Move preview rendering to preview render engine

Discard the QT image functionality in favor of Pillow's

src/dymoprint/cli/cli.py

@@ -305,7 +305,11 @@ def run():
         max_width_px=max_payload_len_px,
         min_width_px=min_payload_len_px,
     )
-    render_context = RenderContext(height_px=dymo_labeler.height_px)
+    render_context = RenderContext(
+        background_color="white",
+        foreground_color="black",
+        height_px=dymo_labeler.height_px,
+    )
 
     # print or show the label
     if args.preview or args.preview_inverted or args.imagemagick or args.browser:

src/dymoprint/gui/gui.py

@@ -5,7 +5,7 @@
 from PIL import Image, ImageQt
 from PyQt6 import QtCore
 from PyQt6.QtCore import QCommandLineOption, QCommandLineParser, QSize, Qt, QTimer
-from PyQt6.QtGui import QColor, QIcon, QPainter, QPixmap
+from PyQt6.QtGui import QIcon, QPixmap
 from PyQt6.QtWidgets import (
     QApplication,
     QComboBox,
@@ -121,8 +121,8 @@ def init_connections(self):
         self.tape_size_mm.currentTextChanged.connect(self.update_params)
         self.min_label_width_mm.valueChanged.connect(self.update_params)
         self.justify.currentTextChanged.connect(self.update_params)
-        self.foreground_color.currentTextChanged.connect(self.label_list.render_label)
-        self.background_color.currentTextChanged.connect(self.label_list.render_label)
+        self.foreground_color.currentTextChanged.connect(self.update_params)
+        self.background_color.currentTextChanged.connect(self.update_params)
         self.label_list.renderPrintPreviewSignal.connect(self.update_preview_render)
         self.label_list.renderPrintPayloadSignal.connect(self.update_print_render)
         self.print_button.clicked.connect(self.print_label)
@@ -184,6 +184,10 @@ def update_params(self):
         tape_size_mm: float = self.tape_size_mm.currentData()
 
         self.dymo_labeler.tape_size_mm = tape_size_mm
+
+        # Update render context
+        self.render_context.foreground_color = self.foreground_color.currentText()
+        self.render_context.background_color = self.background_color.currentText()
         self.render_context.height_px = self.dymo_labeler.height_px
 
         self.label_list.update_params(
@@ -197,16 +201,6 @@ def update_params(self):
     def update_preview_render(self, preview_bitmap):
         qim = ImageQt.ImageQt(preview_bitmap)
         q_image = QPixmap.fromImage(qim)
-
-        mask = q_image.createMaskFromColor(
-            QColor("255, 255, 255"), Qt.MaskMode.MaskOutColor
-        )
-        q_image.fill(QColor(self.background_color.currentText()))
-        p = QPainter(q_image)
-        p.setPen(QColor(self.foreground_color.currentText()))
-        p.drawPixmap(q_image.rect(), mask, mask.rect())
-        p.end()
-
         self.label_render.setPixmap(q_image)
         self.label_render.adjustSize()
         self.info_label.setText(f"← {px_to_mm(preview_bitmap.size[0])} mm →")

src/dymoprint/lib/render_engines/print_preview.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from PIL import Image, ImageOps
+from PIL import Image, ImageColor, ImageOps
 
 from dymoprint.lib.render_engines.margins import MarginsMode, MarginsRenderEngine
 from dymoprint.lib.render_engines.render_context import RenderContext
@@ -28,6 +28,23 @@ def __init__(
             min_width_px=min_width_px,
         )
 
-    def render(self, context: RenderContext) -> Image.Image:
+    def _get_preview_bitmap(self, context: RenderContext):
         label_bitmap = self.render_engine.render(context)
-        return ImageOps.invert(label_bitmap.convert("L"))
+        bitmap = ImageOps.invert(label_bitmap.convert("L")).convert("RGBA")
+        pixel_map = {
+            "black": context.foreground_color,
+            "white": context.background_color,
+        }
+        pixel_map = {
+            ImageColor.getcolor(k, "RGBA"): ImageColor.getcolor(v, "RGBA")
+            for k, v in pixel_map.items()
+        }
+        pixdata = bitmap.load()
+        width, height = bitmap.size
+        for x in range(0, width):
+            for y in range(0, height):
+                pixdata[x, y] = pixel_map[pixdata[x, y]]
+        return bitmap
+
+    def render(self, context: RenderContext) -> Image.Image:
+        return self._get_preview_bitmap(context)

src/dymoprint/lib/render_engines/render_context.py

@@ -2,7 +2,9 @@
 
 
 class _RenderContextFieldName(Enum):
-    HEIGHT_PX = 1
+    BACKGROUND_COLOR = 1
+    FOREGROUND_COLOR = 2
+    HEIGHT_PX = 3
 
 
 class RenderContext:

src/dymoprint/lib/unicode_blocks.py

@@ -5,25 +5,32 @@
 LH = "▄"
 FB = "█"
 NB = "\xa0"
+LS = "░"
 
 assert UH == "\N{UPPER HALF BLOCK}"
 assert LH == "\N{LOWER HALF BLOCK}"
 assert FB == "\N{FULL BLOCK}"
 assert NB == "\N{NO-BREAK SPACE}"
+assert LS == "\N{LIGHT SHADE}"
 
+BLACK_PIXEL = (255, 255, 255, 255)
+WHITE_PIXEL = (0, 0, 0, 255)
+TRANSPARENT_PIXEL = (0, 0, 0, 0)
 
 dict_unicode = {
-    (255, 255): FB,
-    (0, 255): LH,
-    (255, 0): UH,
-    (0, 0): NB,
+    (BLACK_PIXEL, BLACK_PIXEL): FB,
+    (WHITE_PIXEL, BLACK_PIXEL): LH,
+    (BLACK_PIXEL, WHITE_PIXEL): UH,
+    (WHITE_PIXEL, WHITE_PIXEL): NB,
+    (BLACK_PIXEL, TRANSPARENT_PIXEL): LS,
 }
 
 dict_unicode_inverted = {
-    (255, 255): NB,
-    (0, 255): UH,
-    (255, 0): LH,
-    (0, 0): FB,
+    (BLACK_PIXEL, BLACK_PIXEL): NB,
+    (WHITE_PIXEL, BLACK_PIXEL): UH,
+    (BLACK_PIXEL, WHITE_PIXEL): LH,
+    (WHITE_PIXEL, WHITE_PIXEL): FB,
+    (BLACK_PIXEL, TRANSPARENT_PIXEL): LS,
 }