#JComponent not displaying/drawing

40 messages · Page 1 of 1 (latest)

south musk
#

if i have a file DrawLines with

public class DrawLine extends JComponent {
    ...
    @Override
    protected void paintComponent(Graphics graphics) {
        super.paintComponent(graphics);

        Graphics2D graphics2d = (Graphics2D) graphics;
        graphics2d.setStroke(new BasicStroke(this.width));
        graphics2d.draw(new Line2D.Float(this.x1, this.y1, this.x2, this.y2));
    }
}

why doesnt this draw a line when i use it in my main JPanel class?

public class LevelBuilder extends JFrame {
    public LevelBuilder() {
        super("Level Builder");
        ...
        for (int horLine = 0; horLine < CELLS_IN_COL; horLine++) {
            getContentPane().add(new DrawLine(...));
        }

        for (int verLine = 0; verLine < CELLS_IN_ROW; verLine++) {
            getContentPane().add(new DrawLine(...));
        }
    }
}
kindred novaBOT
#

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south musk
errant seal
#

the bounds of the component are not specified, the components size is therefore 0 and it is not displayed

south musk
#

woah

errant seal
#

Btw you can achieve the same behavior by using a custom JPanel, you don't need to create that many objects for something so trivial

south musk
#

what do you mean a custom JPanel?

#

im a bit new to java haha

errant seal
#

a class that extends JPanel that overrides its paintComponent method and does custom drawing in there. You can then set that JPanel as the contentPane of the JFrame.

south musk
#

oh i see

#

so like what you had done earlier for me?

#

let me try that

#

but with my other DrawCells class

errant seal
south musk
#

it seems to work but newer and newer bugs pop up hahah

#

thanks a lot!

kindred novaBOT
# south musk thanks a lot!

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south musk
#

ill keep fixing this one step at a time

errant seal
#

you can share these bugs here.

south musk
#

this is what my DrawCells.java looks like

public class DrawCell extends JComponent {
    private int xIdx;
    private int yIdx;
    private int size;
    private Color colour;

    public DrawCell(int xIdx, int yIdx, int size, Color colour) {
        this.xIdx = xIdx;
        this.yIdx = yIdx;
        this.size = size;
        this.colour = colour;

        this.setBounds(this.xIdx * this.size, this.yIdx * this.size, this.size, this.size);
        this.setOpaque(true);
        
    }

    @Override
    protected void paintComponent(Graphics graphics) {
        super.paintComponent(graphics);
        graphics.setColor(colour);
        graphics.fillRect(this.xIdx * this.size, this.yIdx * this.size, this.size, this.size);
    }
}
#

and when i do this in my main class

# 
                    DrawCell cell = new DrawCell(mouseXIdx, mouseYIdx, CELL_SIZE, Color.black);
                    add(cell);
#

nothing pops up

#

BUT

#

if i get rid of * this.size in DrawCells.java i see a square pop up but in the wrong position

#

i need to multiply the size of the cell in order to get the rid placing

#

which is weird

errant seal
#

is xIx the horizontal and yIdx the vertical index ?

south musk
#

yes

#

top to bottom

#

left to right

errant seal
#

You are currently thinking in the wrong system. The coordinates that are used in the paintComponent method should be relative to the component. Therefore
graphics.fillRect(0,0,this.size,this.size);

south musk
#

oh...

#

oh wow that works

#

DAMN i am dumb

#

THANK YOU SO MUCH

kindred novaBOT
# south musk THANK YOU SO MUCH

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