Launcher3文件夹九宫格显示

最新推荐文章于 2025-07-04 14:23:22 发布

rm_wankai

最新推荐文章于 2025-07-04 14:23:22 发布

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本文详细分析了Android Launcher3中文件夹样式的实现原理，重点介绍了如何通过修改源码来改变文件夹的显示风格。

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转载：http://blog.youkuaiyun.com/zzj000/article/details/53163447（转载只是记录学习，如有侵权请告知）

现在市面上大多数手机的桌面文件夹都是类似iOS那样的风格，将内部包含的app缩略展示在icon图标上；但是Google原生的文件夹风格是圆形背景，app以45度角向外叠起来的。据说Android早期版本也是ios那样的，后来被苹果告侵权才改的。不管怎么说，我个人还是觉得缩略图展示是比较好的，方便查看内部包含的app。正好这段时间比较闲，就来改的玩玩。

以下只是对Launcher3中Folder的源码作了分析，看懂了源码，想要改风格是非常容易的。

Folder的创建起源于Workspace.Java的onDrop回调，每次onDrop都需要判断是否需要创建文件夹。添加文件夹时，首先要将targetCell位置的app从CellLayout中移除，然后再调用Launcher.java的addFolder，将创建好的FolderIcon添加回targetCell这个位置；最后清除放入文件夹的两个app的坐标（因为他们被移出了workspace），并将这两个app添加到FolderIcon中。

boolean createUserFolderIfNecessary(View newView, long container, CellLayout target,
            int[] targetCell, float distance, boolean external, DragView dragView,
            Runnable postAnimationRunnable) {
                            …………
            target.removeView(v);

            FolderIcon fi =
                mLauncher.addFolder(target, container, screenId, targetCell[0], targetCell[1]);
            destInfo.cellX = -1;
            destInfo.cellY = -1;
            sourceInfo.cellX = -1;
            sourceInfo.cellY = -1;

            // If the dragView is null, we can't animate
            boolean animate = dragView != null;
            if (animate) {
                fi.performCreateAnimation(destInfo, v, sourceInfo, dragView, folderLocation, scale,
                        postAnimationRunnable);
            } else {
                fi.addItem(destInfo);
                fi.addItem(sourceInfo);
            }
            return true;
        }
        return false;
    }
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在Launcher.java的addFolder中创建了2个实例，folderInfo和newFolder，并通过Workspace的addInScreen将foler添加到屏幕上。

FolderIcon addFolder(CellLayout layout, long container, final long screenId, int cellX,
            int cellY) {
        final FolderInfo folderInfo = new FolderInfo();
        folderInfo.title = getText(R.string.folder_name);

        // Update the model
        LauncherModel.addItemToDatabase(Launcher.this, folderInfo, container, screenId,
                cellX, cellY);
        sFolders.put(folderInfo.id, folderInfo);

        // Create the view
        FolderIcon newFolder =
            FolderIcon.fromXml(R.layout.folder_icon, this, layout, folderInfo, mIconCache);
        mWorkspace.addInScreen(newFolder, container, screenId, cellX, cellY, 1, 1,
                isWorkspaceLocked());
        // Force measure the new folder icon
        CellLayout parent = mWorkspace.getParentCellLayoutForView(newFolder);
        parent.getShortcutsAndWidgets().measureChild(newFolder);
        return newFolder;
    }
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FolderIcon实际上是一个自定义View，继承自FrameLayout，其核心改写在dispatchDraw。为什么不是onDraw？因为FrameLayout是ViewGroup啊。

@Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);

        if (mFolder == null) return;
        if (mFolder.getItemCount() == 0 && !mAnimating) return;

        ArrayList<View> items = mFolder.getItemsInReadingOrder();
        Drawable d;
        TextView v;

        // Update our drawing parameters if necessary
        if (mAnimating) {
            computePreviewDrawingParams(mAnimParams.drawable);
        } else {
            v = (TextView) items.get(0);
            d = getTopDrawable(v);
            computePreviewDrawingParams(d);
        }

        int nItemsInPreview = Math.min(items.size(), NUM_ITEMS_IN_PREVIEW);
        if (!mAnimating) {
            for (int i = nItemsInPreview - 1; i >= 0; i--) {
                v = (TextView) items.get(i);
                if (!mHiddenItems.contains(v.getTag())) {
                    d = getTopDrawable(v);
                    mParams = computePreviewItemDrawingParams(i, mParams);
                    mParams.drawable = d;
                    drawPreviewItem(canvas, mParams);
                }
            }
        } else {
            drawPreviewItem(canvas, mAnimParams);
        }
    }
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