I have a program containing five buttons:
i) Square ii) Rectangle iii) Circle iv) Triangle v) Clear
Clicking on any of the first four buttons will draw the respective shape on the drawing canvas using the following code:
The shapes can be dragged. They also should be resized. I was just trying to change the cursor of the mouse around the four edges of the shape (NW, NE, SW, SE). This works fine for squares and rectangles since they have four sides. However, I have some problem implementing the same for the circle and triangle.
This is what I did in my mouseClicked event:
What I want to do is that if the string shape_type contains circle, for example, it draws a border around it so that the user can see the boundaries of the shape.
However, I can't just use the following code inside the if statement:
How can I draw the border please? Thanks :)
You are correct that you can't do painting in a MouseListener method. What you can do is set shapeUnderMouse in your mouseClicked method, then call repaint. You'll get better performance if you only repaint the areas that you know are changing visually, but it's not strictly necessary.
The if (shapeUnderMouse != null) block should be placed in your paint method.
Related
I'm trying to figure out if there's any way to draw images (drawRect(), drawOval(), etc.) based on if/else statements or by using an ActionListener.
I don't want to post the complete problem because this is for an assignment, but for my own scenario:
If I have a button on a JPanel named "draw rectangle" and I have the x, y, width, and height from user input, is there any way I can attach an actionListener to "draw rectangle" that could somehow draw the rectangle using those values (passed by reference?).
I know I can use paintComponent, but I can't put that into the ActionListener and it seems to do things of its own accord and not based on a specific user's actions.
I don't really have any code for this because I can't figure out how to do it at all.
If I have a button on a
JPanel named "draw rectangle" and I have the
x, y, width, and height from user input, is there any way I can attach
an actionListener to "draw rectangle" that could somehow draw the
rectangle using those values (passed by reference?).
The short answer is yes.
Generally, you'll need to save the rectangle instructions in a model, and have the JPanel redraw the model when any of the shape buttons are pressed.
Let's take your rectangle example. What do you need to know to draw a rectangle on a JPanel? You need a starting point (upper left) and an ending point (lower right). You can use a java.awt.Point to hold the starting and ending point. You can set the thickness of the line, in pixels. You can set the color of the rectangle, using a JColorChooser. You can also set the rectangle to be an outline or filled with the chosen color.
That description will be similar for a line and a triangle. A circle is a little different, with a center point and a radius. As you can see, we already have a lot of information to keep track of just with these simple geometric shapes.
Then there's the issue of the drawing surface itself. It's possible to have a drawing surface larger than your computer screen can show. You can put the drawing surface inside of a JScrollPane.
All of these things must be determined so you can build the model of your application. You do this before you build the view using Swing components and the controller using action listeners.
I made a sketch with the behavior I'm trying to get.
Sketch
So I want to display a rectangle in the middle of the screen and a triangle that covers part of the rectangle. The problem is, when I use a Stackpanethe rectangle is centered but the triangle as well and I can't move it to the bottom right position. When I use a Groupit is not centered. Is there any way to get my intended behavior?
Set alignment of your triangle. Use static setAlignment(Node child, Pos value) method:
StackPane.setAlignment(triangle, Pos.BOTTOM_RIGHT)
Let's say that I have drawn a square on the screen using the following code:
I want that if the user clicks on the shape, a border with four small boxes (north, south, east and west) is drawn on the shape. Hovering on any of the small boxes changes the cursor to the resize cursor and, if the user drags the small box to a new location, the shape is resized.
How can this be done please?
Instead of using drawRect() method create Shape object for the rectangle and draw the Shape. For Shape you can use getBounds() to get main rectangle. Use the bounds to find the small boxes rectangles (also Shapes).
When mouse is moved (or dragged) check whether one of the boxes shapes contains the mouse event coordinates.
On drag you can change original Shape using AffineTransfrorm.
I am writing a zigzag drawer as my school assignment. Basically what is expected is to be able to draw zigzags on a canvas, to be able to move vertices of the zigzags and to be able to move the entire zigzag. Also we can change the color and thickness of the zigzags.
I could manage to draw zigzags, a left click starts and subsequent left clicks continues the zigzag, and a right click finishes it. In this way i can draw several zigzags.
What i can not do is how i can make the vertices of the zigzags movable? I am keeping the point coordinates in an arraylist of type mypoint which consists of x, y and depth values. I am drawing all the painting on a canvas which is an extended class of JPanel. in the paintcomponent method i call drawline methode for every vertex in the list. As these are just paintings i cannot figure out how i will detect that the user is clicking on the vertex. Can i have little button like controllers when clicked will do the job i want. i tried to use labels and standard buttons, but neither can i position them appropriately nor are they too large to be just handlers for vertices.
Do you have suggestions on these?
You could have two modes of operations, which must be chosen by the user by selecting a radio button, for example: one for drawing zigzags, and the other one for selecting vertices.
While the chosen mode is "zigzag", the mouse clicks allow drawing zigzags as you have already implemented. When the chosen mode is "vertex selection", then a mouse click could find a vertex whose distance from the clicked point is less than 3 pixels, and the dragging of the mouse could move the vertex from its original position, following the mouse pointer.
You could inform the user about the selected vertex by displaying a small squere around the vertex.
If I draw some circles using Java2D. Is there a way display some text when I hover over any of the circles? i.e. I want to display the ID of that circle and some other stuff.
There are a number of ways to accomplish what you want. This is one solution. I assume that you are using Ellipse2D to create the circle. And I assume that you are drawing the circle on a JComponent like a JPanel.
So you declare the Ellipse.
Shape circle = new Ellispe2D.Double(x, y, width, height);
Then you implement MouseMotionListener to detect when the user moves the Mouse over the JPanel.
public void mouseMoved(MouseEvent e){
if(circle.contains(e.getPoint())){
//the mouse pointer is over the circle. So set a Message or whatever you want to do
msg = "You are over circle 1";
}else{
msg = "You are not over the circle";
}
}
Then in the paint() or paintComponent method (whichever one you are overriding to do the painting):
g2.fill(circle);
g2.drawString(msg, 10, 10); //write out the message
I don't know if You can do this directly. But You can use simple math to check cursors position: (x-a)^2+(y-b)^2=r^2 where x,y is cursors position a,b is circles center and r is radius.
You'll have to save all the centers and radius and test it against the current mouse position.
it's pretty simple operation. If the distance of the mouse position and the center of one of the circle is smaller then the radius, the mouse is inside it and you can draw the hover message you want.
there is a question here that shows the math: Equation for testing if a point is inside a circle
Hope that helps...
There is a Polygon class that might do it for you (the contains method), but none of the implementing classes is a circle :S