add option column set support to blitImage, needed for Blueprint single-buffer code

Author: gfwilliams

libs/pipboy/jswrap_pipboy.c

@@ -1971,12 +1971,14 @@ are for previous pixels
 * `options.ydiff` (default 1) is the y difference used when averaging rows above and below
 * `options.y1` (default 0) is the min row to start updating
 * `options.y2` (default 319) is the max row to start updating
+* `options.x` (default 0) is the start column to update
+* `options.w` (default 480) is number of columns to update
 */
 
 void jswrap_pb_blitScreen(JsVar *image, JsVar *options) {
   uint32_t filter = 0x00010123;
   int yoffset = 0, ydiff = 1;
-  int y1 = 0, y2 = 319;
+  int xoffset = 0, y1 = 0, y2 = 319, w = 0;
   if (jsvIsObject(options)) {
     uint32_t v = (uint32_t)jsvGetIntegerAndUnLock(jsvObjectGetChildIfExists(options, "filter"));
     if (v) filter = v;
@@ -1988,21 +1990,25 @@ void jswrap_pb_blitScreen(JsVar *image, JsVar *options) {
     y1 = jsvGetIntegerAndUnLock(jsvObjectGetChildIfExists(options, "y1"));
     v = jsvGetIntegerAndUnLock(jsvObjectGetChildIfExists(options, "y2"));
     if (v) y2=v;
+    xoffset = jsvGetIntegerAndUnLock(jsvObjectGetChildIfExists(options, "x"));
+    w = jsvGetIntegerAndUnLock(jsvObjectGetChildIfExists(options, "w"));
   }
   if (y1<0) y1=0;
   if (y1>=319) y1=319;
   if (y2>=319) y2=319;
   if (y2<y1) y2=y1;
+  if (w<=0) w=480;
+  if (w&3) return jsExceptionHere(JSET_ERROR, "Width must be multiple of 4");
   scanlinePos = ((long long)(jshGetMillisecondsFromTime(jshGetSystemTime())*(480/4000.0)) % 640LL) - 110;
 
   JsGraphics *gfx = &graphicsInternal;
   GfxDrawImageInfo img;
   if (!_jswrap_graphics_parseImage(gfx, image, 0, &img))
     return;
 
-  if (img.width!=480 || img.height!=320 || img.bpp!=2) {
+  if (img.width!=w || img.height!=320 || img.bpp!=2) {
     _jswrap_graphics_freeImageInfo(&img);
-    return jsExceptionHere(JSET_ERROR, "Image must be 480x320x2bpp");
+    return jsExceptionHere(JSET_ERROR, "Image must be %dx320x2bpp", w);
   }
   JSV_GET_AS_CHAR_ARRAY_NO_ERROR( imgPtr, imgLen, img.buffer );
   if (!imgPtr) {
@@ -2021,19 +2027,20 @@ void jswrap_pb_blitScreen(JsVar *image, JsVar *options) {
   }
 
   uint16_t palette[16];
+  int w4 = w>>2; // 480 pixels, 2bpp = 120 bytes per row
   const uint8_t *row1 = &imgPtr[0], *row2, *row3;
   yoffset += 320; // to avoid negative values
-  lcdFSMC_blitStart(gfx, 0,y1, 480,y2+1-y1);
+  lcdFSMC_blitStart(gfx, xoffset,y1, w,y2+1-y1);
   for (int y=y1;y<=y2;y++) {
     // work out row pointers
-    row1 = &imgPtr[((y+yoffset-ydiff)%320)*120]; // 480 pixels, 2bpp = 120 bytes per row
-    row2 = &imgPtr[((y+yoffset)%320)*120]; // 480 pixels, 2bpp = 120 bytes per row
-    row3 = &imgPtr[((y+yoffset+ydiff)%320)*120]; // 480 pixels, 2bpp = 120 bytes per row
+    row1 = &imgPtr[((y+yoffset-ydiff)%320)*w4];
+    row2 = &imgPtr[((y+yoffset)%320)*w4];
+    row3 = &imgPtr[((y+yoffset+ydiff)%320)*w4];
     getPaletteForLine4bpp(y, palette);
 
     uint32_t pixels = 0;
     uint8_t pixelUp, pixelDn;
-    for (int x=0;x<120;x++) {
+    for (int x=0;x<w4;x++) {
       uint8_t p4up = *(row1++);
       uint8_t p4 = *(row2++);
       uint8_t p4dn = *(row3++);