先看一下调整前后的效果图：

         // Layout AllApps
        AppsCustomizeTabHost host = (AppsCustomizeTabHost)
                launcher.findViewById(R.id.apps_customize_pane);
        if (host != null) {
            // Center the all apps page indicator
            int pageIndicatorHeight = (int) (pageIndicatorHeightPx * Math.min(1f,
                    (allAppsIconSizePx / DynamicGrid.DEFAULT_ICON_SIZE_PX)));
            pageIndicator = host.findViewById(R.id.apps_customize_page_indicator);
            if (pageIndicator != null) {
                lp = (FrameLayout.LayoutParams) pageIndicator.getLayoutParams();
                lp.gravity = Gravity.CENTER_HORIZONTAL | Gravity.BOTTOM;
                lp.width = LayoutParams.WRAP_CONTENT;
                lp.height = pageIndicatorHeight;
                pageIndicator.setLayoutParams(lp);
            }

            AppsCustomizePagedView pagedView = (AppsCustomizePagedView)
                    host.findViewById(R.id.apps_customize_pane_content);
            padding = new Rect();
            if (pagedView != null) {
                // Constrain the dimensions of all apps so that it does not span the full width
                    // TChip ZJ Add START: 去掉所有应用列表，横屏时左右两侧的Margin
                int paddingLR = (availableWidthPx - (allAppsCellWidthPx * allAppsNumCols)) /
                        (2 * (allAppsNumCols + 1));
                int paddingTB = (availableHeightPx - (allAppsCellHeightPx * allAppsNumRows)) /
                        (2 * (allAppsNumRows + 1));
                paddingLR = Math.min(paddingLR, (int)((paddingLR + paddingTB) * 0.75f));
                paddingTB = Math.min(paddingTB, (int)((paddingLR + paddingTB) * 0.75f));
                    paddingLR = (int)(paddingLR * 0.75f);
                    paddingTB = (int)(paddingTB * 0.75f);
                    // TChip ZJ Add END
                   
                    // TChip ZJ Minus START: 去掉所有应用列表，横屏时左右两侧的Margin
                    /*
                    int paddingLR = 2;
                    int paddingTB = 2;
                    */
                    // TChip ZJ Minus END
                int maxAllAppsWidth = (allAppsNumCols * (allAppsCellWidthPx + 2 * paddingLR));
                int gridPaddingLR = (availableWidthPx - maxAllAppsWidth) / 4;
                // Only adjust the side paddings on landscape phones, or tablets
                if ((isTablet() || isLandscape) && gridPaddingLR > (allAppsCellWidthPx / 4)) {
                    padding.left = padding.right = gridPaddingLR;
                }
                // The icons are centered, so we can't just offset by the page indicator height
                // because the empty space will actually be pageIndicatorHeight + paddingTB
                padding.bottom = Math.max(0, pageIndicatorHeight - paddingTB);
                pagedView.setAllAppsPadding(padding);
                pagedView.setWidgetsPageIndicatorPadding(pageIndicatorHeight);
            }
        }

Android Launcher3去掉所有应用列表，横屏时左右两侧的留空