Work on Scripts.

Add script for spectrograms.
Add Script for 'after' with effects examples.
Add space and dc bias to afters script.
Add docimages_all.py script to call all scripts.
Shared part of scripts extracted into docimages_core.py

scripts/piped-work/docimages_spectro.py

@@ -0,0 +1,58 @@
+# docimages_spectro.py
+# Sends commands to get images for the manual.
+# Images for https://alphamanual.audacityteam.org/man/Spectrogram_View
+
+# Make sure Audacity is running first and that mod-script-pipe is enabled
+# before running this script.
+
+#load and run the common core.
+exec( open("docimages_core.py" ).read() )
+
+
+
+# 11 2KHz tones, of decreasing amplitude.
+# With label track to annotate it.
+def makeStepper():
+    makeWayForTracks()
+    do( 'NewMonoTrack' )
+    do( 'Select: Start=0 End=22')
+    do( 'Silence' ) #Just so we can watch.
+    do( 'FitInWindow')
+    for i in range( 0, 11 ):
+        do( 'Select: Start='+str(i*2)+' End='+str(i*2+2) )
+        do( 'Chirp: StartFreq=2000 EndFreq=2000 StartAmp=' + str( (400**(0.1 * (10-i)))/400 )+' EndAmp=' + str( (400**(0.1 * (10-i) ))/400 ))
+    do( 'Select: Start=0 End=22')
+    do( 'Join' )
+    do( 'FitInWindow')
+    do( 'AddLabelTrack' )
+    for i in range( 0, 11 ):
+        do( 'Select: Start='+str(i*2)+' End='+str(i*2+2) )
+        do( 'AddLabel' )
+        do( 'SetLabel: Label=' + str(i)+' Selected=0 Text='+str( -(i*10) ))
+    do( 'Select: Start=0 End=0')
+  
+
+def spectro_image1and2() :
+    loadStereoTracks(1)
+    # A stereo track
+    capture( 'Spectral001.png', 'First_Track' )
+    # As spectrogram.
+    do( 'SetTrack: Track=0 Display=Spectrogram')
+    do( 'SetTrack: Track=1 Display=Spectrogram')
+    do( 'Select: Start=55 End=70 First=0 Last=1')
+    capture( 'Spectral002.png', 'First_Track' )
+
+def spectro_image3and4():
+    makeStepper();
+    # Stepper tone, viewed in dB.
+    do( 'SetTrack: Scale=dB')
+    capture( 'Spectral003.png', 'First_Two_Tracks' )
+    # As spectrogram.
+    do( 'SetTrack: Display=Spectrogram')
+    capture( 'Spectral004.png', 'First_Two_Tracks' )
+    
+#quickTest()
+
+spectro_image1and2()
+spectro_image3and4()
+