I have a JPanel to which I'd like to add JPEG and PNG images that I generate on the fly.
All the examples I've seen so far in the Swing Tutorials, specially in the Swing examples use ImageIcons.
I'm generating these images as byte arrays, and they are usually larger than the common icon they use in the examples, at 640x480.
Is there any (performance or other) problem in using the ImageIcon class to display an image that size in a JPanel?
What's the usual way of doing it?
How to add an image to a JPanel without using the ImageIcon class?
Edit: A more careful examination of the tutorials and the API shows that you cannot add an ImageIcon directly to a JPanel. Instead, they achieve the same effect by setting the image as an icon of a JLabel. This just doesn't feel right...
If you are using JPanels, then are probably working with Swing. Try this:
BufferedImage myPicture = ImageIO.read(new File("path-to-file"));
JLabel picLabel = new JLabel(new ImageIcon(myPicture));
add(picLabel);
The image is now a swing component. It becomes subject to layout conditions like any other component.
Here's how I do it (with a little more info on how to load an image):
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
public class ImagePanel extends JPanel{
private BufferedImage image;
public ImagePanel() {
try {
image = ImageIO.read(new File("image name and path"));
} catch (IOException ex) {
// handle exception...
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, this); // see javadoc for more info on the parameters
}
}
Fred Haslam's way works fine. I had trouble with the filepath though, since I want to reference an image within my jar. To do this, I used:
BufferedImage wPic = ImageIO.read(this.getClass().getResource("snow.png"));
JLabel wIcon = new JLabel(new ImageIcon(wPic));
Since I only have a finite number (about 10) images that I need to load using this method, it works quite well. It gets file without having to have the correct relative filepath.
I think there is no need to subclass of anything. Just use a Jlabel. You can set an image into a Jlabel. So, resize the Jlabel then fill it with an image. Its OK. This is the way I do.
You can avoid rolling your own Component subclass completely by using the JXImagePanel class from the free SwingX libraries.
Download
JLabel imgLabel = new JLabel(new ImageIcon("path_to_image.png"));
You can subclass JPanel - here is an extract from my ImagePanel, which puts an image in any one of 5 locations, top/left, top/right, middle/middle, bottom/left or bottom/right:
protected void paintComponent(Graphics gc) {
super.paintComponent(gc);
Dimension cs=getSize(); // component size
gc=gc.create();
gc.clipRect(insets.left,insets.top,(cs.width-insets.left-insets.right),(cs.height-insets.top-insets.bottom));
if(mmImage!=null) { gc.drawImage(mmImage,(((cs.width-mmSize.width)/2) +mmHrzShift),(((cs.height-mmSize.height)/2) +mmVrtShift),null); }
if(tlImage!=null) { gc.drawImage(tlImage,(insets.left +tlHrzShift),(insets.top +tlVrtShift),null); }
if(trImage!=null) { gc.drawImage(trImage,(cs.width-insets.right-trSize.width+trHrzShift),(insets.top +trVrtShift),null); }
if(blImage!=null) { gc.drawImage(blImage,(insets.left +blHrzShift),(cs.height-insets.bottom-blSize.height+blVrtShift),null); }
if(brImage!=null) { gc.drawImage(brImage,(cs.width-insets.right-brSize.width+brHrzShift),(cs.height-insets.bottom-brSize.height+brVrtShift),null); }
}
There shouldn't be any problem (other than any general problems you might have with very large images).
If you're talking about adding multiple images to a single panel, I would use ImageIcons. For a single image, I would think about making a custom subclass of JPanel and overriding its paintComponent method to draw the image.
(see 2)
JPanel is almost always the wrong class to subclass. Why wouldn't you subclass JComponent?
There is a slight problem with ImageIcon in that the constructor blocks reading the image. Not really a problem when loading from the application jar, but maybe if you're potentially reading over a network connection. There's plenty of AWT-era examples of using MediaTracker, ImageObserver and friends, even in the JDK demos.
I'm doing something very similar in a private project I'm working on. Thus far I've generated images up to 1024x1024 without any problems (except memory) and can display them very quickly and without any performance problems.
