圆形背景文本(如 Instagram、ReplacementSpan 无法按要-移动开发问题

Rounded Background text like Instagram, ReplacementSpan not working as required(圆形背景文本(如 Instagram、ReplacementSpan 无法按要求工作))

本文介绍了圆形背景文本(如 Instagram、ReplacementSpan 无法按要求工作)的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我试图在下面做一些类似于 Instagram 的事情 -

I was trying to do something similar to Instagram below -

但我想要像 Instagram 这样的曲线 -

But i want this curves like Instagram -

现在我又遇到了一个问题-当我键入时，.文本不会自动转到下一行，我必须按 return ，就像通常 editText 以固定宽度工作一样.(简而言之，multiline 不能与 ReplacementSpan 一起正常工作)

Now i am stuck in one more problem - When i types,. text does not goes automatically to next line, I have to press return , like normally editText works in fixed width. (In short multiline is not working fine with ReplacementSpan)

下面是我所做的示例代码 -

Below is sample code for what i have done -

public class EditextActivity extends AppCompatActivity {

    EditText edittext;
    RoundedBackgroundSpan roundedBackgroundSpan;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.editext_screen);
        edittext=(EditText)findViewById(R.id.edittext);
       // edittext.setText("Hello My name is Karandeep Atwal.

 Hii this is test");
        roundedBackgroundSpan= new RoundedBackgroundSpan(Color.RED,Color.WHITE);
        edittext.getText().setSpan(roundedBackgroundSpan, 0, edittext.getText().length(), Spannable.SPAN_INCLUSIVE_INCLUSIVE);
    }


    public class RoundedBackgroundSpan extends ReplacementSpan implements LineHeightSpan {

        private static final int CORNER_RADIUS = 15;
        private static final int PADDING_X = 10;

        private int   mBackgroundColor;
        private int   mTextColor;

        /**
         * @param backgroundColor background color
         * @param textColor text color
         */
        public RoundedBackgroundSpan(int backgroundColor, int textColor) {
            mBackgroundColor = backgroundColor;
            mTextColor = textColor;
        }

        @Override
        public int getSize(Paint paint, CharSequence text, int start, int end, Paint.FontMetricsInt fm) {
            return (int) (PADDING_X + paint.measureText(text,start, end) + PADDING_X);
        }

        @Override
        public void draw(Canvas canvas, CharSequence text, int start, int end, float x, int top, int y, int bottom, Paint paint) {
            float width = paint.measureText(text,start, end);
            RectF rect = new RectF(x, top, x + width + 2 * PADDING_X, bottom);
            paint.setColor(mBackgroundColor);
            canvas.drawRoundRect(rect, CORNER_RADIUS, CORNER_RADIUS, paint);
            paint.setColor(mTextColor);
            canvas.drawText(text, start, end, x + PADDING_X, y, paint);
        }

        @Override
        public void chooseHeight(CharSequence text, int start, int end, int spanstartv, int v, Paint.FontMetricsInt fontMetricsInt) {

        }
    }

}

下面是我的xml -

Below is my xml -

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    android:layout_gravity="center"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:padding="5dp"
        android:background="@drawable/border"
        android:id="@+id/edittext"
        android:layout_centerInParent="true"
        android:textColor="@android:color/black"
        android:gravity="center"
        android:hint="hi"
        android:singleLine="false"
        android:inputType="textMultiLine"
        android:textSize="30sp"
        android:maxWidth="100dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</RelativeLayout>

以下是我使用 setSpan 键入时得到的结果 -

Below is what i am getting when i type using setSpan -

这是我想要的固定宽度的正常行为 -

This is normal behaviour for fixed width, that i want -

推荐答案

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/holo_purple"
    tools:context="com.tttzof.demotext.MainActivity">

    <EditText
        android:id="@+id/editText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Enter text"
        android:textSize="30sp"
        android:gravity="center"
        android:textColor="@android:color/black"
        android:background="@android:color/transparent"
        android:layout_gravity="center"/>

