java - Android - 在位图上绘制文本很困难

Question

我正在尝试在位图上绘制一些文本并将其作为幻灯片的一部分。我一直在关注这个教程:http://www.skoumal.com/en/android-how-draw-text-bitmap/

问题是位图上没有绘制任何内容。我没有收到错误，但是当应包含文本的两张“幻灯片”通过时，没有任何显示(R.drawable.message_background 目前只是白色背景，所以我猜测它在技术上是“显示”)。没有文字出现。这是我的代码:

package midamcorp.com.burgerkingapp;

import android.content.Context;
import android.content.SharedPreferences;
import android.content.res.Resources;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Handler;
import android.os.Looper;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ImageView;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {

    public Bitmap drawText(Context c, int resource, String text) {

        Resources resources = c.getResources();
        Bitmap bitmap = BitmapFactory.decodeResource(resources, resource);
        android.graphics.Bitmap.Config config = bitmap.getConfig();
        if(config == null) {
            config  = android.graphics.Bitmap.Config.ARGB_8888;

        }
        bitmap = bitmap.copy(config, true);
        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        float scale = resources.getDisplayMetrics().density;
        paint.setColor(Color.BLACK);
        paint.setTextSize(18 * scale);

        Rect outline = new Rect();
        paint.getTextBounds(text, 0, text.length(), outline);
        int x = ((bitmap.getWidth() - outline.width() / 2));
        int y = ((bitmap.getWidth() + outline.height() / 2));

        canvas.drawText(text, x, y, paint);
canvas.save();
        return bitmap;
    }
    ArrayList<Bitmap> imageList = new ArrayList<Bitmap>();
    int slideCounter = 0;
    ImageView slide;
    Cursor images;


    final Handler handler = new Handler(Looper.getMainLooper());

    private int counter = 0;

    private Runnable runnable = new Runnable() {
        @Override
        public void run() {

            slide.setImageBitmap(imageList.get(counter));
            if(counter == (imageList.size() - 1)) {
                counter = 0;
            } else {
                counter++;
            }

        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        databaseHelper dbHelper = new databaseHelper(this);

        SQLiteDatabase db = dbHelper.getReadableDatabase();

        SharedPreferences preferences = getSharedPreferences("config", MODE_PRIVATE);
        final String store = preferences.getString("store", "");

        String managerMessageText = "";
        String mainMessageText = "";

        try {
            File managerFile = new File(this.getFilesDir(), store + ".txt");
            File universalFile = new File(this.getFilesDir(), "universal.txt");

            BufferedReader reader = new BufferedReader(new FileReader(managerFile));

            managerMessageText = reader.readLine();

            reader = new BufferedReader(new FileReader(universalFile));

            mainMessageText = reader.readLine();


        } catch (Exception e) {
            Log.e("Error opening file: ", e.getMessage());
        }


        images = db.rawQuery("SELECT " + databaseHelper.IMAGE + " FROM " + databaseHelper.TABLE_NAME + " where " + databaseHelper.LTO + " = 1", null);
        images.moveToFirst();

        while(!images.isAfterLast()) {
            imageList.add(BitmapFactory.decodeByteArray(images.getBlob(images.getColumnIndex(databaseHelper.IMAGE)), 0, images.getBlob(images.getColumnIndex(databaseHelper.IMAGE)).length ));
            images.moveToNext();
        }

        imageList.add(drawText(this, R.drawable.message_background, "Message from the manager: "));
        imageList.add(drawText(this, R.drawable.message_background, "Message from MidAm: "));
        slide = (ImageView) findViewById(R.id.imageView);
        Timer timer = new Timer();
        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                updateGUI();
            }}, 0, 5000);
    };



    private void updateGUI() {

        handler.post(runnable);
    }


}

非常感谢!

Answer 1

我实际上已经弄清楚了这个问题。以下行中存在一些运算顺序/括号问题:

int x = ((bitmap.getWidth() - outline.width() / 2));
    int y = ((bitmap.getWidth() + outline.height() / 2));

应该阅读:

int x = ((bitmap.getWidth() - outline.width() )) / 2;
    int y = ((bitmap.getWidth() + outline.height() )) / 2;