android：在布局尺寸（sceen尺寸）内拖动视图 [英] android : Dragging view within the layout size (sceen size)

问题描述

我希望 imageview 仅可在屏幕尺寸内拖动。但是下面的代码的问题是，只有左和上边距才能停止 imageview ，如何实现if语句的右和下边距以使视图停止输出的重点。下面是代码，在此先感谢

I want the imageview to be draggable only within the screen size . But the problem with the below code is , only left and top margin stops the imageview,how to implement if statement for right and bottom margin so that it stops the view from going out of focus. below is the code , Thanks in advance

            public boolean onTouch(View view, MotionEvent event) {

            DisplayMetrics displaymetrics = new DisplayMetrics();
            getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
            float screenHeight = displaymetrics.heightPixels;
            float screenWidth = displaymetrics.widthPixels;

            final int x = (int) event.getRawX();
            final int y = (int) event.getRawY();

            if(view==image1){
                switch (event.getAction() & MotionEvent.ACTION_MASK) {

                    case MotionEvent.ACTION_DOWN:
                        LinearLayout.LayoutParams lParams = (LinearLayout.LayoutParams)
                                view.getLayoutParams();
                        xDelta = x - lParams.leftMargin;
                        yDelta = y - lParams.topMargin;
                        x1Delta = lParams.rightMargin;
                        y2Delta = lParams.bottomMargin;
                        break;

                    case MotionEvent.ACTION_UP:                        
                        break;

                    case MotionEvent.ACTION_MOVE:
                        LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) view
                                .getLayoutParams();
                         //below leftMargin , topMargin works fine
                        if((x - xDelta) > 0 && (x - xDelta) < screenWidth ){layoutParams.leftMargin = x - xDelta;}
                        if((y - yDelta) > 0 && (y - yDelta) < screenHeight){layoutParams.topMargin = y - yDelta;}
                        layoutParams.rightMargin = 0;//how to make this stops the imageview on rightMargin
                        layoutParams.bottomMargin = 0;//how to make this stops the imageview on bottomMargin
                            view.setLayoutParams(layoutParams);
                        break;
                }
                mainLayout.invalidate();
            }
            return true;
        }
    };

推荐答案

经过长时间的研究，我自己找到了答案还将 LinearLayout 更改为 AbsoluteLayout ..

After a Long research I found the answer myself and I also changed LinearLayout to AbsoluteLayout..

 @Override
        public boolean onTouch(View view, MotionEvent event) {

                switch (event.getAction() & MotionEvent.ACTION_MASK) {

                    case MotionEvent.ACTION_DOWN:
                        xDelta = event.getX();
                        yDelta = event.getY();
                        break;

                    case MotionEvent.ACTION_POINTER_DOWN:
                        oldDist = spacing(event);
                        if (oldDist > 10f) {
                            mode = ZOOM;
                        }

                    case MotionEvent.ACTION_UP:
                        break;

                    case MotionEvent.ACTION_MOVE:
                        x1Delta = event.getX() - xDelta ;
                        y2Delta = event.getY() - yDelta;

                        m_posX = m_prevX + x1Delta;
                        m_posY = m_prevY + y2Delta;

                        if (m_posX > 0 && m_posY > 0 && (m_posX + view.getWidth()) < mainLayout.getWidth() && (m_posY + view.getHeight()) < mainLayout.getHeight())
                        {
                            view.setLayoutParams(new AbsoluteLayout.LayoutParams(view.getMeasuredWidth(), view.getMeasuredHeight(), (int) m_posX, (int) m_posY));

                            m_prevX = m_posX;
                            m_prevY = m_posY;
                        }

                        break;
                }
                mainLayout.invalidate();
            return true;
        }
    };

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