writer.py: support framebuf_utils.mpy.

writer/WRITER.md

@@ -44,14 +44,15 @@ Labels and Fields (from nanogui.py).
   1.3 [Fonts](./WRITER.md#11-fonts)  
  2. [Writer and CWriter classes](./WRITER.md#2-writer-and-cwriter-classes)  
   2.1 [The Writer class](./WRITER.md#21-the-writer-class) For monochrome displays.  
-   2.1.1 [Static Method](./WRITER.md#211-static-method)  
-   2.1.2.[Constructor](./WRITER.md#212-constructor)  
-   2.1.3 [Methods](./WRITER.md#213-methods)  
+        2.1.1 [Static Method](./WRITER.md#211-static-method)  
+        2.1.2.[Constructor](./WRITER.md#212-constructor)  
+        2.1.3 [Methods](./WRITER.md#213-methods)  
   2.2 [The CWriter class](./WRITER.md#22-the-cwriter-class) For colour displays
   and for upside-down rendering.  
-   2.2.1 [Static Method](./WRITER.md#221-static-method)  
-   2.2.2 [Constructor](./WRITER.md#222-constructor)  
-   2.2.3 [Methods](./WRITER.md#223-methods)  
+        2.2.1 [Static Method](./WRITER.md#221-static-method)  
+        2.2.2 [Constructor](./WRITER.md#222-constructor)  
+        2.2.3 [Methods](./WRITER.md#223-methods)  
+        2.2.4 [A performance boost](./WRITER.md#224-a-performance-boost)  
  3. [Notes](./WRITER.md#4-notes)
 
 ###### [Main README](../README.md)
@@ -80,9 +81,7 @@ very simple version still exists as `writer_minimal.py`.
 
 Tests and demos assume a 128*64 SSD1306 OLED display connected via I2C or SPI.
 Wiring is specified in `ssd1306_setup.py`. Edit this to use a different bus or
-for a non-Pyboard target. At the time of writing the default of software I2C
-should be used: the official SSD1306 driver is not compatible with hardware I2C
-(see [Notes](./WRITER.md#3-notes)).
+for a non-Pyboard target.
 
 ## 1.2 Files
 
@@ -251,6 +250,28 @@ The `printstring` method works as per the base class except that the string is
 rendered in foreground color on background color (or reversed if `invert` is
 `True`).
 
+### 2.2.4 A performance boost
+
+Rendering performance of the `Cwriter` class is slow: owing to limitations in
+the `frmebuf.blit` method the class renders glyphs one pixel at a time. There
+is a way to improve performance. It was developed by Jim Mussared (@jimmo) and
+consists of a native C module.
+
+On import, `writer.py` attempts to import a module `framebuf_utils`. If this
+succeeds (i.e. a file `framebuf_utils.mpy` is found), glyph rendering will be
+substantially faster.
+
+The directory `framebuf_utils` contains the source file, the makefile and a
+version of `framebuf_utils.mpy` for `armv7m` architecture (e.g. Pyboards).
+ESP32 users with access to the development toolchain should change `Makefile`
+to specify the `xtensawin` arch and rebuild.
+
+It is suggested that moving the appropriate `framebuf_utils.mpy` to the target
+is only done once the basic operation of an application has been verified.
+
+The native module does not support the `CWriter.invert_display` option. If this
+is used, the presence of the native module will have no effect.
+
 # 3. Notes
 
 Possible future enhancements:
@@ -259,9 +280,4 @@ Possible future enhancements:
  2. Extend word wrapping to cases where words are separated by tabs or hyphens.
  3. An asynchronous version.
 
-As stated above the official SSD1306 driver is incompatible with hardware I2C
-and this problem cannot efficiently be fixed. [PR4020](https://github.com/micropython/micropython/pull/4020)
-proposes an enhncement which will facilitate an improved SSD1306 driver capable
-of using hard or soft I2C.
- 
 ###### [Contents](./WRITER.md#contents)

writer/framebuf_utils/Makefile

@@ -0,0 +1,13 @@
+# Location of top-level MicroPython directory
+MPY_DIR = ../../..
+
+# Name of module (different to built-in framebuf so it can coexist)
+MOD = framebuf_utils
+
+# Source files (.c or .py)
+SRC = framebuf_utils.c
+
+# Architecture to build for (x86, x64, armv7m, xtensa, xtensawin)
+ARCH = armv7m
+
+include $(MPY_DIR)/py/dynruntime.mk

