Question

我希望在长时间点击视图时启动动画。

代码如下。

public class Example_Dialog extends Dialog implements AnimationListener{
    TextView    view_Description1 = null;
    View        view_Button1 = null;
    MessageCreateTask task;

    public Example_Dialog( Context context , int theme ){
        super( context , theme );

        setContentView(R.layout.infomation_dialog);

        view_Button1 = findViewById(R.id.common_dialog_button_1);
        view_Description1 = (TextView)findViewById(R.id.common_dialog_description_1);
        view_Description1.setHeight(0);

        view_Button1.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                task = new MessageCreateTask(view_Description1);
                task.execute();
            }
        });
    }

    @Override
    public void onAnimationEnd(Animation animation) {
    }

    @Override
    public void onAnimationRepeat(Animation animation) {
    }

    @Override
    public void onAnimationStart(Animation animation) {
    }


    class MessageCreateTask extends AsyncTask<Void, Void, String> {
        TextView textView;

        String messageOutput;
        int totalLineNum;

        public MessageCreateTask(TextView textView) {
            this.textView = textView;

            messageOutput = "";
            totalLineNum = 0;
        }

        @Override
          protected void onPreExecute() {
        }

        @Override
        protected String doInBackground(Void... params) {
            for( int i= 0 ; i< 10 ; i++ ){
                messageOutput += "a" + "<br>";
                totalLineNum++;
            }
            return messageOutput;
        }

        @Override
        protected void onPostExecute(String message) {
            int dialogWidth     = 838;
            int dialogHeight    = 26*totalLineNum;

            textView.setWidth( dialogWidth );
            textView.setText(Html.fromHtml(message));

            HeightAnimation hanime_open = new HeightAnimation(textView , 0 , dialogHeight );
            hanime_open = new HeightAnimation(textView , 0 , dialogHeight );
            hanime_open.setDuration(300);

            textView.startAnimation(hanime_open);
        }
    }
}


public class HeightAnimation extends Animation {

    int targetHeight;
    int startHeight;
    TextView textView;

    public HeightAnimation(TextView textView,int startHeight, int targetHeight) {
        this.textView = textView;
        this.targetHeight = targetHeight;
        this.startHeight = startHeight;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        int newHeight = (int)(startHeight + (targetHeight - startHeight)*interpolatedTime);
        textView.setHeight(newHeight);

        if( (startHeight != 0) && (newHeight == 0) ){
            textView.setVisibility(View.GONE);
        }
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        super.initialize(width, height, ((View)textView.getParent()).getWidth(), parentHeight);
    }
}

动画不是用上面的代码启动的，但它是通过用onlongclick替换onclick来启动的，如下所示。

        view_Button1.setOnLongClickListener(new View.OnLongClickListener(){
            public boolean onLongClick(View v){
                task = new MessageCreateTask(view_Description1);
                task.execute();

                return true;
            }
        });

我想知道在onclick的情况下动画无法启动的原因。

Answer 1

它不与onClickListener()合作的原因是，view没有焦点。因此，您需要按两次按钮，或者必须使用onlongClickListener()。要首次制作view clickable，请执行以下操作：

在触摸模式下启用焦点，在XML布局中作为属性：

android:focusableInTouchMode="true"

或初始化按钮后以编程方式：

view_button1.setFocusableInTouchMode(true);

然后您可以将焦点设置为视图：

view_button1.requestFocus();

使用AsyncTask进行onLongClick动画

1 个答案: