add means for setting image resolution when saving

core/src/processing/core/PImage.java

@@ -31,6 +31,7 @@ import java.lang.reflect.Method;
 import java.util.Iterator;
 
 import javax.imageio.*;
+import javax.imageio.metadata.*;
 
 
 /**
@@ -3089,8 +3090,6 @@ public class PImage implements PConstants, Cloneable {
       // JPEG and BMP images that have an alpha channel set get pretty unhappy.
       // BMP just doesn't write, and JPEG writes it as a CMYK image.
       // http://code.google.com/p/processing/issues/detail?id=415
-//      String lower = path.toLowerCase();
-//      if (lower.endsWith("bmp") || lower.endsWith("jpg") || lower.endsWith("jpeg")) {
       if (extension.equals("bmp") || extension.equals("jpg") || extension.equals("jpeg")) {
         outputFormat = BufferedImage.TYPE_INT_RGB;
       }
@@ -3100,31 +3099,36 @@ public class PImage implements PConstants, Cloneable {
 
       File file = new File(path);
 
+      ImageWriter writer = null;
+      ImageWriteParam param = null;
+      IIOMetadata metadata = null;
       if (extension.equals("jpg") || extension.equals("jpeg")) {
-        ImageWriter writer = null;
-        Iterator<ImageWriter> iter = ImageIO.getImageWritersByFormatName("jpeg");
-        if (iter.hasNext()) {
-          writer = iter.next();
-
+        if ((writer = imageioWriter("jpeg")) != null) {
           // Set JPEG quality to 90% with baseline optimization. Setting this
           // to 1 was a huge jump (about triple the size), so this seems good.
-          // Oddly, a smaller file size than Photoshop at 90%, but it's a
-          // completely different algorithm, I suppose.
-          ImageWriteParam param = writer.getDefaultWriteParam();
+          // Oddly, a smaller file size than Photoshop at 90%, but I suppose
+          // it's a completely different algorithm.
+          param = writer.getDefaultWriteParam();
           param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
           param.setCompressionQuality(0.9f);
-
-          BufferedOutputStream output =
-            new BufferedOutputStream(new FileOutputStream(file));
-          writer.setOutput(ImageIO.createImageOutputStream(output));
-          writer.write(null, new IIOImage(bimage, null, null), param);
-          writer.dispose();
-
-          output.flush();
-          output.close();
-          return true;
         }
       }
+      if ((writer = imageioWriter("png")) != null) {
+        param = writer.getDefaultWriteParam();
+        metadata = imageioDPI(writer, param, 100);
+      }
+      if (writer != null) {
+        BufferedOutputStream output =
+          new BufferedOutputStream(PApplet.createOutput(file));
+        writer.setOutput(ImageIO.createImageOutputStream(output));
+//        writer.write(null, new IIOImage(bimage, null, null), param);
+        writer.write(metadata, new IIOImage(bimage, null, metadata), param);
+        writer.dispose();
+
+        output.flush();
+        output.close();
+        return true;
+      }
       // If iter.hasNext() somehow fails up top, it falls through to here
       return javax.imageio.ImageIO.write(bimage, extension, file);
 
@@ -3135,6 +3139,52 @@ public class PImage implements PConstants, Cloneable {
   }
 
 
+  private ImageWriter imageioWriter(String extension) {
+    Iterator<ImageWriter> iter = ImageIO.getImageWritersByFormatName(extension);
+    if (iter.hasNext()) {
+      return iter.next();
+    }
+    return null;
+  }
+
+
+  private IIOMetadata imageioDPI(ImageWriter writer, ImageWriteParam param, double dpi) {
+    // http://stackoverflow.com/questions/321736/how-to-set-dpi-information-in-an-image
+    ImageTypeSpecifier typeSpecifier =
+      ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB);
+    IIOMetadata metadata =
+      writer.getDefaultImageMetadata(typeSpecifier, param);
+
+    if (!metadata.isReadOnly() && metadata.isStandardMetadataFormatSupported()) {
+      // for PNG, it's dots per millimeter
+      double dotsPerMilli = dpi / 25.4;
+
+      IIOMetadataNode horiz = new IIOMetadataNode("HorizontalPixelSize");
+      horiz.setAttribute("value", Double.toString(dotsPerMilli));
+
+      IIOMetadataNode vert = new IIOMetadataNode("VerticalPixelSize");
+      vert.setAttribute("value", Double.toString(dotsPerMilli));
+
+      IIOMetadataNode dim = new IIOMetadataNode("Dimension");
+      dim.appendChild(horiz);
+      dim.appendChild(vert);
+
+      IIOMetadataNode root = new IIOMetadataNode("javax_imageio_1.0");
+      root.appendChild(dim);
+
+      try {
+        metadata.mergeTree("javax_imageio_1.0", root);
+        return metadata;
+
+      } catch (IIOInvalidTreeException e) {
+        System.err.println("Could not set the DPI of the output image");
+        e.printStackTrace();
+      }
+    }
+    return null;
+  }
+
+
   protected String[] saveImageFormats;
 
   /**

core/todo.txt

@@ -12,6 +12,12 @@ X   getFloatContent()
 X   getContent() or getStringContent()?
 X switch to CATEGORY instead of CATEGORICAL
 X removed createXML() and createTable()... just use 'new' for these
+X implement means for setting dpi in PNG images
+X   need to add something for API yet
+o   JAI handles setting image size for png (check javax.imageio?) 
+o   PNGEncodeParam png = PNGEncodeParam.getDefaultEncodeParam(bufImage);
+o   png.setPhysicalDimension(round(dpi*39.370079), round(dpi*39.370079), 1);
+o   JAI.create("filestore", bufImage, filename+".png", "PNG");
 
 mouse wheel
 X add mouse wheel support to 2.0 event system
@@ -44,6 +50,13 @@ X   ref: "negative values if the mouse wheel was rotated up or away from the use
 X   http://docs.oracle.com/javase/6/docs/api/java/awt/event/MouseWheelEvent.html#getWheelRotation()
 X   http://docs.oracle.com/javase/7/docs/api/java/awt/event/MouseWheelEvent.html#getWheelRotation()
 
+_ add options for image.save() (or sageImage?)
+_   add quality=[0,1] for jpeg images
+_   add dpi=[0,n] for for png images
+
+_ PImage.loadPixels() shouldn't be calling out to the renderer
+_   setting image.parent = null for it makes it work again for get().save() case
+_ PShape should be cached as well
 
 before release
 _ "deleted n framebuffer objects"