writer/framebuf_utils/framebuf_utils.c

@@ -0,0 +1,118 @@
+#define MICROPY_PY_FRAMEBUF (1)
+
+#include "py/dynruntime.h"
+
+#if !defined(__linux__)
+void *memset(void *s, int c, size_t n) {
+    return mp_fun_table.memset_(s, c, n);
+}
+#endif
+
+// Match definition from modframebuf.c.
+typedef struct _mp_obj_framebuf_t {
+    mp_obj_base_t base;
+    mp_obj_t buf_obj; // need to store this to prevent GC from reclaiming buf
+    void *buf;
+    uint16_t width, height, stride;
+    uint8_t format;
+} mp_obj_framebuf_t;
+
+// This points to the real mp_type_framebuf from modframebuf.c.
+mp_obj_type_t *mp_type_framebuf;
+
+// Unbound FrameBuffer.pixel function.
+mp_obj_t framebuf_pixel_obj;
+
+// render(dest, src, x, y, fgcolor, bgcolor=0)
+STATIC mp_obj_t framebuf_render(size_t n_args, const mp_obj_t *args) {
+    // Convert dest/src subclass to the native mp_type_framebuf.
+    mp_obj_t dest_in = mp_obj_cast_to_native_base(args[0], MP_OBJ_FROM_PTR(mp_type_framebuf));
+    if (dest_in == MP_OBJ_NULL) {
+        mp_raise_TypeError(NULL);
+    }
+    mp_obj_framebuf_t *dest = MP_OBJ_TO_PTR(dest_in);
+
+    mp_obj_t source_in = mp_obj_cast_to_native_base(args[1], MP_OBJ_FROM_PTR(mp_type_framebuf));
+    if (source_in == MP_OBJ_NULL) {
+        mp_raise_TypeError(NULL);
+    }
+    mp_obj_framebuf_t *source = MP_OBJ_TO_PTR(source_in);
+
+    // Pre-build args list for calling framebuf.pixel().
+    mp_obj_t args_getpixel[3] = { source_in };
+    mp_obj_t args_setpixel[4] = { dest_in };
+
+    mp_int_t x = mp_obj_get_int(args[2]);
+    mp_int_t y = mp_obj_get_int(args[3]);
+    mp_int_t fgcol = mp_obj_get_int(args[4]);
+    mp_int_t bgcol = 0;
+    if (n_args > 5) {
+        bgcol = mp_obj_get_int(args[5]);
+    }
+
+    if (
+        (x >= dest->width) ||
+        (y >= dest->height) ||
+        (-x >= source->width) ||
+        (-y >= source->height)
+        ) {
+        // Out of bounds, no-op.
+        return mp_const_none;
+    }
+
+    // Clip.
+    int x0 = MAX(0, x);
+    int y0 = MAX(0, y);
+    int x1 = MAX(0, -x);
+    int y1 = MAX(0, -y);
+    int x0end = MIN(dest->width, x + source->width);
+    int y0end = MIN(dest->height, y + source->height);
+
+    for (; y0 < y0end; ++y0) {
+        int cx1 = x1;
+        for (int cx0 = x0; cx0 < x0end; ++cx0) {
+            // source.pixel(cx1, y1)
+            args_getpixel[1] = MP_OBJ_NEW_SMALL_INT(cx1);
+            args_getpixel[2] = MP_OBJ_NEW_SMALL_INT(y1);
+            uint32_t col = mp_obj_get_int(mp_call_function_n_kw(framebuf_pixel_obj, 3, 0, args_getpixel));
+
+            // dest.pixel(cx0, y0, bgcol/fgcol)
+            args_setpixel[1] = MP_OBJ_NEW_SMALL_INT(cx0);
+            args_setpixel[2] = MP_OBJ_NEW_SMALL_INT(y0);
+            if (col == 0) {
+                args_setpixel[3] = MP_OBJ_NEW_SMALL_INT(bgcol);
+            } else {
+                args_setpixel[3] = MP_OBJ_NEW_SMALL_INT(fgcol);
+            }
+
+            mp_call_function_n_kw(framebuf_pixel_obj, 4, 0, args_setpixel);
+
+            ++cx1;
+        }
+        ++y1;
+    }
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(framebuf_render_obj, 5, 6, framebuf_render);
+
+mp_obj_t mpy_init(mp_obj_fun_bc_t *self, size_t n_args, size_t n_kw, mp_obj_t *args) {
+    MP_DYNRUNTIME_INIT_ENTRY
+
+    // import framebuf
+    mp_obj_t modframebuf = mp_import_name(MP_QSTR_framebuf, mp_const_none, 0);
+    // mp_type_framebuf = framebuf.FrameBuffer
+    mp_type_framebuf = MP_OBJ_TO_PTR(mp_load_attr(modframebuf, MP_QSTR_FrameBuffer));
+
+    // framebuf_pixel_obj = mp_type_framebuf.pixel
+    mp_obj_t dest[2];
+    mp_load_method(MP_OBJ_FROM_PTR(mp_type_framebuf), MP_QSTR_pixel, dest);
+
+    // The resulting reference might be heap allocated due to MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG.
+    // So store a reference to it in globals so the GC knows about it.
+    framebuf_pixel_obj = dest[0];
+    mp_store_global(MP_QSTR_pixel, framebuf_pixel_obj);
+
+    mp_store_global(MP_QSTR_render, MP_OBJ_FROM_PTR(&framebuf_render_obj));
+
+    MP_DYNRUNTIME_INIT_EXIT
+}

