Canvas:onMouseWheel(delta, buttons) event


This event is fired when the user rotates the mouse wheel while beeing over the Canvas.

Parameters

delta

A numberthat indicates the distance the wheel is rotated, expressed in multiples or divisions of 120.
A positive value indicates that the wheel was rotated forward, away from the user, a negative value indicates that the wheel was rotated backward, toward the user.

buttons

A table which fields indicates if mouse buttons or special keys have been pressed during the mouse up event :

  • "left": true if left mouse button is pressed, false otherwise
  • "right": true if right mouse button is pressed, false otherwise
  • "middle": true if middle mouse button is pressed, false otherwise
  • "control": true if the CONTROL key is pressed, false otherwise
  • "shift": true if the SHIFT mouse button is pressed, false otherwise

Return value

The event returns no value.

Example

local ui = require "ui" require "canvas" local win = ui.Window("Canvas - onMouseWheel event example", "fixed", 320, 240) local c = ui.Canvas(win) c.align = "all" local width = c.width/2 local height = c.height/2 local scale = 1 function c:onMouseWheel(delta) scale = scale + 0.05*delta/120 end function c:onPaint() self:begin() self:clear() c:identity() c:scale(scale, scale) c:fillrect(width-35, height-35, width+35, height+35, 0xA569BDFF) self:flip() end ui.run(win):wait()