Overriding the paint method of JPanel subclass is overkill and requires more work than you need to do.
The way I do it is:
Class MapIcon implements Icon {...}
OR
Class MapIcon extends ImageIcon {...}
The code you use to generate the image will be in this class. I use a BufferedImage to draw onto then when the paintIcon() is called, use g.drawImvge(bufferedImage); This reduces the amount of flashing done while you generate your images, and you can thread it.
Next I extend JLabel:
Class MapLabel extends Scrollable, MouseMotionListener {...}
This is because I want to put my image on a scroll pane, I.e. display part of the image and have the user scroll around as needed.
So then I use a JScrollPane to hold the MapLabel, which contains only the MapIcon.
MapIcon map = new MapIcon ();
MapLabel mapLabel = new MapLabel (map);
JScrollPane scrollPane = new JScrollPane();
scrollPane.getViewport ().add (mapLabel);
But for your scenario (just show the whole image every time). You need to add the MapLabel to the top JPanel, and make sure to size them all to the full size of the image (by overriding the GetPreferredSize()).
This answer is a complement to #shawalli's answer...
I wanted to reference an image within my jar too, but instead of having a BufferedImage, I simple did this:
JPanel jPanel = new JPanel();
jPanel.add(new JLabel(new ImageIcon(getClass().getClassLoader().getResource("resource/images/polygon.jpg"))));
Create a source folder in your project directory, in this case I called it Images.
JFrame snakeFrame = new JFrame();
snakeFrame.setBounds(100, 200, 800, 800);
snakeFrame.setVisible(true);
snakeFrame.add(new JLabel(new ImageIcon("Images/Snake.png")));
snakeFrame.pack();
You can avoid using own Components and SwingX library and ImageIO class:
File f = new File("hello.jpg");
JLabel imgLabel = new JLabel(new ImageIcon(file.getName()));
I can see many answers, not really addressing the three questions of the OP.
1) A word on performance: byte arrays are likely unefficient unless you can use an exact pixel byte ordering which matches to your display adapters current resolution and color depth.
To achieve the best drawing performance, simply convert your image to a BufferedImage which is generated with a type corresponding to your current graphics configuration. See createCompatibleImage at https://docs.oracle.com/javase/tutorial/2d/images/drawonimage.html
These images will be automatically cached on the display card memory after drawing a few times without any programming effort (this is standard in Swing since Java 6), and therefore the actual drawing will take negligible amount of time - if you did not change the image.
Altering the image will come with an additional memory transfer between main memory and GPU memory - which is slow. Avoid "redrawing" the image into a BufferedImage therefore, avoid doing getPixel and setPixel at all means.
For example, if you are developing a game, instead of drawing all the game actors to a BufferedImage and then to a JPanel, it is a lot faster to load all actors as smaller BufferedImages, and draw them one by one in your JPanel code at their proper position - this way there is no additional data transfer between the main memory and GPU memory except of the initial transfer of the images for caching.
ImageIcon will use a BufferedImage under the hood - but basically allocating a BufferedImage with the proper graphics mode is the key, and there is no effort to do this right.
2) The usual way of doing this is to draw a BufferedImage in an overridden paintComponent method of the JPanel. Although Java supports a good amount of additional goodies such as buffer chains controlling VolatileImages cached in the GPU memory, there is no need to use any of these since Java 6 which does a reasonably good job without exposing all of these details of GPU acceleration.
Note that GPU acceleration may not work for certain operations, such as stretching translucent images.
3) Do not add. Just paint it as mentioned above:
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, this);
}
"Adding" makes sense if the image is part of the layout. If you need this as a background or foreground image filling the JPanel, just draw in paintComponent. If you prefer brewing a generic Swing component which can show your image, then it is the same story (you may use a JComponent and override its paintComponent method) - and then add this to your layout of GUI components.
4) How to convert the array to a Bufferedimage
Converting your byte arrays to PNG, then loading it is quite resource intensive. A better way is to convert your existing byte array to a BufferedImage.
