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"stream" animated gif frames via ImageReader instead of keeping them all around in memory before converting to ASCII

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This commit is contained in:
Gered 2014-04-05 16:05:00 -04:00
parent f7d2519ab1
commit f496c450ac
2 changed files with 44 additions and 49 deletions
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35
src/clojure/clj_image2ascii/core.clj
View file

@ -90,14 +90,6 @@
20
ms)))
(defn- get-ascii-gif-frames [^ImageInputStream image-stream scale-to-width color?]
(->> (AnimatedGif/read image-stream)
(mapv
(fn [^ImageFrame frame]
(-> (.image frame)
(convert-image scale-to-width color?)
(assoc :delay (fix-gif-frame-delay (.delay frame))))))))
(defn convert-animated-gif-frames
"converts an ImageInputStream created from an animated GIF to a series of ASCII
frames representing each frame of animation in the source GIF. scale-to-width is
@ -123,10 +115,23 @@
([^ImageInputStream image-stream color?]
(convert-animated-gif-frames image-stream nil color?))
([^ImageInputStream image-stream scale-to-width color?]
(let [frames (get-ascii-gif-frames image-stream scale-to-width color?)
width (-> frames first :width)
height (-> frames first :height)]
{:width width
:height height
:color? (if color? true false) ; forcing an explicit true/false because i am nitpicky like that
:frames (mapv #(select-keys % [:image :delay]) frames)})))
(let [converted-frames (atom '())
image-props (atom nil)]
(AnimatedGif/read
image-stream
(fn [^BufferedImage frame-image delay]
(let [converted (convert-image frame-image scale-to-width color?)]
; on the first image, we should use it's properties to populate the general image properties map
; (AnimatedGif/read will see to it that all gif frames will have the same width/height)
(if (nil? @image-props)
(reset! image-props
{:color? (if color? true false) ; forcing an explicit true/false because i am nitpicky like that
:width (:width converted)
:height (:height converted)}))
; and append the converted frame's ascii to the list
(swap! converted-frames conj {:image (:image converted)
:delay delay}))))
(merge
@image-props
{:frames @converted-frames}))))

58
src/java/clj_image2ascii/java/AnimatedGif.java
View file

@ -1,5 +1,6 @@
package clj_image2ascii.java;
import clojure.lang.IFn;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
@ -12,8 +13,6 @@ import javax.imageio.stream.ImageInputStream;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Iterator;
import java.util.LinkedList;
/**
* Helper for extracting each frame of animation from a GIF as a separate BufferedImage.
@ -25,12 +24,14 @@ import java.util.LinkedList;
* @author gered (_extremely_ minor tweaks)
*/
public class AnimatedGif {
public static LinkedList<ImageFrame> read(ImageInputStream stream) throws IOException {
public static void read(ImageInputStream stream, IFn fn) throws IOException {
ImageReader reader = ImageIO.getImageReadersByFormatName("gif").next();
reader.setInput(stream, false);
// note: using a LinkedList so we can do some quick filtering out of zero delay frames in the future
LinkedList<ImageFrame> frames = new LinkedList<ImageFrame>();
// will hold a copy of the last frame's "full" image which we can use to restore from a "restoreToPrevious"
// disposal method if found in a subsequent frame. this will constantly be changed as we read through the
// gif's frames and come across non-restoreToPrevious disposal method frames.
BufferedImage lastFullFrame = null;
// will hold the size of the "canvas" which we will be drawing each frame into to generate complete
// BufferedImage instances for each frames ImageFrame instance. this is the full width/height of the entire
@ -60,10 +61,9 @@ public class AnimatedGif {
}
// canvas image. this is going to be our "scratch space" which we will draw each frame into to generate a full
// BufferedImage object for and set in an ImageFrame instance for each frame of animation. this is necessary
// because some types of animation will specify some frames as smaller images which need to be rendered at
// certain positions on top of the previous frame, so having a canvas to draw on makes generating the full
// image for each frame much simpler
// BufferedImage object for. this is necessary because some types of animation will specify some frames as
// smaller images which need to be rendered at certain positions on top of the previous frame, so having a
// canvas to draw on makes generating the full image for each frame much simpler
BufferedImage canvas = null;
Graphics2D canvasGraphics = null;
@ -121,10 +121,14 @@ public class AnimatedGif {
// draw this frame into our canvas
canvasGraphics.drawImage(image, x, y, null);
// create an ImageFrame instance for this frame, using the current contents of our canvas image (which
// should at this point have the full image contents to accurately draw this frame of animation)
BufferedImage copy = new BufferedImage(canvas.getColorModel(), canvas.copyData(null), canvas.isAlphaPremultiplied(), null);
frames.add(new ImageFrame(copy, delay, disposal));
// invoke the passed Clojure function given passing the delay and the current canvas image which will
// contain a copy of this frame's "full" image. skip over this for zero-delay frames, which are just
// intermediate frames to "prep" the canvas for subsequent frames (i guess as a way to clear/fill the
// background for a bunch of upcoming frames which don't fill the entire canvas? anyway, we don't need them
// anymore as they aren't meant to be displayed).
// More info: http://www.imagemagick.org/Usage/anim_basics/#zero
if (delay > 0)
fn.invoke(canvas, delay);
// handle certain disposal methods
if (disposal.equals("restoreToPrevious")) {
@ -132,16 +136,9 @@ public class AnimatedGif {
// overlaid. If the previous frame image also used a ['restoreToPrevious'] disposal method, then the
// result will be that same as what it was before that frame.. etc.. etc.. etc..."
// -- http://www.imagemagick.org/Usage/anim_basics/#dispose
BufferedImage from = null;
for (int i = frameIndex - 1; i >= 0; i--) {
if (!frames.get(i).disposal.equals("restoreToPrevious") || frameIndex == 0) {
from = frames.get(i).image;
break;
}
}
// reset the canvas to the previous frame which we found above
canvas = new BufferedImage(from.getColorModel(), from.copyData(null), from.isAlphaPremultiplied(), null);
// reset the canvas
canvas = new BufferedImage(lastFullFrame.getColorModel(), lastFullFrame.copyData(null), lastFullFrame.isAlphaPremultiplied(), null);
canvasGraphics = canvas.createGraphics();
canvasGraphics.setBackground(new Color(0, 0, 0, 0));
@ -156,20 +153,13 @@ public class AnimatedGif {
// ready for the next frame
canvasGraphics.clearRect(x, y, image.getWidth(), image.getHeight());
}
// keep a copy of the current canvas image if this frame can be used to recover from a "restoreToPrevious"
// disposal method in a future frame
if (!disposal.equals("restoreToPrevious") || lastFullFrame == null)
lastFullFrame = new BufferedImage(canvas.getColorModel(), canvas.copyData(null), canvas.isAlphaPremultiplied(), null);;
}
reader.dispose();
// remove zero-delay frames, which are just intermediate frames to "prep" the canvas for subsequent frames
// (i guess as a way to clear/fill the background for a bunch of upcoming frames which don't fill the entire
// canvas? anyway, we don't need them anymore as they aren't meant to be displayed)
// More info: http://www.imagemagick.org/Usage/anim_basics/#zero
Iterator<ImageFrame> itor = frames.iterator();
while (itor.hasNext()) {
if (itor.next().delay == 0)
itor.remove();
}
return frames;
}
}