How to Accurately Center a Resizable JFrame and Detect Collisions with its Edges?

Resolving Exact Center Positioning in Resizable JFrame

Your query presents two challenges: precise collision detection with the frame's edges and determining the exact center, regardless of screen size.

Collision Detection Correction

The observed 10-pixel offset in collision detection likely stems from a misunderstanding of the frame's dimensions. A JFrame includes a border, JRootPane, and other components around the actual content pane. Therefore, you need to adjust your calculations to account for the border's width and height.

To obtain the exact paintable region, use the formula:

Width - border.width
Height - border.height

Exact Screen Center Determination

To find the exact center of the screen, consider the following:

• Frame's Perspective: The center is at (100x100) based on the frame's dimensions.
• Content Pane's Perspective: The center is at (92x81) based on the content pane's dimensions.

The choice of which value to use depends on your purpose:

• For positioning the frame, use the frame's center point.
• For painting, use the content pane's center point.

Method for Centering the Frame

To easily center the frame on the screen, call Window#setLocationRelativeTo(null).

Alternatively, you can use the following formula:

JFrame frame = ...;
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
int x = (screenSize.width - frame.getWidth()) / 2;
int y = (screenSize.height - frame.getHeight()) / 2;
frame.setLocation(x, y);

The above is the detailed content of How to Accurately Center a Resizable JFrame and Detect Collisions with its Edges?. For more information, please follow other related articles on the PHP Chinese website!