Specify output dimensions in pixels or density-independent pixels with Inkscape

README.md

@@ -28,7 +28,9 @@ icons:
 
       - path: Resources/images/android
         prepend: 'ic_'
-        dpi: 82
+        screen-dpi: 480
+        width-dp: 30
+        height-dp: 30
 
    images:
       - icons/foo.ai
@@ -98,9 +100,15 @@ You can use wildcards (as well as other special characters supported by
 Python's [glob module](https://docs.python.org/3.1/library/glob.html)) to specify
 groups of images under a path.
 
-Since Illustrator accepts a 'scaling' property for rendering and not a DPI,
+Since Illustrator accepts a `scaling` property for rendering and not a DPI,
 it is assumed your files were created with a DPI of 72.  If they weren't,
-use the 'srcdpi' to specify the source dpi.
+use the `srcdpi` to specify the source dpi.
+
+Inkscape accepts pixel and density-independent dimension properties.
+To specify output dimensions in pixels, use `width-px` and `height-px`.
+To specify output dimensions in density-independent pixels, use `width-dp`,
+`height-dp`, and `screen-dpi`, where `screen-dpi` is the target device screen DPI.
+These properties override `dpi` - they're mutually exclusive.
 
 If you create `images/Icon.svg` at 57x57 *points* in inkscape, the above group
 called `appicons`

plugin.py

@@ -1,6 +1,7 @@
  #!/usr/bin/env python
 
 import os, subprocess, inspect, yaml, shutil, sys, glob
+from math import ceil
 
 class ModCheck (object):
     """handles checking of modification times to see if we need to
@@ -36,6 +37,10 @@ def launch (command):
         print unicode(err, errors='ignore')
         raise Exception('Command failed, check output')
 
+def dp_to_px (dp, screen_dpi):
+    """Translate density-independent pixels to pixels for a given screen DPI."""
+    return int(ceil(dp * (screen_dpi/float(160))))
+
 def illustrator (infile, outfile, outputConfig, pluginConfig):
     """Render an image with illustrator"""
     print 'Rendering', infile, 'to', outfile, 'at dpi', outputConfig['dpi'], 'with Illustrator.'
@@ -58,15 +63,49 @@ def illustrator (infile, outfile, outputConfig, pluginConfig):
 
 def inkscape (infile, outfile, outputConfig, pluginConfig):
     """Render an image with inkscape"""
-    print 'Rendering', infile, 'to', outfile, 'at dpi', outputConfig['dpi'], 'with Inkscape.'
-    command = [
-        "inkscape",
-        "-d",
-        str(outputConfig['dpi']),
+    command = ["inkscape"]
+
+    # Use pixel dimension properties (width-px, height-px)
+    if {'width-px', 'height-px'} <= set(outputConfig):
+
+        print 'Rendering', infile, 'to', outfile, 'at', outputConfig['width-px'], 'x', outputConfig['height-px'], 'px with Inkscape.'
+        command.extend([
+            "-w",
+            str(outputConfig['width-px']),
+            "-h",
+            str(outputConfig['height-px'])
+        ])
+
+    # Use density-independent pixel dimension properties (width-dp, height-dp, screen-dpi)
+    elif {'width-dp', 'height-dp', 'screen-dpi'} <= set(outputConfig):
+
+        print 'Rendering', infile, 'to', outfile, 'at', outputConfig['width-dp'], 'x', outputConfig['height-dp'], 'dp for', outputConfig['screen-dpi'], 'DPI screen with Inkscape.'
+        width_px = dp_to_px(outputConfig['width-dp'], outputConfig['screen-dpi'])
+        height_px = dp_to_px(outputConfig['height-dp'], outputConfig['screen-dpi'])
+        command.extend([
+            "-w",
+            str(width_px),
+            "-h",
+            str(height_px)
+        ])
+
+    # Use DPI property
+    elif 'dpi' in outputConfig:
+        print 'Rendering', infile, 'to', outfile, 'at dpi', outputConfig['dpi'], 'with Inkscape.'
+        command.extend([
+            "-d",
+            str(outputConfig['dpi'])
+        ])
+
+    else:
+        raise Exception("Invalid Inkscape export configuration for " + outfile)
+
+    command.extend([
         "-e",
         outfile,
         infile
-    ]
+    ])
+
     launch(command)
 
 def checkProps (names, pluginConfig, outputConfig):