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Android Launcher 3 简单分析

2024-08-12 11:25:06   222人阅读

 

最近在学习Android Launcher的相关知识，在github上找到可以在Android studio上编译的Launcher 3代码，地址：https://github.com/rydanliu/Launcher3

 

Launcher 3的界面主要由SearchDropTargetBar、Workspace、CellLayout、PageIndicator、Hotseat组成。如下图：

技术分享

 

Launcher 3 最主要的是一个Activity，基本上所有操作都集中在这个Activity上。这个Activity文件为Launcher.java，他的布局文件为launcher.xml。

下面为竖屏的布局文件，路径为res/layout-port/launcher.xml。

 

 1 <?xml version="1.0" encoding="utf-8"?> 2  3 <!-- Full screen view projects under the status bar and contains the background --> 4 <com.android.launcher3.LauncherRootView xmlns:android="http://schemas.android.com/apk/res/android" 5     xmlns:launcher="http://schemas.android.com/apk/res-auto" 6     android:id="@+id/launcher" 7     android:layout_width="match_parent" 8     android:layout_height="match_parent" 9     android:fitsSystemWindows="true">10 11     <com.android.launcher3.DragLayer12         android:id="@+id/drag_layer"13 14         android:layout_width="match_parent"15         android:layout_height="match_parent">16 17         <com.android.launcher3.FocusIndicatorView18             android:id="@+id/focus_indicator"19             android:layout_width="22dp"20             android:layout_height="22dp" />21 22         <!-- The workspace contains 5 screens of cells -->23         <!-- DO NOT CHANGE THE ID -->24         <com.android.launcher3.Workspace25             android:id="@+id/workspace"26             android:layout_width="match_parent"27             android:layout_height="match_parent"28             launcher:defaultScreen="@integer/config_workspaceDefaultScreen"29             launcher:pageIndicator="@+id/page_indicator"></com.android.launcher3.Workspace>30 31         <!-- DO NOT CHANGE THE ID -->32         <include33             android:id="@+id/hotseat"34             layout="@layout/hotseat"35             36             android:layout_width="match_parent"37             android:layout_height="match_parent" />38 39         <include40             android:id="@+id/overview_panel"41             layout="@layout/overview_panel"42             android:visibility="gone" />43 44         <!-- Keep these behind the workspace so that they are not visible when45              we go into AllApps -->46         <include47             android:id="@+id/page_indicator"48             layout="@layout/page_indicator"49             android:layout_width="wrap_content"50             android:layout_height="wrap_content"51             android:layout_gravity="center_horizontal" />52 53         <include54             android:id="@+id/search_drop_target_bar"55 56             layout="@layout/search_drop_target_bar" />57 58         <include59             android:id="@+id/widgets_view"60             layout="@layout/widgets_view"61             android:layout_width="match_parent"62             android:layout_height="match_parent"63             android:visibility="invisible" />64 65         <include66             android:id="@+id/apps_view"67             layout="@layout/all_apps"68             android:layout_width="match_parent"69             android:layout_height="match_parent"70             android:visibility="invisible" />71     </com.android.launcher3.DragLayer>72 73     <ViewStub74         android:id="@+id/launcher_overlay_stub"75         android:layout_width="match_parent"76         android:layout_height="match_parent"77         android:inflatedId="@+id/launcher_overlay"78         android:layout="@layout/launcher_overlay" />79 </com.android.launcher3.LauncherRootView>

 

SearchDropTargetBar

屏幕最上方有个搜索框，在我们拖动图标的时候，搜索框会替换成“删除“

 

Workspace

就是屏幕上左右滑的好几屏幕的容器

 

 

CellLayout

 

Workspace里面可以滑动的单独一屏，CellLayout负责图标和小部件的显示和整齐摆放。

 

PageIndicator

滑动屏幕的时候看见下方的指示器

 

Hotseat

用来放置比较常用的应用，比如拨号，短信，相机等。

 

 

下面介绍几个类

 

 

CellLayout 类

mCountX 和 mCountY   分别表示 “x方向icon的个数” 和 “y方向icon的个数” 

mOccupied 二维数组用来标记每个cell是否被占用，内部类CellInfo为静态类，其对象用于存储cell的基本信息。 

 

 

DeviceProfile 类 

设置各元素布局的padding  。修改workspace的padding使用getWorkspacePadding方法。

 

