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Most efficient way to render a dynamic image

I want to show an image (in a JPanel) that must update quickly (about 30 fps). I also want to keep my CPU usage as low as possible.
Each image update will consist of either:
Moving a block of pixels to a new location
Replacing a block of pixels with a new block
The first solution that came to mind was something like this:
private BufferedImage screen;
public void runBlockUpdate(int x, int y, int pieceWidth, int pieceHeight byte[] piece){
ImageIcon imgPiece = new ImageIcon(piece);
Graphics2D g = screen.createGraphics();
g.drawImage(imgPiece.getImage(), x, y, pieceWidth, pieceHeight, null);
repaint();
}
#Override
public void paintComponent(Graphics g) {
g.drawImage(screen, 0, 0, (int) (screenRect.width * screenScale), (int) (screenRect.height * screenScale), this);
}
My main performance concern regards the paint() method. I want to know if there are any more efficient ways of doing this before I fully implement this technique.

You can try to use a swing timer an call the refresh method(JFrame.repaint()) every 30millisec

How to add an image to an already drawn box using LWJGL & Slick2D

I am creating a simple 2D game for my computer class. I already have a box that moves around through a level. But, i want to change this box to instead display a stickman standing that I drew. Then, more specifically, i would like in my MovementInput class (where i assign movements to the buttons), I want when neither A(my moving left button) or D(my moving right button) OR when both A and D are held down to display this standing.png image. How would i go about doing this?!
This is my code for drawing the box
public class Man extends AbstractMoveableEntity {
public Man(double x, double y, double width, double height) {
super(x, y, width, height);
}
#Override
public void draw() {
glColor3d(0, 0, 255);
glRectd(x - width / 2, y, x + width / 2, y + height);
}
}
And in my MovementInput class, this is my code for the A&D thing
if ((Keyboard.isKeyDown(Keyboard.KEY_D) &&Keyboard.isKeyDown(Keyboard.KEY_A))||(!Keyboard.isKeyDown(Keyboard.KEY_D) && !Keyboard.isKeyDown(Keyboard.KEY_A))) {
man.setDX(0);
}

Use something called Texture Atlases for multiple frames of animation and a simple timer to loop through the frames. ThinMatrix on YouTube has a really good tutorial for this here as well as many other concepts.

How to create a healthbar in Libgdx?

I have been wondering how I would go by making a health bar in libgdx/java. I am looking into a Shape Renderer thinking I can use a filled shape to create a health bar, though I am not sure on how to make an approach in that direction. On the other hand I have been looking into using scene2D and NinePatches to create a healthbar for the game. I have tried to use a NinePatch/Scene2D by looking up websites on google, though it seems when I add the code I always get an issue when I try to render it to my screen. So if anybody can help me create a functional health bar in libgdx using whatever method, I would be extremely thankful. Thank you.
I cannot post pictures yet, because I have not posted 10 posts. So here is the link http://gyazo.com/6650f3d820f31c99c3f8061ebed0bdec. Sorry

I don't have any experience with Scene2D and stages but here is how i would do a simple healthbar:
Create a rectangle and fill this with a color or texture.
When a player loses HP shorten that rectangle by the same percentage as the HP lost.
Create a basic Orthographic camera with the height/width of the screen. I usually call this viewportCam.
Below all the other draw logic you change the SpriteBatch too spriteBatch(viewportCam.Combined)
Within this spritebatch you draw the healthbar.
public void Draw()
{
spriteBatch(normalCam.combined);
spriteBatch.begin();
//Normal draw logic.
spriteBatch.end();
spriteBatch(viewportCam.combined);
spriteBatch.begin();
//Draw UI elements last so the will be drawn on top of the rest.
spriteBatch.end();
}
If you draw a slightly larger rectangle behind the healthbar you have yourself a border.
You can change color depending on how much percentage health is left.
Edit
Just came across this again and currently using another method. I a ninepatch from a 1 pixel wide red gradient. health = new NinePatch(gradient, 0, 0, 0, 0) this makes sure no artifacts occur while stretching it. From here I just calculate how long it needs to be and draw it.
width = currentHealth / totalHealth * totalBarWidth;
Now you can draw it anywhere you want.
health.draw(batch, 10, 10, width, gradient.getHeight);
If you want somekind of container for it you setup a ninepatch for it and draw it before the dynamic health in the background. So let's say the container is 2 bigger at top/bottom and 5 at left/right.
container = new NinePatch(containerRegion, 5, 5, 2, 2);
//Offset it by the dynamic bar, let's say the gradient is 4 high.
container.draw(batch, 5, 8, totalBarWidth + 10, 8);
health.draw(batch, 10, 10, width, 4);
I "hardcoded" the container 5 to the left and made it 10 longer so it fits horizontally. Vertically I lowered it by 2 and made it 8 high to fit the bar perfectly.

