Develop Reference

Java Add span to image background color

i want to add additional space in images, lets call it "span".
My code is:
BufferedImage newImage = new BufferedImage(image2.getWidth(), image2.getHeight()+200, image2.getType());
Graphics g = newImage.getGraphics();
g.setColor(Color.white);
g.fillRect(0,0,image.getWidth(),image.getHeight()+100);
g.drawImage(image, 0, 100, null);
g.setColor(Color.white);
g.dispose();
RenderedImage rendImage = newImage;
String newUrl8006002 = splitUrl[0]+"-800x6002.jpg";
File file = new File(newUrl8006002);
ImageIO.write(rendImage, "jpg", file);
The problem is, that image at the bottom has black background and i expect white (at the top is white).
Do you know what to change to add white background in whole image?

How about this:
static BufferedImage growY(BufferedImage im, int span, Color color)
{
BufferedImage newImage = new BufferedImage(im.getWidth(), im.getHeight()+span, im.getType());
int topSpan = span/2;
int botSpan = span - topSpan;
Graphics g = newImage.getGraphics();
g.setColor(color);
g.fillRect(0, 0, newImage.getWidth(), topSpan);
g.fillRect(0, topSpan+im.getHeight(), newImage.getWidth(), botSpan);
g.drawImage(im, 0, topSpan, null);
g.dispose();
return newImage;
}

Java Image, after scaled get black color, how to make it white?

I try to scale image to 50x50 px, but I got black color. I need to make black to white
after scaled
this my code:
BufferedImage imgs = urlToBufferImage("src//imgTest.jpg");
BufferedImage resizedImage = new BufferedImage(50, 50, imgs.getType());
Graphics2D g = resizedImage.createGraphics();
// g.setBackground(Color.WHITE);
// g.drawImage(imgs, 0, 0, 50, 50,Color.WHITE, null);
g.drawImage(imgs.getScaledInstance(50, -1, Image.SCALE_DEFAULT), 0, 0, this);
g.dispose();

This is pretty simple.
My approach would be not to create a new BufferedImage, but to do:
BufferedImage imgs = urlToBufferImage("src//imgTest.jpg");
Graphics g = imgs.createGraphics();
g.drawImage(imgs, x, y, 50, 50, null);
or instead of drawing the image inside of the bounds, you could do
Graphics2D g2d = imgs.createGraphics();
g2d.scale(0.5, 0.5);
g2d.drawImage(imgs, x, y, null);

Java AffineTransform makes drawString disappear

This is super-weird. When I create a BufferedImage, and do not change the Graphics2D.transform(), then I can draw a line and text with no problem.
When I do set the transform (I am setting the user space to use EMUs instead of pixels), then I can draw the line using EMU coordinates, but I can't draw text.
code here:
public void testBitmaps2() throws Exception {
// no scaling
BufferedImage image = new BufferedImage(300, 300, BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics = image.createGraphics();
graphics.setBackground(new Color(0x00FFFFFF, true));
graphics.clearRect(0, 0, 300, 300);
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
java.awt.Font javaFont = new java.awt.Font("Arial", java.awt.Font.PLAIN, 24);
graphics.setFont(javaFont);
graphics.setColor(Color.BLACK);
graphics.setStroke(new BasicStroke(1));
graphics.draw(new Line2D.Float(100, 150, 200, 150));
graphics.drawString("hi there", 100, 150);
ImageIO.write(image, "png", new File("c:/temp/", "no_scaling.png"));
// scaling
image = new BufferedImage(300, 300, BufferedImage.TYPE_INT_ARGB);
graphics = image.createGraphics();
// scale to use EMUs, assuming 300DPI image
AffineTransform scaleToEmus = AffineTransform.getScaleInstance(300f / 914400f, 300f / 914400f);
graphics.transform(scaleToEmus);
graphics.setBackground(new Color(0x00FFFFFF, true));
graphics.clearRect(0, 0, 914400, 914400);
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
javaFont = new java.awt.Font("Arial", java.awt.Font.PLAIN, 24);
graphics.setFont(javaFont);
graphics.setColor(Color.BLACK);
graphics.setStroke(new BasicStroke(914400 / 300));
graphics.draw(new Line2D.Float(914400 / 3, 914400 / 2, 914400 * 0.666f, 914400 / 2));
graphics.drawString("hi there", 914400 / 3, 914400 / 2);
ImageIO.write(image, "png", new File("c:/temp/", "scaling.png"));
}

Ok, the javadocs are wrong! The docs say:
size - the point size of the Font
However, you need to scale it up to match the transform scaling.

