Is there anything obvious wrong with this line of code? I want rectangle to stay centered regardless the size of the window. But this don´t work for some reason, the rectangle stays the same place.
public void run() {
setSize(800, 800);
createEntireFigure();
}
private void createEntireFigure(){
int centerOfWindowWidth = getWidth() / 2;
int centerOfWindowHeight = getHeight() / 2;
GRectWithGLabel ("A String",centerOfWindowWidth, centerOfWindowHeight);
}
Your rectangle size code is only called on rectangle creation, and so it makes sense that the rectangle's position will not change if the GUI is re-sized. You need to somehow listen for size changes in your GUI and call code to re-position the rectangle then for this to work. What graphics library are you using?
Related
If you run the code below, you will see that there is a red square with a blue line along the bottom and right edges of the square. However, as you can see in the code, the parameters for the rectangle being drawn are the same as the rectangle being filled.
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel panel = new JPanel() {
#Override
public void paintComponent(Graphics g) {
g.setColor(Color.blue);
g.drawRect(50, 50, 100, 100);
g.setColor(Color.red);
g.fillRect(50, 50, 100, 100);
}
};
panel.setPreferredSize(new Dimension(200, 200));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
Does anyone know the reasoning behind this behavior? Or is this a bug in Java's codebase?
It seems like drawing the rectangle adds 1 to the width and height of the rectangle you specify. This seems like un-intuitive behavior for one, but in my case it is also causing some undesired effects for a gui I am building.
This behavior is also found when drawing polygons with horizontal/vertical lines. Is there a simple way of getting some consistency in what is painted between the graphics draw and fill functions? It would be great if there was a way for any arbitrary polygon to completely paint over a previously drawn polyline using the same points.
One approach I had thought of was to both draw and fill whenever I want to fill a polygon and then just draw when I want to draw the polygon.
This would actually work in cases of opaque polygons, but in my case I have both opaque and transparent polygons so this approach is not an option.
This is clearly documented in the Graphics API:
drawRect
public void drawRect(int x,
int y,
int width,
int height)
Draws the outline of the specified rectangle. The left and right edges of the rectangle are at x and x + width. The top and bottom edges are at y and y + height. The rectangle is drawn using the graphics context's current color.
and
fillRect
public abstract void fillRect(int x,
int y,
int width,
int height)
Fills the specified rectangle. The left and right edges of the rectangle are at x and x + width - 1. The top and bottom edges are at y and y + height - 1. The resulting rectangle covers an area width pixels wide by height pixels tall. The rectangle is filled using the graphics context's current color.
Note the difference in the calculation for the right and bottom edges. Although this difference is clearly documented, there is no justification for this difference.
Finally, note that the first line of paintComponent() should be super.paintComponent(g);. This will ensure that the super class has a chance to initialize things, including clearing the region where you will draw.
I am having an issue getting this code to run properly. It compiles and initially the frame displays properly. The problem is that when I manually re-size the frame by either maximizing or by dragging the side of the frame over, the text disappears. I am using jGRASP, not sure if that is the issue or not. The code seems to make sense to me, and like I said, it compiles(I know that does not necessarily make it right). I'm still a newbie at this so if anyone can point me in the right direction I would be very appreciative.
import javax.swing.*;
import java.awt.*;
public class JFontSizes extends JFrame {
int x = 5;
int y = 50;
String homework = "This is the first homework assignment";
public JFontSizes() {
super("Increasing Font Sizes");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void paint(Graphics brush) {
super.paint(brush);
// This works sometimes. I am not sure if it is a jGRASP issue or something else.
// If I resize the frame, the text disappears, and I cannot get the text to start at the top of the frame
for(int n = 6; n<= 20; ++n) {
brush.setFont(new Font("Serif", Font.PLAIN, n));
brush.drawString(homework, x, y);
y += 15;
}
}
public static void main(String[] args) {
JFontSizes frame = new JFontSizes();
frame.setSize(400, 500);
frame.setVisible(true);
}
}
When first time paint() is called the value of y was 5. And it is incremented in a loop. So that before leaving paint() its value will be 275.
But when you resize your frame paint() is called again and this time the value of y is 275 and when brush.drawString(homework, x, y); is called the homework is printed at 275px bottom from top left corner.
So what you need to do is re-initialize y every time :
public void paint(Graphics brush) {
y = 50;
....
