EV3-G API Display (#410)

* EV3-G API Display

* EV3-G API Display - add text_grid()

* Bring back original image()

* Display: fix asserts in text_grid()

* Display: fix asserts in text_grid()

* Display: added doc strings

Author: dwalton76

ev3dev/display.py

@@ -31,6 +31,8 @@
 import os
 import mmap
 import ctypes
+import ev3dev.fonts as fonts
+from PIL import Image, ImageDraw
 from struct import pack
 import fcntl
 
@@ -179,14 +181,18 @@ def _map_fb_memory(fbfid, fix_info):
         )
 
 
-class Screen(FbMem):
+class Display(FbMem):
     """
     A convenience wrapper for the FbMem class.
     Provides drawing functions from the python imaging library (PIL).
     """
 
-    def __init__(self):
-        from PIL import Image, ImageDraw
+    GRID_COLUMNS = 22
+    GRID_COLUMN_PIXELS = 8
+    GRID_ROWS = 12
+    GRID_ROW_PIXELS = 10
+
+    def __init__(self, desc='Display'):
         FbMem.__init__(self)
 
         self._img = Image.new(
@@ -195,6 +201,10 @@ def __init__(self):
                 "white")
 
         self._draw = ImageDraw.Draw(self._img)
+        self.desc = desc
+
+    def __str__(self):
+        return self.desc
 
     @property
     def xres(self):
@@ -267,3 +277,120 @@ def update(self):
             self.mmap[:] = self._img_to_rgb565_bytes()
         else:
             raise Exception("Not supported")
+
+    def image_filename(self, filename, clear_screen=True, x1=0, y1=0, x2=None, y2=None):
+
+        if clear_screen:
+            self.clear()
+
+        filename_im = Image.open(filename)
+
+        if x2 is not None and y2 is not None:
+            return self._img.paste(filename_im, (x1, y1, x2, y2))
+        else:
+            return self._img.paste(filename_im, (x1, y1))
+
+    def line(self, clear_screen=True, x1=10, y1=10, x2=50, y2=50, line_color='black', width=1):
+        """
+        Draw a line from (x1, y1) to (x2, y2)
+        """
+
+        if clear_screen:
+            self.clear()
+
+        return self.draw.line((x1, y1, x2, y2), fill=line_color, width=width)
+
+    def circle(self, clear_screen=True, x=50, y=50, radius=40, fill_color='black', outline_color='black'):
+        """
+        Draw a circle of 'radius' centered at (x, y)
+        """
+
+        if clear_screen:
+            self.clear()
+
+        x1 = x - radius
+        y1 = y - radius
+        x2 = x + radius
+        y2 = y + radius
+
+        return self.draw.ellipse((x1, y1, x2, y2), fill=fill_color, outline=outline_color)
+
+    def rectangle(self, clear_screen=True, x=10, y=10, width=80, height=40, fill_color='black', outline_color='black'):
+        """
+        Draw a rectangle 'width x height' where the top left corner is at (x, y)
+        """
+
+        if clear_screen:
+            self.clear()
+
+        return self.draw.rectangle((x, y, width, height), fill=fill_color, outline=outline_color)
+
+    def point(self, clear_screen=True, x=10, y=10, point_color='black'):
+        """
+        Draw a single pixel at (x, y)
+        """
+
+        if clear_screen:
+            self.clear()
+
+        return self.draw.point((x, y), fill=point_color)
+
+    def text_pixels(self, text, clear_screen=True, x=0, y=0, text_color='black', font=None):
+        """
+        Display `text` starting at pixel (x, y).
+
+        The EV3 display is 178x128 pixels
+        - (0, 0) would be the top left corner of the display
+        - (89, 64) would be right in the middle of the display
+
+        'text_color' : PIL says it supports "common HTML color names". There
+        are 140 HTML color names listed here that are supported by all modern
+        browsers. This is probably a good list to start with.
+            https://www.w3schools.com/colors/colors_names.asp
+
+        'font' : can be any font displayed here
+            http://ev3dev-lang.readthedocs.io/projects/python-ev3dev/en/stable/other.html#bitmap-fonts
+        """
+
+        if clear_screen:
+            self.clear()
+
+        if font is not None:
+            assert font in fonts.available(), "%s is an invalid font" % font
+            return self.draw.text((x, y), text, fill=text_color, font=fonts.load(font))
+        else:
+            return self.draw.text((x, y), text, fill=text_color)
+
+    def text_grid(self, text, clear_screen=True, x=0, y=0, text_color='black', font=None):
+        """
+        Display 'text' starting at grid (x, y)
+
+        The EV3 display can be broken down in a grid that is 22 columns wide
+        and 12 rows tall. Each column is 8 pixels wide and each row is 10
+        pixels tall.
+
+        'text_color' : PIL says it supports "common HTML color names". There
+        are 140 HTML color names listed here that are supported by all modern
+        browsers. This is probably a good list to start with.
+            https://www.w3schools.com/colors/colors_names.asp
+
+        'font' : can be any font displayed here
+            http://ev3dev-lang.readthedocs.io/projects/python-ev3dev/en/stable/other.html#bitmap-fonts
+        """
+
+        assert 0 <= x < Display.GRID_COLUMNS,\
+            "grid columns must be between 0 and %d, %d was requested" %\
+            ((Display.GRID_COLUMNS - 1, x))
+
+        assert 0 <= y < Display.GRID_ROWS,\
+            "grid rows must be between 0 and %d, %d was requested" %\
+            ((Display.GRID_ROWS - 1), y)
+
+        return self.text_pixels(text, clear_screen,
+                                x * Display.GRID_COLUMN_PIXELS,
+                                y * Display.GRID_ROW_PIXELS,
+                                text_color, font)
+
+    def reset_screen(self):
+        self.clear()
+        self.update()