, Pt(x2, y2));
+	p1 = Pt(x1, y1);
+	p2 = Pt(x2, y2);
 	if(!nostroke)
-		line(screen, p1, p2, 0, 0, strokewidth, stroke, ZP);
+		line(canvas, p1, p2, 0, 0, strokewidth, stroke, ZP);
 	return 0;
 }
 
@@ -102,13 +114,13 @@
 	x = luaL_checkinteger(L, 1);
 	y = luaL_checkinteger(L, 2);
 	w = luaL_checkinteger(L, 3);
-	p1 = addpt(screen->r.min, Pt(x, y));
+	p1 = Pt(x, y);
 	p2 = addpt(p1, Pt(w, w));
 	r = Rpt(p1, p2);
 	if(!nofill)
-		draw(screen, r, fill, nil, ZP);
+		draw(canvas, r, fill, nil, ZP);
 	if(!nostroke)
-		border(screen, r, strokewidth, stroke, ZP);
+		border(canvas, r, strokewidth, stroke, ZP);
 	return 0;
 }
 
@@ -123,13 +135,13 @@
 	y = luaL_checkinteger(L, 2);
 	w = luaL_checkinteger(L, 3);
 	h = luaL_checkinteger(L, 4);
-	p1 = addpt(screen->r.min, Pt(x, y));
+	p1 = Pt(x, y);
 	p2 = addpt(p1, Pt(w, h));
 	r = Rpt(p1, p2);
 	if(!nofill)
-		draw(screen, r, fill, nil, ZP);
+		draw(canvas, r, fill, nil, ZP);
 	if(!nostroke)
-		border(screen, r, strokewidth, stroke, ZP);
+		border(canvas, r, strokewidth, stroke, ZP);
 	return 0;
 }
 
@@ -142,11 +154,11 @@
 	x = luaL_checkinteger(L, 1);
 	y = luaL_checkinteger(L, 2);
 	a = luaL_checkinteger(L, 3);
-	p = addpt(screen->r.min, Pt(x, y));
+	p = Pt(x, y);
 	if(!nofill)
-		fillellipse(screen, p, a, a, fill, ZP);
+		fillellipse(canvas, p, a, a, fill, ZP);
 	if(!nostroke)
-		ellipse(screen, p, a, a, strokewidth, stroke, ZP);
+		ellipse(canvas, p, a, a, strokewidth, stroke, ZP);
 	return 0;
 }
 
@@ -160,11 +172,11 @@
 	y = luaL_checkinteger(L, 2);
 	a = luaL_checkinteger(L, 3);
 	b = luaL_checkinteger(L, 4);
-	p = addpt(screen->r.min, Pt(x, y));
+	p = Pt(x, y);
 	if(!nofill)
-		fillellipse(screen, p, a, b, fill, ZP);
+		fillellipse(canvas, p, a, b, fill, ZP);
 	if(!nostroke)
-		ellipse(screen, p, a, b, strokewidth, stroke, ZP);
+		ellipse(canvas, p, a, b, strokewidth, stroke, ZP);
 	return 0;
 }
 
@@ -180,11 +192,11 @@
 	b = luaL_checkinteger(L, 4);
 	c = luaL_checkinteger(L, 5);
 	d = luaL_checkinteger(L, 6);
-	p = addpt(screen->r.min, Pt(x, y));
+	p = Pt(x, y);
 	if(!nofill)
-		fillarc(screen, p, a, b, fill, ZP, c, d);
+		fillarc(canvas, p, a, b, fill, ZP, c, d);
 	if(!nostroke)
-		arc(screen, p, a, b, strokewidth, stroke, ZP, c, d);
+		arc(canvas, p, a, b, strokewidth, stroke, ZP, c, d);
 	return 0;
 }
 
--- a/slug.c
+++ b/slug.c
@@ -11,7 +11,7 @@
 	if(!lua_isfunction(L, -1))
 		return;
 	lua_call(L, 0, 0);
-	flushimage(display, 1);
+	drawcanvas();
 }
 
 void
@@ -21,7 +21,7 @@
 	if(!lua_isfunction(L, -1))
 		return;
 	lua_call(L, 0, 0);
-	flushimage(display, 1);
+	drawcanvas();
 }
 
 Image*