Edit :
As commented by camickr you should override paintComponent(...) instead of paint(...) until you have some specific reason to override paint().
And you mean you are not able to print text at top (even in beginning) then it is because you had initialized y with 50. Which means the text will be drawn at 50px from top.
There are many questions of the converse, inserting a JTextPane into a JPanel. This is not my question. I need to be able to insert a custom JPanel (with drag and drop, drag, and mouse click listeners) into a JTextPane, which is then put into a JScrollPane, and finally put into a JFrame for displaying. The reason is because I need to have an image with support for resizing by dragging it within a chat client, which is itself primarily text.
Conveniently enough, there is a relevant method in JTextPane: insertComponent(Component c), but whenever I use it, my components end up being squished to exactly one line of text worth of space (even though they report having a larger size). This is perfect for plain buttons, but if I need anything larger, I'm out of luck. I can insert images by themselves just fine, with ImageIcons, but images wrapped inside a JPanel don't work at all (plus I can't add any listeners to ImageIcons, since they're not GUI elements; overriding one isn't an option).
Whenever a user drags an image into the chat client, this bit of code inserts the custom JPanel:
private void sendImage(BufferedImage im, int cl) throws IOException {
if(output == null) return;
//Send the image itself over to your friend
byte[] toSend = toBytes(im, cl);
sendString(nickname.hashCode() + "image"); //Header for image
output.writeInt(toSend.length); //Tells how many bytes to read.
output.write(toSend);
//Let the user know that the image was sent
float linmb = (float)(toSend.length / 1048576.0); //Size of file sent
addText("\n" + nickname + " sent an image! (" + linmb + " MB)\n", Color.RED.darker());
//Show the image itself
DraggerPanel d = new DraggerPanel(im, true);
text.insertComponent(d);
d.repaint();
//Spacer
addText("\n");
}
This is the source for DraggerPanel, the custom JPanel that holds an image:
public class DraggerPanel extends JPanel {
private BufferedImage image; //The image we're drawing
private Point startingPoint = null; //Starting point for resizing
private boolean first = true; //Is this the first drag?
private boolean lockedDrag; //If true, then lock x and y to be proportionally dragged.
public DraggerPanel(BufferedImage image, boolean lockedDrag) {
super();
this.image = image;
this.lockedDrag = lockedDrag;
//The listener for dragging events.
addMouseMotionListener(new MouseMotionListener() {
private int inWidth = 0, inHeight = 0; //Initial height and width values
private double ratio = 0; //Ratio of height to width for locked drag.
public void mouseDragged(MouseEvent m) {
if (first) { //If we're first, record initial position.
startingPoint = m.getPoint();
first = false;
inWidth = getWidth();
inHeight = getHeight();
ratio = (double)inHeight / inWidth;
} else { //Otherwise, change the size of the window.
if (!lockedDrag) {
int w = (int)startingPoint.getX() - m.getX();
int h = (int)startingPoint.getY() - m.getY();
setSize(Math.abs(inWidth - w), Math.abs(inHeight - h));
} else {
int w = (int)startingPoint.getX() - m.getX();
int h = (int)((double)ratio * w);
setSize(Math.abs(inWidth - w), Math.abs(inHeight - h));
}
}
repaint();
}
public void mouseMoved(MouseEvent m){
}
});
//Lets us know when you're not dragging anymore.
addMouseListener(new MouseAdapter(){public void mouseReleased(MouseEvent m){first = true;}});
//Set appropriate size.
if(image != null) setSize(image.getWidth(), image.getHeight());
else setSize(200,200);
//We're live, baby.
setVisible(true);
}
public void paint(Graphics g) {
if (image == null) super.paint(g);
else g.drawImage(image, 0, 0, getWidth(), getHeight(), null);
}
}
Update 1: I followed #camickr 's advice, and updated the DraggerPanel to use setPreferredSize instead of setSize, as well as overrode paintComponent() instead of paint(). Now, the image has the proper height, but is stretched to the width of the JTextPane (which seems like what it was doing before). Furthermore, resizing doesn't seem to matter- the image doesn't change its size at all. Mouse events are definitely going through, but not affecting the size. It seems as though the original problem isn't fully resolved, since the JPanel's size isn't what I need it to be, and the solution to that will also lead to a solution to the resizing issue.
