WIP: print text labels

README.md

@@ -97,9 +97,50 @@ The most important command is the `print` command and here is its CLI signature:
       --margin                        Print margin 
       --help                          Show this message and exit.
 
+## Printing text labels
+
+Some people may wish to automatically print text on their labels, rather
+than having to manually generate images first.  For this, `brother_pt` has
+the `text` command, which takes one or more lines of text to be printed as
+parameters (be sure to quote them in your shell!).  Consider something along
+the lines of:
+
+```
+$ brother_pt text --preview "This is a larger label, rendered to your screen only."
+$ brother_pt text "This is a larger label."
+$ brother_pt text -f 1 "This is a single line in a smaller font."
+$ brother_pt text "Here is one line" "and here is a second line."
+$ brother_pt text "A label printer" "prints three lines at a time, but" "only haiku."
+```
+
+You can also specify a font with `--font` and `--size` (both must be
+specified; `--font` takes a fontconfig-style pattern; consider something
+along the lines of `--font "Comic Sans MS:style=Bold" --size 40` to show
+that you are serious about your labels.)
+
+### Default fonts
+
+The default fonts selected are those distributed with the P-Touch software
+-- in particular, the Helsinki font family, which seems to be hinted well
+for black and white rendering on a P-Touch printer.  To install these
+fonts, either [install the latest P-Touch Editor software on your
+Mac](https://www.brother-usa.com/ptouch/ptouch-label-editor-software), or if
+on Linux, download the Windows version of the software and extract the fonts
+with something like:
+
+```
+$ cabextract pew67001.exe ptedit6.msi    # grab the installer bundle out of the InstallShield archive
+$ msiextract ptedit6.msi                 # unpack the installer bundle TO THE CURRENT DIRECTORY
+$ mv .\:Fonts/ Fonts
+$ mv ./Program\ Files/Brother/P-touch\ Editor/6/Fonts/* Fonts/
+$ cp Fonts/BRHE* ~/.local/share/fonts/   # install at least the Helsinki font set
+$ fc-cache -f -v                         # update fontconfig
+```
+
 ## Author
 
  * Thomas Reidemeister
+ * Text rendering support was contributed by Joshua Wise
 
 ## Contributing
 

brother_pt/__main__.py

@@ -15,9 +15,12 @@
 """
 import argparse
 
+import PIL.ImageOps
+
 from brother_pt import VERSION
 from .printer import *
-
+from .cmd import *
+from .font import *
 
 def show_status(serial):
     printers = find_printers(serial)
@@ -27,6 +30,7 @@ def show_status(serial):
     found_printer = BrotherPt(printers[0].serial_number)
     print("%s %s (%s):" % (printers[0].manufacturer, printers[0].product, printers[0].serial_number))
     print(" + Media width: %dmm" % found_printer.media_width)
+    print("                (%dpx)" % MediaWidthToTapeMargin.to_print_width(found_printer.media_width))
     print(" + Media type : %s" % found_printer.media_type.name)
     print(" + Tape color : %s" % found_printer.tape_color.name)
     print(" + Text color : %s" % found_printer.text_color.name)
@@ -85,6 +89,80 @@ def do_print(args):
     return 0
 
