Android 仿iOS 侧滑关闭Activity框架透底问题解决

背景

问题描述

在项目中使用 SwipeBackLayout 或 SlidingMenu 侧滑关闭Activity框架时，因为windowIsTranslucent这个属性设置为了true，致使按home键退到桌面在返回App时会出现两个问题。

• 先显示上层的Activity,再显示当前交互的Activity。（感受闪一下）
• 几率出现当前Activity整个页面为透明,屏幕显示的是上一个界面的Activity,可是当前Activity并无销毁，而且能够交互

这个是比较严重的用户体验问题，特别在小米手机上会特别明显。

过程

问题猜测

以前就出现过首页透底显示桌面的状况，是由于Theme中windowIsTranslucent = true致使这个问题，经过修改windowIsTranslucent = false属性，完全解决了首页透底问题。

实施

方案A: 修改全部Activity Theme windowIsTranslucent = true 属性

一样的配方一样的味道 替换全部全部Activity Theme 将window 改成不透明，背景颜色改成透明

<style name="AppBaseTheme" parent="@style/Theme.AppCompat.Light.NoActionBar">
        <item name="android:windowIsTranslucent">false</item>
        <item name="android:windowBackground">@color/transparent</item>
    </style>
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运行后的效果图：

闪烁透底的问题是解决了，可是侧滑框架出现了侧滑后看不到底部内容，方案A失败；

方案B：动态设置Activity Theme

在当前App退到后台时替换Activity为非透明主题，在Activity恢复到前台被点击时替换为透明主题； 如何动态修改Activity Theme？

@Override
    protected void onCreate(Bundle savedInstanceState) {
        if (current_theme!= -1){
            this.setTheme(current_theme);
        }
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.bt_theme).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                changeTheme(GREEN_THEME);
            }
        });
    }


    public void changeTheme(int index) {
        switch (index) {
            case DEFAULT_THEME:
                current_theme = R.style.DefaultTheme;
                break;
            case GREEN_THEME:
                current_theme = R.style.GreenTheme;
                break;
            case ORANGE_THEME:
                current_theme = R.style.OrangeTheme;
                break;
            default:
                break;
        }
    }

    protected void reload() {
        Intent intent = getIntent();
        overridePendingTransition(0, 0);
        intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
        finish();
        overridePendingTransition(0, 0);
        startActivity(intent);
    }
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其实设置主题必须在任何view建立以前，因此咱们不可能在activity的onCreate以后来更改主题，若是必定要作，就只能调用setTheme()，而后调用recreate()，从新建立一个activity，而且销毁上一个activity; 因此这个方案并不可行，整个界面必须销毁重建。 已知的Android theme修改方式

• AndroidManifest 设置Activity Theme
• 在Activity setContentView执行前 调用setTheme

能够经过其余方式修改Activity windowIsTranslucent 属性吗？

方案B+：反射动态设置Activity windowIsTranslucent

查阅Activity源码，看一下他是如何变成透明的

/** * Convert a translucent themed Activity {@link android.R.attr#windowIsTranslucent} back from * opaque to translucent following a call to {@link #convertFromTranslucent()}. * <p> * Calling this allows the Activity behind this one to be seen again. Once all such Activities * have been redrawn {@link TranslucentConversionListener#onTranslucentConversionComplete} will * be called indicating that it is safe to make this activity translucent again. Until * {@link TranslucentConversionListener#onTranslucentConversionComplete} is called the image * behind the frontmost Activity will be indeterminate. * <p> * This call has no effect on non-translucent activities or on activities with the * {@link android.R.attr#windowIsFloating} attribute. * * @param callback the method to call when all visible Activities behind this one have been * drawn and it is safe to make this Activity translucent again. * @param options activity options delivered to the activity below this one. The options * are retrieved using {@link #getActivityOptions}. * @return <code>true</code> if Window was opaque and will become translucent or * <code>false</code> if window was translucent and no change needed to be made. * * @see #convertFromTranslucent() * @see TranslucentConversionListener * * @hide */
    @SystemApi
    public boolean convertToTranslucent(TranslucentConversionListener callback, ActivityOptions options) {
        boolean drawComplete;
        try {
            mTranslucentCallback = callback;
            mChangeCanvasToTranslucent = ActivityManager.getService().convertToTranslucent(
                    mToken, options == null ? null : options.toBundle());
            WindowManagerGlobal.getInstance().changeCanvasOpacity(mToken, false);
            drawComplete = true;
        } catch (RemoteException e) {
            // Make callback return as though it timed out.
            mChangeCanvasToTranslucent = false;
            drawComplete = false;
        }
        if (!mChangeCanvasToTranslucent && mTranslucentCallback != null) {
            // Window is already translucent.
            mTranslucentCallback.onTranslucentConversionComplete(drawComplete);
        }
        return mChangeCanvasToTranslucent;
    }
 
