Develop Reference

Resize Java BufferedImage keeping aspect ratio and fill with background

I'm working with Java to store and modify .jpg images, (not Android or Swing). I want to transform an image with a new dimension keeping the aspect ratio and filling the background with white color if the new dimension is not proportional to the original image.
BufferedImage image = /*Here i read from disk and load the image */;
image = resizeImage(image, newWidth, newHeight);
ImageIO.write(image, extension, new File(filename + "_" + page + "." + extension));
The function I'm trying to implement is resizeImage: in the example resizes the image but it doesn't keep the aspect ratio.
private static BufferedImage resizeImage(BufferedImage originalImage, int width, int height) {
BufferedImage resizedImage = new BufferedImage(width, height, originalImage.getType());
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, width, height, null);
g.dispose();
return resizedImage;
}
I think a picture will be more illustrative of what I'm asking for:
If the original image is 200x200 and is asked to resize to 400x300 the result should be a picture with white margin and the original picture resized inside. In this example should be 300x300.
The problem is not how to resize, it's how to fill the remaining image with white and the original resized image on the center of it.

This code worked for me:
private static BufferedImage resizeImage(BufferedImage originalImage, int newWidth, int newHeight) {
BufferedImage resizedImage = new BufferedImage(newWidth, newHeight, originalImage.getType());
Graphics2D graphics = resizedImage.createGraphics();
graphics.setColor(Color.WHITE);
// fill the entire picture with white
graphics.fillRect(0, 0, newWidth, newHeight);
int maxWidth = 0;
int maxHeight = 0;
// go along the width and height in increments of 1 until one value is equal to the specified resize value
while (maxWidth <= newWidth && maxHeight <= newHeight)
{
++maxWidth;
++maxHeight;
}
// calculate the x value with which the original image is centred
int centerX = (resizedImage.getWidth() - maxWidth) / 2;
// calculate the y value with which the original image is centred
int centerY = (resizedImage.getHeight() - maxHeight) / 2;
// draw the original image
graphics.drawImage(originalImage, centerX, centerY, maxWidth, maxHeight, null);
graphics.dispose();
return resizedImage;
}
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How to make JButton with transparent icon and non-transparent text?

I need to make a JButton with an image icon and regular text. This question is not duplicate of How to make JButton with transparent background and regular text?, as I need to upload an image as icon and make it transparent as well. I tried to use overriden paintComponent() method
#Override
public void paintComponent(java.awt.Graphics g) {
java.awt.Graphics2D g2 = (java.awt.Graphics2D) g;
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));
super.paintComponent(g2);
}
But all it does is paints icon and text both transparent, also button does not refresh properly.
Are there any possible workarounds?
UPDATE
The way I am setting the button is the following (item.getImage() returns array of bytes):
setFocusable(true);
setFocusPainted(true);
setVerticalTextPosition(SwingConstants.CENTER);
setHorizontalTextPosition(SwingConstants.CENTER);
if(item.getImage() != null) {
int w = BUTTON_SIZE - 10;
int h = BUTTON_SIZE - 10;
if(menuItem.isShowImageOnly()) {
setIcon(menuItem.getScaledImage(w, h));
}
else {
w = 80;
h = 40;
setIcon(menuItem.getScaledImage(w, h));
}

Just draw the transparency on the Image first
Image im = ...;
java.awt.Graphics2D g2 = (java.awt.Graphics2D) im.getGraphics();
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));
g2.drawImage(0,0, im, null);
g2.dispose();
ImageIcon icon = ...