Update 2: I did it! I finally did it. To the future time travelers who have this issue, I basically yelled at the JTextPane by not only using setSize() in my overridden JPanel, but also setPreferredSize() and setMaximumSize(). The preferred one works well with height, and the maximum sets the width (God knows why). Thanks for your tips, #camickr!
my components end up being squished to exactly one line of text worth of space (even though they report having a larger size).
I would guess the size is not important.
I would think you need to override the getPreferredSize() method of your DraggerPanel to return the preferred size of the panel so the text pane can display the panel.
Also, custom painting is done by overriding the paintComponent(...) method NOT the paint() method.
When drawing on my extended JPanel I want the size to be variable. I've worked out the code to always outline a 1 pixel margin. My code works but I don't understand why I must adjust the height and width and height of the dimension by -1 when drawing the rectangle.
If I draw a rectangle that has 1,1 as a size it draws a single pixel square so shouldn't drawing the width and the height work without the -1 modifier.
If any one can explain why there is a discrepancy between the size of my extended JPanel or explain a better way to get the exact dimensions of the drawing area I would appreciate it.
public class Engine extends JPanel {
Engine(){
}
#Override
public void paintComponent(Graphics g){
Dimension a = this.getSize();
g.setColor(Color.RED);
g.drawRect(0, 0, a.width-1, a.height-1);
}
}
Remember, most values are 0 based. But instead of having to say, " I want the width of my panel to be 199" so you get a panel that is 200 pixels wide (0-199), Swing allows you to specify 1 based values and makes adjustments internally
If you create a rectangle of 1, 1, 1, 1, your actually creating a rectangle at position 1x1, whose width & height is 1 pixel (1 + 1 would be 2)
"or explain a better way to get the exact dimensions of the drawing area I would appreciate it."
Override getPreferredSize() in your JPanel class
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
When you you paint, make use of getWidth() and getHeight(), inherited from the JPanel class. Using these methods, your painting will resize dynamically with the resizing of the panel.
int width = getWidth();
int height = getHeight();
g.fillRect((int)(width * 0.9), (int)(height * 0.9),
(int)(width * 0.8), (int)(height * 0.8));
Side Note
You should call super.paintComponent inside the paintComponent method so as not to break the paint chain.
paintComponent should be protected not public
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
}
I've worked out the code to always outline a 1 pixel margin.
Don't do custom painting. Use a Swing Border. See How to Use Borders. You probably want a LineBorder.
I know I am being an idiot and that's why I can't figure it out but I am trying to paint a bunch of rectangles with randoms size and position using paintComponent. I am trying to make sure that all of them are painted within the frame. I am able to do it with the following code (snippet) but I am wondering if there is a better way to do it than me hardcoding numbers into the program. Is there a method that I should take a look at that might be what I'm looking for?
Here's the inner class that overrides the paintComponent() method:
class DrawPanel extends JPanel {
public void paintComponent(Graphics g) {
int red = (int)(Math.random()*256);
int blue = (int)(Math.random()*256);
int green = (int)(Math.random()*256);
g.setColor(new Color(red, blue, green));
//The following 4 lines keep the rects within the frame
//The frame is 500,500
int ht = (int)(Math.random()*400);
int wd = (int)(Math.random()*400);
int x = (int)(Math.random()*100);
int y = (int)(Math.random()*100);
g.fillRect(x,y,ht,wd);
}
}
You should base your co-ordinates & sizes on the DrawPanel component size. Also using Random.nextInt instead of Math.random() will make it easier to keep within range based on the current size of the panel:
Random random = new Random();
int ht = random.nextInt(getHeight());
int wd = random.nextInt(getWidth());
int x = random.nextInt(getWidth() - wd);
int y = random.nextInt(getHeight() - ht);
I am wondering if there is a better way to do it than me hardcoding numbers into the program.
Yes there is
call getSize() on the enclosing JPanel, the DrawPanel, so you can see the actual boundaries of the component that is being drawn upon. (edit: or getWidth() and getHeight() as recommended by Lucas -- 1+ to his answer!).
Also, you will usually want to call the super's paintComponent(...) method within the child's override.
Also you will usually want to do your randomization elsewhere, such as in the DrawPanel's constructor so as not to change your rectangles each time you re-size the GUI.
There is a method to get the length and width of the panel you are working in.
getHeight();
getWidth();
These will return the current size of the JPanel you are working in, meaning if you resize the window it'll actually still draw them inside.
http://docs.oracle.com/javase/7/docs/api/javax/swing/JComponent.html#getWidth()