Why can the cursor on a PC go off screen to the right and bottom but not to the top or to the left?



Why can the cursor on a PC go off screen to the right and bottom but not to the top or to the left?

In: Technology

The point at the end of the cursor is the exact location of the mouse, which means the rest of the cursor icon is not taken into account. So that exact point is at the end of monitor, which appears as if the mouse went off the screen when it really hasn’t, as far as the OS is concerned.

The point of the cursor is at the top left and it is the reference point of what you’re actually pointing at and it is the thing that really has to reach all points on screen and the rest is just an animation. So at the top and left side it will hit the bounds and stop with the animation on the bottom right still visible but when it hits the bounds bottom and right this animation being bottom right of the actual point moves out of bounds/isn’t displayed anymore.

In reality, the cursor is a single pixel big. This pixel is bound to the screen. With a standard cursor, this pixel is located in the top left of the arrow, at the very tip. The cursor you see is just an image attached to that pixel.

Since this pixel can’t leave the screen, when you move to the right or bottom, the pixel is still on the screen (albiet at the very extreme edge) but the rest of the cursor image is off the screen. Going to the top or left, since that pixel is bound to the screen, the image of the cursor can’t go off.

You can go into your mouse options and set your cursor to a crosshair, which naturally clicks at its center. If you do so, you’ll be able to put half your cursor off of every edge – and at the corners you’ll only have a quarter visible.

It’s purely a convention steeped in what’s proven to be useful that the mouse pointer doesn’t actually surround the single pixel to be clicked, but instead minimizes the obscuring effect to a portion of a single quadrant.

It can go off in any direction you configure actually. It depends on how many monitors you have and how you want your desktop to stretch across them.

The origin of the cursor always remains on screen. The origin is rendered at the cursor position and the rest of the cursor is drawn relative to that point. The default arrow cursor has its origin at the top left, but cursors can have an origin anywhere.