捏在Android中调整LinearLayout [英] Pinch Zoom For LinearLayout in Android

问题描述

我需要缩放包含Image，TextViews等的整个布局.我发现缩放功能仅适用于Imageview.

I need to zoom the entire layout contains Image,TextViews etc.i found zoom functionalities only for Imageview.

推荐答案

创建自定义的 Layout 类，称为 ZoomeLinearLayout .

Create a Custom Layout Class Called ZoomeLinearLayout.

ZoomLinearLayout.java

public class ZoomLinearLayout extends LinearLayout implements ScaleGestureDetector.OnScaleGestureListener {

    private enum Mode {
        NONE,
        DRAG,
        ZOOM
    }

    private static final float MIN_ZOOM = 1.0f;
    private static final float MAX_ZOOM = 4.0f;

    private Mode mode = Mode.NONE;
    private float scale = 1.0f;
    private float lastScaleFactor = 0f;

    private float startX = 0f;
    private float startY = 0f;

    private float dx = 0f;
    private float dy = 0f;
    private float prevDx = 0f;
    private float prevDy = 0f;

    public ZoomLinearLayout(Context context) {
        super(context);
        init(context);
    }

    public ZoomLinearLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public ZoomLinearLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    public void init(Context context) {
        final ScaleGestureDetector scaleDetector = new ScaleGestureDetector(context, this);
        this.setOnTouchListener(new OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {
                    case MotionEvent.ACTION_DOWN:
                        if (scale > MIN_ZOOM) {
                            mode = Mode.DRAG;
                            startX = motionEvent.getX() - prevDx;
                            startY = motionEvent.getY() - prevDy;
                        }
                        break;
                    case MotionEvent.ACTION_MOVE:
                        if (mode == Mode.DRAG) {
                            dx = motionEvent.getX() - startX;
                            dy = motionEvent.getY() - startY;
                        }
                        break;
                    case MotionEvent.ACTION_POINTER_DOWN:
                        mode = Mode.ZOOM;
                        break;
                    case MotionEvent.ACTION_POINTER_UP:
                        mode = Mode.DRAG;
                        break;
                    case MotionEvent.ACTION_UP:
                        mode = Mode.NONE;
                        prevDx = dx;
                        prevDy = dy;
                        break;
                }
                scaleDetector.onTouchEvent(motionEvent);

                if ((mode == Mode.DRAG && scale >= MIN_ZOOM) || mode == Mode.ZOOM) {
                    getParent().requestDisallowInterceptTouchEvent(true);
                    float maxDx = (child().getWidth() - (child().getWidth() / scale)) / 2 * scale;
                    float maxDy = (child().getHeight() - (child().getHeight() / scale)) / 2 * scale;
                    dx = Math.min(Math.max(dx, -maxDx), maxDx);
                    dy = Math.min(Math.max(dy, -maxDy), maxDy);
                    applyScaleAndTranslation();
                }

                return true;
            }
        });
    }

    @Override
    public boolean onScaleBegin(ScaleGestureDetector scaleDetector) {
        return true;
    }

    @Override
    public boolean onScale(ScaleGestureDetector scaleDetector) {
        float scaleFactor = scaleDetector.getScaleFactor();
        if (lastScaleFactor == 0 || (Math.signum(scaleFactor) == Math.signum(lastScaleFactor))) {
            scale *= scaleFactor;
            scale = Math.max(MIN_ZOOM, Math.min(scale, MAX_ZOOM));
            lastScaleFactor = scaleFactor;
        } else {
            lastScaleFactor = 0;
        }
        return true;
    }

    @Override
    public void onScaleEnd(ScaleGestureDetector scaleDetector) {
    }

    private void applyScaleAndTranslation() {
        child().setScaleX(scale);
        child().setScaleY(scale);
        child().setTranslationX(dx);
        child().setTranslationY(dy);
    }

    private View child() {
        return getChildAt(0);
    }

}

然后在 Layout 文件中，用 ZoomLinearLayout 包裹要缩放的 LinearLayout .请注意， ZoomLinearLayout 只有一个直接子级.

Then in Layout file, Wrap your LinearLayout which you want to zoom with ZoomLinearLayout. Note that you have only one direct child for ZoomLinearLayout.

 <com.asif.test.ZoomLinearLayout
    android:layout_width="match_parent"
    android:id="@+id/zoom_linear_layout"
    android:layout_height="match_parent">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </LinearLayout>

</com.asif.test.ZoomLinearLayout>

现在在 Activity 中，创建 ZoomLinearLayout 对象，并为其设置 onTouch()事件.

Now in Activity, create ZoomLinearLayout object and set the onTouch() event for it.

final ZoomLinearLayout zoomLinearLayout = (ZoomLinearLayout) findViewById(R.id.zoom_linear_layout);
zoomLinearLayout.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        zoomLinearLayout.init(MainActivity.this);
        return false;
    }
});

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