 1     /** Returns the workspace padding in the specified orientation */ 2     Rect getWorkspacePadding(boolean isLayoutRtl) { 3         Rect searchBarBounds = getSearchBarBounds(isLayoutRtl); 4         Rect padding = new Rect(); 5         if (isLandscape && transposeLayoutWithOrientation) { 6             // Pad the left and right of the workspace with search/hotseat bar sizes 7             if (isLayoutRtl) { 8                 padding.set(hotseatBarHeightPx, edgeMarginPx, 9                         searchBarBounds.width(), edgeMarginPx);10             } else {11                 padding.set(searchBarBounds.width(), edgeMarginPx,12                         hotseatBarHeightPx, edgeMarginPx);13             }14         } else {15             if (isTablet) {16                 // Pad the left and right of the workspace to ensure consistent spacing17                 // between all icons18                 float gapScale = 1f + (dragViewScale - 1f) / 2f;19                 int width = getCurrentWidth();20                 int height = getCurrentHeight();21                 int paddingTop = searchBarBounds.bottom;22                 int paddingBottom = hotseatBarHeightPx + pageIndicatorHeightPx;23                 int availableWidth = Math.max(0, width - (int) ((inv.numColumns * cellWidthPx) +24                         (inv.numColumns * gapScale * cellWidthPx)));25                 int availableHeight = Math.max(0, height - paddingTop - paddingBottom26                         - (int) (2 * inv.numRows * cellHeightPx));27                 padding.set(availableWidth / 2, paddingTop + availableHeight / 2,28                         availableWidth / 2, paddingBottom + availableHeight / 2);29             } else {30                 // Pad the top and bottom of the workspace with search/hotseat bar sizes31 32                 padding.set(desiredWorkspaceLeftRightMarginPx - defaultWidgetPadding.left,33                         searchBarBounds.bottom,34                         desiredWorkspaceLeftRightMarginPx - defaultWidgetPadding.right,35                         hotseatBarHeightPx + pageIndicatorHeightPx);36 37                 38             }39         }40         return padding;41     }

 

比如我要将workspace里图标顶部不留空隙，需要设置padding.set的第二个参数为0.

1 padding.set(desiredWorkspaceLeftRightMarginPx - defaultWidgetPadding.left,2                         0,//searchBarBounds.bottom, 3                         desiredWorkspaceLeftRightMarginPx - defaultWidgetPadding.right,4                         hotseatBarHeightPx + pageIndicatorHeightPx);

 

 

InvariantDeviceProfile类

 一些不变的设备相关参数管理类，landscapeProfile 和 portraitProfile为横竖屏模式的DeviceProfile。 

getPredefinedDeviceProfiles方法 负责加载在不同设备上不同的布局，和图标大小等。

 

 

 1 ArrayList<InvariantDeviceProfile> getPredefinedDeviceProfiles() { 2         ArrayList<InvariantDeviceProfile> predefinedDeviceProfiles = new ArrayList<>(); 3         // width, height, #rows, #columns, #folder rows, #folder columns, 4         // iconSize, iconTextSize, #hotseat, #hotseatIconSize, defaultLayoutId. 5         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Super Short Stubby", 6                 255, 300,     2, 3, 2, 3, 3, 48, 13, 3, 48, R.xml.default_workspace_4x4)); 7         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Shorter Stubby", 8                 255, 400,     3, 3, 3, 3, 3, 48, 13, 3, 48, R.xml.default_workspace_4x4)); 9         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Short Stubby",10                 275, 420,     3, 4, 3, 4, 4, 48, 13, 5, 48, R.xml.default_workspace_4x4));11         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Stubby",12                 255, 450,     3, 4, 3, 4, 4, 48, 13, 5, 48, R.xml.default_workspace_4x4));13         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Nexus S",14                 296, 491.33f, 4, 4, 4, 4, 4, 48, 13, 5, 48, R.xml.default_workspace_4x4));15         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Nexus 4",16                 335, 567,     4, 4, 4, 4, 4, DEFAULT_ICON_SIZE_DP, 13, 5, 56, R.xml.default_workspace_4x4));17 18        19 20         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Nexus 5",21                 359, 567,     4, 4, 4, 4, 4, DEFAULT_ICON_SIZE_DP, 13, 5, 56, R.xml.default_workspace_4x4));22         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Large Phone",23                 406, 694,     5, 5, 4, 4, 4, 64, 14.4f,  5, 56, R.xml.default_workspace_5x5));24         // The tablet profile is odd in that the landscape orientation25         // also includes the nav bar on the side26         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Nexus 7",27                 575, 904,     5, 6, 4, 5, 4, 72, 14.4f,  7, 60, R.xml.default_workspace_5x6));28         // Larger tablet profiles always have system bars on the top & bottom29         predefinedDeviceProfiles.add(new InvariantDeviceProfile("Nexus 10",30                 727, 1207,    5, 6, 4, 5, 4, 76, 14.4f,  7, 64, R.xml.default_workspace_5x6));31         predefinedDeviceProfiles.add(new InvariantDeviceProfile("20-inch Tablet",32                 1527, 2527,   7, 7, 6, 6, 4, 100, 20,  7, 72, R.xml.default_workspace_4x4));33         return predefinedDeviceProfiles;34     }

 

比如我在上面代码的17行加入下列代码，将Hotseat设置成3格，图标大小为72dp

1         predefinedDeviceProfiles.add(new InvariantDeviceProfile("MX 4",2                 359, 567,     4, 4, 4, 4, 4, DEFAULT_ICON_SIZE_DP, 13, 3, 72, R.xml.default_workspace_4x4));

 

由于launcher是有许多自定义控件构成的，这里涉及到onMesure,onLayout,onDraw方法的复写

 

onMesure方法顾名思义,主要是用来重新测量自定义控件的高度和宽度,就是设置它的dimesion,一般所有自定义VIEW都需要复写这个方法。

onLayout则主要是ViewGroup需要复写这个方法,其作用给这个ViewGroup下子View布局好显示的位置。

onDraw则是需要真真正正画出内容的控件需要复写的方法,比如textview,或者其子类,其最终利用一个很重要的类Canvas的对象来实现一系列的画图,比如canvas.drawcircle,canvas.drawline.

 

Android Launcher 3 简单分析


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