</FrameLayout>

MainActivity.java

import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.Spannable;
import android.text.TextWatcher;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final EditText editText = (EditText) findViewById(R.id.editText);

        int padding = dp(8);
        int radius = dp(5);

        final Object span = new BackgroundColorSpan(
                        Color.WHITE,
                        (float)padding,
                        (float) radius
        );

        editText.setShadowLayer(padding, 0f, 0f, 0);
        editText.setPadding(padding, padding, padding, padding);

        editText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
            public void afterTextChanged(Editable s) {
                s.setSpan(span, 0, s.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            }
        });
    }

    private int dp(int value) {
        return (int) (getResources().getDisplayMetrics().density * value + 0.5f);
    }
}

BackgroundColorSpan.java

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.text.style.LineBackgroundSpan;

public class BackgroundColorSpan implements LineBackgroundSpan {
    private float padding;
    private float radius;

    private RectF rect = new RectF();
    private Paint paint = new Paint();
    private Paint paintStroke = new Paint();
    private Path path = new Path();

    private float prevWidth = -1f;
    private float prevLeft = -1f;
    private float prevRight = -1f;
    private float prevBottom = -1f;
    private float prevTop = -1f;


    public BackgroundColorSpan(int backgroundColor,
                               float padding,
                               float radius) {
        this.padding = padding;
        this.radius = radius;

        paint.setColor(backgroundColor);
        //paintStroke.setStyle(Paint.Style.STROKE);
        //paintStroke.setStrokeWidth(5f);
        paintStroke.setColor(backgroundColor);
    }

    @Override
    public void drawBackground(
                    final Canvas c,
                    final Paint p,
                    final int left,
                    final int right,
                    final int top,
                    final int baseline,
                    final int bottom,
                    final CharSequence text,
                    final int start,
                    final int end,
                    final int lnum) {

        float width = p.measureText(text, start, end) + 2f * padding;
        float shift = (right - width) / 2f;

        rect.set(shift, top, right - shift, bottom);

        if (lnum == 0) {
            c.drawRoundRect(rect, radius, radius, paint);
        } else {
            path.reset();
            float dr = width - prevWidth;
            float diff = -Math.signum(dr) * Math.min(2f * radius, Math.abs(dr/2f))/2f;
            path.moveTo(
                            prevLeft, prevBottom - radius
            );

            path.cubicTo(
                            prevLeft, prevBottom - radius,
                            prevLeft, rect.top,
                            prevLeft + diff, rect.top
            );
            path.lineTo(
                            rect.left - diff, rect.top
            );
            path.cubicTo(
                            rect.left - diff, rect.top,
                            rect.left, rect.top,
                            rect.left, rect.top + radius
            );
            path.lineTo(
                            rect.left, rect.bottom - radius
            );
            path.cubicTo(
                            rect.left, rect.bottom - radius,
                            rect.left, rect.bottom,
                            rect.left + radius, rect.bottom
            );
            path.lineTo(
                            rect.right - radius, rect.bottom
            );
            path.cubicTo(
                            rect.right - radius, rect.bottom,
                            rect.right, rect.bottom,
                            rect.right, rect.bottom - radius
            );
            path.lineTo(
                            rect.right, rect.top + radius
            );
            path.cubicTo(
                            rect.right, rect.top + radius,
                            rect.right, rect.top,
                            rect.right + diff, rect.top
            );
            path.lineTo(
                            prevRight - diff, rect.top
            );
            path.cubicTo(
                            prevRight - diff, rect.top,
                            prevRight, rect.top,
                            prevRight, prevBottom - radius
            );
            path.cubicTo(
                            prevRight, prevBottom - radius,
                            prevRight, prevBottom,
                            prevRight - radius, prevBottom

            );
            path.lineTo(
                            prevLeft + radius, prevBottom
            );
            path.cubicTo(
                            prevLeft + radius, prevBottom,
                            prevLeft, prevBottom,
                            prevLeft, rect.top - radius
            );
            c.drawPath(path, paintStroke);
        }

        prevWidth = width;
        prevLeft = rect.left;
        prevRight = rect.right;
        prevBottom = rect.bottom;
        prevTop = rect.top;
    }
}

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