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.
Related
for my current work, I need to add images on top of other images at runtime. I already searched and I don't want to draw it on a Swing component, I use it in an external API.
Ideally, I would like a library (or a java-native way) with which I can specify several images to "layer", and it would return me a BufferedImage (or any Image object by the way).
If you want a single image (BufferedImage) in return, then you need to compose your images.
This answer may help you stackoverflow.com/questions/2318020/merging-two-images.
Have a look at the documentation for method drawImage to control position and scaling of any drawing through the Graphics object.
I'm creating a java implantation of http://alteredqualia.com/visualization/evolve/, as a hobby project. I'm using HW-accelerated Graphics2D to draw the polygons on a volatile image, I then want to create a texture from the volatileImage so I can use glReadPixels to compare the generated image to the original (which is also a texture).
I spent the last 2 hours spitting through various Textures documentations, but there doesn't seem to an easy way to create a texture out of a volatileImage. Did I miss something here, or is this just not possible? I know you can convert the volatileImage to a BufferedImage and then create the Texture, but this method is very slow. Which is a bad thing considering performance is crucial for this program.
There is no direct way because a VolatileImage has no API for obtaining the image data, except by making a copy using snapshot().
In practice, simply use a BufferedImage from the start - there is some magic under the hood of BufferedImage that will make use of hardware acceleration where possible. One thing you must avoid is obtaining a reference of a BufferedImage's DataBuffer, that may break the acceleration.
I use using WorldWind to plot data, and I also require a 2D interface as an overlay. I have been creating a new BufferedImage a few times per second to update the data, but this requires a lot of overhead. I'd like to redraw on an existing image to decrease the overall usage, both in terms of CPU and memory. I'm using this code before redrawing:
BufferedImage img = TrackingService.img.get(width).get(height);
g = img.createGraphics();
g.setComposite(AlphaComposite.getInstance(AlphaComposite.CLEAR));
g.fillRect(0,0,img.getWidth(),img.getHeight());
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
image = img;
ach element which can add to the UI returns a HashMap of BufferedImage to Point. Each BufferedImage and point is transformed into a ButtonAnnotation and added to an AnnotationLayer. Each x milliseconds, the system will:
layer.removeAllAnnotations();
layer.addAnnotations(buttonAnnotations);
redraw()
on the AWT Event queue. This works fine for markers, etc. but these images will never change from the first image I use. I've tried replacing the layer, disposing it, etc. I've tried writing the images to a debug file and noted that the BufferedImage is changing as expected. The problem is that WorldWind must be caching the images at some level. Since I am providing the same instance of BufferedImage to each new ButtonAnnotation, with a few modifications made using Graphics2D, it appears to be assuming that no changes have been made, when, in fact, there have been. This works perfectly fine if I use a new BufferedImage each time I want the data to change.
I have also tried the suggestions in This Question, and they did not work for me.
I am a C/C++ programmer trying my hand at Java for the first time. I'm currently working on a program that reads in a bunch of data and builds a map. I want to give the user the option to toggle various features of the map using check boxes.
In the Win32 API, I was able to accomplish this by pre-building the features on transparent bitmaps and then BitBlt()ing them over top one another. Does Java Swing support something similar? I imagine I'm not the only person who has ever wanted to do this. Building the features is relatively slow, so I only want to generate the layers once and then block copy them to the JPanel I'm using as a display.
Thanks in advance!
You could dynamically create BufferedImage objects, with alpha channels, then only paint this on a frame if the checkbox is checked.
You can store images in Swing using the BufferedImage class, and then use that to later draw the final image.
http://docs.oracle.com/javase/6/docs/api/java/awt/image/BufferedImage.html
The final image can later be painted on to the JPanel (probably by overriding the JPanel's paintComponent method) by using the alpha values of the images.
I'm in the process of writing a custom heatmap generator. I'm wondering what the fastest way is to draw boxes (up to around 1 million) in Java. Most questions I've found have concentrated on dynamic images (like in games), and I'm wondering if there's a better way to go for static images. I've tried using swing (via a GridLayout and adding a colored canvas to each box), drawing directly on the panel with Graphics2D, and also by using the Processing libraries. While Processing is pretty fast and generates a clean image, the window seems to have problems keeping it; it generates different parts of the image whenever you minimize, move the windows, etc.
I've heard of OpenGL, but I've never touched it, and I wanted some feedback as to whether that (or something else) would be a better approach before investing time in it.
For static images, I paint them to a BufferedImage (BI) and then draw that via Graphics2D.
I keep a boolean that tells me whether the BI is up to date. That way I only incur the expensive painting cost once. If you want to get fancy, you can scale the BI to handle minor resizing. For a major resizing you'll probably want to repaint the BI so as not to introduce artifacts. It's also useful for overlaying data (such as cross hairs, the value under the cursor, etc) as you're only painting the BI and the data.