For that: do not use for loops and copy pixels. That is very very slow. Instead:
learn the preferred byte structure of the BufferedImage (nowadays it is safe to assume RGB or RGBA, which is 4 bytes per pixel)
learn the scanline and scansize in use (e.g. you might have a 142 pixels wide image - but in the real life that will be stored as a 256 pixel wide byte array since it is faster to process that and mask the unused pixes by the GPU hardware)
then once you have an array build according to these principles, the setRGB array method of the BufferedImage can copy your array to the BufferedImage.
Related
SUMMARY:
Basically I want to be able to render items based on their Image/Batch/Sprite to speed up my game, but I also have to sort the entities based on y position so that it draws in the correct order.
QUESTION:
How can I do this theoretically? (block of code is nice, but reasoning is better, thanks!)
FULL SITUATION:
I am creating a 2.5 D side-scroller in which I have found that ~500 fps is decent for the early stage of development (on my crap computer at least) but i want this to be higher as I am going to be adding more aspects later (further reducing fps) so I want to be as optimized as I can right now.
What I was wondering is if it is possible to render all entities with the same image file at the same time, to save on time loading up the image files. The struggle I have is that I can't just sort entities by their image file (or at least not that I can think of, that's why I'm asking) because I also need to render them from back to front because its a 2.5 D game.
Right now I am storing the Images in a HashMap, so it isn't completely terrible, I just want to know what I can improve on.
EDIT: Also to note I am using the Jframe and Jpanel classes with Graphics for rendering
You don't need to post a block of code if you don't want. I just want more of the theoretical reasoning.
Thanks!
-Kore
One thought that comes to mind is that if you have an image that you know will be used a lot, you can cache it and that might help.
There are ways to directly reference an image file using BufferedImage and ImageIcon (I would link directly, but i don't have enough points :/ ).
Possibly mixing caching and a direct reference with the image file could help speed up the process. Along with the caching you could possibly find a way to group all of the objects that need the same image file together (this could be done by making an arrayList of all of the objects that use this sprite.), so once one of the objects renders the file, they all render it from the cache at that time. Then the cache is cleared for the next image.
Also, if you were to have variables that pointed to your sprites, then you could have the objects load the variable instead of them all having to point to the image file.
i.e.
String path = "Image1.jpg";
File file = new File(path);
BufferedImage image = ImageIO.read(file);
and then all of your objects referenced image for the source of their image. However, I am not sure if this would be any faster than individually pointing each object to the file, this was just a thought.
Hope some of this answers what you were asking. Good luck!
---edit---
So my next thought could be implemented using a parent class and or just another class that would hold an ArrayList. So the idea is that you don't want to have to use the method images.get(imgPath) every time you want to load an image.
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import javax.swing.ImageIcon;
class SomeClass{
ImageIcon imgOne = new ImageIcon(new BufferedImage(images.get(imgPath)))
ImageIcon imgTwo = new ImageIcon(new BufferedImage(images.get(imgPathTwo)))
private ArrayList<ImageIcon> imagesHolder = new ArrayList<ImageIcon>(){{
add(imgOne);
add(imgTwo);
}};
public ImageIcon getImageIcon(int index){
return imagesHolder.get(index);
}
}
class test{
SomeClass imageHolder = new SomeClass();
JLabel label = new JLabel(imageHolder.getImageIcon(0));
JFrame f = new JFrame();
f.getContentPane().add(label);
}
In this, we have a class (someclass) whose object (that we only need one of) is storing every single image in an arraylist to the most processed state (imageIcon or whatever you are using can be used here) before actually putting it on the JFrame can create an object from to get all of the already rendered images.
This means that all you have to do at this point is add the image to the JFrame. you don't have to do a lot of the preprocessing of each image over and over again, because it's ready to just go on the JFrame.
While this does not particularly help a lot with rendering (cause most of this is processing of the image) it does help a lot with memory, because you are just creating 1 of each processed image and just repainting that same processed image.
hopefully this idea of processing all of the images once can help lead you to a way to have to only render the image once.
