[ENH] Add PDF format to image exporters

Orange/widgets/io.py

@@ -1,3 +1,6 @@
+import os
+import tempfile
+
 from AnyQt import QtGui, QtCore, QtSvg
 from AnyQt.QtCore import QMimeData
 from AnyQt.QtWidgets import (
@@ -59,8 +62,8 @@ def write_image(cls, filename, scene):
                 scene.render(painter, target, rect)
             except TypeError:
                 scene.render(painter)  # QWidget.render() takes different params
-            cls._save_buffer(buffer, filename)
             painter.end()
+            cls._save_buffer(buffer, filename)
 
     @classmethod
     def write(cls, filename, scene):
@@ -139,6 +142,9 @@ def _get_target(scene, painter, buffer, source):
 
     @staticmethod
     def _save_buffer(buffer, filename):
+        dev = buffer.outputDevice()
+        if dev is not None:
+            dev.flush()
         pass
 
     @staticmethod
@@ -164,3 +170,38 @@ def write_image(cls, filename, scene):
                 pass
 
         super().write_image(filename, scene)
+
+
+if hasattr(QtGui, "QPdfWriter"):
+    class PdfFormat(ImgFormat):
+        EXTENSIONS = ('.pdf', )
+        DESCRIPTION = 'Portable Document Format'
+        PRIORITY = 110
+
+        @classmethod
+        def write_image(cls, filename, scene):
+            # export via svg to temp file then print that
+            # NOTE: can't use NamedTemporaryFile with delete = True
+            # (see https://bugs.python.org/issue14243)
+            fd, tmpname = tempfile.mkstemp(suffix=".svg")
+            os.close(fd)
+            try:
+                SvgFormat.write_image(tmpname, scene)
+                with open(tmpname, "rb") as f:
+                    svgcontents = f.read()
+            finally:
+                os.unlink(tmpname)
+
+            svgrend = QtSvg.QSvgRenderer(QtCore.QByteArray(svgcontents))
+            vbox = svgrend.viewBox()
+            if not vbox.isValid():
+                size = svgrend.defaultSize()
+            else:
+                size = vbox.size()
+            writer = QtGui.QPdfWriter(filename)
+            writer.setPageSizeMM(QtCore.QSizeF(size) * 0.282)
+            painter = QtGui.QPainter(writer)
+            svgrend.render(painter)
+            painter.end()
+            del svgrend
+            del painter

Orange/widgets/tests/test_io.py

@@ -0,0 +1,20 @@
+import os
+import tempfile
+import unittest
+
+from AnyQt.QtWidgets import QGraphicsScene, QGraphicsRectItem
+from Orange.widgets.tests.base import GuiTest
+
+from Orange.widgets import io as imgio
+
+@unittest.skipUnless(hasattr(imgio, "PdfFormat"), "QPdfWriter not available")
+class TestIO(GuiTest):
+    def test_pdf(self):
+        sc = QGraphicsScene()
+        sc.addItem(QGraphicsRectItem(0, 0, 20, 20))
+        fd, fname = tempfile.mkstemp()
+        os.close(fd)
+        try:
+            imgio.PdfFormat.write_image(fname, sc)
+        finally:
+            os.unlink(fname)

Orange/widgets/utils/saveplot.py

@@ -1,4 +1,5 @@
 import os.path
+import traceback
 
 from AnyQt.QtWidgets import QMessageBox
 from AnyQt.QtCore import QSettings
@@ -24,8 +25,13 @@ def save_plot(data, file_formats, filename=""):
     try:
         writer.write(filename, data)
     except Exception as e:
-        QMessageBox.critical(
-            None, "Error", 'Error occurred while saving file "{}": {}'.format(filename, e))
+        mb = QMessageBox(
+            None,
+            windowTitle="Error",
+            text='Error occurred while saving file "{}": {}'.format(filename, e),
+            detailedText=traceback.format_exc(),
+            icon=QMessageBox.Critical)
+        mb.exec_()
     else:
         settings.setValue(_LAST_DIR_KEY, os.path.split(filename)[0])
         settings.setValue(_LAST_FILTER_KEY, filter)