10 Mouse Operations

The graphics library contains functions that determine where the mouse is, if there are any clicks, etc. The functions get-mouse-click and ready-mouse-click first return a “mouse-click descriptor,” and then other functions take the descriptor and return the mouse’s position, which button was pushed, etc. Mouse clicks are buffered and returned in the same order in which they occurred. Thus, the descriptors returned by get-mouse-click and ready-mouse-click may be from clicks that occurred long before these functions were called.

(get-mouse-click viewport) → mouse-click?

viewport : viewport?

Returns the next mouse click in viewport, waiting for a click if necessary.

(ready-mouse-click viewport) → (or/c mouse-click? false/c)

viewport : viewport?

Returns either a mouse click descriptor or #f if none is available. Unlike get-mouse-click, ready-mouse-click always returns immediately.

(ready-mouse-release viewport) → (or/c mouse-click? false/c)

viewport : viewport?

Returns either a click descriptor from a mouse-release (button-up) event or #f if none is available.

(query-mouse-posn viewport) → (or/c posn? false/c)

viewport : viewport?

Returns either the position of the mouse cursor within viewport or else #f if the cursor is currently outside viewport.

(mouse-click-posn mouse-click) → posn?

mouse-click : mouse-click?

Returns the position of the pixel within a viewport where a given mouse click occurred.

(left-mouse-click? mouse-click) → boolean?

mouse-click : mouse-click?

Returns #t if the mouse click occurred with the left mouse button, #f otherwise.

(middle-mouse-click? mouse-click) → boolean?

mouse-click : mouse-click?

Returns #t if the mouse click occurred with the middle mouse button, #f otherwise.

(right-mouse-click? mouse-click) → boolean?

mouse-click : mouse-click?

Returns #t if the mouse click occurred with the right mouse button, #f otherwise.