Qt For Andorid 的绘制机制?



  • Qt For Andorid 的绘制机制探讨

    有关 Qt For Andorid 的绘制机制的探讨。先前在做 WellChat 这个项目的时候遇到一个问题,就是输入法弹出后,界面无法自适应的问题。

    具体的表现是:设置 android:windowSoftInputMode="adjustResize" 后,输入法弹出会闪烁。

    还有,在 Qt For Andorid 中,如果有多个 ApplicationWindow 或者 Window,这些窗体进行切换的时候,会僵死,退入后台,再返回应用,窗体才完成切换。

    于是我对 Qt For Andorid 的绘制机制有了比较浓厚的兴趣。

    首先 ApplicationWindow 继承自 WindowWindow 继承自 QQuickWindowQQuickWindow继承自 QWindowQWindow 的父类是 QObject,实现接口 QSurface

    而 Qt For Andorid 中,Java 代码的入口类是 Qt 官方重写的 QtActivity。这个与 QSurface 或许有这直接联系。

    这里直接说说我的看法吧:QSurface 根据 QtActivity 的大小和位置进行内容绘制。当QtActivity 大小和位置变化的时候,QSurface 进行重绘,但是这一步,却发生了闪烁。。。。

    当然以上说法是没有源码依据的。。



  • android这一块还是稍显复杂一些。比如说这样的问题,代码有私有的实现。这些实现是为了配合Android底层的机制而存在的。
    这个时候,为了清楚地调查情况,还是必须对源代码进行分析才行。:star2:



  • @qyvlik 给你看看QtSurface.java。它位于qt5/qtbase/src/android/jar/src/org/qtproject/qt5/android:u6709:

    /****************************************************************************
    **
    ** Copyright (C) 2014 BogDan Vatra <bogdan@kde.org>
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the Android port of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
    ** Commercial License Usage
    ** Licensees holding valid commercial Qt licenses may use this file in
    ** accordance with the commercial license agreement provided with the
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    ** Alternatively, this file may be used under the terms of the GNU Lesser
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    ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
    **
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    ****************************************************************************/
    
    package org.qtproject.qt5.android;
    
    import android.app.Activity;
    import android.content.Context;
    import android.graphics.PixelFormat;
    import android.view.GestureDetector;
    import android.view.MotionEvent;
    import android.view.SurfaceHolder;
    import android.view.SurfaceView;
    
    import java.lang.reflect.Constructor;
    import java.lang.reflect.Method;
    
    public class QtSurface extends SurfaceView implements SurfaceHolder.Callback
    {
        private GestureDetector m_gestureDetector;
        private Object m_accessibilityDelegate = null;
    
        public QtSurface(Context context, int id, boolean onTop, int imageDepth)
        {
            super(context);
            setFocusable(false);
            setFocusableInTouchMode(false);
            setZOrderMediaOverlay(onTop);
            getHolder().addCallback(this);
            if (imageDepth == 16)
                getHolder().setFormat(PixelFormat.RGB_565);
            else
                getHolder().setFormat(PixelFormat.RGBA_8888);
    
            if (android.os.Build.VERSION.SDK_INT < 11)
                getHolder().setType(SurfaceHolder.SURFACE_TYPE_GPU);
    
            setId(id);
            m_gestureDetector =
                new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
                    public void onLongPress(MotionEvent event) {
                        QtNative.longPress(getId(), (int) event.getX(), (int) event.getY());
                    }
                });
            m_gestureDetector.setIsLongpressEnabled(true);
        }
    
        @Override
        public void surfaceCreated(SurfaceHolder holder)
        {
        }
    
        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
        {
            if (width < 1 || height < 1)
                return;
    
            QtNative.setSurface(getId(), holder.getSurface(), width, height);
        }
    
        @Override
        public void surfaceDestroyed(SurfaceHolder holder)
        {
            QtNative.setSurface(getId(), null, 0, 0);
        }
    
        @Override
        public boolean onTouchEvent(MotionEvent event)
        {
            QtNative.sendTouchEvent(event, getId());
            m_gestureDetector.onTouchEvent(event);
            return true;
        }
    
        @Override
        public boolean onTrackballEvent(MotionEvent event)
        {
            QtNative.sendTrackballEvent(event, getId());
            return true;
        }
    }
    


  • @jiangcaiyang 说:

    SurfaceView

    surfaceView和View最本质的区别

    这个surfaceView的特性貌似是Qt界面和安卓原生界面交互的关键点呢。


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