fix(i1): fix compiler and runtime issues with I1 rendering (#6714)

Co-authored-by: Liam <30486941+liamHowatt@users.noreply.github.com>

docs/porting/display.rst

@@ -136,7 +136,6 @@ or anything else to optimize while the waiting for flush.
 If ``flush_wait_cb`` is not set, LVGL assume that `lv_display_flush_ready`
 is used.
 
-
 Rotation
 --------
 
@@ -173,7 +172,7 @@ The default color format of the display is set according to :c:macro:`LV_COLOR_D
 - :c:macro:`LV_COLOR_DEPTH` ``24``: RGB888 (3 bytes/pixel)
 - :c:macro:`LV_COLOR_DEPTH` ``16``: RGB565 (2 bytes/pixel)
 - :c:macro:`LV_COLOR_DEPTH` ``8``: L8 (1 bytes/pixel)
-- :c:macro:`LV_COLOR_DEPTH` ``1``: I1 (1 bit/pixel) Only support for horizontal mapped buffers.
+- :c:macro:`LV_COLOR_DEPTH` ``1``: I1 (1 bit/pixel) Only support for horizontal mapped buffers. See :refr:`monochrome` for more details:
 
 The ``color_format`` can be changed with
 :cpp:expr:`lv_display_set_color_depth(display, LV_COLOR_FORMAT_...)`.
@@ -205,6 +204,40 @@ to
 
 ``GGG BBBBB | RRRRR GGG``.
 
+.. _monochrome:
+
+Monochrome Displays
+-------------------
+
+LVGL supports rendering directly in a 1-bit format for monochrome displays.
+To enable it, set ``LV_COLOR_DEPTH 1`` or use :cpp:expr:`lv_display_set_color_format(display, LV_COLOR_FORMAT_I1)`.
+
+The :cpp:expr:`LV_COLOR_FORMAT_I1` format assumes that bytes are mapped to rows (i.e., the bits of a byte are written next to each other).
+The order of bits is MSB first, which means:
+
+.. code::
+
+             MSB           LSB
+   bits       7 6 5 4 3 2 1 0
+   pixels     0 1 2 3 4 5 6 7
+             Left         Right
+
+Ensure that the LCD controller is configured accordingly.
+
+Internally, LVGL rounds the redrawn areas to byte boundaries. Therefore, updated areas will:
+
+- Start on an ``Nx8`` coordinate.
+- End on an ``Nx8 - 1`` coordinate.
+
+When setting up the buffers for rendering (:cpp:func:`lv_display_set_buffers`), make the buffer 8 bytes larger.
+This is necessary because LVGL reserves 2 x 4 bytes in the buffer, as these are assumed to be used as a palette.
+
+To skip the palette, include the following line in your ``flush_cb`` function: ``px_map += 8``.
+
+As usual, monochrome displays support partial, full, and direct rendering modes as well.
+In full and direct modes, the buffer size should be large enough for the whole screen, meaning ``(horizontal_resolution x vertical_resolution / 8) + 8`` bytes.
+As LVGL can not handle fractional width make sure to round the horizontal resolution to 8-
+(For example 90 to 96)
 
 User data
 ---------

lv_conf_template.h

@@ -26,7 +26,7 @@
    COLOR SETTINGS
  *====================*/
 
-/*Color depth: 8 (A8), 16 (RGB565), 24 (RGB888), 32 (XRGB8888)*/
+/*Color depth: 1 (I1), 8 (L8), 16 (RGB565), 24 (RGB888), 32 (XRGB8888)*/
 #define LV_COLOR_DEPTH 16
 
 /*=========================

src/core/lv_refr.c

@@ -291,6 +291,13 @@ void lv_inv_area(lv_display_t * disp, const lv_area_t * area_p)
     suc = lv_area_intersect(&com_area, area_p, &scr_area);
     if(suc == false)  return; /*Out of the screen*/
 
