android拖拽ImageView onTouchListener [英] android drag and drop ImageView onTouchListener

问题描述

你好
我已经在我的应用程序中为 ImageView 设置了一个 onTouchListener，我的目标是拥有一个 ImageView，用户可以在应用程序中拖动并放置他们想要的任何位置.

我已经使用网上找到的示例代码为 onTouchListener 编写了一些代码，我认为它可以工作，但我遇到了一些问题，而不是允许我拖动图像，图像调整大小并变大或在您将手指拖过它时变小.

有谁知道为什么?
这是我的代码:

Hello
I've set up an onTouchListener within my application for an ImageView, my aim was to have an ImageView that the user would be able to drag around and place where ever they want within the app.

I've written some code using sample code found on the web for an onTouchListener that I thought would work but I'm having some problems with it, rather than allowing me to drag the image around, the image resizes and gets bigger or smaller when you drag your finger over it.

Does anyone have any ideas why?
Here's my code:

    ImageView t1img;

    t1img = (ImageView) findViewById(R.id.imgT1);

    windowWidth = getWindowManager().getDefaultDisplay().getWidth();
    windowHeight = getWindowManager().getDefaultDisplay().getHeight();

    t1img.setOnTouchListener(new View.OnTouchListener() {

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

            layoutParams = (LayoutParams) t1img.getLayoutParams();

            switch (event.getAction()) {

                case MotionEvent.ACTION_DOWN:

                break;

                case MotionEvent.ACTION_MOVE:

                    int xCoord = (int) event.getRawX();
                    int yCoord = (int) event.getRawY();

                    if (xCoord > windowWidth) {

                        xCoord = windowWidth;
                    }

                    if (yCoord > windowHeight) {

                        yCoord = windowHeight;
                    }

                    layoutParams.leftMargin = xCoord - 25;
                    layoutParams.topMargin = yCoord - 75;

                    t1img.setLayoutParams(layoutParams);

                break;

                default:

                break;
            }

            return true;
        }
    });

推荐答案

如果你需要支持姜饼，可以看看我的例子

If you need to support gingerbread you can take a look at my example here

https://github.com/NAYOSO/android-dragview

如果你只需要支持上面的果冻豆，你可以使用android库中的拖放，你可以从这篇文章中看到它

if you only need to support jelly bean above you can use the Drag and Drop from android library you can see it from this article

http://developer.android.com/guide/topics/ui/drag-drop.html

有关拖放视图的一些说明首先，您不需要创建触摸侦听器，然后调用 startDrag 开始拖动.就这么简单.

For some explanation about the Drag and Drop view at first you need t create the touch listener and then call startDrag to start draging. As simple as that.

private final class dragTouchListener implements OnTouchListener {

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            if (event.getAction() == MotionEvent.ACTION_DOWN) {
                DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(v);
                v.startDrag(data, shadowBuilder, v, 0);
                return true;
            } else {
                return false;
            }
        }

    }

你可以使用 onDragListener 来监控放置的目标

To monitor the target of dropping place you can use onDragListener

private class dropListener implements OnDragListener {

    View draggedView;
    CustomTextView dropped;

    @Override
    public boolean onDrag(View v, DragEvent event) {
        switch (event.getAction()) {
        case DragEvent.ACTION_DRAG_STARTED:
            draggedView = (View) event.getLocalState();
            dropped = (CustomTextView) draggedView;
            draggedView.setVisibility(View.INVISIBLE);
            break;
        case DragEvent.ACTION_DRAG_ENTERED:
            break;
        case DragEvent.ACTION_DRAG_EXITED:
            break;
        case DragEvent.ACTION_DROP:

            CustomTextView dropTarget = (CustomTextView) v;
            dropTarget.setText(dropped.getText().toString());
            break;
        case DragEvent.ACTION_DRAG_ENDED:
            break;
        default:
            break;
        }
        return true;
    }

}

正如您从我的代码中看到的那样，有很多事件，但主要的是当视图开始被拖放和结束时.

As you can see from my code there is many event but the main one is when the view is start being dragged, dropped and ended.

别忘了设置监听器来查看

Don't forget to set the listener to view

    tvDrag.setOnTouchListener(new dragTouchListener());
    tvDrop.setOnDragListener(new dropListener())

我希望我的解释足够清楚！如果您还有其他问题，我会在今晚或明天尝试回答:)

I hope my explanation is clear enough! If you have further question I will try to answer it tonight or tomorrow :)

这篇关于android拖拽ImageView onTouchListener的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！