Add Landing Page When No Library Is Opened (#258)

* Add landing page when no library is open

- Add landing page when no library is open
- Add linear_gradient method
- Reformat main_window.py with spaces instead of tabs because apparently it wasn't formatted already?

* Add color_overlay methods, ClickableLabel widget

- Add color_overlay helper methods
- Add clickable_label widget
- Add docstrings to landing.py methods
- Add logo easter egg
- Refactor landing.py content

* Fix redefinition

* Fix macOS shortcut text

tagstudio/src/qt/helpers/color_overlay.py

@@ -0,0 +1,59 @@
+# Copyright (C) 2024 Travis Abendshien (CyanVoxel).
+# Licensed under the GPL-3.0 License.
+# Created for TagStudio: https://github.com/CyanVoxel/TagStudio
+
+
+from PIL import Image
+from PySide6.QtCore import Qt
+from PySide6.QtGui import QGuiApplication
+from src.qt.helpers.gradient import linear_gradient
+
+# TODO: Consolidate the built-in QT theme values with the values
+# here, in enums.py, and in palette.py.
+_THEME_DARK_FG: str = "#FFFFFF55"
+_THEME_LIGHT_FG: str = "#000000DD"
+
+
+def theme_fg_overlay(image: Image.Image) -> Image.Image:
+    """
+    Overlay the foreground theme color onto an image.
+
+    Args:
+        image (Image): The PIL Image object to apply an overlay to.
+    """
+
+    overlay_color = (
+        _THEME_DARK_FG
+        if QGuiApplication.styleHints().colorScheme() is Qt.ColorScheme.Dark
+        else _THEME_LIGHT_FG
+    )
+    im = Image.new(mode="RGBA", size=image.size, color=overlay_color)
+    return _apply_overlay(image, im)
+
+
+def gradient_overlay(image: Image.Image, gradient=list[str]) -> Image.Image:
+    """
+    Overlay a color gradient onto an image.
+
+    Args:
+        image (Image): The PIL Image object to apply an overlay to.
+        gradient (list[str): A list of string hex color codes for use as
+            the colors of the gradient.
+    """
+
+    im: Image.Image = _apply_overlay(image, linear_gradient(image.size, gradient))
+    return im
+
+
+def _apply_overlay(image: Image.Image, overlay: Image.Image) -> Image.Image:
+    """
+    Internal method to apply an overlay on top of an image, using
+    the image's alpha channel as a mask.
+
+    Args:
+        image (Image): The PIL Image object to apply an overlay to.
+        overlay (Image): The PIL Image object to act as the overlay contents.
+    """
+    im: Image.Image = Image.new(mode="RGBA", size=image.size, color="#00000000")
+    im.paste(overlay, (0, 0), mask=image)
+    return im

tagstudio/src/qt/helpers/gradient.py

@@ -5,7 +5,9 @@
 from PIL import Image, ImageEnhance, ImageChops
 
 
-def four_corner_gradient_background(image: Image.Image, adj_size, mask, hl):
+def four_corner_gradient_background(
+    image: Image.Image, adj_size, mask, hl
+) -> Image.Image:
     if image.size != (adj_size, adj_size):
         # Old 1 color method.
         # bg_col = image.copy().resize((1, 1)).getpixel((0,0))
@@ -48,3 +50,16 @@ def four_corner_gradient_background(image: Image.Image, adj_size, mask, hl):
     hl_soft.putalpha(ImageEnhance.Brightness(hl.getchannel(3)).enhance(0.5))
     final.paste(ImageChops.soft_light(final, hl_soft), mask=hl_soft.getchannel(3))
     return final
+
+
+def linear_gradient(
+    size=tuple[int, int],
+    colors=list[str],
+    interpolation: Image.Resampling = Image.Resampling.BICUBIC,
+) -> Image.Image:
+    seed: Image.Image = Image.new(mode="RGBA", size=(len(colors), 1), color="#000000")
+    for i, color in enumerate(colors):
+        c_im: Image.Image = Image.new(mode="RGBA", size=(1, 1), color=color)
+        seed.paste(c_im, (i, 0))
+    gradient: Image.Image = seed.resize(size, resample=interpolation)
+    return gradient