html5 canvas 如何实现双指触摸局部的缩小和放大 - V2EX
ffx0s

html5 canvas 如何实现双指触摸局部的缩小和放大

  •  
  •   ffx0s Dec 2, 2016 8742 views
    This topic created in 3447 days ago, the information mentioned may be changed or developed.

    如题,通过给 canvas 绑定了 touch 事件,计算出了缩放的比例以及两指之间的中心点。现在就是缩放的时候 canvas 的 y 和 y 坐标的取值问题。如何以触摸的那个点为原点(origin)进行缩小放大,我要怎么计算 x 和 y 的值。如果有 demo 的话那就更好了!

    3 replies    2016-12-11 21:59:45 +08:00
    MMxiao
        1
    MMxiao  
       Dec 2, 2016
    http://demo.mmxiaohx.net/home/upload 一年前做的东西。 用过。 很急 一个星期 前端加后台 就一个人。 代码有点乱 主要 是用了 那个 facetouch.js 然后 具体的都是那个 app.js 里面的。 代码 很乱 很挫 误喷。
    ffx0s
        3
    ffx0s  
    OP
       Dec 11, 2016
    @MMxiao @shpasspass 感谢,已经解决了。在 stackoverflow 上找到了答案,参考了他们的做法实现了, http://stackoverflow.com/questions/2916081/zoom-in-on-a-point-using-scale-and-translate
    About     Help     Advertise     Blog     API     FAQ     Solana     959 Online   Highest 6679       Select Language
    创意工作者们的社区
    World is powered by solitude
    VERSION: 3.9.8.5 57ms UTC 21:17 PVG 05:17 LAX 14:17 JFK 17:17
    Do have faith in what you're doing.
    ubao msn snddm index pchome yahoo rakuten mypaper meadowduck bidyahoo youbao zxmzxm asda bnvcg cvbfg dfscv mmhjk xxddc yybgb zznbn ccubao uaitu acv GXCV ET GDG YH FG BCVB FJFH CBRE CBC GDG ET54 WRWR RWER WREW WRWER RWER SDG EW SF DSFSF fbbs ubao fhd dfg ewr dg df ewwr ewwr et ruyut utut dfg fgd gdfgt etg dfgt dfgd ert4 gd fgg wr 235 wer3 we vsdf sdf gdf ert xcv sdf rwer hfd dfg cvb rwf afb dfh jgh bmn lgh rty gfds cxv xcv xcs vdas fdf fgd cv sdf tert sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf shasha9178 shasha9178 shasha9178 shasha9178 shasha9178 liflif2 liflif2 liflif2 liflif2 liflif2 liblib3 liblib3 liblib3 liblib3 liblib3 zhazha444 zhazha444 zhazha444 zhazha444 zhazha444 dende5 dende denden denden2 denden21 fenfen9 fenf619 fen619 fenfe9 fe619 sdf sdf sdf sdf sdf zhazh90 zhazh0 zhaa50 zha90 zh590 zho zhoz zhozh zhozho zhozho2 lislis lls95 lili95 lils5 liss9 sdf0ty987 sdft876 sdft9876 sdf09876 sd0t9876 sdf0ty98 sdf0976 sdf0ty986 sdf0ty96 sdf0t76 sdf0876 df0ty98 sf0t876 sd0ty76 sdy76 sdf76 sdf0t76 sdf0ty9 sdf0ty98 sdf0ty987 sdf0ty98 sdf6676 sdf876 sd876 sd876 sdf6 sdf6 sdf9876 sdf0t sdf06 sdf0ty9776 sdf0ty9776 sdf0ty76 sdf8876 sdf0t sd6 sdf06 s688876 sd688 sdf86