Trim image: Allow specifying the size of the trim rectangle using numbers. Fixes #2056116 [Trim Cover: Trim to specified size/ratio](https://bugs.launchpad.net/calibre/+bug/2056116)

src/calibre/gui2/dialogs/trim_image.py

@@ -7,14 +7,68 @@ __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 import os
 import sys
 from qt.core import (
-    QDialog, QDialogButtonBox, QHBoxLayout, QIcon, QKeySequence,
-    QLabel, QSize, Qt, QToolBar, QVBoxLayout
+    QCheckBox, QDialog, QDialogButtonBox, QFormLayout, QHBoxLayout, QIcon, QKeySequence,
+    QLabel, QSize, QSpinBox, Qt, QToolBar, QVBoxLayout,
 )
 
 from calibre.gui2 import gprefs
 from calibre.gui2.tweak_book.editor.canvas import Canvas
 
 
+class Region(QDialog):
+
+    ignore_value_changes = False
+
+    def __init__(self, parent, width, height, max_width, max_height):
+        super().__init__(parent)
+        self.setWindowTitle(_('Set size of selected area'))
+        self.l = l = QFormLayout(self)
+        l.setFieldGrowthPolicy(QFormLayout.FieldGrowthPolicy.AllNonFixedFieldsGrow)
+        self.width_input = w = QSpinBox(self)
+        w.setRange(20, max_width), w.setSuffix(' px'), w.setValue(width)
+        w.valueChanged.connect(self.value_changed)
+        l.addRow(_('&Width:'), w)
+        self.height_input = h = QSpinBox(self)
+        h.setRange(20, max_height), h.setSuffix(' px'), h.setValue(height)
+        h.valueChanged.connect(self.value_changed)
+        l.addRow(_('&Height:'), h)
+        self.const_aspect = ca = QCheckBox(_('Keep the ratio of width to height fixed'))
+        ca.toggled.connect(self.const_aspect_toggled)
+        l.addRow(ca)
+        k = QKeySequence('alt+1', QKeySequence.SequenceFormat.PortableText)
+        la = QLabel('<p>'+_('Note that holding down the {} key while dragging the selection handles'
+                          ' will resize the selection while preserving its aspect ratio.').format(
+            k.toString(QKeySequence.SequenceFormat.NativeText)))
+        la.setWordWrap(True)
+        la.setMinimumWidth(400)
+        l.addRow(la)
+        self.bb = bb = QDialogButtonBox(QDialogButtonBox.StandardButton.Ok | QDialogButtonBox.StandardButton.Cancel, self)
+        bb.accepted.connect(self.accept)
+        bb.rejected.connect(self.reject)
+        l.addRow(bb)
+        self.resize(self.sizeHint())
+        self.current_aspect = width / height
+
+    def const_aspect_toggled(self):
+        if self.const_aspect.isChecked():
+            self.current_aspect = self.width_input.value() / self.height_input.value()
+
+    def value_changed(self):
+        if self.ignore_value_changes or not self.const_aspect.isChecked():
+            return
+        src = self.sender()
+        self.ignore_value_changes = True
+        if src is self.height_input:
+            self.width_input.setValue(int(self.current_aspect * self.height_input.value()))
+        else:
+            self.height_input.setValue(int(self.width_input.value() / self.current_aspect))
+        self.ignore_value_changes = False
+
+    @property
+    def selection_size(self):
+        return self.width_input.value(), self.height_input.value()
+
+
 class TrimImage(QDialog):
 
     def __init__(self, img_data, parent=None):
@@ -44,6 +98,8 @@ class TrimImage(QDialog):
         ac.setToolTip('{} [{}]'.format(_('Trim image by removing borders outside the selected region'),
                                    ac.shortcut().toString(QKeySequence.SequenceFormat.NativeText)))
         ac.setEnabled(False)
+        self.size_selection = ac = self.bar.addAction(QIcon.ic('resize.png'), _('&Region'), self.do_region)
+        ac.setToolTip(_('Specify a selection size using numbers to allow for precise control'))
         c.selection_state_changed.connect(self.selection_changed)
         c.selection_area_changed.connect(self.selection_area_changed)
         l.addWidget(c)
@@ -73,6 +129,13 @@ class TrimImage(QDialog):
     def sizeHint(self):
         return QSize(900, 600)
 
+    def do_region(self):
+        rect = self.canvas.selection_rect_in_image_coords
+        d = Region(self, int(rect.width()), int(rect.height()), self.canvas.current_image.width(), self.canvas.current_image.height())
+        if d.exec() == QDialog.DialogCode.Accepted:
+            width, height = d.selection_size
+            self.canvas.set_selection_size_in_image_coords(width, height)
+
     def do_trim(self):
         self.canvas.trim_image()
         self.selection_changed(False)

src/calibre/gui2/tweak_book/editor/canvas.py

@@ -4,25 +4,26 @@
 __license__ = 'GPL v3'
 __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 
-import sys, weakref
+import sys
+import weakref
 from functools import wraps
 from io import BytesIO
-
 from qt.core import (
-    QWidget, QPainter, QColor, QApplication, Qt, QPixmap, QRectF, QTransform,
-    QPointF, QPen, pyqtSignal, QUndoCommand, QUndoStack, QIcon, QImage,
-    QImageWriter)
+    QApplication, QColor, QIcon, QImage, QImageWriter, QPainter, QPen, QPixmap, QPointF,
+    QRect, QRectF, Qt, QTransform, QUndoCommand, QUndoStack, QWidget, pyqtSignal,
+)
 
 from calibre import fit_image
 from calibre.gui2 import error_dialog, pixmap_to_data
 from calibre.gui2.dnd import (
-    image_extensions, dnd_has_extension, dnd_has_image, dnd_get_image, DownloadDialog)
-from calibre.gui2.tweak_book import capitalize
-from calibre.utils.imghdr import identify
-from calibre.utils.img import (
-    remove_borders_from_image, gaussian_sharpen_image, gaussian_blur_image, image_to_data, despeckle_image,
-    normalize_image, oil_paint_image
+    DownloadDialog, dnd_get_image, dnd_has_extension, dnd_has_image, image_extensions,
 )
+from calibre.gui2.tweak_book import capitalize
+from calibre.utils.img import (
+    despeckle_image, gaussian_blur_image, gaussian_sharpen_image, image_to_data,
+    normalize_image, oil_paint_image, remove_borders_from_image,
+)
+from calibre.utils.imghdr import identify
 
 
 def painter(func):
@@ -575,6 +576,20 @@ class Canvas(QWidget):
                     self.selection_state.current_mode = 'select'
                     self.selection_state.rect = None
                     self.selection_state_changed.emit(False)
+    @property
+    def selection_rect_in_image_coords(self):
+        if self.selection_state.current_mode == 'selected':
+            left, top, width, height = self.rect_for_trim()
+            return QRect(0, 0, int(width), int(height))
+        return self.current_image.rect()
+
+    def set_selection_size_in_image_coords(self, width, height):
+        self.selection_state.reset()
+        i = self.current_image
+        self.selection_state.rect = QRectF(self.target.left(), self.target.top(),
+                                           width * self.target.width() / i.width(), height * self.target.height() / i.height())
+        self.selection_state.current_mode = 'selected'
+        self.update()
 
     def mouseMoveEvent(self, ev):
         changed = False