I'm searching for a method to properly scale (almost) all of a JFrame's content. All the solutions I have tried so far had a huge lack in rendering speed. What I am looking for is a speed similar to what you have when scaling content on your smartphone.
The JFrame's content should be rescalable quickly and stay scaled even if you overdraw the JFrame with new content. It should also be flexible enough so it let's you choose which BufferedImage's (which is essentially the only type I'm drawing, I don't draw any other "shapes") to redraw. I'm drawing using an ordinary Graphics, resp. Graphics2D object.
What I've tried before is the Graphic2D's scale-method and using an AffineTransformat object to scale each BufferedImage individually:
g.scale(scalingFactorX, scalingFactorY);
or alternatively:
BufferedImage img = someImageToScale();
AffineTransform scaleTransform = AffineTransform.getScaleInstance(scalingFactorX, scalingFactorY);
AffineTransformOp bilinearScaleOp = new AffineTransformOp(scaleTransform,
AffineTransformOp.TYPE_NEAREST_NEIGHBOR);
return bilinearScaleOp.filter(img, new BufferedImage(targetWidth, targetHeight,
BufferedImage.TYPE_INT_ARGB));
where scalingFactorX/Y are the factors the content should be scaled by and targetWidth, resp. targetHeight denote the resulting (scaled) dimensions of the BufferedImage.
Both approaches are rather slow which seems to be because in both cases, each frame, the scaled version of the contents have to be recalculated. I feel like I'm missing something very obvious here.
While drawImage() can resample an image, it must must do so each time paintComponent() is called. As suggested here, AffineTransformOp lets you choose the interpolation type; use the fastest one that meets your image quality requirements. Once you've satisfactorily resampled an image, ensure that you do not inadvertently resample the image a second time when rendering in a particular Graphics context. Override getPreferredSize() to make the destination component the same size as the resampled image, as shown in these examples.
My images are only 32x32, but there are a large amount of them (~500).
Consider using the flyweight pattern to render only visible images. JTable and JList are examples, as outlined here.
Are there performance benefits or other advantages to using separate components?
You may need to prototype and profile to be sure, perhaps by comparing representative examples:
Typical component-based examples include the button-based game cited here, or the chess games examined here, here and here.
The tile-based game cited here illustrates a single tile panel and multiple accessory panels that all listen to a common game model.
I have an application that plots images on a JPanel. I want to dispose of the GUI altogether, so that the application is called from code only, with no user interface, and so that the images are saved to a gif file only.
I have experimented with code from this question, and it seems to work fine when I call the save gif code from within the old GUI. However, the save gif code is not seeming to work when I remove the GUI, and I am wondering if that might be because the JPanel it is trying to print has not actually made it to a GUI container like a JFrame, etc.
The reason I am not posting code is that it is too verbose, an I am just asking for a simple, boilerplate answer.
I have experimented with writeablerasters for other applications. But that would require a major recoding project for this application, which paints by using the graphics.drawLine() method. Can anyone suggest a code-efficient way to take contents of a "phantom" JPanel, get it into a BufferedImage, and then save it as a gif without ever putting the JPanel in a GUI?
Since your application draws on a JPanel then it just needs a Graphics object. You can use one from a BufferedImage which then you will save to file. Example code:
BufferedImage image = new BufferedImage(100, 100, BufferedImage.TYPE_INT_ARGB);
Graphics g = image.getGraphics();
// Pass this graphics object to your application to perform the drawing
g.setColor(Color.red);
g.drawRoundRect(10, 10, 20, 20, 5, 5);
// save it to disk
ImageIO.write(image, "png", new File("test.png"));
This is difficult to answer without any example code, however.
If the component you are trying to render is not displayed on the screen, it is likely that it has not being laid out.
Before painting, you should make sure you size the component.
componentToBePainted.setSize(componentToBePainted.getPreferredSize());
You should also be using print or printAll over paint. When not attached to a native peer, paint can cause issue
I am implementing a board game where each player has several units and each unit is shown to a user using a common image which I read from a file using the following method. I read this image at application startup and going to use it later.
private static BufferedImage readBufferedImage (String imagePath) {
try {
InputStream is = IconManager.class.getClassLoader().getResourceAsStream(imagePath);
BufferedImage bimage = ImageIO.read(is);
is.close();
return bimage;
} catch (Exception e) {
return null;
}
}
Units differ with various colorful tokens located on the top of that common image.
