wasp: Add a simple font renderer

1 files changed, 91 insertions, 0 deletions

diff --git a/wasp/draw565.py b/wasp/draw565.py
new file mode 100644
index 0000000..4c5f25f
--- /dev/null
+++ b/wasp/draw565.py
@@ -0,0 +1,91 @@
+import fonts.sans24
+import micropython
+
+@micropython.viper
+def bitblit(bitbuf, pixels, bgfg: int, count: int):
+    mv = ptr8(bitbuf)
+    px = ptr8(pixels)
+
+    bghi = (bgfg >> 24) & 0xff
+    bglo = (bgfg >> 16) & 0xff
+    fghi = (bgfg >>  8) & 0xff
+    fglo = (bgfg      ) & 0xff
+
+    bitselect = 0x80
+    pxp = 0
+    mvp = 0
+
+    for bit in range(count):
+        # Draw the pixel
+        active = px[pxp] & bitselect
+        mv[mvp] = fghi if active else bghi
+        mvp += 1
+        mv[mvp] = fglo if active else bglo
+        mvp += 1
+
+        # Advance to the next bit
+        bitselect >>= 1
+        if not bitselect:
+            bitselect = 0x80
+            pxp += 1
+
+def bounding_box(s, font):
+    w = 0
+    for ch in s:
+        (_, h, wc) = font.get_ch(ch)
+        w += wc + 1
+
+    return (w, h)
+
+def draw_glyph(display, glyph, x, y, bgfg):
+    (px, h, w) = glyph
+
+    buf = memoryview(display.linebuffer)[0:2*(w+1)]
+    bytes_per_row = (w + 7) // 8
+
+    for row in range(h):
+        bitblit(buf, px[row*bytes_per_row:], bgfg, w)
+        buf[2*w] = 0
+        buf[2*w + 1] = 0
+        display.rawblit(buf, x, y+row, w+1, 1)
+
+class Draw565(object):
+    def __init__(self, display):
+        self._display = display
+        self.set_color(0xffff)
+        self.set_font(fonts.sans24)
+
+    def set_color(self, color, bg=0):
+        self._bgfg = (bg << 16) + color
+
+    def set_font(self, font):
+        self._font = font
+
+    def string(self, s, x, y, width=None):
+        display = self._display
+        bgfg = self._bgfg
+        font = self._font
+
+        if width:
+            (w, h) = bounding_box(s, font)
+            leftpad = (width - w) // 2
+            rightpad = width - w - leftpad
+            display.fill(0, x, y, leftpad, h)
+            x += leftpad
+
+        for ch in s:
+            glyph = font.get_ch(ch)
+            draw_glyph(display, glyph, x, y, bgfg)
+            x += glyph[2] + 1
+
+        if width:
+            display.fill(0, x, y, rightpad, h)
+
+#import watch
+#draw = Draw(watch.display)
+#
+#def test():
+#    watch.display.poweron()
+#    watch.backlight.set(2)
+#
+#    draw.string('10-Jan-2020', 0, 24, width=240)