Writing String into a image in java

I am trying to write a string into a image using ImageIo. But while writing a large string ,full string is not written into that image.
Here's my code:
File url=new File(imgUrl);
BufferedImage image = ImageIO.read(url);
Graphics g = image.getGraphics();
g.setPaintMode();
g.setFont(g.getFont().deriveFont(30f));
g.drawString(text, 100, 100);
g.dispose();
This code works fine for small strings.but when the width of the string exceeds the width of the image,then full string is not displayed on that image.
Any suggestions?

i have an old method try it
public BufferedImage stringToImage(String text, Font font, Color bgColor, Color fgColor) {
BufferedImage image = new BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = (Graphics2D) image.getGraphics();
g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
FontRenderContext fc = g2d.getFontRenderContext();
Rectangle2D bounds = font.getStringBounds(text, fc);
//calculate the size of the text
int width = (int) bounds.getWidth();
int height = (int) bounds.getHeight();
image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
g2d = (Graphics2D) image.getGraphics();
g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setFont(font);
g2d.setColor(bgColor);
g2d.fillRect(0, 0, width, height);
g2d.setColor(fgColor);
g2d.drawString(text, 0, (int)-bounds.getY());
g2d.dispose();
return image;
}
and use
BufferedImage image = stringToImage(text, font, bgColor, fgColor);
ImageIO.write(image, "jpg", file);

Not tested, but it could be done as this:
JLabel label = new JLabel("<html><h2>Title</h2><p>large text ...</p>");
int w = image.getWidth();
int h = image.getHeigth();
label.setBounds(0, 0, w, h);
SwingUtilities.paintComponent(g, label, null, 0, 0, w, h);

There are many ways to acheive this.
FontRenderContext/GlyphVector as mentioned by pbaris. See this answer for an e.g.
FontMetrics as seen in this answer.
A JLabel (possibly multi-line) to contain and size the text. As mentioned by Joop E.G. LabelRenderTest

You can use JTextArea to layout text:
JTextArea textArea = new JTextArea(text);
textArea.setFont(g.getFont().deriveFont(30f));
textArea.setOpaque(false);
textArea.setWrapStyleWord(true);
textArea.setLineWrap(true);
textArea.setBounds(0, 0, image.getWidth(), image.getHeight());
textArea.paint(g);

Drawing pixels on Canvas with BufferedImage not filling the whole Canvas

I'm trying to draw pixels on a Canvas using a BufferedImage. In my Canvas constructor I am initializing the image and pixel array like so:
public MyCanvas() {
Dimension size = new Dimension(WIDTH, HEIGHT);
setSize(size);
setPreferredSize(size);
setMinimumSize(size);
setMaximumSize(size);
image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
pixels = ((DataBufferInt) img.getRaster().getDataBuffer()).getData();
}
I draw every render by doing:
private void render() {
BufferStrategy bs = getBufferStrategy();
if (bs == null) {
createBufferStrategy(3);
return;
}
for (int i = 0; i < pixels.length; i++) {
pixels[i] = 0xFFFFFF;
}
Graphics g = bs.getDrawGraphics();
g.fillRect(0, 0, getWidth(), getHeight());
g.drawImage(img, 0, 0, WIDTH, HEIGHT, null);
g.dispose();
bs.show();
}
I'm expecting that my canvas is filled with white pixels, but I get black borders on the right and bottom of the white area, i.e. it's doesn't seem to be filling my entire canvas, or it has some negative offset. I've checked that the length of the pixel array is WIDTH * HEIGHT. I'm putting the canvas into a JPanel with BorderLayout.CENTER, in a JFrame.
EDIT:
Changing
g.drawImage(img, 0, 0, WIDTH, HEIGHT, null);
to
g.drawImage(img, 0, 0, getWidth(), getHeight(), null);
makes it do what I expect. However I don't understand why I have to fetch the canvas size when I have set the size myself (to WIDTH, HEIGHT), and it doesn't seem to be the same as the size I gave it.

I don't see where you're setting the color for the rectangle fill.
Try this:
Graphics g = bs.getDrawGraphics();
// g.setColor(Color.WHITE);
// g.fillRect(0, 0, getWidth(), getHeight());
g.drawImage(img, 0, 0, getWidth(), getHeight(), null);
g.dispose();
bs.show();