ScrollView 中的可缩放 TextView

Question

我想做一个TextView，它可以根据捏缩放来改变文本的大小。 TextView 在 ScrollView 内。我有TextView 可以在捏合时进行缩放，但只有当您几乎完全水平地移动手指时。如果捏缩放有垂直组件，则默认为滚动而不是缩放

有没有办法在 ScrollView 上有超过 1 个指针时禁用滚动，然后在指针计数返回 1 或 0 时重新启用滚动？是创建CustomScrollView 小部件的最佳方法还是有更简单的方法？

Answer 1

受此答案的启发https://stackoverflow.com/a/14577399/2014236

scaleGD = new ScaleGestureDetector(this, new simpleOnScaleGestureListener());
mTextView.setOnTouchListener(new OnTouchListener() {

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if(event.getPointerCount() == 1){
            //stuff for 1 pointer
        }else{ //when 2 pointers are present
            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                // Disallow ScrollView to intercept touch events.
                v.getParent().requestDisallowInterceptTouchEvent(true);
                scaleGD.onTouchEvent(event);
                break;

            case MotionEvent.ACTION_MOVE:
                // Disallow ScrollView to intercept touch events.
                v.getParent().requestDisallowInterceptTouchEvent(true);
                scaleGD.onTouchEvent(event);
                break;

            case MotionEvent.ACTION_UP:
                // Allow ScrollView to intercept touch events.
                v.getParent().requestDisallowInterceptTouchEvent(false);
                break;
            }
        }
        return true;
    }
});

编辑：

//later in the code
public class simpleOnScaleGestureListener extends SimpleOnScaleGestureListener {

    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        float size = codedText.getTextSize();
        float factor = detector.getScaleFactor();
        int increase = 0;
        if(factor > 1.0f)
            increase = 2;
        else if(factor < 1.0f)
            increase = -2;

        size += increase;

        codedText.setTextSize(TypedValue.COMPLEX_UNIT_PX, size);
        plainText.setTextSize(TypedValue.COMPLEX_UNIT_PX, size);            
        try {
            Thread.sleep(200);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //remembering the favourable text size
        Editor edit = sp.edit();
        edit.putFloat("TXTSIZE", size);
        edit.commit();
        return true;
    }
}

绝不是完美的，但对我来说已经足够好 - 请随时进行改进。

Answer 2

我觉得用起来比较简单：

   textView.setOnTouchListener(new View.OnTouchListener() {

        public boolean onTouch(View v, MotionEvent event) {
            // TODO Auto-generated method stub
            if(event.getPointerCount() == 1) {
                Log.d("Scroll","1-pointer touch");
                v.getParent().requestDisallowInterceptTouchEvent(false);

            }
            if(event.getPointerCount() == 2){
                Log.d("Zoom","2-pointer touch");
                v.getParent().requestDisallowInterceptTouchEvent(true);

            }
            return false;
        }
    });

Answer 3

这是来自 android-dev 博客的一个很好的示例代码，展示了如何实现手指捏合。

Android touch example

您不能禁用滚动条的滚动功能，除非您不覆盖 onTouchEvent 方法以在您的条件下返回 false。这里有几个线程可以帮助您了解如何禁用滚动视图中的滚动。

How to disable scrolling in ScrollView when the viewSwitcher is enabled?

How to disable ScrollView scrolling?

Disable ScrollView Programmatically?

谢谢你:)

Answer 4

我正在使用这个解决方案。 此vídeo中的缩放算法的功劳

使用不带 ScrollView 的 TextView，只需使用 android:scrollbars="vertical"

        <TextView
        android:id="@+id/activity_content_text_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_weight="1"
        android:gravity="fill"
        android:textSize="8pt"
        android:scrollbars="vertical"
        />

Java：

public class MainActivity extends Activity implements View.OnTouchListener {

   private TextView textContent = null;
   private final static float move = 200;
   private float ratio = 1.0f;
   private int baseDist;
   private float baseRatio;

   @Override
   protected void onCreate(@Nullable Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.teste_layout);
       textContent = findViewById(R.id.activity_content_text_content);
       textContent.setText("Lorem ipsum dolor sit amet......");

       textContent.setMovementMethod(new ScrollingMovementMethod());
       textContent.setOnTouchListener(this);
    }


    @Override
    public boolean onTouch(View v, MotionEvent event) {
        return onTouchEvent(event);
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if(event.getPointerCount() == 2){

            int action = event.getAction();
            int mainAction = action&MotionEvent.ACTION_MASK;

            if(mainAction == MotionEvent .ACTION_POINTER_DOWN){
                    baseDist = getDisTance(event);
                    baseRatio = ratio;
                } else {
                    float scale = (getDisTance(event)-baseDist)/move;
                    float factor = (float)Math.pow(2, scale);
                ratio = Math.min(1024.0f, Math.max(0.1f, baseRatio*factor));
                textContent.setTextSize(ratio+15);
            }
        } else {
            return false;
        }
        return true;
    }

    private int getDisTance(MotionEvent event) {
        int dx = (int) (event.getX(0)-event.getX(1));
        int dy = (int) (event.getY(0)-event.getY(1));
        return (int) (Math.sqrt(dx*dx+dy*dy));
    }
}

开发者Frevo Studios