This is how you can do it ,implement logic your self
import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Pixmap;
import com.badlogic.gdx.graphics.Pixmap.Format;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
public class MyGdxGame extends ApplicationAdapter {
SpriteBatch batch;
int i=0;
Texture texture,texture2;
#Override
public void create () {
batch = new SpriteBatch();
initTestObjects() ;
}
#Override
public void render () {
Gdx.gl.glClearColor(0, 0, 0, 0);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.begin();
batch.draw(texture2,100,100,300,20);
batch.draw(texture,100,100,i,20);
if(i>300)
{
i=0;
}
i++;
batch.end();
}
private void initTestObjects() {
int width =1 ;
int height = 1;
Pixmap pixmap = createProceduralPixmap(width, height,0,1,0);
Pixmap pixmap2 = createProceduralPixmap(width, height,1,0,0);
texture = new Texture(pixmap);
texture2 = new Texture(pixmap2);
}
private Pixmap createProceduralPixmap (int width, int height,int r,int g,int b) {
Pixmap pixmap = new Pixmap(width, height, Format.RGBA8888);
pixmap.setColor(r, g, b, 1);
pixmap.fill();
return pixmap;
}
}

Opacity in images with Processing

Very simple thing I'm trying to do here. I would like to have 2 images on top of one another. When i use my mouse event dragged and clicked on the top image, the area of the top level image selected will fade and make the lower image visible.
The way I see it, there are 2 ways I can do this:
I can make the top image Transparent over time (within the selected area)
or
I can delete the pixels individually in a spray can style fashion. Think the spray can tool from MS paint back in the day.
Heres some very basic code that i started which just lays the images on top of eachother
PImage sand;
PImage fossil;
void setup()
{
size(400,400);
background(255,255,0);
frameRate(30);
fossil = loadImage("foss.jpg");
sand = loadImage("sand.jpeg");
}
void draw()
{
image(fossil, 0, 0, width,height);
image(sand, 0, 0, width,height);
smooth();
if (mousePressed) {
fill(0);
tint(255,127); //the opacity function
} else {
fill(255);
}
}
So has anyone any comments on these 2 ways of creating opacity or perhaps there an easier way I've overlooked?
Perhaps I wasn't clear in my Spec as the 2 comments below are asking for clarification.
In its simplest terms, I have 2 images on top of each other. I would like to be able to make some modification to the top level image which would make the bottom image visible. However I need to make this modification to only part of the top level image.
I would like to know which is the better option. To make part of the top image become transparent using tint() or to delete the pixels from the top layer.
Then I will proceed with that approach. Any indication as to how to do it is also appreciated.
I hope this clears up any confusion.

If you simply want to crossfade between images, it can be with tint() as you code suggest. You were in fact quite close:
PImage sand;
PImage fossil;
void setup()
{
size(400, 400);
fossil = loadImage("CellNoise.jpg");
sand = loadImage("CellVoronoi.jpg");
}
void draw()
{
//tint from 255 to 0 for the top image
tint(255,map(mouseX,0,width,255,0));
image(fossil, 0, 0, width, height);
//tint from 0 to 255 for the bottom image - 'cross fade'
tint(255,map(mouseX,0,width,0,255));
image(sand, 0, 0, width, height);
}
For the "spray can style " erosion you can simply copy pixels from a source image into the destination image. It's up to you how you loop through pixels (how many, what order, etc.) to get the "spray" like effect you want, but here's a basic example of how to use the copy() function:
PImage sand,fossil;
int side = 40;//size of square 'brush'
void setup()
{
size(400, 400);
fossil = loadImage("CellNoise.jpg");
sand = loadImage("CellVoronoi.jpg");
}
void draw()
{
image(fossil, 0, 0, 400, 400);
if(mousePressed) {
for(int y = 0 ; y < side ; y++){
for(int x = 0; x < side; x++){
//copy pixel from 'bottom' image to the top one
//map sketch dimensions to sand/fossil an dimensions to copy from/to right coords
int srcX = (int)map(mouseX+x,0,width+side,0,sand.width);
int srcY = (int)map(mouseY+y,0,height+side,0,sand.height);
int dstX = (int)map(mouseX+x,0,width+side,0,fossil.width);
int dstY = (int)map(mouseY+y,0,height+side,0,fossil.height);
fossil.set(dstX, dstY, sand.get(srcX,srcY));
}
}
}
}
Note what I am simply looping to copy a square (40x40 in my case), but you can find other fun ways to loop and get different effects.
Have fun!

How to draw a two dimensional graphic at Java?

I have 2 different lists. Each of them holds x and y value pairs(they have both positive and negative values). How can I draw them on a 2D axis? I want to put points for every value and they will blue for first list and red for second list.
My lists' type:
List<List<Double>>
List<Double> inside of List<...> has 2 variables, first of it for x value and the second one is for y value.
However just I need to how to draw a two dimensional graphic at Java(desktop application) and put points wherever I want, improving code for my variables is less important.
PS:
I want the more and more simple of that kind of graphic:
Something like:

you could use a library like http://www.jfree.org/jfreechart/ (LGPL-License) there are lots of examples around the web, and it's quite easy to use.
here's an example, that seems to match your requirements:
http://www.java2s.com/Code/Java/Chart/JFreeChartMarkerDemo1.htm

Assuming you are using Swing with a panel, you can use the following:
public class JImagePanelExample extends JPanel {
private BufferedImage image;
private Graphics2D drawingBoard;
private int x, y; // Image position in the panel
// Let's assume image is a chart and you need to draw lines
public JImagePanelExample(BufferedImage image, int x, int y) {
super();
this.image = image;
// Retrieving a mean to draw lines
drawingBoard = image.createGraphics();
// Draw what you need to draw (see other methods too)
drawingBoard.drawLine(0, 10, 35, 55);
}
// Called by Swing to draw the image in the panel
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, x, y, null);
}
}
If you don't want to use Swing and you just need to draw in 2D, focus on BufferedImage and Graphics2D only.

There is a Java 2D API: http://java.sun.com/products/java-media/2D/ and many charting libraries easily found with a web search.