{"id":537,"date":"2022-12-29T11:02:38","date_gmt":"2022-12-29T03:02:38","guid":{"rendered":"https:\/\/iichen.cn\/?p=537"},"modified":"2022-12-29T11:02:38","modified_gmt":"2022-12-29T03:02:38","slug":"android-view%e5%8f%af%e8%a7%81%e6%80%a7%e6%a3%80%e6%b5%8b","status":"publish","type":"post","link":"https:\/\/iichen.cn\/?p=537","title":{"rendered":"Android-View\u53ef\u89c1\u6027\u68c0\u6d4b"},"content":{"rendered":"<pre><code class=\"language-java line-numbers\">fun View.onVisibilityChange(\n    viewGroups: List&lt;ViewGroup&gt; = emptyList(), \/\/ \u4f1a\u88ab\u63d2\u5165 Fragment \u7684\u5bb9\u5668\u96c6\u5408\n    needScrollListener: Boolean = true,\n    block: (view: View, isVisible: Boolean) -&gt; Unit\n) {\n    val KEY_VISIBILITY = \"KEY_VISIBILITY\".hashCode()\n    val KEY_HAS_LISTENER = \"KEY_HAS_LISTENER\".hashCode()\n    \/\/ \u82e5\u5f53\u524d\u63a7\u4ef6\u5df2\u76d1\u542c\u53ef\u89c1\u6027\uff0c\u5219\u8fd4\u56de\n    if (getTag(KEY_HAS_LISTENER) == true) return\n\n    \/\/ \u68c0\u6d4b\u53ef\u89c1\u6027\n    val checkVisibility = {\n        \/\/ \u83b7\u53d6\u4e0a\u4e00\u6b21\u53ef\u89c1\u6027\n        val lastVisibility = getTag(KEY_VISIBILITY) as? Boolean\n        \/\/ \u5224\u65ad\u63a7\u4ef6\u662f\u5426\u51fa\u73b0\u5728\u5c4f\u5e55\u4e2d\n        val isInScreen = this.isInScreen\n        \/\/ \u9996\u6b21\u53ef\u89c1\u6027\u53d8\u66f4\n        if (lastVisibility == null) {\n            if (isInScreen) {\n                block(this, true)\n                setTag(KEY_VISIBILITY, true)\n            }\n        } \n        \/\/ \u975e\u9996\u6b21\u53ef\u89c1\u6027\u53d8\u66f4\n        else if (lastVisibility != isInScreen) {\n            block(this, isInScreen)\n            setTag(KEY_VISIBILITY, isInScreen)\n        }\n    }\n\n    \/\/ \u5168\u5c40\u91cd\u7ed8\u76d1\u542c\u5668\n    class LayoutListener : ViewTreeObserver.OnGlobalLayoutListener {\n        \/\/ \u6807\u8bb0\u4f4d\u7528\u4e8e\u533a\u522b\u662f\u5426\u662f\u906e\u6321case\n        var addedView: View? = null\n        override fun onGlobalLayout() {\n            \/\/ \u906e\u6321 case\n            if (addedView != null) {\n                \/\/ \u63d2\u5165\u89c6\u56fe\u77e9\u5f62\u533a\u57df\n                val addedRect = Rect().also { addedView?.getGlobalVisibleRect(it) }\n                \/\/ \u5f53\u524d\u89c6\u56fe\u77e9\u5f62\u533a\u57df\n                val rect = Rect().also { this@onVisibilityChange.getGlobalVisibleRect(it) }\n                \/\/ \u5982\u679c\u63d2\u5165\u89c6\u56fe\u77e9\u5f62\u533a\u57df\u5305\u542b\u5f53\u524d\u89c6\u56fe\u77e9\u5f62\u533a\u57df\uff0c\u5219\u89c6\u4e3a\u5f53\u524d\u63a7\u4ef6\u4e0d\u53ef\u89c1\n                if (addedRect.contains(rect)) {\n                    block(this@onVisibilityChange, false)\n                    setTag(KEY_VISIBILITY, false)\n                } else {\n                    block(this@onVisibilityChange, true)\n                    setTag(KEY_VISIBILITY, true)\n                }\n            } \n            \/\/ \u975e\u906e\u6321 case\n            else {\n                checkVisibility()\n            }\n        }\n    }\n\n    val layoutListener = LayoutListener()\n    \/\/ \u7f16\u8f91\u5bb9\u5668\u76d1\u542c\u5176\u63d2\u5165\u89c6\u56fe\u65f6\u673a\n    viewGroups.forEachIndexed { index, viewGroup -&gt;\n        viewGroup.setOnHierarchyChangeListener(object : ViewGroup.OnHierarchyChangeListener {\n            override