捕捉Mac触控板变焦 [英] Catching Mac trackpad zoom

问题描述

目前在我的应用程序中，我捕捉鼠标滚轮事件并在Canvas元素上执行放大或缩小操作。如果用户使用Mac并尝试使用触控板执行缩放，则没有事件，实际发生的是放大/缩小浏览器。

有没有办法捕获使用触控板执行缩放事件？

解决方案

至少在Chrome中，触控板捏到缩放触发轮/鼠标滚轮事件，就像按下了ctrl键一样。您可以像任何其他wheel / mousewheel事件一样捕获此事件，并防止其发生默认情况。这里是一个使用jQuery的例子：
$ b $ $ $ $ $ $ $ $ $ $ $ $ $（canvas）。on（mousewheel，function（e）{
if（e.ctrlKey）{
e.preventDefault（）;
e.stopImmediatePropagation（）;

//在这里执行所需的缩放操作
}
}）;

Currently in my application i am catching the mouse wheel events and perform zoom in or out on a Canvas element. If user uses Mac and tries to perform zoom with the trackpad, there is no event and what actually happens is zoom in/out of browser.

Is there a way to catch the zoom event performed with the trackpad?

解决方案

At least in Chrome, trackpad "pinch-to-zoom" triggers a wheel/mousewheel event that appears as though the ctrl key is pressed. You can capture this event just like any other wheel/mousewheel event and prevent its default from occurring. Here is an example using jQuery:

$("canvas").on("mousewheel", function(e) {
    if (e.ctrlKey) {
        e.preventDefault();
        e.stopImmediatePropagation();

        // perform desired zoom action here
    }
});

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