 
+def do_text(args):
+    printers = find_printers(args.printer)
+    if len(printers) == 0:
+        print("No supported printers found, make sure the device is switched on", file=sys.stderr)
+        return 1
+
+    found_printer = BrotherPt(printers[0].serial_number)
+    required_height = MediaWidthToTapeMargin.to_print_width(found_printer.media_width)
+
+    FONT_DEFAULTS = [
+        ( "Helsinki Narrow:style=Bold", 40, 6 ),
+        ( "Helsinki", 22, 8 ),
+        ( "Helsinki", 22, 4 ),
+    ]
+    baseline_spacing = 4
+
+    fontpattern = args.font
+    fontsize = args.size
+    if args.font and args.font.isdigit():
+        # The font is a number -- so we choose it as an index into
+        # FONT_DEFAULTS.
+        fontpattern, fontsize, baseline_spacing = FONT_DEFAULTS[int(args.font)]
+        font = Font(pattern = fontpattern, size = fontsize)
+        totheight = 0
+        for t in args.text:
+            if totheight:
+                totheight += baseline_spacing
+            w,h,baseline = font.text_dimensions(t)
+            totheight += h
+        if totheight > required_height:
+            print(f"text does not fit on label with font {args.font} -- total height is {totheight} px, but label is {required_height} px!")
+            return 1
+    elif not fontpattern or not fontsize:
+        # Try to pick some sensible defaults.
+        nlines = 1
+        print(f"{nlines} lines on media size {required_height} px")
+        for fontpattern, fontsize, baseline_spacing in FONT_DEFAULTS:
+            font = Font(pattern = fontpattern, size = fontsize)
+            totheight = 0
+            for t in args.text:
+                if totheight:
+                    totheight += baseline_spacing
+                w,h,baseline = font.text_dimensions(t)
+                totheight += h
+            print(f"{fontpattern} @ {fontsize} is {totheight} px")
+            if totheight <= required_height:
+                print("that fits, good enough for me")
+                break
+    else:
+        font = Font(pattern = fontpattern, size = fontsize)
+    image = font.render_texts(args.text, height = required_height, vcenter = True, hcenter = False, spacing = baseline_spacing).pixels
+
+    # Margin check
+    margin = args.margin
+    if (image.width + margin) < MINIMUM_TAPE_POINTS:
+        print("Image (%i) + cut margin (%i) is smaller than minimum tape width (%i) ...\n"
+              "cutting length will be extended" % (image.width, margin, MINIMUM_TAPE_POINTS))
+        margin = MINIMUM_TAPE_POINTS - image.width
+
+    if args.preview:
+        w,h = image.size
+        im2 = Image.new('L', (w + margin * 2, h), 0)
+        im2.paste(image, (margin, 0))
+        PIL.ImageOps.invert(im2).show()
+        return
+
+    # Raster image
+    data = raster_image(image, found_printer.media_width)
+
+    found_printer.print_data(data, margin)
+
+    return 0
+
+
 def list_printers(serial):
     printers = find_printers(serial)
     if len(printers) == 0:
@@ -120,7 +198,7 @@ def cli():
     discover.set_defaults(cmd='info')
 
     # Complex subparsers
-    print_menu = subparsers.add_parser('print')
+    print_menu = subparsers.add_parser('print', help="Print an image")
     print_menu.add_argument("-r", "--rotate", default='auto',
                             choices=['auto', '0', '90', '180', '270'],
                             help='Rotate the image (counter clock-wise) by this amount of degrees. '
@@ -133,6 +211,15 @@ def cli():
     print_menu.add_argument("-f", "--file", type=str, required=True, help="Image file to print")
     print_menu.set_defaults(cmd='print')
 
+    text_menu = subparsers.add_parser('text', help="Print some text")
+    text_menu.add_argument("-m", "--margin", type=int, default=50,
+                           help="Print margin in dots.")
+    text_menu.add_argument("-f", "--font", type=str, default=None, help="Font face, or a number specifying an index into the default table of fonts")
+    text_menu.add_argument("-s", "--size", type=int, default=None, help="Font size")
+    text_menu.add_argument("--preview", action='store_true', help="just show a preview, don't print a label")
+    text_menu.add_argument("text", nargs='+', help="Text to print")
+    text_menu.set_defaults(cmd='text')
+
     args = parser.parse_args()
 
     if args.version:
@@ -155,6 +242,8 @@ def cli():
             return 0
     elif args.cmd == 'print':
         return do_print(args)
+    elif args.cmd == 'text':
+        return do_text(args)
 
     return 0
 

brother_pt/cmd.py

@@ -19,7 +19,8 @@
 PRINT_HEAD_PINS = 128
 USBID_BROTHER = 0x04f9
 LINE_LENGTH_BYTES = 0x10
-MINIMUM_TAPE_POINTS = 174 # 25.4 mm @ 180dpi
+#MINIMUM_TAPE_POINTS = 174 # 25.4 mm @ 180dpi
+MINIMUM_TAPE_POINTS = 50
 USB_OUT_EP_ID = 0x2
 USB_IN_EP_ID = 0x81
 USB_TRX_TIMEOUT_MS = 15000