Android 如何在不显示文字时获取文字宽度

雨点打透心脏的1/2处 2022-11-18 01:38 182阅读 0赞

# Android 如何在不显示文字时获取文字宽度 #

正确方式：

在canvas中使用：`paint.measureText(text)`  
在TextView中使用：`textView.getPaint()..measureText(text)`

代码示例：

package com.demo.myapplication3;
    
    import android.graphics.Bitmap;
    import android.graphics.Canvas;
    import android.graphics.Paint;
    import android.graphics.Rect;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.text.TextPaint;
    import android.util.Log;
    import android.util.TypedValue;
    import android.view.View;
    import android.widget.TextView;
    
    public class MainActivity extends AppCompatActivity {
    
        private final String TAG = "MainActivity";
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            canvasMeasure();
            textViewMeasure();
        }
    
    
        private void canvasMeasure() {
            String text = "测试：XYZ xyz";
    
            Bitmap bitmap = Bitmap.createBitmap(800, 1000, Bitmap.Config.ARGB_8888);
            Canvas canvas = new Canvas(bitmap);
            canvas.drawBitmap(bitmap, 0, 0, null);
    
            Paint paint = new Paint();
            paint.setTextSize(30);
            canvas.drawText(text, 100, 100, paint);
    
            //1. 粗略计算文字宽度
            Log.d(TAG, "measureText=" + paint.measureText(text));
    
            //2. 计算文字所在矩形，可以得到宽高
            Rect rect = new Rect();
            paint.getTextBounds(text, 0, text.length(), rect);
            int w = rect.width();
            int h = rect.height();
            Log.d(TAG, "w=" + w + "  h=" + h);
    
            //3. 精确计算文字宽度
            int textWidth = getTextWidth(paint, text);
            Log.d(TAG, "textWidth=" + textWidth);
        }
    
        private static int getTextWidth(Paint paint, String str) {
            int iRet = 0;
            if (str != null && str.length() > 0) {
                int len = str.length();
                float[] widths = new float[len];
                paint.getTextWidths(str, widths);
                for (int j = 0; j < len; j++) {
                    iRet += (int) Math.ceil(widths[j]);
                }
            }
            return iRet;
        }
    
    
        private void textViewMeasure() {
            String text = "测试：XYZ xyz";
            TextView textView = findViewById(R.id.tv_test);
            textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, 30);
            textView.setText(text);
    
            int spec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
            textView.measure(spec, spec);
    
            // getMeasuredWidth
            int measuredWidth = textView.getMeasuredWidth();
    
            // new textpaint measureText
            TextPaint newPaint = new TextPaint();
            newPaint.setTextSize(30);
            float newPaintWidth = newPaint.measureText(text);
    
            // textView getPaint measureText
            TextPaint textPaint = textView.getPaint();
            float textPaintWidth = textPaint.measureText(text);
    
            Log.e(TAG, "测试字符串:" + text);
            Log.e(TAG, "getMeasuredWidth:" + measuredWidth);
            Log.e(TAG, "newPaint measureText:" + newPaintWidth);
            Log.e(TAG, "textView getPaint measureText:" + textPaintWidth);
    
        }
    
        //    print
        //2021-04-11 12:51:50.428 15976-15976/com.demo.myapplication3 D/MainActivity: measureText=202.0
        //2021-04-11 12:51:50.429 15976-15976/com.demo.myapplication3 D/MainActivity: w=200  h=30
        //2021-04-11 12:51:50.429 15976-15976/com.demo.myapplication3 D/MainActivity: textWidth=202
        //2021-04-11 12:51:50.430 15976-15976/com.demo.myapplication3 E/MainActivity: 测试字符串:测试：XYZ xyz
        //2021-04-11 12:51:50.430 15976-15976/com.demo.myapplication3 E/MainActivity: getMeasuredWidth:202
        //2021-04-11 12:51:50.430 15976-15976/com.demo.myapplication3 E/MainActivity: newPaint measureText:202.0
        //2021-04-11 12:51:50.430 15976-15976/com.demo.myapplication3 E/MainActivity: textView getPaint measureText:202.0
    }