Before I just add several commonImages to JPanel and tokens were implemented using JLabels which were floating on the top of commonImage
//at startup
ImageIcon commonImage = new ImageIcon(readBufferedImage("image.png"));
...
JPanel panel = new JPanel();
panel.add(commonImage);
panel.add(commonImage);
//located JLabels with token on the top of each commonImage
However, now I want to use JScrollPane instead of JPanel, so I think it is a better approach to drawString() and drawImage() to each commonImage before I show it to a user.
I estimate roughly a number of units as 20. So now every turn for every unit I would need to generate on-the-fly separate BufferedImage with various tokens configuration.
The question is whether I should cache already generated BufferedImages depending on token configuration to extract from cache if the image has been generated before with same configuration?
The question you ask depends on a few factors:
How long it takes to generate the image from scratch
How long it takes to check if the image was generated before
How large each image will be
The probability of the image being reused
So without having a good knowledge of your application, no one is going to be able to give you an answer accurate for every situation.
In general, if you're only moving tokens around, it should be quick to implement an update and the paintComponent method of the panel your drawing. If you save your base image, token image and the current resulting image (basically what you proposed), I wouldn't anticipate a performance problem. The key is to do your updating of the image in your custom update method, and always draw the current resulting image in the paintComponent method.
Update
For example, you can cache the current display using code similar to this:
private BufferedImage cachedImage;
...
#Override
public void paintComponent(Graphics g){
//If the image needs to be refreshed draw it to the cache first
if(cachedImage == null){
cachedImage = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
super.paintComponent(cachedImage.getGraphics());
}
//Draw the image from cache
g.drawImage(cachedImage, 0, 0, this);
}
When you want to clear the cache, in your method that does the update, you'd set cachedImage = null;
But in your situation,
Any performance problems at the scale of 200x200 you experience would have to do with the number of drawings you're doing. Since I'm guessing you're not concerned about a frames/second rate, I doubt you'll have performance problems (you can collect timings to see exactly how long it takes to draw - I'd guess well under 100 ms)
The easiest thing to do would be cache the images of the tokens and their strings (I'm assuming they rarely change), but still dynamically create the layout of the tokens. (Any other performance gains in your situation aren't going to be so easy).
Caching previous rendering of the screen will essentially break the swing display model (not much point in using it - just do the layout yourself). This actually applies to pretty much any caching of a container.
I've read the java api, but I still do not understand the main difference between:
1) ImageIcon
2) BufferedImage
3) VolatileImage
4) Image
Can someone tell me when each one is used?
I wouldn't call this explanation below the absolute standard of using Java Image types, but these are the rules of thumb that I follow:
1. ImageIcon
This is typically used when you have small images that you want to add to buttons or to use as window icons. These may be created directly from anything that implements the Image interface.
2. BufferedImage
Typically used when you need to manipulate individual pixels within an image, or when you want to double-buffer a custom paint(Graphics g) method. The image resides in RAM, so it can take up a lot of space, and modifications to BufferedImage instances are not typically hardware-accelerated.
3. VolatileImage
Hardware-accelerated image, so it's fast, but you run the risk of the hardware-backed buffer being overwritten before you're done painting (although this rarely happens and according to Oracle, is only an issue for Windows-based machines). It's a little more difficult to use than BufferedImage for double-buffering custom paint(Graphics g) methods, but is well worth it if you find yourself doing a lot of pre-processing before rendering to screen.
4. Image
This is basically just an interface that defines some bare-bones functionality that every Image should have. You should use this when you don't need to modify an image's contents and/or want to make methods that handle read-only-image data most flexible.
Also, ImageIcon implements serializable so you can send it through java sockets. If you have Image objects, you have to convert them to ImageIcon and send. When the client side took the ImageIcons, it can convert them to Images again.