Current Coordinate of bufferedImage Object in java

Is there anyway to find the current position of a buffered image on jpanel?
I draw an image on buffer, named it currentImage. Now I want to move it around a Panel by using affine transform.
To do translation by using mouse, I have to know the current position, new position and update the new position.
But I have trouble in getting the current position of the BufferedImage. There is no method in the IDE's suggestion working.
Can anyone give me an idea how to do this ?? Thanks!
EDIT
this is my draw and paintComponent method:
private void draw(){
AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC);
int w = this.getWidth(); int h = this.getHeight();
if (currentImage == null || width != w || height != h){
width = w;
height = h;
currentImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
graphics = currentImage.createGraphics();
graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_GASP);
drawClearAndGradedArea(graphics);
drawActualRunway(graphics, width, height, width, height);
drawLeftToRight(graphics);
drawRightToLeft(graphics);
drawCentralLine(graphics);
graphics.setComposite(ac);
}
}
paintComponent()
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.clearRect(0,0, this.getWidth(), this.getHeight());
RenderingHints rh = new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHints(rh);
g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_GASP);
/*
* main components on panel
*/
this.draw();
this.animation();
g2d.drawImage(currentImage, transform, this);
drawNote(g2d);
g2d.dispose();
}

Draw Random thickness lines

I'm trying to use setStroke and BasicStroke to draw random thickness lines.
here is the painting code
public void paintComponent(Graphics g1) {
Random rand = new Random();
Graphics g2 = (Graphics2D) g1;
//set background color
g2.setColor(Color.white);
g2.fillRect(0, 0, getWidth(), getHeight());
Dimension d = getPreferredSize();
//set line's color
float r = rand.nextFloat();
float g = rand.nextFloat();
float b = rand.nextFloat();
Color randomColor = new Color(r,g,b);
g2.setColor(randomColor);
//set line's stroke
float width = rand.nextFloat();
BasicStroke randomStroke = new BasicStroke(width);
((Graphics2D) g2).setStroke(randomStroke);
for (Line2D.Double line : lines) {
g2.drawLine(
(int)line.getX1(),
(int)line.getY1(),
(int)line.getX2(),
(int)line.getY2()
);
}
}
when I set the width of stroke to a certain number, it can draw correctly. I looked up the BasicStroke class, it have the following parameters:
float width;
int join;
int cap;
float miterlimit;
float[] dash;
float dash_phase;
Besides width, I'm not sure what are the others function.
How can I use the BasicStroke to generate random thickness lines?

I think the biggest problem is that nextFloat() is returning values between 0 and 1 - where I'm guessing you want numbers greater than 1 in order to be able to see any visible difference in line thickness.
Besides width, I'm not sure what are the others function.
Please refer to the Javadocs .

Changing Image Opacity

In a project, I want to simultaneously resize and change the opacity of an image. So far I think I've got the resizing down. I use a method defined like so to accomplish the resizing:
public BufferedImage resizeImage(BufferedImage originalImage, int type){
initialWidth += 10;
initialHeight += 10;
BufferedImage resizedImage = new BufferedImage(initialWidth, initialHeight, type);
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, initialWidth, initialHeight, null);
g.dispose();
return resizedImage;
}
I got this code from here. What I can't find a solution to is changing the opacity. That's what I'm wondering how to do (if it's possible at all). Thanks in advance.
UPDATE:
I tried this code to display a picture of a circle with transparent insides and outsides (see below image) growing and becoming less and less opaque, but it didn't work. I'm not sure what's wrong. All the code is in a class called Animation
public Animation() throws IOException{
image = ImageIO.read(new File("circleAnimation.png"));
initialWidth = 50;
initialHeight = 50;
opacity = 1;
}
public BufferedImage animateCircle(BufferedImage originalImage, int type){
//The opacity exponentially decreases
opacity *= 0.8;
initialWidth += 10;
initialHeight += 10;
BufferedImage resizedImage = new BufferedImage(initialWidth, initialHeight, type);
Graphics2D g = resizedImage.createGraphics();
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, opacity));
g.drawImage(originalImage, 0, 0, initialWidth, initialHeight, null);
g.dispose();
return resizedImage;
}
I call it like this:
Animation animate = new Animation();
int type = animate.image.getType() == 0? BufferedImage.TYPE_INT_ARGB : animate.image.getType();
BufferedImage newImage;
while(animate.opacity > 0){
newImage = animate.animateCircle(animate.image, type);
g.drawImage(newImage, 400, 350, this);
}

first make sure the type you're passing into to method contains an alpha channel, like
BufferedImage.TYPE_INT_ARGB
and then just before you paint the new image, call the Graphics2D method setComposite like so:
float opacity = 0.5f;
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, opacity));
that will set the drawing opacity to 50%.