From 277e65ddddebb5aea0196239be835a6d3e1d1b2c Mon Sep 17 00:00:00 2001
From: tehn <tehn@monome.org>
Date: Thu, 23 Mar 2023 22:38:00 +0000
Subject: [PATCH] export png

---
 lua/core/screen.lua          |  4 ++++
 matron/src/hardware/screen.c | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/lua/core/screen.lua b/lua/core/screen.lua
index 7903a3add..d4de20c32 100644
--- a/lua/core/screen.lua
+++ b/lua/core/screen.lua
@@ -309,6 +309,10 @@ _norns.screen_circle = function(x, y, r)
   _norns.screen_arc(x, y, r, 0, math.pi*2)
 end
 
+--- export png
+-- @param filename: saved to dust/data/(script)/(filename).png
+Screen.export_png = function(filename) _norns.screen_export_png(norns.state.data..filename..'.png') end
+
 --- display png
 -- @param filename
 -- @tparam number x x position
diff --git a/matron/src/hardware/screen.c b/matron/src/hardware/screen.c
index d0cf86e04..6eaf43d15 100644
--- a/matron/src/hardware/screen.c
+++ b/matron/src/hardware/screen.c
@@ -396,7 +396,38 @@ double *screen_text_extents(const char *s) {
 
 extern void screen_export_png(const char *s) {
     CHECK_CR
-    cairo_surface_write_to_png(surface, s);
+    static cairo_surface_t *png;
+    static cairo_t *temp; // for bg fill
+    // width = 640 (128*4 pixels with 64 pixel black border)
+    // hieght = 384 (64*4 pixels plus border) 
+    png = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 640, 384);
+    temp = cairo_create(png);
+    // fill
+    cairo_set_source_rgb(temp, 0, 0, 0);
+    cairo_rectangle(temp, 0, 0, 640, 384);
+    cairo_fill(temp);
+    // copy big pixles
+    uint32_t *src = (uint32_t *)cairo_image_surface_get_data(surface);
+    uint32_t *dst = (uint32_t *)cairo_image_surface_get_data(png);
+    if (!src || !dst) return;
+    dst += 64 + 640*64;
+    for(int y=0;y<64;y++) {
+        for(int x=0;x<128;x++) {
+            // FIXME: needs some sort of gamma correction?
+            uint32_t p = *src++ | 0xFF000000; // FF for alpha
+            for(int xx=0;xx<4;xx++) {
+                *(dst+1920) = p;
+                *(dst+1280) = p;
+                *(dst+640) = p;
+                *dst++ = p;
+            }
+        }
+        dst += 640*4 - 128*4;
+    }
+    // cleanup
+    cairo_destroy(temp);
+    cairo_surface_write_to_png(png, s);
+    cairo_surface_destroy((cairo_surface_t *)png);
 }
 
 void screen_display_png(const char *filename, double x, double y) {