+    if(disp->color_format == LV_COLOR_FORMAT_I1) {
+        /*Make sure that the X coordinates start and end on byte boundary.
+         *E.g. convert 11;27 to 8;31*/
+        com_area.x1 &= ~0x7; /*Round down: Nx8*/
+        com_area.x2 |= 0x7;    /*Round up: Nx8 - 1*/
+    }
+
     /*If there were at least 1 invalid area in full refresh mode, redraw the whole screen*/
     if(disp->render_mode == LV_DISPLAY_RENDER_MODE_FULL) {
         disp->inv_areas[0] = scr_area;
@@ -1101,10 +1108,11 @@ static void refr_obj(lv_layer_t * layer, lv_obj_t * obj)
 
 static uint32_t get_max_row(lv_display_t * disp, int32_t area_w, int32_t area_h)
 {
-    bool has_alpha = lv_color_format_has_alpha(disp->color_format);
+    lv_color_format_t cf = disp->color_format;
-    lv_color_format_t cf = has_alpha ? LV_COLOR_FORMAT_ARGB8888 : disp->color_format;
     uint32_t stride = lv_draw_buf_width_to_stride(area_w, cf);
-    int32_t max_row = (uint32_t)disp->buf_act->data_size / stride;
+    uint32_t overhead = LV_COLOR_INDEXED_PALETTE_SIZE(cf) * sizeof(lv_color32_t);
+
+    int32_t max_row = (uint32_t)(disp->buf_act->data_size - overhead) / stride;
 
     if(max_row > area_h) max_row = area_h;
 

src/draw/lv_draw_buf.c

@@ -168,9 +168,9 @@ void lv_draw_buf_clear(lv_draw_buf_t * draw_buf, const lv_area_t * a)
     if(lv_area_get_width(&a_clipped) <= 0) return;
     if(lv_area_get_height(&a_clipped) <= 0) return;
 
-    uint8_t px_size = lv_color_format_get_size(header->cf);
     uint8_t * buf = lv_draw_buf_goto_xy(draw_buf, a_clipped.x1, a_clipped.y1);
-    uint32_t line_length = lv_area_get_width(&a_clipped) * px_size;
+    uint8_t bpp = lv_color_format_get_bpp(header->cf);
+    uint32_t line_length = (lv_area_get_width(&a_clipped) * bpp + 7) >> 3;
     int32_t y;
     for(y = a_clipped.y1; y <= a_clipped.y2; y++) {
         lv_memzero(buf, line_length);

src/lv_conf_internal.h

@@ -83,7 +83,7 @@
    COLOR SETTINGS
  *====================*/
 
-/*Color depth: 8 (A8), 16 (RGB565), 24 (RGB888), 32 (XRGB8888)*/
+/*Color depth: 1 (I1), 8 (L8), 16 (RGB565), 24 (RGB888), 32 (XRGB8888)*/
 #ifndef LV_COLOR_DEPTH
     #ifdef CONFIG_LV_COLOR_DEPTH
         #define LV_COLOR_DEPTH CONFIG_LV_COLOR_DEPTH

src/misc/lv_color.h

@@ -171,7 +171,10 @@ typedef enum {
     LV_COLOR_FORMAT_YUV_END           = LV_COLOR_FORMAT_UYVY,
 
     /*Color formats in which LVGL can render*/
-#if LV_COLOR_DEPTH == 8
+#if LV_COLOR_DEPTH == 1
+    LV_COLOR_FORMAT_NATIVE            = LV_COLOR_FORMAT_I1,
+    LV_COLOR_FORMAT_NATIVE_WITH_ALPHA = LV_COLOR_FORMAT_I1,
+#elif LV_COLOR_DEPTH == 8
     LV_COLOR_FORMAT_NATIVE            = LV_COLOR_FORMAT_L8,
     LV_COLOR_FORMAT_NATIVE_WITH_ALPHA = LV_COLOR_FORMAT_AL88,
 #elif LV_COLOR_DEPTH == 16
@@ -183,7 +186,10 @@ typedef enum {
 #elif LV_COLOR_DEPTH == 32
     LV_COLOR_FORMAT_NATIVE            = LV_COLOR_FORMAT_XRGB8888,
     LV_COLOR_FORMAT_NATIVE_WITH_ALPHA = LV_COLOR_FORMAT_ARGB8888,
+#else
+#error "LV_COLOR_DEPTH should be 1, 8, 16, 24 or 32"
 #endif
+
 } lv_color_format_t;
 
 #define LV_COLOR_FORMAT_IS_ALPHA_ONLY(cf) ((cf) >= LV_COLOR_FORMAT_A1 && (cf) <= LV_COLOR_FORMAT_A8)