Mozilla2:Image Encoding: Difference between revisions

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Revision as of 06:17, 8 March 2005

317 bytes added , 8 March 2005

→‎Interface

Pavlov

569

edits

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 == Interface ==
-We need to add a new interface.  Do we want to support passing in an output stream?  When you read from the stream should we encode just that much?  Thoughts?
+We need to add a new interface.  When you read from the stream should we encode just that much?  Thoughts?
 Something like:
-  interface imgIEncoder : nsISupports
+  interface imgIEncoder : nsIInputStream
   {
-    nsIOutputStream encode(imgIContainer image);
+    /* input image data
+    * result width
-   /* Output width/height */
+    * result height
-   attribute unsigned long width;
+    */
-   attribute unsigned long height;
+    void init(in imgIContainer input,
+             in unsigned long width, in unsigned long height);
-   /* type of scaling */
-    const unsigned long SCALE_BAD = 0;
-   const unsigned long SCALE_NORMAL = 1;
-   const unsigned long SCALE_GOOD = 2;
-   attribute unsigned long scaling;
   };
+=== Scaling ===
+Do we want to support different types of scaling?  I'd prefer to just do nice Bicubic resampling. [http://members.bellatlantic.net/~vze2vrva/design.html] [http://astronomy.swin.edu.au/~pbourke/colour/bicubic/]
+=== Brendan's comments ===
+A reader should get the bytes requested, if not greater than length of encoded image, and it's up to the encoder to buffer more if it encodes more bytes, reading from the buffer on next read.
+This expresses the idea that the encoder is something you read from.
+== Use ==
 You would create one by doing:
   createInstance("@mozilla.org/image/encoder;2?type=image/png");