 /** * Convert a translucent themed Activity {@link android.R.attr#windowIsTranslucent} to a * fullscreen opaque Activity. * <p> * Call this whenever the background of a translucent Activity has changed to become opaque. * Doing so will allow the {@link android.view.Surface} of the Activity behind to be released. * <p> * This call has no effect on non-translucent activities or on activities with the * {@link android.R.attr#windowIsFloating} attribute. * * @see #convertToTranslucent(android.app.Activity.TranslucentConversionListener, * ActivityOptions) * @see TranslucentConversionListener * * @hide */
    @SystemApi
    public void convertFromTranslucent() {
        try {
            mTranslucentCallback = null;
            if (ActivityManager.getService().convertFromTranslucent(mToken)) {
                WindowManagerGlobal.getInstance().changeCanvasOpacity(mToken, true);
            }
        } catch (RemoteException e) {
            // pass
        }
    }
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能够看到这个两个Api就是将Activity转化为投透明和非透明经过 ActivityManager.getService() 和 WindowManagerGlobal.getInstance().changeCanvasOpacity()修改Window透明属性;

• convertToTranslucent //将当前Activity Window 设置为透明
• convertFromTranslucent //将当前 Activity Window 设置为非透明

因为是系统Api 并有 @hide 标注 正常是没法调用的，能够经过反射来调用； 反射调用以下：

/** * Convert a translucent themed Activity * 将Activity 改成透明 */
	public static void convertActivityToTranslucent(Activity activity) {
		long timeMillis = SystemClock.currentThreadTimeMillis();
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
			convertActivityToTranslucentAfterL(activity);
		} else {
			convertActivityToTranslucentBeforeL(activity);
		}
		FxLog.d("convertActivity : convertActivityToTranslucent time = " + (SystemClock.currentThreadTimeMillis() - timeMillis));
	}

	/** * Calling the convertToTranslucent method on platforms before Android 5.0 */
	public static void convertActivityToTranslucentBeforeL(Activity activity) {
		try {
			Class<?>[] classes = Activity.class.getDeclaredClasses();
			Class<?> translucentConversionListenerClazz = null;
			for (Class clazz : classes) {
				if (clazz.getSimpleName().contains("TranslucentConversionListener")) {
					translucentConversionListenerClazz = clazz;
				}
			}
			Method method = Activity.class.getDeclaredMethod("convertToTranslucent",
					translucentConversionListenerClazz);
			method.setAccessible(true);
			method.invoke(activity, new Object[] {
					null
			});
		} catch (Throwable t) {
		}
	}

	/** * Calling the convertToTranslucent method on platforms after Android 5.0 */
	private static void convertActivityToTranslucentAfterL(Activity activity) {
		try {
			Method getActivityOptions = Activity.class.getDeclaredMethod("getActivityOptions");
			getActivityOptions.setAccessible(true);
			Object options = getActivityOptions.invoke(activity);

			Class<?>[] classes = Activity.class.getDeclaredClasses();
			Class<?> translucentConversionListenerClazz = null;
			for (Class clazz : classes) {
				if (clazz.getSimpleName().contains("TranslucentConversionListener")) {
					translucentConversionListenerClazz = clazz;
				}
			}
			Method convertToTranslucent = Activity.class.getDeclaredMethod("convertToTranslucent",
					translucentConversionListenerClazz, ActivityOptions.class);
			convertToTranslucent.setAccessible(true);
			convertToTranslucent.invoke(activity, null, options);
		} catch (Throwable t) {
		}
	}

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性能问题的思考

这样的反射是否对性能有损耗呢？在调用时作了耗时测试 在日志打印中能够看到性能彻底不会受影响；

为了进一步优化并减小反射调用，仅在用户触发侧滑、侧滑彻底闭合时修改Activity透明属性

public void setWindowToTranslucent(boolean translucent) {
		if (isTranslucentWindow == translucent || !isSlidingEnabled()){
			return;
		}
		isTranslucentWindow = translucent;
		if (isTranslucentWindow) {
			convertActivityToTranslucent(((Activity) getContext()));
		} else {
			convertActivityFromTranslucent(((Activity) getContext()));
		}
	}
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稳定性问题的思考

因为是系统Api 在不一样版本会略有不一样，作了版本区分。并对反射Api作了try/catch保护，在反射Api调用异常的状况下，不会对App功能有影响。原Activity windowIsTranslucent 属性不变

总结

1. 设置windowIsTranslucent =true 后，退后台再打开App时上层的Activity 会被再次绘制

2. Activity 替换主题的两种方式

• AndroidManifest 设置Activity Theme
• 在Activity setContentView执行前 调用setTheme

3. Activity 源码分析

• convertToTranslucent //将当前Activity Window 设置为透明
• convertFromTranslucent //将当前 Activity Window 设置为非透明

4. 反射调用

思考

1.在9.0后 @hide Api 经过反射是没法调用，后续是解决方案 2.除了修改windowIsTranslucent 尚未有其余的解决方案？ 3.如何从根源思考、解决问题