fun onChildViewAdded(parent: View?, child: View?) {\n                \/\/ \u5f53\u63a7\u4ef6\u63d2\u5165\uff0c\u5219\u7f6e\u6807\u8bb0\u4f4d\n                layoutListener.addedView = child\n            }\n\n            override fun onChildViewRemoved(parent: View?, child: View?) {\n                \/\/ \u5f53\u63a7\u4ef6\u79fb\u9664\uff0c\u5219\u7f6e\u6807\u8bb0\u4f4d\n                layoutListener.addedView = null\n            }\n        })\n    }\n    viewTreeObserver.addOnGlobalLayoutListener(layoutListener)\n    \/\/ \u5168\u5c40\u6eda\u52a8\u76d1\u542c\u5668\n    var scrollListener:ViewTreeObserver.OnScrollChangedListener? = null\n    if (needScrollListener) {\n         scrollListener = ViewTreeObserver.OnScrollChangedListener { checkVisibility() }\n        viewTreeObserver.addOnScrollChangedListener(scrollListener)\n    }\n    \/\/ \u5168\u5c40\u7126\u70b9\u53d8\u5316\u76d1\u542c\u5668\n    val focusChangeListener = ViewTreeObserver.OnWindowFocusChangeListener { hasFocus -&gt;\n        val lastVisibility = getTag(KEY_VISIBILITY) as? Boolean\n        val isInScreen = this.isInScreen\n        if (hasFocus) {\n            if (lastVisibility != isInScreen) {\n                block(this, isInScreen)\n                setTag(KEY_VISIBILITY, isInScreen)\n            }\n        } else {\n            if (lastVisibility == true) {\n                block(this, false)\n                setTag(KEY_VISIBILITY, false)\n            }\n        }\n    }\n    viewTreeObserver.addOnWindowFocusChangeListener(focusChangeListener)\n    \/\/ \u4e3a\u907f\u514d\u5185\u5b58\u6cc4\u6f0f\uff0c\u5f53\u89c6\u56fe\u88ab\u79fb\u51fa\u7684\u540c\u65f6\u53cd\u6ce8\u518c\u76d1\u542c\u5668\n    addOnAttachStateChangeListener(object : View.OnAttachStateChangeListener {\n        override fun onViewAttachedToWindow(v: View?) {\n        }\n\n        override fun onViewDetachedFromWindow(v: View?) {\n            v ?: return\n            \/\/ \u6709\u65f6\u5019 View detach \u540e\uff0c\u8fd8\u4f1a\u6267\u884c\u5168\u5c40\u91cd\u7ed8\uff0c\u4e3a\u6b64\u9000\u540e\u53cd\u6ce8\u518c\n            post {\n                try {\n                    v.viewTreeObserver.removeOnGlobalLayoutListener(layoutListener)\n                } catch (_: java.lang.Exception) {\n                    v.viewTreeObserver.removeGlobalOnLayoutListener(layoutListener)\n                }\n                v.viewTreeObserver.removeOnWindowFocusChangeListener(focusChangeListener)\n                if(scrollListener !=null) v.viewTreeObserver.removeOnScrollChangedListener(scrollListener)\n                viewGroups.forEach { it.setOnHierarchyChangeListener(null) }\n            }\n            removeOnAttachStateChangeListener(this)\n        }\n    })\n    \/\/ \u6807\u8bb0\u5df2\u8bbe\u7f6e\u76d1\u542c\u5668\n    setTag(KEY_HAS_LISTENER, true)\n}\n<\/code><\/pre>\n<p><a class=\"wp-editor-md-post-content-link\" href=\"https:\/\/mp.weixin.qq.com\/s\/a6WHOdm9L1rQbjVFOUlSsA\" title=\"\u539f\u6587\u5730\u5740\">\u539f\u6587\u5730\u5740<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>fun View.onVisibilityChange( viewGroups: List&lt;ViewGr [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11,8],"tags":[],"class_list":["post-537","post","type-post","status-publish","format-standard","hentry","category-android","category-8"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v24.4 - 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