Add ColorPicker dialog with checkerboard alpha

src/windows/color_picker.py

@@ -0,0 +1,156 @@
+"""
+ @file
+ @brief A non-modal Qt color picker dialog launcher
+ @author FeRD (Frank Dana) <[email protected]>
+
+ @section LICENSE
+
+ Copyright (c) 2008-2020 OpenShot Studios, LLC
+ (http://www.openshotstudios.com). This file is part of
+ OpenShot Video Editor (http://www.openshot.org), an open-source project
+ dedicated to delivering high quality video editing and animation solutions
+ to the world.
+
+ OpenShot Video Editor is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ OpenShot Video Editor is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with OpenShot Library.  If not, see <http://www.gnu.org/licenses/>.
+ """
+
+from classes.logger import log
+
+from PyQt5.QtCore import Qt, QTimer, QRect, QPoint
+from PyQt5.QtGui import QColor, QBrush, QPen, QPalette, QPainter, QPixmap
+from PyQt5.QtWidgets import QColorDialog, QWidget, QLabel
+
+
+class ColorPicker(QWidget):
+    """Show a non-modal color picker.
+    QColorDialog.colorSelected(QColor) is emitted when the user picks a color"""
+
+    def __init__(self, initial_color: QColor, callback, extra_options=0,
+                 parent=None, title=None, *args, **kwargs):
+        super().__init__(parent=parent, *args, **kwargs)
+        self.setObjectName("ColorPicker")
+        # Merge any additional user-supplied options with our own
+        options = QColorDialog.DontUseNativeDialog
+        if extra_options > 0:
+            options = options | extra_options
+        # Set up non-modal color dialog (to avoid blocking the eyedropper)
+        log.debug(
+            "Loading QColorDialog with start value %s",
+            initial_color.getRgb())
+        self.dialog = CPDialog(initial_color, parent)
+        self.dialog.setObjectName("CPDialog")
+        if title:
+            self.dialog.setWindowTitle(title)
+        self.dialog.setWindowFlags(Qt.Tool)
+        self.dialog.setOptions(options)
+        # Avoid signal loops
+        self.dialog.blockSignals(True)
+        self.dialog.colorSelected.connect(callback)
+        self.dialog.finished.connect(self.dialog.deleteLater)
+        self.dialog.finished.connect(self.deleteLater)
+        self.dialog.setCurrentColor(initial_color)
+        self.dialog.blockSignals(False)
+        self.dialog.open()
+        # Seems to help if this is done AFTER init() returns
+        QTimer.singleShot(0, self.add_alpha)
+    def add_alpha(self):
+        self.dialog.replace_label()
+
+
+class CPDialog(QColorDialog):
+    """Show a modified QColorDialog which supports checkerboard alpha"""
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        log.debug("CPDialog initialized")
+        self.alpha_label = CPAlphaShowLabel(self)
+        self.alpha_label.setObjectName("alpha_label")
+        self.currentColorChanged.connect(self.alpha_label.updateColor)
+    def replace_label(self):
+        log.debug("Beginning discovery for QColorShowLabel widget")
+        # Find the dialog widget used to display the current
+        # color, so we can replace it with our implementation
+        try:
+            qcs = [
+                a for a in self.children()
+                if hasattr(a, "metaObject")
+                and a.metaObject().className() == 'QColorShower'
+                ][0]
+            log.debug("Found QColorShower: %s", qcs)
+            qcsl = [
+                b for b in qcs.children()
+                if hasattr(b, "metaObject")
+                and b.metaObject().className() == 'QColorShowLabel'
+                ][0]
+            log.debug("Found QColorShowLabel: %s", qcsl)
+        except IndexError as ex:
+            child_list = [
+                a.metaObject().className()
+                for a in self.children()
+                if hasattr(a, "metaObject")
+                ]
+            log.debug("%d children of CPDialog %s", len(child_list), child_list)
+            raise RuntimeError("Could not find label to replace!") from ex
+        qcslay = qcs.layout()
+        log.debug(
+            "QColorShowLabel found at layout index %d", qcslay.indexOf(qcsl))
+        qcs.layout().replaceWidget(qcsl, self.alpha_label)
+        log.debug("Replaced QColorShowLabel widget, hiding original")
+        # Make sure it doesn't receive signals while hidden
+        qcsl.blockSignals(True)
+        qcsl.hide()
+        self.alpha_label.show()
+
+
+class CPAlphaShowLabel(QLabel):
+    """A replacement for QColorDialog's QColorShowLabel which
+    displays the currently-active color using checkerboard alpha"""
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        # Length in pixels of a side of the checkerboard squares
+        # (Pattern is made up of 2×2 squares, total size 2n × 2n)
+        self.checkerboard_size = 8
+        # Start out transparent by default
+        self.color = super().parent().currentColor()
+        self.build_pattern()
+        log.debug("CPAlphaShowLabel initialized, creating brush")
+    def updateColor(self, color: QColor):
+        self.color = color
+        log.debug("Label color set to %s", str(color.getRgb()))
+        self.repaint()
+    def build_pattern(self) -> QPixmap:
+        """Construct tileable checkerboard pattern for paint events"""
+        # Brush will be an n×n checkerboard pattern
+        n = self.checkerboard_size
+        pat = QPixmap(2 * n, 2 * n)
+        p = QPainter(pat)
+        p.setPen(Qt.NoPen)
+        # Paint a checkerboard pattern for the color to be overlaid on
+        self.bg0 = QColor("#aaa")
+        self.bg1 = QColor("#ccc")
+        p.fillRect(pat.rect(), self.bg0)
+        p.fillRect(QRect(0, 0, n, n), self.bg1)
+        p.fillRect(QRect(n, n, 2 * n, 2 * n), self.bg1)
+        p.end()
+        log.debug("Constructed %s checkerboard brush", pat.size())
+        self.pattern = pat
+    def paintEvent(self, event):
+        """Show the current color, with checkerboard alpha"""
+        event.accept()
+        p = QPainter(self)
+        p.setPen(Qt.NoPen)
+        if self.color.alphaF() < 1.0:
+            # Draw a checkerboard pattern under the color
+            p.drawTiledPixmap(event.rect(), self.pattern, QPoint(4,4))
+        p.fillRect(event.rect(), self.color)
+        p.end()