writer/framebuf_utils/test.py

@@ -0,0 +1,32 @@
+import framebuf_utils
+import framebuf
+
+# Emulate a display driver subclassed from framebuf.FrameBuffer
+class Display(framebuf.FrameBuffer):
+    def __init__(self):
+        self.buf = bytearray(4 * 4 * 2)
+        super().__init__(self.buf, 4, 4, framebuf.RGB565)
+
+device = Display()
+
+def foo():
+    width = 2  # Glyph dimensions
+    height = 2
+    i = 0
+
+    while True:
+        buf = bytearray(width * height // 8 + 1)
+        fbc = framebuf.FrameBuffer(buf, width, height, framebuf.MONO_HMSB)
+        fbc.pixel(0, 0, 1)
+        print(buf)
+
+        framebuf_utils.render(device, fbc, 1, 1, 0x5555, 0xaaaa)
+        print(device.buf)
+        print(device.pixel(0, 0))
+        print(device.pixel(1, 1))
+        print(device.pixel(2, 1))
+
+        i += 1
+        print(i)
+
+foo()

writer/writer.py

@@ -1,10 +1,10 @@
 # writer.py Implements the Writer class.
-# V0.3 Peter Hinch 11th Aug 2018
+# V0.35 Peter Hinch Sept 2020 Fast rendering option for color displays
 # Handles colour, upside down diplays, word wrap and tab stops
 
 # The MIT License (MIT)
 #
-# Copyright (c) 2016 Peter Hinch
+# Copyright (c) 2016-2020 Peter Hinch
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -32,7 +32,18 @@
 # Using CWriter's slow rendering: _printchar 9.5ms typ, 13.5ms max.
 # Using Writer's fast rendering: _printchar 115μs min 480μs typ 950μs max.
 
+# CWriter on Pyboard D SF2W at standard clock rate
+# Fast method 500-600μs typical, up to 1.07ms on larger fonts
+# Revised fast method 691μs avg, up to 2.14ms on larger fonts
+# Slow method 2700μs typical, up to 11ms on larger fonts
+
 import framebuf
+try:
+    from framebuf_utils import render
+    fast_mode = True
+except ImportError:
+    fast_mode = False
+from uctypes import bytearray_at, addressof
 
 class DisplayState():
     def __init__(self):
@@ -264,19 +275,24 @@ class CWriter(Writer):
             self.fgcolor = fgcolor
         self.def_bgcolor = self.bgcolor
         self.def_fgcolor = self.fgcolor
+        fm = fast_mode and not self.usd
+        self._printchar = self._pchfast if fm else self._pchslow
+        verbose and print('Render {} using fast mode'.format('is' if fm else 'not'))
 
-    def setcolor(self, fgcolor=None, bgcolor=None):
-        if fgcolor is None and bgcolor is None:
-            self.fgcolor = self.def_fgcolor
-            self.bgcolor = self.def_bgcolor
-        else:
-            if fgcolor is not None:
-                self.fgcolor = fgcolor
-            if bgcolor is not None:
-                self.bgcolor = bgcolor
-        return self.fgcolor, self.bgcolor
+    def _pchfast(self, char, invert=False, recurse=False):
+        s = self._getstate()
+        self._get_char(char, recurse)
+        if self.glyph is None:
+            return  # All done
+        buf = bytearray_at(addressof(self.glyph), len(self.glyph))
+        fbc = framebuf.FrameBuffer(buf, self.char_width, self.char_height, self.map)
+        fgcolor = self.bgcolor if invert else self.fgcolor
+        bgcolor = self.fgcolor if invert else self.bgcolor
+        render(self.device, fbc, s.text_col, s.text_row, fgcolor, bgcolor)
+        s.text_col += self.char_width
+        self.cpos += 1
 
-    def _printchar(self, char, invert=False, recurse=False):
+    def _pchslow(self, char, invert=False, recurse=False):
         s = self._getstate()
         self._get_char(char, recurse)
         if self.glyph is None:
@@ -309,3 +325,14 @@ class CWriter(Writer):
                 break
         s.text_col += -char_width if usd else char_width
         self.cpos += 1
+
+    def setcolor(self, fgcolor=None, bgcolor=None):
+        if fgcolor is None and bgcolor is None:
+            self.fgcolor = self.def_fgcolor
+            self.bgcolor = self.def_bgcolor
+        else:
+            if fgcolor is not None:
+                self.fgcolor = fgcolor
+            if bgcolor is not None:
+                self.bgcolor = bgcolor
+        return self.fgcolor, self.bgcolor